Nghiên cứu chế tạo và tính chất của cấu trúc lai ferit từ kim loại (ag, au) kích thước nano định hướng ứng dụng trong y sinh tt tiếng anh

MINISTRY OF EDUCATION AND TRAINING VIETNAM ACADEMY OF SCIENCE AND TECHNOLOGY GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY _ NGUYEN THI NGOC LINH SYNTHESIS AND PROPERTIES OF FERRITE - METAL (Ag, Au) HYBRID NANOSTRUCTURES FOR BIOMEDICAL APPLICATION Major: Inorganic chemistry Code: 9.44.01.13 SUMMARY OF CHEMISTRY DOCTORAL THESIS Ha Noi - 2020 This thesis was done at: Laboratory of Electronic-Electrical Engineering, Institute for tropical technology, Vietnam Academy of Science and Technology Laboratory of Biomedical Nanomaterials, Institute of Materials and Science, Vietnam Academy of Science and Technology Supervisor 1: PhD Le Trong Lu Supervisor 2: Assoc.Prof., PhD Ngo Dai Quang Reviewer 1: Prof., PhD Thai Hoang Reviewer 2: Assoc.Prof., PhD Huynh Dang Chinh Reviewer 3: Assoc.Prof., PhD Nguyen Thi Hien Lan The dissertation will be defended at Graduate University of Science and Technology, 18 Hoang Quoc Viet street, Hanoi Time: ., , 2020 This thesis could be found at National Library of Vietnam, Library of Graduate University of Science and Technology, Library of Vietnam Academy of Science and Technology INTRODUCTION The necessary of the thesis In recent years, hybrid nanomaterials have attracted the attention of many researchers due to their integrated properties from individual components The combination of magnetic and optical properties on a nanostructure has improved the application of single nanoparticles (NPs) and opened new directions in biomedical applications, especially in diagnosis and treatment The advantage of magnetoplasmonic hybrid nanostructures in this area is that the desired target has merely been achieved after being activated by a physical stimulus, thus minimizing damaging effects on body Furthermore, several functions can work synergically to enhance the efficiency in therapeutic methods Currently, many magneto-plasmonic hybrid nanostructures have been studied in order to apply in the biomedical field in which Fe3O4/Au material has been one of the most typical materials The studies on Fe3O4/Au hybrid NPs for magnetic resonance imaging (MRI) and magneto-photothermal therapy in cancer treatment have obtained some remarkable results However, Fe3O4@Au core-shell hybrid NPs with Au layer coated on the surface of Fe 3O4 core significantly limit the connection of protons to the magnetic materials, leading to the reduction of the T2-weighted MRI contrast signal In addition, Fe3O4-Au hybrid NPs exhibit the surface plasmon resonance (SPR) position in the range from 530 to 600 nm, limiting the deep penetration into thick tissue layers and reducing the efficiency of the photothermal therapy In order to improve the effectiveness of the thermal therapy, the materials have to absorb radiation in near-infrared (NIR) region (650 ÷ 950 nm), also known as "biological windows” region, because the NIR radiation has the highest ability to penetrate the body The previously fabricated hollow Fe3O4/Au hybrid NPs can meet this criterion, however, their large size (40 ÷ 100 nm) impact the blood circulation Therefore the fabrication of the hollow Fe3O4/Au hybrid NPs with particle size below 20 nm and the integration of both magnetic and plasmonic properties is still a big challenge In Vietnam, to our best knowledge, the publication of the fabrication of the magnetic – noble metals hybrid nanomaterials (Ag, Au) integrated magnetic and plasmonic properties, which can be applied in the biomedical field, is still limited Research that results on the application of Fe3O4-(Ag, Au) hybrid NPs as MRI contrast agents under both T1- and T2-weighted modes, and as a heat (optical/magnetic-thermal) substance in cancer treatment has not been reported For these reasons, we conduct the thesis on topic “Synthesis and properties of ferrite - metal (Ag, Au) hybrid nanostructures for biomedical application” Research objectives of the thesis This work aims to fabricate ferrite - (Ag, Au) hybrid nanomaterials with a SPR peak located in the near-infrared region, high magnetic/optical-to-thermal conversion and ability to contrast MRI images for both T1- and T2- weighted modes, which are strongly bactericidal and able to be applied in biomedicine The main research contents of the thesis Synthesis of magnetic ferrite nanoparticles MFe2O4 (M: Fe, Co, Mn) with uniform size and shape, monodisperse, and high saturation magnetization using thermal decomposition method in organic solvents Synthesis of small Fe3O4/Ag hybrid particles (below 20 nm) by seeded-growth method, and synthesis of Fe3O4/Au hollow hybrid nanoparticles with size below 20 nm and NIR light absorption by using Fe3O4/Ag nanoparticles as template via Galvanic replacement approach in organic solvents Phase transfer of the as-synthesized NPs from organic solvent to aqueous solvent, and evaluation of toxicity and durability of the hybrid particles in aqueous water Study on the applicability of the hybrid particle solution in biomedical: antibacterial activity, ability to convert optical/magnetic energy into heat, and the ability to contrast MRI images CHAPTER OVERVIEW ABOUT MAGNETIC FERRITE - NOBLE METAL NANOMATERIALS 1.1 General introduction of magnetic ferrite - noble metal nanomaterials 1.1.1 Magnetic properties of magnetic ferrite materials The magnetic properties of materials vary depending on their electronic structure The magnetic moments of an atom are generated by the magnetic moments of the electrons related to the intrinsic motion of the electron (spin motion) and the moment from the orbit caused by the motion of the electron around the atomic nucleus 1.1.2 Plasmonic properties of noble metallic (Ag, Au) * The phenomenon of surface plasmon resonance: this phenomenon occurs when all the conducting electrons on the metal surface are stimulated simultaneously to form a collective oscillation * Mie theory: Mie theory found that the extinction cross section (ext) includes the absorption (abs) and scattering (sct) cross sections of a particle The absorbance A of a sample of nanoparticles dispersed in a homogeneous medium is given by: where (ext) is the extinction coefficient of the sample at wavelength , N is the number of particles in one litter, and l is the thickness of the absorbing medium (cm) 1.1.3 Magnetic ferrite - noble metal materials When different materials are integrated in a nanostructure, in addition to inheriting the unique properties of each component, the hybrid structure also exhibits new properties generated from the interaction between the two material systems 1.2 Properties of the magnetic ferrite - noble metal hybrid nanomaterials 1.2.1 Magnetic properties 1.2.2 Plasmonic properties 1.2.3 Biocompatibility and physiochemical stability 1.3 The magnetic ferrite - noble metal hybrid nanomaterials for biomedical application The combination of magnetic ferrite components and noble metals creates more diverse applications than individual nanoparticles 1.3.1 Application of thermal therapy in cancer treatment 1.3.2 Bioimaging 1.3.3 Antibacterial application 1.3.4 Targeted drug delivery 1.4 Methods for synthesizing ferrite - noble metal hybrid nanomaterials There are many methods to synthesize magnetic ferrite - noble metal materials Generally, the synthesis process consists of two steps: 1) Synthesize seeds which can be magnetic ferrite or noble metal (Ag, Au) nanoparticles 2) Develop another component (noble metals or magnetic ferrite) on pre-synthesized seeds This thesis focuses on the method of synthesizing magnetic ferrite NPs (seeds), then developing noble metal components (Ag, Au) on these seeds 1.4.1 Synthesis of magnetic ferrite nanomaterials 1.4.2 Synthesis of magnetic ferrite - noble metal nanomaterials 1.4.2.1 Seeded-growth method 1.4.2.2 Synthesis of some magnetic ferrite - noble metal hybrid nanomaterials by the seeded-growth method 1.4.3 Surface modification of hybrid nanomaterials 1.4.3.1 Ligand-exchange method 1.4.3.2 Coating hybrid particles by bipolar polymers CHAPTER EXPERIMENTAL AND RESEARCH METHODS 2.1 Raw materials and chemicals 2.2 Synthesis of materials 2.2.1 Synthesis of magnetic ferrite NPs 2.2.1.1 Synthesis of Fe3O4 NPs with a low concentration of precursors 2.2.1.2 Synthesis of magnetic ferrite NPs with a high concentration of precursors 2.2.2 Synthesis of magnetic ferrite - noble metal (Ag, Au) hybrid NPs 2.2.2.1 Fe3O4/Ag hybrid NPs Fe3O4/Ag hybrid NPs were synthesized by seeded-growth method (Fe3O4 NPs were used as seeds) in the ODE solvent The reactions were carried out with  = [Ag]/[Fe] in the range of 0.5 ÷ 13.6 The effect of temperature on the hybrid structure was investigated 2.2.2.2 Fe3O4/Au hybrid NPs a) Fe3O4/Au hybrid NPs The synthesis of Fe3O4/Au NPs was similar to that of Fe3O4/Ag nanoparticles (section 2.2.2.1) but H[AuCl4].3H2O was used instead of AgNO3 b) Hollow Fe3O4/Au hybrid NPs The hollow Fe3O4/Au hybrid NPs were synthesized by the Galvanic replacement method and Fe3O4/Ag nanoparticles (section 2.2.2.1) were used as a template The effect of the amount of the H[AuCl4] solution on the formation of the hollow Fe3O4/Au structure was investigated 2.2.3 Phase transfer nanoparticles into water After synthesized, NPs were transferred phase into water using PMAO 2.3 Material characterization 2.3.1 Transmission electron microscopy 2.3.2 X-ray diffraction 2.3.3 Vibrating sample magnetometer 2.3.4 Molecular absorption spectroscopy UV-Vis 2.3.5 Fourier Transform Infrared Spectroscopy 2.3.6 Energy Dispersive X-Ray Spectroscopy 2.3.7 Thermal gravimetric analysis 2.3.8 Dynamic light scattering 2.4 Methods of evaluating the toxicity of materials The toxicity of hybrid nanomaterials on AGS and MKN45 cells was evaluated by MTT method 2.5 Methods of evaluating antibacterial activity of materials The evaluation of the antibacterial activity of materials was carried out by the agar well diffusion method Bacterial species tested: Gram-positive bacteria: Bacillus subtilis (B subtilis), Lactobacillus plantarum (L.plantarum), Sarcina lutea (S lutea) + Gram-negative bacteria: Serratia marcescens (S marcescens), Escherichia coli (E coli) 2.6 Determination of the magneto-photothermal conversion efficiency The magnetic/photo induced heating efficiency of materials was carried out under three conditions: (i) Magnetic hyperthermia (MHT) at the magnetic field with an intensity of 100 - 300 Oe and frequency of 450 kHz, (ii) Photothermial therapy (PTT) at 808 nm laser, a power density of 0.2 – 0.65 W/cm2, and (iii) combined magnetic field and laser at the exact same conditions (MHT + PTT) 2.7 Magnetic resonance imaging MRI images of different material concentrations were taken on a Siemens magnetic resonance device (Model: MAGNETOM Avanto 1.5 T) with an alternating magnetic field (64 MHz and 1.5 tesla) CHAPTER RESULTS AND DISCUSSION 3.1 Magnetic ferrite nanoparticles 3.1.1 Morphology 3.1.1.1 Synthesis of Fe3O4 NPs at low concentration of precursors Normally, Fe3O4 NPs were synthesized by thermal decomposition in dibenzyl ether, a toxic organic solvent In this thesis, 1-octadecene, a solvent with much lower toxicity level, was tested and used as a solvent The effect of several factors such as time, reaction temperature, surfactant concentration, and inorganic precursor concentration on Fe3O4 nanoparticle size was determined by TEM and the results are presented in Table 3.1 Table 3.1 Effect of reaction conditions on Fe3O4 nanoparticle size Precursor concentration (mM) Surfactant concentration (mM) Tempe rature (oC) Fe(acac)3 FeSO4 7H2O FeCl2 4H2O OA OLA 190 0 372 372 295 190 0 558 558 295 190 0 744 744 295 190 0 930 930 295 126.7 63.3 558 558 126.7 63.3 558 558 270 295 315 315 Time (min) 30 60 120 10 30 60 120 10 30 60 120 10 30 60 60 Samples dTEM (nm) F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 3.6 ± 0.7 4.5 ± 0.7 7.2 ± 1.0 3.2 ± 0.5 4.1 ± 0.6 6.3 ± 0.9 10.7 ± 1.4 3.4 ± 0.5 6.7 ± 0.7 8.1 ± 0.7 13.9 ± 1.1 5.8 ± 0.9 11.3 ± 1.2 14.7 ± 1.3 4.8 ± 1.0 8.4 ± 1.5 10.2 ± 0.5 10.8 ± 2.4 a) Effect of reaction time Figure 3.1 TEM images of the samples F8 (a), F9 (b), F10 (c), F11 (d) and corresponding particle size distribution histograms (e) All the Fe3O4 NPs are spherical, monodisperse, and uniform in size When the reaction time increases from 10 ÷ 120 minutes, the particle size increases and is in the range of 3.2 ÷ 14.7 nm b) Effect of surfactant concentration Figure 3.2 TEM images of the samples F2 (a), F6 (b), F10 (c) and F14 (d) and corresponding particle size distribution histograms (e) The obtained particles are spherical, uniform, and monodisperse, and the average particle size increases as the concentration of OA and OLA increases c) Effect of inorganic precursors In order to reduce the cost and widen the applications, Fe(acac)3 was partly replaced by inorganic Fe(II) salts which are much cheaper than Fe(acac)3 *) Effect of the amount of H[AuCl4] solution on the formation of hollow Fe3O4/Au hybrid structure When the volume of H[AuCl4] solution used in the reaction is 0.5 mL, the hollow structure is not formed For larger amounts of H[AuCl4] (from 1.0 to 2.0 mL), the particles are converted into cage like structures, and the void size gradually increased At 2.0 mL, the largest size of material reaches 17.0 nm Further increasing the volume of H[AuCl4], the hollow spheres are gradually broken, and at 3.5 mL, the hollow structure is completely ruined Figure 3.17 TEM images of Fe3O4@Ag NPs (a), Fe3O4/Au NPs (b-i) at different amounts of H[AuCl4] solution and particle size distribution histograms (k) of (a and e) The development of Fe3O4/Au hybrid structure morphology depends on the amount of H[AuCl4] solution used This relationship can be summarized according to Figure 3.18 Figure 3.18 Effect of amounts of H[AuCl4] solution on the morphology of Fe3O4/Au hybrid structure 14 3.2.2 Crystalline structure On the XRD pattern of Fe3O4@Ag core-shell structure, only characteristic peaks of Ag cubic structure can be observed while XRD data of Fe3O4-Ag dumbbell structure shows typical peaks of both Fe3O4 spinel (low intensity) and Ag (high intensity) Figure 3.19 XRD patterns of 3.2.3 Optical properties Fe3O4, Ag and Fe3O4/Ag NPs In the wavelength range from 300 - 900 nm, Fe3O4 NPs not have absorption peaks Ag NPs have an SPR peak at 405 nm, Fe3O4/Ag hybrid NPs have SPR peaks at 410 nm with the core-shell structure (sample F10@A60, 16.0 nm) and 420 nm with dumbbell structure (sample F10-A60, 8.1-16.3 nm) In general, the SPR peak of Fe3O4/Ag hybrid nanoparticles is below 450 nm Figure 3.20 UV-Vis spectra of NPs in n-hexane solvent: a) Fe3O4, Ag and Fe3O4/Ag NPs, b) Fe3O4 and Fe3O4/Au NPs The optical properties of Fe3O4/Au hybrid NPs depend on the morphology and structure of the materials Fe3O4/Au hybrid NPs have an SPR peak at 530 nm, while hollow Fe3O4/Au hybrid NPs have an SPR peak at 707 nm (the sample with mL of Au3+) The SPR position of the hollow Fe3O4/Au hybrid NPs depends on the amount of H[AuCl4] solution (Table 3.10) Table 3.10 Effect of the amounts of H[AuCl4] solution on the SPR position of Fe3O4/Au hybrid NPs H[AuCl4] (mL) The SPR position of Fe3O4/Au (nm) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 410 587 627 645 707 592 585 565 15 3.2.4 Magnetic property The values of saturation magnetization and coercivity of Fe3O4/Ag hybrid samples are lower than pure magnetic NPs, but the magnetic response of hybrid NPs is relatively good Figure 3.22 The magnetization curves of Fe3O4@Ag template and Fe3O4/Au NPs and image (inset) of hollow Fe3O4/Au hybrid NPs in n-hexane without and with magnet Figure 3.21 a) The magnetization curves of Fe3O4 and Fe3O4/Ag NPs; b) Photographs of Fe3O4/Ag NPs in n-hexane without and with magnet The formation of hollow Fe3O4/Au structure does not change the superparamagnetic properties when compared to that of Fe3O4@Ag template, but the value of saturation magnetization increases slightly (Figure 3.22) 3.2.5 Chemical composition The composition of Fe3O4/Ag hybrid NPs consists of the main elements Fe, Ag and O, and that of Fe3O4/Au, includes Fe, Ag, Au and O According to SEM-EDS elemental mapping analysis, Fe3O4/Au hollow NPs (the sample with mL of Au3+) Figure 3.25 SEM-EDS elemental show the good distribution of all elements in the hollow mapping of hollow Fe3O4/Au hybrid NPs nanostructure (Figure 3.25) Summary of results of section 3.2: Fe3O4/Ag hybrid NPs were successfully fabricated by the seeded-growth method in ODE solvent and their morphology can be controlled by varying  = [Ag]/[Fe] and reaction time With   6.8, the particles have Fe3O4@Ag core-shell structure, while with  = Fe3O4-Ag dumbbell structure is formed The size of the Ag shell in the 16 core-shell structure and the Ag particles in the dumbbell structure increase as the reaction time increases The hollow Fe3O4/Au hybrid NPs were fabricated by using Fe3O4/Ag NPs as the template via Galvanic replacement reaction between Ag and Au3+ The obtained material has an average size of 17 nm and its SPR peak can be controlled to 707 nm With [Au]/[Ag] = 0.83, Fe3O4/Au hybrid NPs have the largest void size, and all elements are well distributed The as-synthesized Fe3O4-(Ag, Au) NPs have superparamagnetic properties at room temperature with the value of the saturation magnetization in the range of ÷ 27 emu/g, lower than that of the Fe3O4 seed samples (50 ÷ 64 emu/g) 3.3 Nanoparticles are coated by PMAO 3.3.1 Phase transfer of nanoparticles by PMAO Before being coated with PMAO, the hybrid NPs are dispersible in n-hexane and after coated, they are well-dispersed in water (Figure 3.26) Figure 3.26 Phase transfer of the NPs by PMAO (a), solutions of Fe3O4@Ag NPs (b), Fe3O4-Ag NPs (c) and hollow Fe3O4/Au NPs (d) before (1) and after phase transfer (2) 3.3.2 Optical properties of materials Figure 3.27 Solution (a) and UV-Vis spectra (b) of Fe3O4@Ag@PMAO and hollow Fe3O4/Au@PMAO NPs at different amounts of Au3+ 17 The change in color of the hybrid NPs solutions is also shown by the shift of the SPR peak of the materials (Figure 3.27) Among the solutions of Fe3O4/Au hybrid NPs coated by PMAO, the 2.0 mL Au3+ sample has the strongest SPR peak shifting to the near-infrared region This sample was selected for further studies 3.3.3 Structure of the coating shell FT - IR spectra confirm that the hybrid NPs were coated with PMAO TGA curves indicate that PMAO shell accounts for 58% and Fe3O4/Au hybrid NPs make up 42% of the sample mass Hình 3.29 TGA curves of hollow Figure 3.28 FT-IR spectra of Fe3O4/Au hybrid NPs before hollow Fe3O4/Au hybrid NPs before and after phase tranfer and after phase tranfer The hydrodynamic diameters determined by DLS of Fe3O4@Ag@PMAO and hollow Fe3O4/Au@PMAO are 25.85 and 28.84 nm, respectively Zeta potential of Fe3O4@Ag@PMAO and hollow Fe3O4/Au@PMAO aqueous solutions is -42.5 mV and -40.0 mV, respectively Moreover, hybrid NPs are stable in NaCl solution at concentration of 150 ÷ 250 mM and pH of ÷ 11 These results demonstrate that the solution of the hybrid NPs is well dispersed and stable under the investigated conditions 3.3.5 Toxicity evaluations of materials The toxicity of the solutions of Fe3O4@Ag@PMAO and hollow Fe3O4/Au@PMAO hybrid NPs was evaluated on two gastric cancer cell lines AGS and MKN45 by MTT method *) Fe3O4@Ag hybrid NPs: At Fe3O4@Ag@PMAO concentration below 20 µg/mL, AGS and MKN45 cells grew normally, similar to those of the control sample At higher sample concentrations (20 ÷ 100 µg/mL), the morphology and nuclei of the cells were altered The IC50 values determined for AGS and MKN45 cell lines are 42 µg/mL and 58 µg/mL, respectively 18 Figure 3.33 The growth rate of AGS (a) and MKN45 (b) cells after treated in 48 h with Fe3O4@Ag@PMAO hybrid NPs Figure 3.34 Morphology (a) and neuclei (b) of AGS cells after treated in 48 h with Fe3O4@Ag@PMAO hybrid NPs Figure 3.35 Morphology (a) and neuclei (b) of MKN45 cells after treated in 48 h with Fe3O4@Ag@PMAO hybrid NPs *) Fe3O4/Au hollow hybrid nanoparticles: Hollow Fe3O4/Au@PMAO hybrid NPs is non-toxic on AGS and MKN45 cells within the test concentration range of 10 ÷ 100 g/mL Figure 3.36 The growth rate of AGS (a) and MKN45 (b) cells after treated in 48 h with hollow Fe3O4/Au@PMAO hybrid NPs 19 Figure 3.37 Morphology (a) and neuclei (b) of AGS cells after treated in 48 h with hollow Fe3O4/Au@PMAO hybrid NPs Figure 3.38 Morphology (a) and neuclei (b) of MKN45 cells after treated in 48 h with hollow Fe3O4/Au@PMAO hybrid NPs Summary of the results of section 3.3: Hybrid NPs were successfully transferred into the water by PMAO, and the optical properties of the materials remain unchanged The SPR peaks of hollow Fe3O4/Au@PMAO hybrid NPs are in the NIR region and can shift to 707 nm The hybrid NPs after the phase transfer are well dispersed and stable in water for 12 months, the their Zeta potential values were over 37 mV The Fe3O4@Ag@PMAO and hollow Fe3O4/Au@PMAO hybrid NPs are stable in the solution with salt concentration of 150 ÷ 250 mM and pH of ÷ 11 Fe3O4@Ag@PMAO hybrid NPs exhibits toxicity to AGS and MKN45 cells, depending on the material concentration The IC50 values determined for AGS and MKN45 cells are 42 µg/mL and 58 µg/mL, respectively The hollow Fe3O4/Au@PMAO hybrid NPs does not show toxicity on AGS and MKN45 cells in the range of 10 ÷ 100 g/mL 3.4 Applicability of hybrid nanomaterials in biomedicine + Study on the antibacterial activity of the solution of Fe3O4/Ag@PMAO hybrid NPs with two structures: Fe3O4@Ag@PMAO core-shell (sample F10@A60@PMAO) and Fe3O4-Ag@PMAO dumbbell (sample F10-A60@PMAO) and compare with Fe3O4@PMAO (sample F10@PMAO) and Ag@PMAO + Study on the magneto-photothermal conversion efficiency and MRI image contrast of hollow Fe3O4/Au@PMAO hybrid NPs (the sample mL Au3+) 20 3.4.1 Antibacterial activity of the materials Fe3O4@PMAO Ag@PMAO Fe3O4@Ag@PMAO Fe3O4-Ag@PMAO Figure 3.39 Antibacterial activity of Fe3O4@PMAO, Ag@PMAO and Fe3O4/Ag@PMAO hybrid NPs Ag@PMAO NPs solution can inhibit the growth of bacteria, but the inhibition zones are not clear with all tested bacteria The Fe3O4@PMAO NPs (seeds) have no antibacterial effect, however, when they combine with silver to form Fe3O4/Ag@PMAO hybrid structure, the antibacterial activity is clearly enhanced 3.4.2 The magneto-photothermal conversion efficiency of the materials 3.4.2.1 The magnetic heating (MHT) Figure 3.40a shows a significantly dependent behavior of magnetic field for the final attained temperature after 1200 s of treatment, and they tend to increase as the magnetic intensity increases The maximum value of SLP ~ 310 W/g is achieved under the applied magnetic field of 300 Oe at a frequency of 450 kHz In order to reach the therapeutic temperature window (42 ÷ 46 oC), a magnetic field with a minimum intensity of 150 Oe is required 21 Figure 3.40 Magnetic hyperthermia: (a) Temperature elevation profile for the hollow Fe3O4/Au @PMAO hybrid NPs under different magnetic fields at a constant frequency, f = 450 kHz (a) and the corresponding SLP value (b) 3.4.2.2 The plasmonic heating (PTT) Figure 3.41 Photothermal therapy: Heating curves for the hollow Fe3O4/Au @PMAO hybrid NPs under irradiation with a 808 nm laser for values of the different power densities (a) and corresponding SLP values (b) When the laser power at a density of 0.2 ÷ 0.35 W/cm2 is applied, the highest temperature is reached below 40 oC after 1200 s To reach the therapeutic temperature window, a minimum power density of P = 0.50 W/cm2 is required When the laser power density increases from 0.2 to 0.65 W/cm2, the SLP value increases from 152.70 to 1074.62 W/g 3.4.2.3 The magneto-plasmonic heating (MHT + PTT) The rate of heating of (MHT + PTT) and PTT is faster than that of MHT: the temperature variation (T) after 300 s of the dual heating method (MHT + PTT) is 36 oC, times larger than that of MHT (6 oC), and that of PTT (21 oC) is larger than that of MHT about 3.5 times After 1200 s of treatment, the temperature varies significantly under all experimental conditions The highest temperature achieved by the three modes of heating MHT, PTT, and (MHT + PTT) is 52.0, 55.0 and 68.5 oC, respectively, corresponding to the temperature variation T of 38.5, 25.0 and 22.0 oC The control sample (distilled water) shows a very low-temperature rise (1.0 ÷ 2.5 oC) for all three experimental modes 22 Figure 3.42 Heating curve (a) and SLP value (b) for the hollow Fe3O4/Au @PMAO hybrid NPs and H2O under combining magnetic field and laser *) Effect of magnetic field intensity (H) Figure 3.43 The magneto-plasmonic heating (MHT + PTT) of hollow Fe3O4/Au@PMAO hybrid NPs under different magnetic fields (a), corresponding SLP value of a (b), the maximum temperature elevation Tmax (after 1200 s) ( c) and the corresponding SLP value (d) under MHT and (MHT + PTT) When the magnetic field intensity (H) increases from 100 to 250 Oe, the highest temperature (Tmax) increases from 47 to 68 oC To achieve therapeutic temperatures with the MHT method, a minimum magnetic field intensity of 150 Oe is required, while for the technique (MHT + PTT) it is 100 Oe (at a laser with P = 0.5 W/cm2 ) Thus, by combining two heating methods (MHT + PTT), the magnetic field intensity has been reduced by 1.5 times compared to the case where only MHT is applied and the therapeutic temperature is still reached * Effect of laser power density (P): When the power density (P) increases from 0.2 to 0.65 W/cm2, the obtained Tmax increases from 46 to 68.5 oC The maximum SLP value obtained in this case is 1082.75 W/g with P = 0.65 W/cm2 In order to 23 reach the target temperature window by using PTT technique, a minimum power density of 0.5 W/cm2 is required, while the technique (MHT + PTT) requires P = 0.2 W/cm2 (at H = 200 Oe) Thus, after combining the two heating methods (MHT + PTT), the laser power density has decreased by 2.5 times when compared to the PTT method and the achieved temperature is still in the therapeutic window Figure 3.44 The magneto-plasmonic heating (MHT + PTT) of hollow Fe3O4/Au@PMAO hybrid NPs under different power densities (a), corresponding SLP value of a (b), the maximum temperature elevation Tmax (after 1200 s) ( c) and the corresponding SLP value (d) under PTT and (MHT + PTT) *Effect of hybrid NPs concentration: Figure 3.45 Effect of hollow Fe3O4 /Au@PMAO hybrid NPs concentration on (MHT + PTT) (a) and corresponding SLP value of a (b) When the hybrid NPs concentration increases from 1.0 to 3.0 mg/mL, the temperature of samples increases from 46.7 to 68.5 oC, and the SLP value rises from 391.37 to 1082.75 W/g To achieve the level of targeted temperature window by (MHT + PTT) mode, the minimum hybrid NPs concentration required is 1.0 mg/mL 24 3.4.3 Evaluate the recovery of r1 and r2 of materials T1- and T2-weighted MRI images of hollow Fe3O4/Au@PMAO hybrid NPs have a clear image contrast that obviously changes when material concentration slightly changes The vertical recovery r1 and the horizontal recovery r2 of the hybrid NPs are 8.47 and 74.45 mM-1s-1, respectively Comparing the results of this thesis with some commercial products and some publications of other research groups, we find that our products have a higher value of r1 than commercial products based on Gd substrate, and the r2 value is also large enough to give a good contrast signal Thus, the fabricated materials can be used as a T1-T2 dual mode MRI contrast agent Figure 3.46 T2 weigted MRI images (a) and linear fitting of 1/T2 (b) of hollow Fe3O4/Au@PMAO hybrid NPs at different concentrations of [Fe] Figure 3.47 T1 weigted MRI images (a) and linear fitting of 1/T1 (b) of hollow Fe3O4/Au@PMAO hybrid NPs at different concentrations of [Fe], T1-weighted MRI images (c) and the intensity (d) of H2O, Dotarem and hollow Fe3O4-Au@PMAO hybrid NPs at different TR values Summary of the results of section 3.4: The antibacterial activity of Fe3O4/Ag@PMAO hybrid NPs is higher than that of Ag@PMAO NPs of the same size The hybrid 25 NPs exhibits strong antibacterial E.coli, L plantarum, B subtilis and medium activity against S lutea, S marcescens The application of the combined technique (MHT + PTT) significantly improves the heating efficiency of the hollow Fe3O4/Au@PMAO hybrid NPs The maximum temperature elevation is 68.5 oC with an SLP value of 1082.75 W/g at a sample concentration of mg/mL after 1200 s of treatment The combination of magnetic field and laser exposure can achieve therapeutic temperatures (42 ÷ 46 °C) while minimizing exposure intensities or reducing the concentration of hybrid NPs compared to the method using separated techniques The hollow Fe3O4/Au@PMAO hybrid NPs has a good image contrast signal which gradually increases with an increase in concentration in both T1- and T2- weighted modes with r1 = 8.47 mM-1 s-1 and r2 = 74.45 mM-1 s-1 CONCLUSION Magnetic ferrite nanoparticles MFe2O4 (M: Fe, Co, Mn) and Fe3O4/Ag and hollow Fe3O4/Au hybrid NPs were successfully fabricated The as-synthesized hybrid NPs with the average size below 20 nm can absorb the radiation in the NIR region After being coated by PMAO, Fe3O4-(Ag, Au) hybrid NPs exhibit high colloidal stability in water The Fe3O4@Ag@PMAO hybrid NPs exhibit toxicity against AGS and MKN45 cells depending on the concentration of the material IC50 values determined for AGS and MKN45 cells are 42 µg/mL and 58 µg/mL, respectively The hollow Fe3O4/Au@PMAO hybrid NPs not show toxicity on AGS and MKN45 cells in the concentration range of 10 ÷ 100 g/mL The antibacterial activity of the Fe3O4/Ag@PMAO hybrid NPs presents on both Gram-positive and Gram-negative bacteria and is higher than that of the Ag@PMAO NPs of the same size The heating efficiency of the hollow Fe3O4/Au@PMAO hybrid NPs is greatly enhanced by the combination of both magnetic field and laser irradiation (MHT + PTT) In the investigation range, the largest SLP value of the hollow Fe3O4/Au@PMAO hybrid NPs is 1082.75 W/g 26 The hollow Fe3O4/Au@PMAO hybrid NPs improve the contrast ability of the magnetic resonance images for both T1- and T2weighted modes with r1 = 8.47 mM-1 s-1 and r2 = 74.45 mM-1s-1 The as-synthesized hybrid NPs show multifunctional properties: magnetic, optical and antibacterial properties All things considered, this study demonstrates a highly applicable potential of Fe3O4-(Ag, Au) hybrid nanostructures for cancer diagnosis and therapy NEW CONTRIBUTIONS OF THE THESIS Magnetic ferrite nanoparticles MFe2O4 (M: Fe, Co, Mn) with uniform in size and shape were successfully synthesized by thermal decomposition in the 1-octadecene solvent The materials were fabricated at a high concentration of precursors to reduce the cost of the process Fe3O4/Ag hybrid NPs were successfully synthesized, their structure (core-shell or dumbbell), size, composition, and uniformity can be controlled by changing experimental conditions (Ag concentration) The hollow Fe3O4/Au hybrid NPs with a small size (less than 20 nm) were successfully synthesized, their surface plasmon resonance position can be shifted to the NIR region (above 700 nm) The hollow Fe3O4/Au@PMAO hybrid NPs can convert electromagnetic energy and light energy into heat with maximum productivity (SLP = 1082.75 W/g) when both magnetic field and laser irradiation are combined Additionally, they can enhance the contrast ability of the magnetic resonance images for both T1and T2-weighted modes and can be used as a dual-modal imaging contrast agent for magnetic resonance imaging LIST OF PUBLISHED PAPERS OF THE THESIS Thi Ngoc Linh Nguyen, Truc Vy Do, Thien Vuong Nguyen, Phi Hung Dao, Van Thanh Trinh, Van Phuc Mac, Anh Hiep Nguyen, Duc Anh Dinh, Tuan Anh Nguyen, Thi Kieu Anh Vo, Dai Lam Tran, Trong Lu Le, “Antimicrobial activity of acrylic polyurethane/Fe3O4-Ag nanocomposite coating”, Progress in Organic Coatings, 132,15-20, 2019 Nguyễn Thị Ngọc Linh, Lê Thị Thanh Tâm, Lê Thế Tâm, Ngô Thanh Dung, Phạm Hồng Nam, Nguyễn Văn Đàm Thiên, 27 Nguyễn Hoa Du, Phan Ngọc Hồng, Trần Đại Lâm, Lê Trọng Lư, “Nghiên cứu chế tạo khảo sát độ bền chất lỏng từ mangan ferit nước”, Tạp chí hóa học, 56(6e2), 214-219, 2018 Nguyễn Thị Ngọc Linh, Ngô Thanh Dung, Lê Thế Tâm, Lê Thị Thanh Tâm, Đào Thị Thu Hà, Trần Đại Lâm, Lê Trọng Lư, “Nghiên cứu chế tạo hạt nano Ag đơn phân tán dung mơi hữu cơ”, Tạp chí hóa học, 57(2E1,2), 11-15, 2019 Nguyễn Thị Ngọc Linh, Lê Thế Tâm, Lê Thị Thanh Tâm, Ngô Thanh Dung, Phạm Hồng Nam, Đoàn Thanh Tùng, Nguyễn Văn Đàm Thiên, Phan Ngọc Hồng, Trần Đại Lâm, Lê Trọng Lư, “Ảnh hưởng tiền chất vơ đến kích thước, độ đồng tính chất hạt nano Fe3O4 chế tạo phương pháp phân hủy nhiệt”, Tạp chí hóa học, 57(2E1,2), 22-26, 2019 Nguyễn Thị Ngọc Linh, Trịnh Đình Khá, Lê Thị Thanh Tâm, Lê Trọng Lư, Lê Thế Tâm, Ngô Thanh Dung, Võ Kiều Anh, “Hoạt tính kháng khuẩn dung dịch nano Ag tổng hợp dung môi hữu nhiệt độ thấp”, Tạp chí Phân tích Hóa, Lý Sinh học, 24(4A), 106-111, 2019 Nguyễn Thị Ngọc Linh, Trịnh Đình Khá, Lê Thị Thanh Tâm, Lê Thế Tâm, Hồng Yến Nhi, Ngơ Thanh Dung, Võ Kiều Anh, Lê Trọng Lư, “Nghiên cứu chế tạo hoạt tính kháng khuẩn hệ nano lai Fe3O4@Ag”, Tạp chí Phân tích Hóa, Lý Sinh học, 24(4A), 112-116, 2019 Nguyen T N Linh, Ngo T Dung, Le T T Tam, Tran D Lam, Nguyen X.Phuc, Nguyen T K Thanh and Le T Lu, “New insight into the synthesis and property of hollow Fe3O4-(Ag, Au) hybrid nanostructures for T1-T2 dual mode MRI imaging and dual magnetic/photo heating”, Proceedings of Nanomaterials for Healthcare conference, Da Nang, 2019 Lê Trọng Lư, Nguyễn Thị Ngọc Linh, Ngô Thanh Dung, Lê Thị Thanh Tâm, Lê Thế Tâm, Đinh Lan Chi, Hoàng Đức Minh, Trần Trung Kiên, Hoàng Thu Hà, Phạm Hồng Nam, Nguyễn Văn Đăng, Trần Đại Lâm, Nguyễn Xuân Phúc, “Quy trình chế tạo hệ vật liệu lai từ-quang có cấu trúc rỗng cho ứng dụng tăng cường hiệu ứng đốt nóng từ/quang ảnh cộng hưởng từ T1-T2”, Sở hữu trí tuệ, số đơn SC 1-2020-00238 (Đã chấp nhận đơn hợp lệ công bố công báo sở hữu công nghiệp số 384/T3, tập A: 69199 A, 2020) 28 ... Hồng Nam, Nguyễn Văn Đăng, Trần Đại Lâm, Nguyễn Xuân Phúc, “Quy trình chế tạo hệ vật liệu lai từ- quang có cấu trúc rỗng cho ứng dụng tăng cường hiệu ứng đốt nóng từ/ quang ảnh cộng hưởng từ T1-T2”,... Khá, Lê Thị Thanh Tâm, Lê Thế Tâm, Hồng Y? ??n Nhi, Ngơ Thanh Dung, Võ Kiều Anh, Lê Trọng Lư, ? ?Nghiên cứu chế tạo hoạt tính kháng khuẩn hệ nano lai Fe3O4@Ag”, Tạp chí Phân tích Hóa, Lý Sinh học, 24(4A),... Thi Ngoc Linh Nguyen, Truc Vy Do, Thien Vuong Nguyen, Phi Hung Dao, Van Thanh Trinh, Van Phuc Mac, Anh Hiep Nguyen, Duc Anh Dinh, Tuan Anh Nguyen, Thi Kieu Anh Vo, Dai Lam Tran, Trong Lu Le, “Antimicrobial