This article was downloaded by: [New York University] On: 04 September 2015, At: 21:57 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Howick Place, London, SW1P 1WG Journal of Macromolecular Science, Part A: Pure and Applied Chemistry Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/lmsa20 Preparation of the Cationic Dendrimer-Based Hydrogels for Controlled Heparin Release ab a c c Nhat-Anh N Tong , Thi Hai Nguyen , Dai Hai Nguyen , Cuu Khoa Nguyen & Ngoc Quyen ac Tran a Institute of Research and Development, Duy Tan University, Da Nang City 550000, Vietnam b School of Biotechnology, International University, Ho Chi Minh City Vietnam National University, Ward 6, Linh Trung, Thu Duc district Ho Chi Minh City 70000, Vietnam c Click for updates Institute of Applied Materials Science, Vietnam Academy Science and Technology, 01 Mac Dinh Chi, District 1, Ho Chi Minh City 70000, Vietnam Published online: 28 Aug 2015 To cite this article: Nhat-Anh N Tong, Thi Hai Nguyen, Dai Hai Nguyen, Cuu Khoa Nguyen & Ngoc Quyen Tran (2015) Preparation of the Cationic Dendrimer-Based Hydrogels for Controlled Heparin Release, Journal of Macromolecular Science, Part A: Pure and Applied Chemistry, 52:10, 830-837, DOI: 10.1080/10601325.2015.1067043 To link to this article: http://dx.doi.org/10.1080/10601325.2015.1067043 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis The accuracy of the Content 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Controlled Heparin Release NHAT-ANH N TONG1,2, THI HAI NGUYEN1, DAI HAI NGUYEN3, CUU KHOA NGUYEN3, and NGOC QUYEN TRAN1,3,* Institute of Research and Development, Duy Tan University, Da Nang City 550000, Vietnam School of Biotechnology, International University, Ho Chi Minh City Vietnam National University, Ward 6, Linh Trung, Thu Duc district Ho Chi Minh City 70000, Vietnam Institute of Applied Materials Science, Vietnam Academy Science and Technology, 01 Mac Dinh Chi, District 1, Ho Chi Minh City 70000, Vietnam Downloaded by [New York University] at 21:57 04 September 2015 Received April 2015, Revised and Accepted June 2015 We introduce a cationic polyamidoamine (PAMAM) dendrimers and tetronic (Te) based hydrogels in which precursor copolymers were prepared with simple methods In the synthetic process, tyramine-conjugated tetronic (TTe) was prepared via activation of its four terminal hydroxyl groups by nitrophenyl chloroformate (NPC) and then substitution of tyramine (TA) into the activated product to obtain TTe Cationic PAMAM dendrimers G3.0 functionalized with p-hydroxyphenyl acetic acid (HPA) by use of carbodiimide coupling agent (EDC) to obtain Den-HPA 1H-NMR confirmed the amount of HPA and TA conjugations The aqueous TTe and Den-HPA copolymer solution rapidly formed the cationic hydrogels in the presence of horseradish peroxidase enzyme (HRP) and hydrogen peroxide (H2O2) at physiological conditions The gelation time of the hydrogels could be modulated ranging from to 73 secs, when the concentrations of HRP and H2O2 varied The hydrogels exhibited minimal swelling degree and low degradation under physical condition In vitro cytotoxicity study indicated that the hydrogels were highly cytocompatible as prepared at 0.15 mg/mL HRP and 0.063 wt% of H2O2 concentration Heparin release profiles show that the cationic hydrogels can sustainably release the anionic anticoagulant drug The obtained results demonstrated a great potential of the cationic hydrogels for coating medical devices or delivering anionic drugs Keywords: Cationic hydrogels, polyamidoamine (PAMAM) dendrimers, injectable hydrogels, drugs delivery Introduction In recent years, special attention has been paid to cationic hydrogels ‘on-off’ controlled drugs and proteins delivery properties Several kinds of these chitosans, gelatin, polyamidoamine (PAMAM), polyethylenimine-based hydrogels have performed potentially biomedical applications because of their electrostatics interaction with negatively bioactive molecules, antibacterial activity and biocompatibility (1–5) These hydrogels have proven its efficiency in releasing insulin in order to regulate blood glucose *Address correspondence to: Ngoc Quyen Tran, Institute of Research and Development, Duy Tan University, Da Nang City 550000, Vietnam; and Institute of Applied Materials Science, Vietnam Academy Science and Technology, 01 Mac Dinh Chi, District 1, Ho Chi Minh City 70000, Vietnam E-mail: tnquyen@iams.vast.vn Color versions of one or more figures in this article can be found online at www.tandfonline.com/lmsa concentration, or deliver genes (cationic nanogel) or anionic drugs (6–8) Cationic PAMAM dendrimers are well known to exhibit some advantages for drugs delivery such as their high drug-loading capacity or highly electrostatic interaction with anionic bioactive molecules, enhancement of hydrophobic drugs solubility, drug slow-release, and easy functionalization of their external groups to prepare drugloaded biomaterials (9–11) Therefore, the use of versatile dendrimers platforms for preparing many cationic hydrogels would be significant in drugs delivery and tissue engineering In fact, Raghavendra et al reported that the cationic PAMAM dendrimers and multi-arm-polyethylene glycol-based hydrogels could sustainably release amoxicillin anionic drug in the intracervical tissue of pregnant guinea pigs (12) Photocurable PAMAM dendrimers hydrogels introduced as a versatile platform for tissue engineering and drug delivery (13) These cationic hydrogels also exhibited biocompatibility and biodegradation The hydrogels would have much more potential if gel formation did not produce by-products or use photocurable Downloaded by [New York University] at 21:57 04 September 2015 Cationic Dendrimer-Based Hydrogels for Heparin Delivery 831 Fig In situ formation of cationic hydrogels from heparin-loaded polymer solutions ultraviolet light As a further matter of clarification, hemolytic toxicity and cell lysis due to a strong interaction of the positively charged dendrimers and the negatively charged cell membrane resulting in membrane disruption are weak points of the original PAMAM dendrimer (9–11) Our study aims to produce cationic and injectable TTePAMAM-based hydrogels via an enzymatic reaction with horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) to carry heparin-anionic drug for coating stent or blood contacting devices (Fig 1) In a system using an enzymatic reaction, the degree of crosslinking of hydrogel can be easily controlled by the feed amount of hydrogen peroxide and therefore, the stability of hydrogel can be varied (15) The heparin-encapsulated hydrogels, when coated to a metal surface, may enhance blood compatibility and reduce platelet adhesion and prolong the material existence due to its high stability In the systems, PAMAM dendrimers (G3.0) were functionalized with p-hydroxy phenyl acetic acid molecules and tetronic (Ethylenediamine tetrakis(propoxylate-block-ethoxylate) tetrol), a nontoxic surfactant which was terminated by tyramine moieties in order to prepare the injectable hydrogel that could reduce toxicity of PAMAM dendrimer in the hydrogel and prevent the contact between the polymer with cell membranes (14) Heparin could be dispersed in polymer solutions and then these mixtures are cured in situ forming a polymeric three-dimension network under several desired shapes or thin layers of hydrogels by spraying or injecting preparation (16, 17) The cationic TTe-PAMAM enzymatic-based hydrogels systems would be essential materials for medical treatment due to its convenient applications Experimental 2.1 Materials Heparin sodium, 4-Nitrophenyl chloroformate 96% (NPC), tyramine (TA) were purchased from Acros Organics Horseradish peroxidase (HRP) enzyme (type VI, 298), 1-thyl-3(-3-(dimethylamino) propyl) carbodiimide (EDC), Nhydroxysuccinimide (NHS) and 4-Hydroxyphenylacetic acid 98% (HPA) were purchased from Sigma-Aldrich Tetronic 1307 (Te, MW D 18,000) was obtained from 832 BASF PAMAM dendrimers at generation 3.0 (G3.0; MwD6,530) were prepared in the Department of Materials and Pharmacy Chemistry (Institute of Applied Materials Science) (18) following the procedure reported by Tomalia et al (19) Downloaded by [New York University] at 21:57 04 September 2015 2.2 Synthesis of Tyramine-Tetronic (TTe) Tyramine-tetronic was prepared by using a simple and organic solvent-free procedure First, the four endhydroxyl groups of tetronic were activated with NPC Finally, TA substituted NPC moieties as shown in Scheme Briefly, tetronic (7.0 g, 1.56 mmol of hydroxyl group) was molten at 75 C for h under stirring in a vacuum atmosphere NPC (0.43 g, 2.13 mmol) was added to the melted tetronic and continuously stirred for h under medium vacuum with HCl entrapment equipment After h, the reaction mixture was adjusted to room temperature (20) To solubilize the solid copolymer and decompose the excess NPC, mL of distilled water and 30 mL THF Sch Synthetic scheme of TTe Tong et al were added to the resulting product and then TA (213 mg, 1.56 mmol) added to the copolymer solution The reaction mixture was stirred overnight Finally, the solution was dialyzed in acetone three times with membrane dialysis (8000 MWCO) The dialyzed copolymer solution was precipitated in diethylether to collect a powdery TTe copolymer and dried in a vacuum oven 1H-NMR (CDCl3)/ppm of TTe, d ppm D 6.78 and 7.02 (d, –CHDCH–, TA) According to integrals of methyl tetronic protons and aromatic TA protons in 1H-NMR, 97% of TA moieties were determined to be conjugated into the tetronic 2.3 Synthesis of PAMAM G3.0-HPA (Den-HPA) PAMAM G3.0 – Hydroxyphenyl acetic acid (Den-HPA) was prepared based on amide formation (-NHCO-) between some external amine groups of PAMAM and carboxylic group of HPA using an EDC coupling agent (Sch 2) Briefly, 40 mL methanol solution containing 10g PAMAM G3.0 (1.54 mmol) was neutralized to pH 6.0 in cool condition by HCl: Methanol (1:2) After 833 Downloaded by [New York University] at 21:57 04 September 2015 Cationic Dendrimer-Based Hydrogels for Heparin Delivery Sch Synthetic scheme of Den-HPA neutralization, methanol was removed and then the neutralized PAMAM was dissolved in 20 mL DI water HPA (1.25 g; 8.22 mmol) and EDC (1.67 g; 8.70 mmol) were respectively added to the neutralized PAMAM solution under stirring for 24 h in nitrogen After this time, the reaction mixture was dialyzed with dialysis membrane (3500 MWCO) in methanol for days The dialyzed solution was removed solvent to obtain Den-HPA 1H-NMR (D2O)/ppm, d ppm D 2.40–2.65 (-CH2CH2CONH-); 2.70–2.85 (-CH2CH2N