Vaginal administration is a promising route for the local treatment of infectious vaginal diseases since it can bypass the first-pass metabolism, drug interactions, and adverse effects. However, the commercial products currently available for topical vulvovaginal treatment have low acceptability and do not adequately explore this route.
Carbohydrate Polymers 261 (2021) 117919 Contents lists available at ScienceDirect Carbohydrate Polymers journal homepage: www.elsevier.com/locate/carbpol Chitosan-based systems aimed at local application for vaginal infections Victor Hugo Sousa Araujo *, Maurício Palmeira Chaves de Souza, Gabriela Corrˆea Carvalho, Jonatas Lobato Duarte, Marlus Chorilli ** School of Pharmaceutical Sciences, S˜ ao Paulo State University, Araraquara, SP, Brazil A R T I C L E I N F O A B S T R A C T Keywords: Chitosan Bacterial vaginosis Vulvovaginal candidiasis Trichomoniasis Vaginitis Vaginal administration is a promising route for the local treatment of infectious vaginal diseases since it can bypass the first-pass metabolism, drug interactions, and adverse effects However, the commercial products currently available for topical vulvovaginal treatment have low acceptability and not adequately explore this route Mucoadhesive systems can optimize the efficacy of drugs administered by this route to increase the retention time of the drug in the vaginal environment Several polymers are used to develop mucoadhesive systems, among them chitosan, a natural polymer that is highly biocompatible and technologically versatile Thus, the present review aimed to analyze the studies that used chitosan to develop mucoadhesive systems for the treatment of local vaginal infections These studies demonstrated that chitosan as a component of mucoadhesive drug delivery systems (DDS) is a promising device for the treatment of vaginal infectious diseases, due to the intrinsic antimicrobial activity of this biopolymer and because it does not interfere with the effec tiveness of the drugs used for the treatment Introduction Alternatives to oral administration have drawn the attention of the scientific community to the local treatment of infections Intravaginal administration for local effect avoids the first-pass metabolism, reduces adverse gastrointestinal effects, and is easy to apply (De Araújo Pereira & Bruschi, 2012; Deshpande, Rhodes, & Danish, 1992) Thus, adminis tration by this route is a promising alternative for the application of contraceptive drugs and for the local treatment of infectious diseases (Da Silva et al., 2014; De Araújo Pereira & Bruschi, 2012) In addition to reducing adverse effects and drug interactions, a vaginal application of therapeutic agents for the treatment of local in fections demonstrated, overall, comparable efficacy of oral administra tion (Palmeira-de-oliveira, Palmeira-de-oliveira, & Martinez-de-oliveira, 2015) However, some aspects must be consid ered for the development of systems for vaginal application, since this microenvironment must be preserved, considering the pH (≈ between 4.0 and 5.0), microbiota, as well as its cyclical changes (De Araújo Pereira & Bruschi, 2012; Srikrishna & Cardozo, 2013) Also, conven tional dosage forms for vaginal application are associated with discomfort and short drug retention time, which makes it necessary to develop mucoadhesive systems to optimize the acceptability of the therapy and its therapeutic efficacy (dos Santos et al., 2020; Palmeir a-De-Oliveira et al., 2015) Mucoadhesion is a form of bioadhesion based on mucusglycoproteins or mucous membranes (P R De Araújo et al., 2019; Johal, Garg, Rath, & Goyal, 2016) Natural polymers have been used to develop mucoadhesive vaginal drug-delivery systems, due to their biocompatibility and ability to remain in the vaginal mucosa, promoting the local and sustained release of the drug (Valenta, 2005) Chitosan is one such polymer because it has biocompatibility and antimicrobial properties, along with high adhesive mucus power, making it a promising candidate for the development of vaginal drug-delivery systems (Valenta, 2005) Thus, considering the mucoadhesive and antimicrobial properties of chitosan, as well as the advantages of vaginal application, the present study analyses the in fluence of this biopolymer on the development of delivery systems for vaginal application to treat local infections General aspects of chitosan Chitin is a structural polysaccharide present in fungi, insects, and marine crustaceans, formed by units of (1 → 4)-2-acetamido-2-deoxyβ-D-glucan (N-acetyl D-glucosamine) (Roberts, 1992) After deacetyla tion of chitin, many units of acetamido become amino units; if the * Corresponding author ** Corresponding author E-mail addresses: victorhunterhsa@hotmail.com (V.H.S Araujo), marlus.chorilli@unesp.br (M Chorilli) https://doi.org/10.1016/j.carbpol.2021.117919 Received 23 November 2020; Received in revised form March 2021; Accepted March 2021 Available online March 2021 0144-8617/© 2021 Elsevier Ltd This article is made available under the Elsevier license (http://www.elsevier.com/open-access/userlicense/1.0/) V.H.S Araujo et al Carbohydrate Polymers 261 (2021) 117919 percentage of deacetylation is superior to 50 % of all units, this new polymer is called chitosan Chitosan is formed by (1 → 4)-2-acet amido-2-deoxy-β-D-glucan (N-acetyl D-glucosamine) and (1 → 4)-2-amino-2-deoxy-β-D-glucan (d-glucosamine) units (Fig 1) It is a renewable material that is extremely available in nature, and it con tributes to reducing environmental pollution since its main source is the tailings from the shrimp and crab fishing industry (Campana-Filho et al., 2007; Jung & Zhao, 2011; Robert et al., 1992; Wang, Li, & Yao, 2011) This biopolymer has a wide application in the health sciences, as it has properties such as biocompatibility, biodegradability, and antimi crobial activity, and it is the second most available polysaccharide in nature (Frade et al., 2018; Nilsen-Nygaard, Strand, Vårum, Draget, & Nordgård, 2015; Shukla, Mishra, Arotiba, & Mamba, 2013; Victorelli, Calixto, Dos Santos Ramos, Bauab, & Chorilli, 2018; Zheng & Zhu, 2003) In other words, in addition to its diverse biological activity, chitosan is a unique biopolymer because it is abundant, cationic, low-toxic, non-immunogenic, and biodegradable (Felt, Buri, & Gurny, 1998; Fonseca-Santos & Chorilli, 2017) However, before using chitosan for developing drug delivery systems (DDS), it is essential to know some of its physicochemical properties and how these properties impact the technological and biofunctional char acteristics Much of its dispersion behavior is related to its polycationic nature in acidic aqueous media (L de S Soares et al., 2019) Another fundamental property is its degree of deacetylation (DD), which corre sponds to the percentage of amine groups concerning the acetamide groups present in the chain DD is proportional to its ability to present low charge density: the more deacetylated the chitosan, the greater its capacity to be protonated and the greater its ability to interact with negatively charged surfaces (Ferreira et al., 2020) The third funda mental property of chitosan is its molecular mass (Mw), which indicates the size of the polymeric chains Low Mw is useful for the production of systems while medium and high Mw are widely used in the production of microsystems (Ferreira et al., 2020; Sreekumar, Goycoolea, Moerschbacher, & Rivera-Rodriguez, 2018) Although chitosan has been widely applied in drug dosage form, its application depends on its dispersion (L de S Soares et al., 2019) However, the chitosan dispersibility mechanism is not yet completely clear Research suggests that dispersibility evolves the protonation of the groups and the chain length (De Souza et al., 2020; Ferreira et al., 2020; L de S Soares et al., 2019) The DD degree can affect mostly hydrophobicity, while molecular weight affects cytotoxicity, solubility, and degradation (Garg, Chauhan, Nagaich, & Jain, 2019) However, neither of these properties acts in isolation, and therefore, chitosan performance is a conjunction of these factors (Garg et al., 2019) Considering that chitosan is obtained by the deacetylation of chitin, chitosan chains in the same batch not exhibit the same degree of Mw and DD Deacetylation is not an accurate and complete process and it does not occur homogeneously The inhomogeneous deacetylation of chitosan compromises the uniformity of structures, which in turn affects the understanding of its impact on the properties of systems, such as mucoadhesion, charge density, solubility, and size (Brück, Slater, & Carney, 2010; Nwe, Furuike, & Tamura, 2010) On the other hand, synthetic polymers have strictly known structures, with reproducibility of synthesis and, consequently, predictable properties (Alexander, 2001; Neuse, 2008), placing chitosan at a disadvantage in relation to synthetic polymers However, chitosan has other characteristics that make it a promising polymer for the development of DDS, such as availability, renewability, low cost, versatility, biocompatibility, and biodegrad ability It is also important to highlight its versatile chemical nature, which enables a variety of covalent and ionic modifications, making it possible to extensively adjust the physicochemical, biological, and me chanical properties of chitosan-based devices (Mogocsanu, Grumezescu, Bejenaru, & Bejenaru, 2016; Vunain, Mishra, & Mamba, 2017) Thus, from a technological point of view, the ability to know and manipulate the molecular characteristics of chitosan to impact its physicochemical properties explains its wide applicability in DDS Another important point to be considered, besides its great technological versatility, is its mucoadhesiveness and antimicrobial activity Thus, chitosan is an important device to compose DDS for the local treatment of infectious vaginal diseases (De Lyra et al., 2007; dos Santos Ramos et al., 2019; Mohammed, Syeda, Wasan, & Wasan, 2017) Chitosan is able to remain adhered to mucous surfaces, thus providing a controlled release over a long period until complete degradation (De Souza et al., 2020) The best-accepted theory for the adhesion between chitosan and mucin is the product of the attraction forces resulting from hydrogen bonds, hydrophobic forces, and espe cially the coulombic forces that are established between the positive charges of chitosan and the negative charges of mucin (Fig 2), which is negatively charged due to the presence of sialic acids and ester sulfates (Sogias, Williams, & Khutoryanskiy, 2008) Mucoadhesion and mucopenetration The vaginal epithelium is structured in multiple layers (Hewitt, Couse, & Korach, 2000) ordered from deepest to most superficial: the mitotically active basal layer (“stratum basale”), the super basal layer, and a superficial layer of flattened cornified cells, stratum corneum (SC) (D J Anderson, Marathe, & Pudney, 2014) As SC is the superficial layer, it is the principal and first point of contact with pathogens and substances in the vagina SC is a specialized structure that has a deposit of glycogen and low keratinization (D J Anderson et al., 2014; Nilsson, Risberg, & Heimer, 1995) It is formed by flattened, thin-layered lipid cells, with no nuclei or organelles, slightly connected (Bragulla & Homberger, 2009) Due to the thin lipid layer, it is possible to transfer water to the deeper layers (epidermal epithelium) (D J Anderson et al., 2014) Other substances present in the mucus composition of the SC are mucin and syaloglycans (Bansil & Turner, 2018) The vaginal aspect must also be considered (D J Anderson et al., 2014; Rampersaud, Randis, & Ratner, 2012; Roggero, P´ erez, Bottasso, Besedovsky, & Del Rey, 2009) The presence of the Lactobacillus sp in the vagina can metabolize the glycogen present in SC and turn it into lactic acid, which reduces the pH of the SC surface (Mirmonsef et al., 2012) The mucus can become more viscous and negatively charged in acid conditions, which is an important factor for the adhesion of positively charged molecules like chitosan (Bansil, Celli, Hardcastle, & Turner, 2013) Although a more viscous mucous layer can be advantageous for adhesion, it is not interesting for the spread and penetration of the drug A high viscosity regime hinders the deeper drug penetration by the drug delivery system entrapped in the mucus, and therefore, in these condi tions, mucopenetration can be an interesting strategy The mucoadhesion can also be achieved by strong interaction with mucin Mucin has a variable Mw range (2–20 million g/mol), and it is one of the main components of mucus (Bansil & Turner, 2018; Bansil et al., 2013; Sogias et al., 2008) When in a state of gelation, mucin tends to form large aggregates due to hydrophobic interactions, hydrogen bonding, and disulfide bonds between cysteine residues, and it can also be negatively charged due to the presence of sialic acids and ester sul fates that are totally ionized at pH > 2.6 (Sogias et al., 2008) However, electrical charge, composition, size, and shape are important factors to be considered when developing DDS that interact Fig Schematic representation of Chitosan V.H.S Araujo et al Carbohydrate Polymers 261 (2021) 117919 Fig General model for the interaction between chitosan and mucin Toxicity and intrinsic antimicrobial action of chitosan with biological barriers, like the mucosa (Collado-Gonz´ alez, Gonz´ alez Espinosa, & Goycoolea, 2019; De Souza et al., 2020; Ferreira et al., 2020) Systems that are able to interact with the mucous layer and remain attached to it are called mucoadhesives, and in the case of chi tosan, the main mechanism involves the interaction between the opposite charge between mucus (-) and chitosan (+)(Collado-Gonz´ alez et al., 2019) Mucopenetration is a property that confers to the systems the ability to permeate the mucus layer reaching the epithelium (Lai, Wang, & Hanes, 2009) Active mucopenetration can be achieved by immobili zation of mucolytic enzymes on a system surface, and this strategy can avoid the entrapment of the drug delivery in the mucus (Lai et al., 2009; ădler, 2020) Passive mucopenetration is achieved Taipaleenmă aki & Sta through the use of negatively or neutrally charged surface DDS, which can promote penetration to the deepest mucosal layer, although in direct contact with SC, these systems must be able to change the charge to positive (Netsomboon & Bernkop-schnürch, 2016a, 2016b) Positively charged surfaces have more cellular uptake than negatively charged ăhlich, 2012) surfaces (Fro In this context, native and unmodified chitosan is not considered a mucopenetrating polysaccharide, but chitosan can disrupt intercellular junctions, increasing epithelium permeability and improving the ădler, 2020, Vllasaliu bioavailability of the drug (Taipaleenmă aki & Sta et al., 2010) However, this mechanism is not completely clear, but still, chitosan has been proposed as a transmembrane drug delivery system (Smith, Wood, & Dornish, 2004) Mucopenetration and mucoadhesion have advantages and limita tions in drug delivery systems An advantage of mucoadhesive DDS is that the particles not disrupt the mucus structure, and a limitation for DDS intended for systemic activity is that the particles interact with mucin and cannot reach the deeper layers Mucopenetrative DDS, in turn, facilitate the diffusion of the particle and allow it to reach the SC, although it can cause temporary or permanent damage to the mucus layer and reach the SC (Netsomboon & Bernkop-schnürch, 2016a, 2016b) However, the systems composed of chitosan demonstrate a mucoadhesive property, as previously mentioned, due to its cationic character, and this property is also related to its interaction with mucin, which is a complex phenomenon involving electrostatic interactions, hydrogen bonds, and hydrophobic effects (Sogias et al., 2008) This mucoadhesive property of chitosan is ideal for the local treatment of vaginal infections, since it aims to increase the residence time of the drug in the region, avoiding systematic action As previously mentioned, chitosan is widely used to develop DDS due to its high biocompatibility, among other aspects As pointed out by the review of Kean and Thanou (Kean & Thanou, 2010), its biocompatibility would vary according to the molecular modifications of this biopolymer, making it more or less toxic Zubareva and colleagues (Zubareva, Shagdarova, Varlamov, Kashirina, & Svirshchevskaya, 2017) evaluated the penetration and toxicity of chitosan and derivatives in different cell lines (HEK-293; HaCaT; MiaPaCa-2; A431; COLO-357; RAW264 7; J774) in vitro The authors observed that chitosan and its derivatives did not cause significant cytotoxicity, except for highly quaternized de rivatives, which promoted interruption of the cell cycle and production of ROS However, there is little information about the biocompatibility of this biopolymer after application on mucous membranes, especially on the vaginal mucosa, except for those present in the gastrointestinal tract (Kean & Thanou, 2010) The lack of studies on the toxicity to vaginal mucosa caused by polymers for local application was also pointed out by dos Santos and collaborators (dos Santos et al., 2020), who highlighted the need for more information related to toxicity However, Pradines et al (Pradines et al., 2015) observed in ex vivo studies of porcine vaginal mucosa that nanoparticles coated with chitosan and thiolated chitosan did not demonstrate significant changes in histopathological analyses, suggesting the absence of toxicity In addition, in the study by Calvo and collaborators (Calvo et al., 2019), films composed entirely of chitosan demonstrated a reduction in the in vitro viability of fibroblasts up to 54 % The authors reported that previous studies had indicated the cyto static potential of chitosan, which may have impacted their results (Calvo et al., 2019; Shahabeddin et al., 1991) In addition to its biocompatibility, the intrinsic antimicrobial activity of chitosan is another characteristic that several studies have explored Chitosan is vastly applied as a natural adjuvant preservative due to its antimicrobial action (Jennings & Bumgardner, 2016) In some studies, chitosan is applied as a preservative agent to pharmaceutical products, food, and beverages (Duan et al., 2019; Raafat & Sahl, 2009; Singh & Campus, 2018) The antibacterial effect of chitosan is more effective in gramnegative than gram-positive bacteria, with its antifungal effect being effective against filamentous fungi and yeasts (Dutta, 2016; Kim, 2010; Raafat & Sahl, 2009) However, the antimicrobial effect of chitosan is dose-dependent, and in some studies it was observed that after its sep aration or removal from the proximity of the bacteria, some resistant V.H.S Araujo et al Carbohydrate Polymers 261 (2021) 117919 bacteria could grow back, being a possible source of selection of resis tant bacteria (Jarry et al., 2001) Concerning the mechanism of action of chitosan, although not clearly defined and elucidated, three hypotheses have been considered: I) interaction with surface constituents of the cell, II) interaction with intracellular targets, and III) antimetabolite action (Goy, De Britto, & Assis, 2009; Raafat & Sahl, 2009) The first mechanism is the interaction of chitosan with cellular sur face constituents This ability of chitosan is considered by many re searchers as a membrane-disturbing compound (Chan, Mao, & Leong, 2001; Dodane, Khan, & Merwin, 1999; Fang, Chan, Mao, & Leong, 2001) because the positively charged chitosan can disrupt the cellular mem brane of the bacteria (Friedman et al., 2013; Kim, 2010; Shahidi, Arachchi, & Jeon, 1999) Polycationic chitosan can interact with the electronegative cell surface and alter the cell permeability (Raafat & Sahl, 2009; Shahidi et al., 1999) In a study conducted by Beck, Yildirim-Aksoy, Shoemaker, Fuller, and Peatman (2019), a greater de gree of adsorption of cationic ions by chitosan at high concentrations was observed on the cell surface The antibacterial mechanism of chi tosan at high concentrations appears to be binding of the cationic- charged chitosan molecules onto the microbial cell surface leading to bacteria–chitosan agglutination At large amounts of chitosan, poly cationic chitosan molecules interact with the predominantly anionic cell wall components of bacteria and link the bacteria together to form chitosan–bacteria electrostatic complexes under acidic conditions, and their interactions depend directly on the charge density of chitosan (Rinaudo, 2006) In addition, at pH > 7.0, chitosan loses its antimicrobial activity This can occur because deprotonation causes chitosan to lose its ability to electrostatically bind to the negatively charged cell membrane (Atay, 2019; Sudarshan, Hoover, & Knorr, 1992) Additionally, at this pH, chitosan is not water-soluble, and its chains interact with the cell sur face Another important hypothesis is that the antibacterial activity is related not only to the amino group and its protonation but also to other functional groups (methyl, and OH) It plays an important role in this complex mechanism (Kim, 2013) Chitosan at high DD is more effective than at low DD, reinforcing the protonation hypothesis (Raafat & Sahl, 2009) Another proposed mechanism is the binding of chitosan and DNA (Andres, Giraud, Gerente, & Le Cloirec, 2007) Linkage to DNA leads to the inhibition of the mRNA and protein synthesis, but before interacting with the genetic material, chitosan needs to enter the cell On this point, the hypothesis is interestingly problematic, but researchers not believe that chitosan can penetrate the bacterial double layer and then penetrate the nuclei of the microorganisms (Goy et al., 2009; Raafat & Sahl, 2009) However, in another study conducted under a confocal microscope, oligomers of chitosan were observed inside E.coli when this bacteria was exposed to chitosan in different conditions (Fei Liu, Lin Guan, Zhi Yang, Li, & De Yao, 2001) In this way, we believe that the Mw of chitosan and its degree of polymerization, together with the DD de gree, are fundamental for this approach Low Mw chitosan may have greater penetrative capacity than high Mw chitosan, and therefore, the use of chitooligosacid may be an option for this type of approach The third mechanism proposed is based on a known physicochemical property of chitosan, the metal chelation The mechanism of the com plex formation depends on the pH and DD degree, because in acid pH and high DD chitosan is more efficient (Sobahi, Abdelaal, & Makki, 2014) The chelating capacity of chitosan is important when it comes to its antimicrobial effect (Goy et al., 2009) Chitosan can act as an antime tabolite, inhibiting the primary routes of bacterial nutrition, by complexation of the metals used in bacterial metabolism, preventing its absorption and cellular nutrition (Goy et al., 2009; Raafat & Sahl, 2009; Sudarshan et al., 1992) On the other hand, the deposition of chitosan on the bacterial surface may also create a physical barrier, which would prevent the passage of nutrients, not chelated and still having an anti metabolite and, consequently, antimicrobial effect (Goy et al., 2009; Raafat & Sahl, 2009; Sudarshan et al., 1992) These hypotheses are complementary and should not occur independently We suggest that this is a simultaneous, complex, and cooperative mechanism resulting in antimicrobial activity, as summarized in Fig Palmeira-de-Oliveira (A Palmeira-De-Oliveira et al., 2010) demon strated that chitosan’s antifungal activity occurs due to membrane damage, as a result of the interaction between the protonated amino groups and the negatively charged membrane proteins of the evaluated candida species This hypothesis is also discussed in the work of Albu querque et al (Alburquenque et al., 2010), who observed that the anti-candida activity of low Mw chitosan increases as the pH decreases, which may be related to the protonation of the amino groups Addi tionally, in order to assess whether the intrinsic chitosan activity varies by its presentation, Perinelli et al (Perinelli et al., 2018) evaluated in vitro the activity of chitosan in suspension and nanoparticles dispersed in HPMC gel, and observed no significant difference between the tested groups The hypothesis of membrane damage was also mentioned by Tavassoli and collaborators (Tavassoli, Imani, Tajik, Moradi, & Pour seyed, 2012), after observing chitosan’s anti-trichomonas activity Infectious vaginal diseases Infectious vaginal diseases are the greatest cause of demand for medical consultations among women, with more than 70 % of adult women having already looked for vaginal products for their treatment (Donders, 2007; R Palmeira-De-Oliveira et al., 2015, 2015) Although the associated mortality rates are low, the symptoms of vaginal in fections have a negative impact on women’s quality of life, affecting their sexual relationships and occupational aspects (dos Santos et al., 2020; Karasz & Anderson, 2003; Palmeira-De-Oliveira et al., 2015) The most common vaginal infections are caused by bacteria (bacterial vag inosis), fungi (vulvovaginal candidiasis), and protozoa (trichomoniasis) (Palmeira-De-Oliveira et al., 2015) Bacterial vaginosis (BV) is vaginitis promoted by changes in the vaginal microenvironment, where there is an increase in the number of anaerobes with a significant reduction in Lactobacilli, resulting in symptoms such as vaginal malodor, increased vaginal pH, and vaginal itching (Hay, 2017; Kenyon, Colebunders, & Crucitti, 2013) BV is the most common vaginitis among women of childbearing age, with prev alence rates ranging from 20 to 60 % (Bautista et al., 2016) However, despite the high prevalence, 50 % of BV cases are asymptomatic, leading to treatment neglect and underreporting of cases (Hay, 2014) Despite not having severe symptoms, BV increases the risk of other infections by simplex virus type, Trichomonas vaginalis, Neisseria gonorrhoeae, and Chlamydia trachomatis (Kenyon et al., 2013) Treatment options for BV rely on oral and topical administration of antibiotic agents with a cure rate between 80–90 % (Bradshaw et al., 2006; Coudray & Madhivanan, 2020) However, there is currently an increase in the number of recur rent cases of BV and species resistance to first-line treatment, making it necessary to search for new therapeutic alternatives (Cobos, Femia, & Vleugels, 2020; Coudray & Madhivanan, 2020) As the second leading cause of vaginitis, Vulvovaginal candidiasis (VVC) is also considered a global public health problem, whose inci dence differs among countries, from 12.1%57.3% (Gonỗalves et al., 2016) This pathology is characterized by the infectious process caused by the fungus of the genus Candida spp after disorders in the vaginal microenvironment caused by stress, hormonal variations, immunosup pression, diabetes, and antibiotics (Mason et al., 2012; Mtibaa et al., ´n-Romero, Sa ´nchez-Vega, & Tay, 2003; 2017; Ruiz-S´ anchez, Caldero Sangamithra, Verma, Sengottuvelu, & Sumathi, 2013) Among several species of Candida spp., the most frequently isolated in CVV samples is Candida albicans (dos Santos Ramos et al., 2016; Gonỗalves et al., 2016; Lee, Puumala, Robbins, & Cowen, 2020; Willems, Ahmed, Liu, Xu, & Peters, 2020) VVC causes nonspecific symptoms such as discharge, burning, irritation, erythema, itching, pain during sex, and dryness of the vaginal mucosa, so it can be confused with other vaginal diseases (M V.H.S Araujo et al Carbohydrate Polymers 261 (2021) 117919 Fig Mechanism of action of chitosan in bacteria, where the following processes occur: 1) electrostatic interaction between chitosan and cell membrane; 2) alteration of membrane permeation; 3) inhibition of replication machinery; 4) DNA damage caused by DNA binding and oxidative stress; 5) metal chelation; 6) efflux of cations Based on the work of Chandrasekaran, Kim, & Chun, 2020 gels, nano and microparticles, and other DDS, such as liquid crystals, tablets, and platelets R Anderson, Klink, & Cohrssen, 2004; Yano et al., 2019) Currently, VVC treatment is performed by the oral or topical routes, with azole agents being the most widely prescribed (Azie, Angulo, Dehn, & Sobel, 2020; Lee et al., 2020) However, in addition to a lack of treatment, there are in the literature reports of ineffective treatments due to the resistance of non-Candida albicans species to azoles, which can lead to complications such as pelvic abscess, pelvic inflammatory disease, abortion, and infertility (Gonỗalves et al., 2016; Jane, Iramiot, & Kalule, 2019; Lee et al., 2020; Marchaim, Lemanek, Bheemreddy, Kaye, & Sobel, 2012) It is, therefore, essential to research on new therapeutic strategies Trichomoniasis is a highly prevalent sexually transmitted vaginal infection caused by the protozoan Trichomonas vaginalis (Edwards, Burke, Smalley, & Hobbs, 2014; Mercer & Johnson, 2018) According to WHO, there were 24,848 new cases of trichomoniasis among adults in 2008, with greater prevalence among women than men (WORLD HEALTH ORGANIZATION, 2012) The main symptoms associated with this infection are vulvar irritation, dysuria, and vaginal discharge The treatment is based on nitroimidazoles, like metronidazole and tinidazole (Edwards et al., 2014; Rein, 2020) However, the literature has reported an increase in drug resistance to these drugs (Dunne, Dunn, Upcroft, O’Donoghue, & Upcroft, 2003; Kirkcaldy et al., 2012), pointing out the importance of research on new therapies for the treatment of this infection The oral therapy for the aforementioned diseases can promote pro nounced diverse effects, abandonment of therapy, and consequent aggravation of the infection It is also worth mentioning the growing number of infections caused by etiologic agents resistant to the current therapy (Palmeira-De-Oliveira et al., 2015) Thus, the use of topical therapy of mucoadhesive systems is an interesting alternative, since these systems increase the drug’s permanence time, overcoming the limitations of conventional pharmaceutical systems (dos Santos et al., 2020) 6.1 Gels The definitions of gels are becoming increasingly sophisticated, addressing the molecular (microscopic) and macroscopic points of view Hermans defines gels as a dispersed and coherent colloidal system of at least two components, which in turn exhibit solid-state mechanical properties where both the dispersion medium and the dispersed component extend continuously throughout the system (Hermans, 1949) Gels with an aqueous dispersed phase are classified as hydrogels (McClements, 2018) The formation of these chitosan gels/hydrogels is explored, espe cially by obtaining methods in which there are necessarily attractive interactions of formal charges (coulombic forces), hydrogen bonds, van der Walls forces, and hydrophobic interactions, such as polyelectrolytic complexation and ionotropic gelation, or even using chemical reactions such as the glutaraldehyde covalent crosslinker (De Souza et al., 2020; Ferreira et al., 2020) Although polyelectrolytic complexation and ion otropic gelation have been widely explored, several other methodolo gies are used to form these systems, making chitosan adaptable to the reality of several research and development laboratories, which may test chitosan as a possible drug delivery system under numerous patholog ical conditions To circumvent the side and toxic effects that conventional VVC treatment can cause by oral administration of antifungal drugs, formu lations using the free drug or a delivery system dispersed in chitosanbased gels have also been studied and shown to be very promising (Berretta et al., 2013; Campos et al., 2020; Rodero et al., 2018; Salmazi et al., 2015) In a study, methanolic extract of Mitracarpus frigidus (Willd Ex Reem Schult.) was incorporated into a chitosan-based gel for the treatment of VVC The formulation showed pseudoplastic behavior and became more viscous and elastic when the extract concentration was increased (intermolecular interactions indication) The in vivo analyses demonstrated that the formulation was better or similar to the reference drug (clotrimazole cream 10 mg/g), reducing not only the fungal load but also the mucosa inflammation, indicating that the developed formulation is an interesting alternative for the treatment of VVC DDS composed and coated with chitosan for the treatment of VI The use of chitosan to develop DDS to treat VI has been extensively explored in the literature Table shows the developed systems, such as V.H.S Araujo et al Carbohydrate Polymers 261 (2021) 117919 Table List of studies that used chitosan for the development of DDS for the local treatment of vaginal infections Pathology DDSa Molecular Weight Deacetylation Degree Reference Trichomoniasis Trichomoniasis Trichomoniasis Trichomoniasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Candidiasis Bacterial vaginosis Bacterial vaginosis Bacterial vaginosis Bacterial vaginosis Bacterial vaginosis Bacterial vaginosis Bacterial vaginosis Polymeric nanoparticles Hydrogel Nanoparticles Nanoparticles Nanoparticles Nanoparticles Nanoemulsion Gel Nanoemulsion Nanoparticles Nanoparticles Microcapsules Liquid crystal system Micro-platelets Liquid Crystal system Hydrogel Tablets Film Nanoparticles Hydrogel Complexes Gel Nanoparticles Nanoparticles Nanofibers Film Membrane Microspheres Tablets 20,000 g/mol 20,000 g/mol – 20,000 g/mol – LMWb – LMWb – – LMWb LMWb LMWb 250,000 g/mol LMWb 263 kDa HMWc 230 kDa – < 50 kDa LMWb – – 150 kDa 50− 190 kDa 310–375 kDa 185.3 kDa 50 kDa – – – – 92 % 75 % ≥ 75 % – – – – – – – 85 % – 83 % – 80.6 % – 90 % – – 75 % 97 % 75− 85% 75–85 % 83.6 % 75− 85% 77.6− 82.5% (Malli et al., 2018) (Malli et al., 2017) (Elmi et al., 2020) (Pradines et al., 2015) (Arumugam & Rajendran, 2020) (D E Araújo et al., 2020) (de Lima et al., 2020) (Campos et al., 2020) (dos Santos Ramos et al., 2019) (Amaral et al., 2019) (Costa et al., 2019) (Moreno et al., 2018) (Rodero et al., 2018) (Grisin et al., 2017) (Salmazi et al., 2015) (Ailincai et al., 2016) (Fitaihi et al., 2018) (Calvo et al., 2019) (Arias et al., 2020) (Perinelli et al., 2018) (Darwesh et al., 2018) (Berretta et al., 2013) (Cover et al., 2012) (Abruzzo et al., 2013) (Zupanˇciˇc, Potrˇc, Baumgartner, Kocbek, & Kristl, 2016) (Abilova et al., 2020) (Tentor et al., 2020) (Maestrelli et al., 2018) (Paczkowska et al., 2020) a b c Drug delivery system Low molecular weight High molecular weight (Campos et al., 2020) In another study, a hydrogel containing chitosan was used as a DDS for metronidazole to treat trichomoniasis (Malli et al., 2017) The formulation was able to control the release of metronidazole, with lower absorption through vaginal pig mucosa in comparison with the metro nidazole solution, which may decrease systemic side effects The hydrogel presented a similar anti-T vaginalis activity to that of the metronidazole solution These results show the potential of using chitosan-based hydrogel for the treatment of trichomoniasis, combining its features as an active pharmaceutical ingredient with its mucoadhe sive properties The results described by the mentioned studies agree with the work carried out by Perioli and collaborators (Perioli et al., 2008) in the previous decade Through the development of gels for vaginal applica tion containing metronidazole, the authors observed that the addition of chitosan and its derivative (5-methyl-pyrrolidinone-chitosan) to hydroxyethylcellulose gel allowed the system to remain in the target area without changing the vaginal pH and maintaining the microbiota On the other hand, the biomedical application of chitosan hydrogels can be limited by the toxicity presented by organic crosslinkers Considering this aspect and looking for new alternatives, Ailincai and collaborators (Ailincai et al., 2016) developed hydrogel containing 2-formylphenylboronic acid as a double cross-linking agent (one cova lent via imine formation and one physical via H bond, forming a chemo-physical chitosan network) and an antifungal agent The authors obtained different degrees of crosslinking by varying the molar ratio between amine and aldehyde, obtaining gels with elastic and rigid characteristics, with high resistance to deformations In addition, the systems demonstrated anti-candida activity against C.albicans and C glabrata, as well as metabolic inhibition of biofilms, which the re searchers attributed to the already described antifungal activity of boronic-imine compounds 6.2 Micro and nanoparticulate systems Chitosan can be used to obtain particles, which can be divided into micro and nanoparticles Microparticles are spherical particles measuring between and 1000 μm, and due to these characteristics, these systems not cross biological barriers, making them safe and ´llai-Szabo ´, Antal, Laki, & pharmacokinetically predictable (Lengyel, Ka Antal, 2019) Microparticles can be classified as microspheres composed of a homogeneous and solid polymer matrix, and microcapsules, which are core-shell microparticles whose core may be solid-liquid or even have hollow spaces Many types of biologically active molecules, indi vidually or simultaneously, can be inserted into a polymer matrix of microspheres or encapsulated inside the microcapsules, and thus such systems are considered extremely versatile (Ju & Chu, 2019) As a DDS, microparticles have improved the efficiency of VI treatments and have attracted researchers’ attention due to their ability to protect bioactive drugs, proteins, and small molecules from degradation and to achieve a controlled release rate of encapsulated drugs over hours or months, along with easy processing and mucoadhesion (Lengyel et al., 2019; McClements, 2018; Mishra, 2015; G Soares et al., 2012) Considering the properties that favor the application of micro systems, some studies have allied to the mucoadhesive properties of chitosan Maestrelli et al (Maestrelli, Jug, Cirri, Kosalec, & Mura, 2018) developed chitosan-alginate microspheres for the delivery of cefixime, which demonstrated good mucoadhesive ability without interfering with the activity of the drug Microscale systems are also promising for VVC treatment, as they present chitosan’s desirable characteristics like mucoadhesiveness, low toxicity, and good biocompatibility (Costa et al., 2019; Moreno et al., 2018) In this sense, the anti-fungal activity of chitosan microcapsules, synthesized by electrospraying and containing various plant extracts, was evaluated against conventionally used tablets containing the same extracts It was observed that in the in vitro test with simulated vaginal fluid, the microcapsules increased the extracts’ V.H.S Araujo et al Carbohydrate Polymers 261 (2021) 117919 solubility, thus increasing their bioavailability in the vaginal environ ment (Moreno et al., 2018) Nanoparticles (NPs) are one of the most widely studied DDS in recent decades, due to advances in the areas of physics and chemistry, which established a new area of science, "nanotechnology" NPs are defined as particles with at least one dimension ranging between and 100 nm in diameter that can alter their physicochemical properties in comparison with their original bulk material (Kataria et al., 2019) Research using NPs has been carried out extensively in the most diverse fields, such as agronomy, environmental sciences, chemistry, physics, biology, and in the development of DDS (Pathak et al., 2019) The physicochemical properties of a nanoparticle can change considering the biointerfaces resulting from the interactions between NP and biological systems This is an unpredictability factor associated with the system and it constitutes one of the greatest challenges for researchers aiming to develop nano medicines (Donahue, Acar, & Wilhelm, 2019) Thus, considering the advantages of the local application of mucoadhesive nanosystems, the incorporation of drugs in nano structured systems composed of chitosan for the treatment of BV has been explored by some research groups Cover and collaborators (Cover, Lai-Yuen, Parsons, & Kumar, 2012) developed chitosan nanoparticles for vaginal doxycycline application The medium-sized nanoparticles of 280 nm and with 56 % ± 10 % of encapsulated drug promoted a sig nificant reduction in the viability of E.coli, as well as the cytotoxicity related to the drug, indicating the potential of chitosan to increase the biocompatibility of drugs Similarly, the use of chitosan nanoparticles for VVC treatment has been shown to be a promising alternative Ionotropic gelation synthesis is the most broadly used method, and the murine model, mainly in fe male BALB/C mice, is the most suitable for in vivo evaluation of the promising nanostructured systems for VVC treatment (Amaral et al., 2019; D E Araújo et al., 2020; Arumugam & Rajendran, 2020; Costa et al., 2019) Among these works, Arumugam and Rajendran (Arumu gam & Rajendran, 2020) developed chitosan nanoparticles for Callo phycin A delivery, and in vitro tests demonstrated that the system optimized drug activity in all clinical isolates ((2-azole resistant; 2-azole sensitive and 1standard strain (NCCPF) A similar result was found in in vivo experiments, which in turn suggests the synergistic effect of chito san nanoparticles and the drug Such studies corroborate the findings of Amaral et.al (Amaral et al., 2019), who observed that chitosan nano particles also increased the therapeutic efficacy of miconazole in vivo (Amaral et al., 2019) Besides polymeric nanoparticles, the use of chi tosan for the coating of nanoemulsions for vaginal application was also a matter of study, demonstrating its ability to increase the mucoadhesion of this system and to optimize the efficacy of the incorporated drugs (Amaral et al., 2019; D E Araújo et al., 2020; Arumugam & Rajendran, 2020; Costa et al., 2019; de Lima et al., 2020) Similar to previous studies, the use of chitosan in pharmaceutical formulations can be used to develop mucoadhesive agents to treat trichomoniasis and as a pharmaceutically active ingredient (Elmi et al., 2020; Malli, Bories, Bourge, Loiseau, & Bouchemal, 2018; Pradines et al., 2015) Malli et al showed that the possible mechanism of action of chitosan-coated nanoparticles could be by morphological alterations, with pits on the parasite membrane, resulting in intracellular leaking and consequently death (Malli et al., 2018) liquid crystals, tablets, platelets, and films Liquid crystals are substances that flow like a liquid but have a de gree of ordering between their molecules (Araujo et al., 2020; Chorilli et al., 2009; Mezzenga et al., 2019; Victorelli, Calixto, dos Santos, Buzz´ a, & Chorilli, 2021) Composed of amphiphilic molecules, they have a high mucoadhesive capacity system depending on their composition, and thus, some studies have used chitosan to increase their mucoadhesive potential for vaginal application and, consequently, increase the effec tiveness against infections in this microenvironment Curcumin is a natural compound that has anti-candida activity However, despite its antimicrobial potential, its lipophilic characteristic makes it impossible to properly explore its clinical application Thus, considering the anti-candida potential of curcumin and the mucoadhesion aggregated by liquid crystals composed of chitosan, studies have used this system to evaluate its potential against VVC (Rodero et al., 2018; Salmazi et al., 2015) Both studies demonstrated a high mucoadhesive potential of liquid crystalline systems, showing efficiency even greater than flu conazole in vivo (Rodero et al., 2018), which can be related to the in crease in the biomolecule’s permanence time in the vaginal environment On the other hand, Calvo and collaborators (Calvo et al., 2019) suggested that the optimization of the in vitro activity of ticona zole chitosan films was due to the amorphous state presented by the drug in the developed matrix Similarly, to increase the therapeutic efficacy of natural substances, Paczkowska and collaborators (Paczkowska et al., 2020) developed tablets for incorporating lyophilized extract of Chelidonium majus In porcine vaginal mucosa, the authors observed mucoadhesive power, and in vitro studies demonstrated anti-S.aureus, S.epidermidis, E.faecalis, S pyogenes, E.coli, P.aeruginosa activity, however smaller than that of the free extract, attributed to the release time Another point to be considered is the antimicrobial activity of chi tosan, which allows therapeutic synergism (Grisin et al., 2017) Such synergistic activity was suggested by Grisim and collaborators (Grisin et al., 2017), in which chitosan micro-platelets containing amphotericin B significantly increased the drug activity, decreasing IC50 and MIC90 (4.5 and 4.8 times), which also corroborates with in vivo studies The combination of chitosan with other mucoadhesive agents has also been the subject of studies for the development of DDS for vaginal application Abruzzo and collaborators (Abruzzo et al., 2013) evaluated the influence of incorporating chlorhexidine digluconate on alginate and chitosan complexes, which in turn demonstrated mucoadhesiviness with optimization of the therapeutic effect Similarly, in order to explore the mucoadhesive potential of alginate and chitosan, Tentor and collabo rators (Tentor et al., 2020) developed a membrane for incorporating metronidazole In vitro studies showed that the developed system is suitable for vaginal application, with high mucoadhesion and resistance to vaginal fluid In addition, the authors noted that the membrane did not alter the drug’s effectiveness against Staphylococcus aureus and Gardnerella vaginalis without promoting significant cytotoxic effects on the cervix epithelial cell line The researchers also indicated that the combination of chitosan with other polymers increases the cyto compatibility of this biopolymer (Calvo et al., 2019; Shahabeddin et al., 1991) The mucoadhesive property of the association of chitosan and another polymer (poly(2-ethyl-2-oxazoline)) was also evaluated in the study of Abilova and collaborators (Abilova et al., 2020) for developing films containing ciprofloxacin for vaginal application By means of ex vivo studies, the authors observed that all developed systems had mucoadhesive potential, but mucoadhesion proved to be inversely proportional to the increase in the proportion of poly (2-ethyl-2- oxazoline), suggesting that the mucoadhesiveness of these systems depended on the presence of chitosan The mucoadhesive potential of chitosan was also highlighted by the study of Fitaihi and collaborators (Fitaihi, Aleanizy, Elsamaligy, Mahmoud, & Bayomi, 2018), who developed chitosan tablets and other mucoadhesive polymers for the dispersion of fluconazole The scientists demonstrated that chitosan had 6.3 Other DDS Chitosan can interact with many polyanionic, natural, and synthetic polymers, such as DNA, alginates, pectins, xanthan, glucosaminogly cans, carboxymethylcellulose and gelatin, poly(lactic-co-glycolic acid), forming polyelectrolytic complexes These complexes may have desir able properties for the development of materials (Ciro, Rojas, Alhajj, Carabali, & Salamanca, 2020; Darwesh, Aldawsari, & Badr-Eldin, 2018) Based on these properties, different studies have used this biopolymer to increase the biocompatibility and mucoadhesion of other DDS, such as V.H.S Araujo et al Carbohydrate Polymers 261 (2021) 117919 an impact on the physical characteristics of the gel, with gels prepared with higher concentrations of chitosan demonstrating greater mucoadhesion Declaration of Competing Interest General aspects and future perspectives Acknowledgments As observed in the reviews by Santos et al and Palmeira-de-Oliveira et al., the development of mucoadhesive systems for vaginal application is a promising alternative for the treatment of infectious vaginal dis eases, since they can increase the residence time of the drugs in the vaginal environment, promoting an increase in therapeutic efficacy and greater comfort of use than the pharmaceutical products available for this route of administration Few studies compared the physicochemical and biological parame ters of the mucoadhesive system with chitosan and the same system without this biopolymer, which in turn compromises the clearer assessment of the influence of chitosan on the final properties of the developed systems However, it was observed that the systems composed of chitosan described in the present study had high mucoadhesive potential in ex vivo and in vivo models As shown in Table 1, there is a predominance of a degree of deacetylation of ≥75 %, indicating that such characteristic is preferable for the development of mucoadhesive systems intended for vaginal application It is estimated that the use of chitosan with these characteristics corroborates previous reports, since chitosan with a higher degree of deacetylation has greater mucoadhesive properties (Bonferoni et al., 2006; Henriksen, Green, Smart, Smistad, & Karlsen, 1996; Kumar, Vimal, & Kumar, 2016) The increase in mucoadhesion is proportional to the increase in the degree of deacetylation since this process increases the number of free and posi tively charged amino groups, favoring the interaction with the nega tively charged sialic acid of the mucous layer (Kumar et al., 2016; ´pez, & Grenha, 2012) Another important char Rodrigues, Dionísio, Lo acteristic to be evaluated is the molecular weight of chitosan, for which different studies demonstrated that high molecular weight chitosan has greater mucoadhesive capacity due to the deeper interpenetration of the polymer and mucus chains favored by the chain length (Khutoryanskiy, 2011; Kumar et al., 2016; Sandri et al., 2012) In relation to the systems, a significant diversity was observed, with emphasis on gels, micro, and nanoparticles, which reinforces the versatility of this biopolymer It was also observed that a significant number of studies used other mucoadhesive polymers in order to opti mize this characteristic of the systems, which can offer an important alternative to optimize the mucoadhesion promoted by chitosan As for its biological influence, few studies have reported references and assessments of the anti-microbial and anti-inflammatory activity isolated from chitosan, which in turn can offer a synergistic potential to the therapy under study In addition, despite its biocompatibility being widely described, few studies have evaluated the biocompatibility of the systems in vivo and in vitro, which may hinder their future commer cialization Regarding the drug under study, a greater number of works used these systems to deliver drugs already marketed to increase their effectiveness and reduce the toxicity associated with them The capacity of these systems to disperse molecules of natural origin has also been observed, making it possible to explore their potential for the treatment of VI In general, by analyzing the studies described in the present work, we observed that chitosan is a promising adjuvant to be used for the development of mucoadhesive systems for vaginal application and local treatment of VI It is worth noting that chitosan can be associated with other mucoadhesive polymers, making it possible to explore the mucoadhesiveness of both However, there is a need for studies in search of a better understanding of the interaction of chitosan with etiologic agents and studies that demonstrate the biocompatibility of the devel oped system, making them eligible for commercialization ˜o de Aperfeicoamento de This work was supported by the Coordenaca Pessoal de Nível Superior – Brasil (CAPES) [Finance Code001] and ˜o de Amparo a ` Pesquisa Estado de S˜ Fundaca ao Paulo – Brasil (FAPESP), numbers 2019/10261-2 and 2019/25125-7 The authors report no declarations of interest References Abilova, G K., Kaldybekov, D B., Irmukhametova, G S., Kazybayeva, D S., Iskakbayeva, Z A., Kudaibergenov, S E., et al (2020) Chitosan/poly(2-ethyl-2oxazoline) films with ciprofloxacin for application in vaginal drug delivery Materials, 13(7) https://doi.org/10.3390/ma13071709 Abruzzo, A., Bigucci, F., Cerchiara, T., Saladini, B., Gallucci, M C., Cruciani, F., … Luppi, B (2013) Chitosan/alginate complexes for vaginal delivery of chlorhexidine digluconate Carbohydrate Polymers, 91(2), 651–658 https://doi.org/10.1016/j carbpol.2012.08.074 Ailincai, D., Marin, L., Morariu, S., Mares, M., Bostanaru, A C., Pinteala, M., … Barboiu, M (2016) Dual crosslinked iminoboronate-chitosan hydrogels with strong antifungal activity against Candida planktonic yeasts and biofilms Carbohydrate Polymers, 152, 306–316 https://doi.org/10.1016/j.carbpol.2016.07.007 Alburquenque, C., Bucarey, S A., Neira-Carrillo, A., Urza, B., Hermosilla, G., & Tapia, C V (2010) Antifungal activity of low molecular weight chitosan against clinical isolates of Candida spp Medical Mycology, 48(8), 1018–1023 https://doi org/10.3109/13693786.2010.486412 Alexander, C (2001) Synthetic polymer systems in drug delivery Expert Opinion on Emerging Drugs, 6(2), 345–363 Amaral, A C., Saavedra, P H V., Oliveira Souza, A C., de Melo, M T., Tedesco, A C., Morais, P C., … Bocca, A L (2019) Miconazole loaded chitosan-based nanoparticles for local treatment of vulvovaginal candidiasis fungal infections Colloids and Surfaces B, Biointerfaces, 174(October 2018), 409–415 https://doi.org/ 10.1016/j.colsurfb.2018.11.048 Anderson, D J., Marathe, J., & Pudney, J (2014) The structure of the human vaginal stratum corneum and its role in immune defense American Journal of Reproductive Immunology, 71(6), 618–623 Anderson, M R., Klink, K., & Cohrssen, A (2004) Evaluation of vaginal complaints Jama, 291(11), 1368–1379 Andres, Y., Giraud, L., Gerente, C., & Le Cloirec, P (2007) Antibacterial effects of chitosan powder: Mechanisms of action Environmental Technology, 28(12), 1357–1363 Araújo, D E., de Oliveira, A A., dos Santos Cabral, M., Costa, A F., Silva, B C., Carmo Silva, L., … Pereira, M (2020) Investigation of thiosemicarbazide free or within chitosan nanoparticles in a murine model of vulvovaginal candidiasis Brazilian Journal of Microbiology, 1–9 Araújo, P R D., Maria, G., Calixto, F., Cristiane, I., Henrique, L., Zago, D P., … Chorilli, M (2019) Mucoadhesive in situ gelling liquid crystalline precursor system to improve the vaginal administration of drugs AAPS PharmSciTech, 20(225), 1–12 https://doi.org/10.1208/s12249-019-1439-3 Araujo, V H S., Duarte, J L., Carvalho, G C., Silvestre, A L P., Fonseca-Santos, B., Marena, G D., … Chorilli, M (2020) Nanosystems against candidiasis: a review of studies performed over the last two decades Critical Reviews in Microbiology, 0(0), 1–40 https://doi.org/10.1080/1040841X.2020.1803208 Arias, L S., Pessan, J P., de Souza Neto, F N., Lima, B H R., de Camargo, E R., Ramage, G., … Monteiro, D R (2020) Novel nanocarrier of miconazole based on chitosan-coated iron oxide nanoparticles as a nanotherapy to fight Candida biofilms Colloids and Surfaces B, Biointerfaces, 192(February), 111080 https://doi.org/ 10.1016/j.colsurfb.2020.111080 Arumugam, G., & Rajendran, R (2020) Callophycin A loaded chitosan and spicules based nanocomposites as an alternative strategy to overcome vaginal candidiasis International Journal of Biological Macromolecules Atay, H Y (2019) Antibacterial activity of chitosan-based systems Functional chitosan (pp 457–489) Springer Azie, N., Angulo, D., Dehn, B., & Sobel, J D (2020) Oral Ibrexafungerp: An investigational agent for the treatment of vulvovaginal candidiasis Expert Opinion on Investigational Drugs, 1–8 https://doi.org/10.1080/13543784.2020.1791820 Bansil, R., & Turner, B S (2018) The biology of mucus: Composition, synthesis and organization Advanced Drug Delivery Reviews, 124, 3–15 Bansil, R., Celli, J P., Hardcastle, J M., & Turner, B S (2013) The influence of mucus microstructure and rheology in Helicobacter pylori infection Frontiers in Immunology, 4(OCT), 310 https://doi.org/10.3389/fimmu.2013.00310 Bautista, C T., Wurapa, E., Sateren, W B., Morris, S., Hollingsworth, B., & Sanchez, J L (2016) Bacterial vaginosis: A synthesis of the literature on etiology, prevalence, risk factors, and relationship with chlamydia and gonorrhea infections Military Medical Research https://doi.org/10.1186/s40779-016-0074-5 Beck, B H., Yildirim-Aksoy, M., Shoemaker, C A., Fuller, S A., & Peatman, E (2019) Antimicrobial activity of the biopolymer chitosan against Streptococcus iniae Journal of Fish Diseases, 42(3), 371–377 V.H.S Araujo et al Carbohydrate Polymers 261 (2021) 117919 Berretta, A A., de Castro, P A., Cavalheiro, A H., Fortes, V S., Bom, V P., Nascimento, A P., … Goldman, G H (2013) Evaluation of mucoadhesive gels with propolis (EPP-AF) in preclinical treatment of candidiasis vulvovaginal infection Evidence-based Complementary and Alternative Medicine, 2013 Bonferoni, M C., Giunchedi, P., Scalia, S., Rossi, S., Sandri, G., & Caramella, C (2006) Chitosan gels for the vaginal delivery of lactic acid: Relevance of formulation parameters to mucoadhesion and release mechanisms AAPS PharmSciTech https:// doi.org/10.1208/pt0704104 Bradshaw, C S., Morton, A N., Hocking, J., Garland, S M., Morris, M B., Moss, L M., … Fairley, C K (2006) High recurrence rates of bacterial vaginosis over the course of 12 months after oral metronidazole therapy and factors associated with recurrence The Journal of Infectious Diseases https://doi.org/10.1086/503780 Bragulla, H H., & Homberger, D G (2009) Structure and functions of keratin proteins in simple, stratified, keratinized and cornified epithelia Journal of Anatomy, 214(4), 516–559 Brück, W M., Slater, J W., & Carney, B F (2010) Chitin and chitosan from marine organisms Chitin, chitosan, oligosaccharides and their derivatives: Biological activities and applications (pp 11–19) Boca Raton: Taylor & Francis Calvo, N L., Svetaz, L A., Alvarez, V A., Quiroga, A D., Lamas, M C., & Leonardi, D (2019) Chitosan-hydroxypropyl methylcellulose tioconazole films: A promising alternative dosage form for the treatment of vaginal candidiasis International Journal of Pharmaceutics, 556 https://doi.org/10.1016/j.ijpharm.2018.12.011 Elsevier B.V Campana-Filho, S P., De Britto, D., Curti, E., Abreu, F R., Cardoso, M B., Battisti, M V., Lavall, R L (2007) Extraỗ ao, estrutura e propriedades de α e β-quitina Quimica Nova, 30(3), 644–650 Campos, L M., de Oliveira Lemos, A S., da Cruz, L F., de Freitas Araújo, M G., de Mello Botti, G C R., Júnior, J L R., et al (2020) Development and in vivo evaluation of chitosan-gel containing Mitracarpus frigidus methanolic extract for vulvovaginal candidiasis treatment Biomedecine & Pharmacotherapy, 130, Article 110609 Chan, V., Mao, H.-Q., & Leong, K W (2001) Chitosan-induced perturbation of dipalmitoyl-sn-glycero-3-phosphocholine membrane bilayer Langmuir, 17(12), 3749–3756 Chandrasekaran, M., Kim, K D., & Chun, S C (2020) Antibacterial activity of chitosan nanoparticles: A review Processes, 8(9), 1–21 https://doi.org/10.3390/PR8091173 Chorilli, M., Prestes, P S., Rigon, R B., Leonardi, G R., Chiavacci, L A., & Scarpa, M V (2009) Development of liquid-crystalline systems using silicon glycol copolymer and polyether functional siloxane Química Nova, 32(4), 1036–1040 https://doi org/10.1590/s0100-40422009000400035 Ciro, Y., Rojas, J., Alhajj, M J., Carabali, G A., & Salamanca, C H (2020) Production and characterization of chitosan–Polyanion nanoparticles by polyelectrolyte complexation assisted by high-intensity sonication for the modified release of methotrexate Pharmaceuticals, 13(1), 11 Cobos, G A., Femia, A., & Vleugels, R A (2020) Bacterial vaginosis: An update on diagnosis and treatment American Journal of Clinical Dermatology, 21(3), 339–353 https://doi.org/10.1007/s40257-020-00502-6 Collado-Gonz´ alez, M., Gonz´ alez Espinosa, Y., & Goycoolea, F M (2019) Interaction between chitosan and mucin: Fundamentals and applications Biomimetics, 4(2), 32 Costa, A F., Araujo, D E., Cabral, M S., Brito, I T., De Menezes Leite, L B., Pereira, M., et al (2019) Development, characterization, and in vitro-in vivo evaluation of polymeric nanoparticles containing miconazole and farnesol for treatment of vulvovaginal candidiasis Medical Mycology, 57(1), 52–62 https://doi.org/10.1093/ mmy/myx155 Coudray, M S., & Madhivanan, P (2020) Bacterial vaginosis—A brief synopsis of the literature European Journal of Obstetrics, Gynecology, and Reproductive Biology, 245, 143–148 https://doi.org/10.1016/j.ejogrb.2019.12.035 Cover, N F., Lai-Yuen, S., Parsons, A K., & Kumar, A (2012) Synergetic effects of doxycycline-loaded chitosan nanoparticles for improving drug delivery and efficacy International Journal of Nanomedicine, 7, 2411–2419 https://doi.org/10.2147/IJN S27328 Da Silva, P B., Ramos, M A D S., Bonif´ acio, B V., Negri, K M S., Sato, M R., Bauab, T M., et al (2014) Nanotechnological strategies for vaginal administration of drugs - A review Journal of Biomedical Nanotechnology, 10(9), 2218–2243 https://doi.org/10.1166/jbn.2014.1890 Darwesh, B., Aldawsari, H M., & Badr-Eldin, S M (2018) Optimized chitosan/anion polyelectrolyte complex based inserts for vaginal delivery of fluconazole: In vitro/in vivo evaluation Pharmaceutics, 10(4) https://doi.org/10.3390/ pharmaceutics10040227 De Araújo Pereira, R R., & Bruschi, M L (2012) Vaginal mucoadhesive drug delivery systems Drug Development and Industrial Pharmacy, 38(6), 643–652 https://doi.org/ 10.3109/03639045.2011.623355 de Lima, L., AS Ramos, M., Toledo, L G., de Rodero, C F., Hil´ ario, F., dos Santos, L C., … Bauab, T M (2020) Syngonanthus nitens (Bong.) ruhland derivatives loaded into a lipid nanoemulsion for enhanced antifungal activity against Candida parapsilosis Current Pharmaceutical Design, 26(14), 1556–1565 De Lyra, M A M., Soares-Sobrinho, J L., Brasileiro, M T., De La Roca, M F., Barraza, J A., Viana, O D S., et al (2007) Sistemas matriciais hidrofớlicos e mucoadesivos para liberaỗ ao controlada de f armacos Latin American Journal of Pharmacy De Souza, M P C., S´ abio, R M., Ribeiro, T D C., Dos Santos, A M., Meneguin, A B., & Chorilli, M (2020) Highlighting the impact of chitosan on the development of gastroretentive drug delivery systems International Journal of Biological Macromolecules, 159, 804–822 https://doi.org/10.1016/j.ijbiomac.2020.05.104 Deshpande, A A., Rhodes, C T., & Danish, M (1992) INTRAVAGINAL DRUG DELIVERY, 18, 1225–1279 Dodane, V., Khan, M A., & Merwin, J R (1999) Effect of chitosan on epithelial permeability and structure International Journal of Pharmaceutics, 182(1), 21–32 Donahue, N D., Acar, H., & Wilhelm, S (2019) Concepts of nanoparticle cellular uptake, intracellular trafficking, and kinetics in nanomedicine Advanced Drug Delivery Reviews, 143, 68–96 Donders, G G G (2007) Definition and classification of abnormal vaginal flora Best Practice & Research Clinical Obstetrics & Gynaecology https://doi.org/10.1016/j bpobgyn.2007.01.002 dos Santos, A M., Carvalho, S G., Araujo, V H S., Carvalho, G C., Gremi˜ ao, M P D., & Chorilli, M (2020) Recent advances in hydrogels as strategy for drug delivery intended to vaginal infections International Journal of Pharmaceutics https://doi org/10.1016/j.ijpharm.2020.119867 dos Santos Ramos, M A., Da Silva, P B., De Toledo, L G., Oda, F B., Da Silva, I C., Dos Santos, L C., et al (2019) Intravaginal delivery of Syngonanthus nitens (Bong.) Ruhland fraction based on a nanoemulsion system applied to vulvovaginal candidiasis treatment Journal of Biomedical Nanotechnology, 15(5), 1072–1089 dos Santos Ramos, M A., de Toledo, L G., Fioramonti Calixto, G M., Bonif´ acio, B V., de Freitas Araújo, M G., dos Santos, L C., … Bauab, T M (2016) Syngonanthus nitens Bong (Rhul.)-loaded nanostructured system for Vulvovaginal candidiasis treatment International Journal of Molecular Sciences https://doi.org/10.3390/ijms17081368 Duan, C., Meng, X., Meng, J., Khan, M I H., Dai, L., Khan, A., … Ni, Y (2019) Chitosan as a preservative for fruits and vegetables: A review on chemistry and antimicrobial properties Journal of Bioresources and Bioproducts, 4(1), 11–21 Dunne, R L., Dunn, L A., Upcroft, P., O’Donoghue, P J., & Upcroft, J A (2003) Drug resistance in the sexually transmitted protozoan Trichomonas vaginalis Cell Research, 13(4), 239–249 https://doi.org/10.1038/sj.cr.7290169 Dutta, P K (2016) Chitin and chitosan for regenerative medicine Springer Edwards, T., Burke, P., Smalley, H., & Hobbs, G (2014) Trichomonas vaginalis : Clinical relevance, pathogenicity and diagnosis Critical Reviews in Microbiology, 1–12 https://doi.org/10.3109/1040841X.2014.958050 Elmi, T., Rahimi Esboei, B., Sadeghi, F., Zamani, Z., Didehdar, M., Fakhar, M., … Tabatabaie, F (2020) In vitro antiprotozoal effects of nano-chitosan on plasmodium falciparum, Giardia lamblia and trichomonas vaginalis Acta Parasitologica , Article 0123456789 https://doi.org/10.1007/s11686-020-00255-6 Fang, N., Chan, V., Mao, H.-Q., & Leong, K W (2001) Interactions of phospholipid bilayer with chitosan: Effect of molecular weight and pH Biomacromolecules, 2(4), 1161–1168 Fei Liu, X., Lin Guan, Y., Zhi Yang, D., Li, Z., & De Yao, K (2001) Antibacterial action of chitosan and carboxymethylated chitosan Journal of Applied Polymer Science, 79(7), 1324–1335 Felt, O., Buri, P., & Gurny, R (1998) Chitosan: A unique polysaccharide for drug delivery Drug Development and Industrial Pharmacy, 24(11), 979–993 Ferreira, L M B., Dos Santos, A M., Boni, F I., Dos Santos, K C., Robusti, L M G., de Souza, M P C., et al (2020) Design of chitosan-based particle systems: A review of the physicochemical foundations for tailored properties Carbohydrate Polymers, Article 116968 Fitaihi, R A., Aleanizy, F S., Elsamaligy, S., Mahmoud, H A., & Bayomi, M A (2018) Role of chitosan on controlling the characteristics and antifungal activity of bioadhesive fluconazole vaginal tablets Journal of the Saudi Pharmaceutical Society, 26(2), 151–161 https://doi.org/10.1016/j.jsps.2017.12.016 Fonseca-Santos, B., & Chorilli, M (2017) An overview of carboxymethyl derivatives of chitosan: Their use as biomaterials and drug delivery systems Materials Science and Engineering C https://doi.org/10.1016/j.msec.2017.03.198 Frade, M L., de Annunzio, S R., Calixto, G M F., Victorelli, F D., Chorilli, M., & Fontana, C R (2018) Assessment of chitosan-based hydrogel and photodynamic inactivation against propionibacterium acnes Molecules https://doi.org/10.3390/ molecules23020473 Friedman, A J., Phan, J., Schairer, D O., Champer, J., Qin, M., Pirouz, A., … Kim, J (2013) Antimicrobial and anti-inflammatory activity of chitosan – Alginate nanoparticles : A targeted therapy for cutaneous pathogens The Journal of Investigative Dermatology, 133(5), 12311239 https://doi.org/10.1038/jid.2012.399 Fră ohlich, E (2012) The role of surface charge in cellular uptake and cytotoxicity of medical nanoparticles International Journal of Nanomedicine, 7, 5577 Garg, U., Chauhan, S., Nagaich, U., & Jain, N (2019) Current advances in chitosan nanoparticles based drug delivery and targeting Advanced Pharmaceutical Bulletin, (2), 195 Gonỗalves, B., Ferreira, C., Alves, C T., Henriques, M., Azeredo, J., & Silva, S (2016) Vulvovaginal candidiasis: Epidemiology, microbiology and risk factors Critical Reviews in Microbiology, 42(6), 905–927 https://doi.org/10.3109/ 1040841X.2015.1091805 Goy, R C., De Britto, D., & Assis, O B G (2009) A review of the antimicrobial activity of chitosan Polimeros, 19(3), 241–247 https://doi.org/10.1590/S010414282009000300013 Grisin, T., Bories, C., Bombardi, M., Loiseau, P M., Rouffiac, V., Solgadi, A., … Bouchemal, K (2017) Supramolecular chitosan micro-platelets synergistically enhance anti-Candida albicans activity of amphotericin B using an immunocompetent murine model Pharmaceutical Research, 34(5), 1067–1082 Hay, P (2014) Bacterial vaginosis Medicine (United Kingdom) https://doi.org/10.1016/ j.mpmed.2014.04.011 Hay, P (2017) Bacterial vaginosis F1000Research, 6, 2–6 https://doi.org/10.12688/ f1000research.11417.1 Henriksen, I., Green, K L., Smart, J D., Smistad, G., & Karlsen, J (1996) Bioadhesion of hydrated chitosans: An in vitro and in vivo study International Journal of Pharmaceutics https://doi.org/10.1016/S0378-5173(96)04776-X ´ HR Kruyt Hermans, P H (1949) Colloid science (pp 483–494) New York: Ed Hewitt, S C., Couse, J F., & Korach, K S (2000) Estrogen receptor transcription and transactivation Estrogen receptor knockout mice: What their phenotypes reveal about mechanisms of estrogen action Breast Cancer Research, 2(5), 1–8 V.H.S Araujo et al Carbohydrate Polymers 261 (2021) 117919 Jane, W J., Iramiot, J S., & Kalule, J B (2019) Prevalence and antifungal susceptibility patterns of Candida Isolated on CHROMagarTMCandida at a tertiary referral hospital, Eastern Uganda Microbiology Research Journal International, 1–6 Jarry, C., Chaput, C., Chenite, A., Renaud, M.–A., Buschmann, M., & Leroux, J.–C (2001) Effects of steam sterilization on thermogelling chitosan-based gels Journal of Biomedical Materials Research: An Official Journal of The Society for Biomaterials, The Japanese Society for Biomaterials, and The Australian Society for Biomaterials and the Korean Society for Biomaterials, 58(1), 127–135 Jennings, J A., & Bumgardner, J D (2016) Chitosan based biomaterials volume 1: Fundamentals Woodhead Publishing Johal, H S., Garg, T., Rath, G., & Goyal, A K (2016) Advanced topical drug delivery system for the management of vaginal candidiasis Drug Delivery https://doi.org/ 10.3109/10717544.2014.928760 Ju, X.-J., & Chu, L.-Y (2019) Lab-on-a-chip fabrication of polymeric microparticles for drug encapsulation and controlled release Microfluidics for pharmaceutical applications (pp 217–280) Elsevier Jung, J., & Zhao, Y (2011) Characteristics of deacetylation and depolymerization of $β $-chitin from jumbo squid (Dosidicus gigas) pens Carbohydrate Research, 346(13), 1876–1884 https://doi.org/10.1016/j.carres.2011.05.021 Karasz, A., & Anderson, M (2003) The vaginitis monologues: Women’s experiences of vaginal complaints in a primary care setting Social Science & Medicine https://doi org/10.1016/S0277-9536(02)00092-8 ˇ c´ Kataria, S., Jain, M., Rastogi, A., Zivˇ ak, M., Brestic, M., Liu, S., et al (2019) Role of nanoparticles on photosynthesis: Avenues and applications Nanomaterials in plants, algae and microorganisms (pp 103–127) Elsevier Kean, T., & Thanou, M (2010) Biodegradation, biodistribution and toxicity of chitosan Advanced Drug Delivery Reviews, 62(1), 3–11 https://doi.org/10.1016/j addr.2009.09.004 Kenyon, C., Colebunders, R., & Crucitti, T (2013) The global epidemiology of bacterial vaginosis: A systematic review American Journal of Obstetrics and Gynecology, 209 (6), 505–523 https://doi.org/10.1016/j.ajog.2013.05.006 Khutoryanskiy, V V (2011) Advances in mucoadhesion and mucoadhesive polymers Macromolecular Bioscience https://doi.org/10.1002/mabi.201000388 Kim, S.-K (2010) Chitin, chitosan, oligosaccharides and their derivatives: Biological activities and applications CRC Press Kim, S.-K (2013) Chitin and chitosan derivatives: Advances in drug discovery and developments CRC press Kirkcaldy, R D., Augostini, P., Asbel, L E., Bernstein, K T., Kerani, R P., Mettenbrink, C J., … Weinstock, H S (2012) Trichomonas vaginalis antimicrobial drug resistance in US cities, STD surveillance network, 2009–2010 Emerging Infectious Diseases, 18(6), 939–943 https://doi.org/10.3201/eid1806.111590 Kumar, A., Vimal, A., & Kumar, A (2016) Why Chitosan? From properties to perspective of mucosal drug delivery International Journal of Biological Macromolecules, 91, 615–622 https://doi.org/10.1016/j.ijbiomac.2016.05.054 Lai, S K., Wang, Y.-Y., & Hanes, J (2009) Mucus-penetrating nanoparticles for drug and gene delivery to mucosal tissues Advanced Drug Delivery Reviews, 61(2), 158–171 https://doi.org/10.1016/j.addr.2008.11.002 Lee, Y., Puumala, E., Robbins, N., & Cowen, L E (2020) Antifungal drug resistance: Molecular mechanisms in Candida albicans and beyond Chemical Reviews https:// doi.org/10.1021/acs.chemrev.0c00199 acs.chemrev.0c00199 Lengyel, M., K´ allai-Szab´ o, N., Antal, V., Laki, A J., & Antal, I (2019) Microparticles, microspheres, and microcapsules for advanced drug delivery Scientia Pharmaceutica, 87(3), 20 Maestrelli, F., Jug, M., Cirri, M., Kosalec, I., & Mura, P (2018) Characterization and microbiological evaluation of chitosan-alginate microspheres for ce fi xime vaginal administration Carbohydrate Polymers, 192(November 2017), 176–183 https://doi org/10.1016/j.carbpol.2018.03.054 Malli, S., Bories, C., Bourge, M., Loiseau, P M., & Bouchemal, K (2018) Surfacedependent endocytosis of poly(isobutylcyanoacrylate) nanoparticles by Trichomonas vaginalis International Journal of Pharmaceutics, 548(1), 276–287 https://doi.org/ 10.1016/j.ijpharm.2018.07.006 Malli, S., Bories, C., Pradines, B., Loiseau, P M., Ponchel, G., & Bouchemal, K (2017) In situ forming pluronic® F127/chitosan hydrogel limits metronidazole transmucosal absorption European Journal of Pharmaceutics and Biopharmaceutics, 112, 143–147 https://doi.org/10.1016/j.ejpb.2016.11.024 Marchaim, D., Lemanek, L., Bheemreddy, S., Kaye, K S., & Sobel, J D (2012) Fluconazole-resistant Candida albicans vulvovaginitis Obstetrics and Gynecology, 120 (6), 1407–1414 Mason, K L., Downward, J R E., Mason, K D., Falkowski, N R., Eaton, K A., Kao, J Y., … Huffnagle, G B (2012) Candida albicans and bacterial microbiota interactions in the cecum during recolonization following broad-spectrum antibiotic therapy Infection and Immunity, 80(10), 3371–3380 McClements, D J (2018) Advances in nanoparticle and microparticle delivery systems for increasing the dispersibility, stability, and bioactivity of phytochemicals Biotechnology Advances, (July)https://doi.org/10.1016/j.biotechadv.2018.08.004, 0–1 Mercer, F., & Johnson, P J (2018) Trichomonas vaginalis: Pathogenesis, symbiont interactions, and host cell immune responses Trends in Parasitology, 34(8), 683–693 https://doi.org/10.1016/j.pt.2018.05.006 Mezzenga, R., Seddon, J M., Drummond, C J., Boyd, B J., Schră oder-Turk, G E., & Sagalowicz, L (2019) Nature-inspired design and application of lipidic lyotropic liquid crystals Advanced Materials https://doi.org/10.1002/adma.201900818 Mirmonsef, P., Gilbert, D., Veazey, R S., Wang, J., Kendrick, S R., & Spear, G T (2012) A comparison of lower genital tract glycogen and lactic acid levels in women and macaques: Implications for HIV and SIV susceptibility AIDS Research and Human Retroviruses, 28(1), 76–81 Mishra, M (2015) Handbook of encapsulation and controlled release CRC press Mogocsanu, G D., Grumezescu, A M., Bejenaru, L E., & Bejenaru, C (2016) Natural and synthetic polymers for drug delivery and targeting Nanobiomaterials in drug delivery (pp 229–284) Elsevier Mohammed, M A., Syeda, J T M., Wasan, K M., & Wasan, E K (2017) An overview of chitosan nanoparticles and its application in non-parenteral drug delivery Pharmaceutics, 9(4) https://doi.org/10.3390/pharmaceutics9040053 Moreno, M A., G´ omez-Mascaraque, L G., Arias, M., Zampini, I C., Sayago, J E., Ramos, L L P., … Isla, M I (2018) Electrosprayed chitosan microcapsules as delivery vehicles for vaginal phytoformulations Carbohydrate Polymers, 201, 425–437 Mtibaa, L., Fakhfakh, N., Kallel, A., Belhadj, S., Belhaj Salah, N., Bada, N., et al (2017) Vulvovaginal candidiasis: Etiology, symptomatology and risk factors Journal de Mycologie Medicale, 27(2), 153–158 https://doi.org/10.1016/j mycmed.2017.01.003 Netsomboon, K., & Bernkop-schnürch, A (2016a) European Journal of Pharmaceutics and Biopharmaceutics Mucoadhesive vs Mucopenetrating particulate drug delivery European Journal of Pharmaceutics and Biopharmaceutics, 98, 76–89 https://doi.org/ 10.1016/j.ejpb.2015.11.003 Netsomboon, K., & Bernkop-Schnürch, A (2016b) Mucoadhesive vs Mucopenetrating particulate drug delivery European Journal of Pharmaceutics and Biopharmaceutics, 98, 76–89 Neuse, E W (2008) Synthetic polymers as drug-delivery vehicles in medicine Metalbased Drugs, 2008 Nilsen-Nygaard, J., Strand, S P., Vårum, K M., Draget, K I., & Nordgård, C T (2015) Chitosan: Gels and interfacial properties Polymers, 7(3), 552–579 Nilsson, K., Risberg, B., & Heimer, G (1995) The vaginal epithelium in the postmenopause—Cytology, histology and pH as methods of assessment Maturitas, 21(1), 51–56 Nwe, N., Furuike, T., & Tamura, H (2010) Chitin and chitosan from terrestrial organisms Chitin, Chitosan, Oligosaccharides and Their Derivatives: Biological Activities and Applications, 3–10 Paczkowska, M., Chanaj-Kaczmarek, J., Romaniuk-Drapała, A., Rubi´s, B., Szymanowska, D., Kobus-Cisowska, J., … Cielecka-Piontek, J (2020) Mucoadhesive chitosan delivery system with Chelidonii Herba Lyophilized extract as a promising strategy for vaginitis treatment Journal of Clinical Medicine, 9(4), 1208 https://doi org/10.3390/jcm9041208 Palmeira-de-oliveira, R., Palmeira-de-oliveira, A., & Martinez-de-oliveira, J (2015) New strategies for local treatment of vaginal infections Advanced Drug Delivery Reviews, 92, 105–122 https://doi.org/10.1016/j.addr.2015.06.008 Palmeira-De-Oliveira, A., Ribeiro, M P., Palmeira-De-Oliveira, R., Gaspar, C., Costa-DeOliveira, S., Correia, I J., et al (2010) Anti-Candida activity of a chitosan hydrogel: Mechanism of action and cytotoxicity profile Gynecologic and Obstetric Investigation, 70(4), 322–327 https://doi.org/10.1159/000314023 Palmeira-De-Oliveira, R., Duarte, P., Palmeira-De-Oliveira, A., Das Neves, J., Amaral, M H., Breitenfeld, L., et al (2015) Women’s experiences, preferences and perceptions regarding vaginal products: Results from a cross-sectional web-based survey in Portugal The European Journal of Contraception and Reproductive Health Care https://doi.org/10.3109/13625187.2014.980501 Pathak, J., Ahmed, H., Singh, D K., Pandey, A., Singh, S P., Sinha, R P., et al (2019) Recent developments in green synthesis of metal nanoparticles utilizing cyanobacterial cell factories Nanomaterials in plants, algae and microorganisms (pp 237–265) Elsevier Perinelli, D R., Campana, R., Skouras, A., Bonacucina, G., Cespi, M., Mastrotto, F., … Casettari, L (2018) Chitosan loaded into a hydrogel delivery system as a strategy to treat vaginal Co-infection Pharmaceutics, 10(1), 1–15 https://doi.org/10.3390/ pharmaceutics10010023 Perioli, L., Ambrogi, V., Venezia, L., Pagano, C., Ricci, M., & Rossi, C (2008) Chitosan and a modified chitosan as agents to improve performances of mucoadhesive vaginal gels Colloids and Surfaces B, Biointerfaces, 66(1), 141–145 https://doi.org/10.1016/ j.colsurfb.2008.06.005 Pradines, B., Bories, C., Vauthier, C., Ponchel, G., Loiseau, P M., & Bouchemal, K (2015) Drug-free chitosan coated poly(isobutylcyanoacrylate) nanoparticles are active against trichomonas vaginalis and non-toxic towards pig vaginal mucosa Pharmaceutical Research, 32(4), 1229–1236 https://doi.org/10.1007/s11095-0141528-7 Raafat, D., & Sahl, H.-G (2009) Chitosan and its antimicrobial potential–a critical literature survey Microbial Biotechnology, 2(2), 186–201 Rampersaud, R., Randis, T M., & Ratner, A J (2012) Microbiota of the upper and lower genital tract Seminars in Fetal and Neonatal Medicine, 17, 51–57 Rein, M F (2020) Trichomoniasis Hunter’s tropical medicine and emerging infectious diseases Elsevier https://doi.org/10.1016/C2016-0-01879-X Rinaudo, M (2006) Chitin and chitosan: Properties and applications Progress in Polymer Science, 31(7), 603–632 Robert, M E., Eric, J B., et al (1992) Chitin chemistry, the Roberts, G A F (1992) Structure of chitin and chitosan Chitin chemistry (pp 1–53) London: Macmillan Education UK https://doi.org/10.1007/978-1-349-11545-7_1 Rodero, C F., Fioramonti Calixto, G M., dos Santos, K C., Sato, M R., dos Santos Ramos, M A., Miro, M S., … Chorilli, M (2018) Curcumin-loaded liquid crystalline systems for controlled drug release and improved treatment of vulvovaginal candidiasis Molecular Pharmaceutics, 15(10), 4491–4504 https://doi.org/10.1021/ acs.molpharmaceut.8b00507 Rodrigues, S., Dionísio, M., L´ opez, C R., & Grenha, A (2012) Biocompatibility of chitosan carriers with application in drug delivery Journal of Functional Biomaterials https://doi.org/10.3390/jfb3030615 10 V.H.S Araujo et al Carbohydrate Polymers 261 (2021) 117919 Sudarshan, N R., Hoover, D G., & Knorr, D (1992) Antibacterial action of chitosan Food Biotechnology, 6(3), 257272 Taipaleenmă aki, E., & Stă adler, B (2020) Recent advancements in using polymers for intestinal mucoadhesion and mucopenetration Macromolecular Bioscience, 20(3), Article 1900342 Tavassoli, M., Imani, A., Tajik, H., Moradi, M., & Pourseyed, S H (2012) Novel in vitro efficiency of Chitosan biomolecule against Trichomonas gallinae Iranian Journal of Parasitology Tentor, F., Siccardi, G., Sacco, P., Demarchi, D., Marsich, E., Almdal, K., … Boisen, A (2020) Long lasting mucoadhesive membrane based on alginate and chitosan for intravaginal drug delivery Journal of Materials Science Materials in Medicine, 31(3) https://doi.org/10.1007/s10856-020-6359-y Valenta, C (2005) The use of mucoadhesive polymers in vaginal delivery Advanced Drug Delivery Reviews, 57(11), 1692–1712 https://doi.org/10.1016/j addr.2005.07.004 Victorelli, F D., Calixto, G M F., dos Santos, K C., Buzz´ a, H H., & Chorilli, M (2021) Curcumin-loaded Polyethyleneimine and chitosan polymer-based Mucoadhesive liquid crystalline systems as a potential platform in the treatment of cervical Cancer Journal of Molecular Liquids https://doi.org/10.1016/j.molliq.2020.115080 Victorelli, F D., Calixto, G M F., Dos Santos Ramos, M A., Bauab, T M., & Chorilli, M (2018) Metronidazole-loaded polyethyleneimine and chitosan-based liquid crystalline system for treatment of staphylococcal skin infections Journal of Biomedical Nanotechnology https://doi.org/10.1166/jbn.2018.2484 Vllasaliu, D., Exposito-Harris, R., Heras, A., Casettari, L., Garnett, M., Illum, L., et al (2010) Tight junction modulation by chitosan nanoparticles: Comparison with chitosan solution International Journal of Pharmaceutics, 400(1–2), 183–193 Vunain, E., Mishra, A K., & Mamba, B B (2017) Fundamentals of chitosan for biomedical applications Chitosan based biomaterials volume (pp 3–30) Elsevier Wang, C., Li, J., & Yao, F (2011) Application of chitosan-based biomaterials in tissue engineering Chitosan-based hydrogels CRC Press https://doi.org/10.1201/b1104810 Willems, H M E., Ahmed, S S., Liu, J., Xu, Z., & Peters, B M (2020) Vulvovaginal candidiasis: A current understanding and burning questions Journal of Fungi, 6(1), 27 https://doi.org/10.3390/jof6010027 WORLD HEALTH ORGANIZATION (2012) Global incidence and prevalence of selected curable sexually transmitted infections – 2008 Switzerland: WORLD HEALTH ORGANIZATION Yano, J., Sobel, J D., Nyirjesy, P., Sobel, R., Williams, V L., Yu, Q., … Fidel, P L (2019) Current patient perspectives of vulvovaginal candidiasis: Incidence, symptoms, management and post-treatment outcomes BMC Women’s Health, 19(1), 48 Zheng, L Y., & Zhu, J F (2003) Study on antimicrobial activity of chitosan with different molecular weights Carbohydrate Polymers https://doi.org/10.1016/j carbpol.2003.07.009 Zubareva, A., Shagdarova, B., Varlamov, V., Kashirina, E., & Svirshchevskaya, E (2017) Penetration and toxicity of chitosan and its derivatives European Polymer Journal, 93, 743–749 https://doi.org/10.1016/j.eurpolymj.2017.04.021 ˇ Potrˇc, T., Baumgartner, S., Kocbek, P., & Kristl, J (2016) Formulation and Zupanˇciˇc, S., evaluation of chitosan/polyethylene oxide nanofibers loaded with metronidazole for local infections European Journal of Pharmaceutical Sciences, 95, 152–160 https:// doi.org/10.1016/j.ejps.2016.10.030 Roggero, E., P´erez, A R., Bottasso, O A., Besedovsky, H O., & Del Rey, A (2009) Neuroendocrine-immunology of experimental chagas’ disease Annals of the New York Academy of Sciences, 1153(1), 264–271 Ruiz-S´ anchez, D., Calder´ on-Romero, L., S´ anchez-Vega, J T., & Tay, J (2003) Intestinal candidiasis A clinical report and comments about this opportunistic pathology Mycopathologia, 156(1), 9–11 Salmazi, R., Calixto, G., Bernegossi, J., Aparecido Dos, M., Ramos, S., Bauab, T M., et al (2015) A Curcumin-loaded liquid crystal precursor mucoadhesive system for the treatment of vaginal candidiasis International Journal of Nanomedicine https://doi org/10.2147/IJN.S82385 Sandri, G., Rossi, S., Bonferoni, M C., Ferrari, F., Mori, M., & Caramella, C (2012) The role of chitosan as a mucoadhesive agent in mucosal drug delivery Journal of Drug Delivery Science and Technology https://doi.org/10.1016/s1773-2247(12)50046-8 Sangamithra, V., Verma, R., Sengottuvelu, S., & Sumathi, R (2013) Candida infections of the genitourinary tract Research Journal of Pharmacy and Technology, 6(10), 1111–1115 https://doi.org/10.1128/CMR.00076-09 Shahabeddin, L., Damour, O., Berthod, F., Rousselle, P., Saintigny, G., & Collombel, C (1991) Reconstructed skin from co-cultured human keratinocytes and fibroblasts on a chitosane cross-linked collagen-GAG matrix Journal of Materials Science Materials in Medicine https://doi.org/10.1007/BF00703375 Shahidi, F., Arachchi, J K V., & Jeon, Y J (1999) Food applications of chitin and chitosans Trends in Food Science & Technology, 10(2), 37–51 https://doi.org/ 10.1016/S0924-2244(99)00017-5 Shukla, S K., Mishra, A K., Arotiba, O A., & Mamba, B B (2013) Chitosan-based nanomaterials: A state-of-the-art review International Journal of Biological Macromolecules https://doi.org/10.1016/j.ijbiomac.2013.04.043 Singh, A., & Campus, B (2018) CHITIN, CHITOSAN AND THEIR PHARMACOLOGICAL ACTIVITIES: A REVIEW Kaushal Tripathi and Anita Singh * department of pharmaceutical sciences, bhimtal campus, kumaun university, Nainital - 263001, uttarakhand, India International Journal OfPharmaceutical Sciences And Research, (7), 2626–2635 https://doi.org/10.13040/IJPSR.0975-8232.9(7).2626-35 Smith, J., Wood, E., & Dornish, M (2004) Effect of chitosan on epithelial cell tight junctions Pharmaceutical Research, 21(1), 43–49 Soares, G., Santos, D., Pereira, G G., Bender, E A., Colom´ e, M., & Guterres, S S (2012) ` Desenvolvimento e Caracterizaỗ ao de Nanopartớculas LIPIDICAS DESTINADAS A TOPICA APLICAÇAO DE DAPSONA Quimica Nova, 35 Soares, L de S., Perim, R B., de Alvarenga, E S., Guimar˜ aes, L M., Teixeira, A V N C., Coimbra, J S R., et al (2019) Insights on physicochemical aspects of chitosan dispersion in aqueous solutions of acetic, glycolic, propionic or lactic acid International Journal of Biological Macromolecules https://doi.org/10.1016/j ijbiomac.2019.01.106 Sobahi, T R A., Abdelaal, M Y., & Makki, M S I (2014) Chemical modification of chitosan for metal ion removal Arabian Journal of Chemistry, 7(5), 741–746 Sogias, I A., Williams, A C., & Khutoryanskiy, V V (2008) Why is chitosan mucoadhesive? Biomacromolecules, 9(7), 1837–1842 https://doi.org/10.1021/ bm800276d Sreekumar, S., Goycoolea, F M., Moerschbacher, B M., & Rivera-Rodriguez, G R (2018) Parameters influencing the size of chitosan-TPP nano- and microparticles Scientific Reports, 8(1), 4695 https://doi.org/10.1038/s41598-018-23064-4 Srikrishna, S., & Cardozo, L (2013) The vagina as a route for drug delivery: A review International Urogynecology Journal and Pelvic Floor Dysfunction, 24(4), 537–543 https://doi.org/10.1007/s00192-012-2009-3 11 ... also the mucosa inflammation, indicating that the developed formulation is an interesting alternative for the treatment of VVC DDS composed and coated with chitosan for the treatment of VI The use... degree of deacetylation of ≥75 %, indicating that such characteristic is preferable for the development of mucoadhesive systems intended for vaginal application It is estimated that the use of chitosan... that chitosan is a promising adjuvant to be used for the development of mucoadhesive systems for vaginal application and local treatment of VI It is worth noting that chitosan can be associated