Summary of doctoral thesis in material science: Study of Magnetic Induction Heating mechanisms of spinel ferrite nanoparticles M1-xZnxFe2O4 (M=Mn, Co)

Research targets of the thesis: Fabricating spinel ferrite nanoparticle M1-xZnxFe2O4 (M = Mn, Co; 0,0 ≤x≤0,7) with controlled parameters affecting to Hc , TC and D. Establishing semi-experimental models based on experimental results to explain the correlation between SLP and (Keff, D) in order to figure out suitable mechanisms for calculating SLP value of CoFe2O4 nanoparticle.

MINISTRY OF EDUCATION AND TRAINING VIETNAM ACADEMY OF SCIENCE AND TECHNOLOGY GRADATE UNIVERSIY OF SCIENCE AND TECHNOLOGY  Pham Hong Nam STUDY OF MAGNETIC INDUCTION HEATING MECHANISMS OF SPINEL FERRITE NANOPARTICLES M1-xZnxFe2O4 (M = Mn, Co) Major: Electronic materials Code: 62.44.01.23 SUMMARY OF DOCTORAL THESIS IN MATERIAL SCIENCE Ha Noi - 2018 This thesis was done at: Laboratory of Biomedical Nanomaterials, Institute of Materials and Sciene, Vietnam Academy of Science and Technology Supervisor: Assoc.Prof., Dr Do Hung Manh Assoc.Prof., Dr Pham Thanh Phong Reviewer 1: Reviewer 2: Reviewer 3: The dissertation will be defended at Graduate University of Science and Technology, 18 Hoang Quoc Viet street, Hanoi Time: ., , 2018 This thesis could be found at National Library of Vietnam, Library of Graduate University of Science and Technology, Library of Institute of Materials and Science, Library of Vietnam Academy of Science and Technology INTRODUCTION Currently, application of nanoparticle in magnetic hyperthermia has been increasingly researched and developed, espescially mechanisms relating heat induced process of nanoparticles Studies mainly use Linear Respones Theory (LRT) to calculate Specific Loss Power (SLP) However, this theory is not always suitable in Magnetic Induction Heating (MIH) Accordingly, application of Stoner-Wohlfarth (SW) model is necessary The first study of Hert related to thermal mechanism magnetic particles being distinguised between hysteresis loss and relaxation loss However, this distinction was not enough to establish a full theoretical model for accurate calculation of SLP A recent study demonstrated the effet of hysteresis to heat induction by using numerical simulation Although the obtained results were suitable the authors have not established a full theoretical model for solving the SLP issue Some reports showed that physical factors such as size, shape, and content effect on the SLP value In which, the effective anisotropy constant (Keff) and size (D) of magnetic particle play the most important effect.Carrery et.al demonstrated that materials with different Keff s are consistent with theory models depending on the Keff value Materials with high Keff is consistent with the LRT model In constrast, materials with low Keff is consistent with the SW model Based on these theory models, the optimal SLP value is calculated by determining the optimal values of Keff and D These values depend on characteristics of nanoparticle including content, synthesis condition and material structure Therefore, how to select theoretical model for calculating SLP of materials is very interesting In Vietnam, magnetic nanopartices for biomedical application are concerned by a number of research groups at Institute of Materials Science (IMS), Institute for Tropical Technology (ITT), Hanoi University of Science and Technology (HUST) However, only research group at IMS studies deeply about physical mechanisms relating to hyperthermia The research group not only focuses on fabircation of spinel ferrite nanoparticles (Fe3O4, MnFe2O4, CoFe2O4), manganite nanoparticles (LSMO), alloy nanoparticles (CoPt, FeCo) but also figures out physical mechanisms through experimental results and theoretical calculation However, contribution of each physical mechanism in nanoparticles is not fully calculated Fe3O4 magnetic nanoparticle is alway the best selection for in-vitro and in-vivo magnetic hyperthermia thanks to easy fabrication and excellent biocompatibility However, the Curie temperature (TC) of Fe3O4 (TC = 823K) is much higher than the required temperature for killing cancer cell Thus, the saturation heating temperature is controlled by changing nanoparticle concentration and magnetic fied intensity Recently, magnetic nanoparticles with suitable Curie temperature (TC = 42 - 46oC), high saturation magnetisation and good biocompatibility have been focusing The spinel- structured nanomaterial M1-xZnxFe2O4 (M= Mn, Co; 0,0 ≤x≤0.7) is high potential because of good ability in controlling TC (or saturation heating temperature) In addition, CoFe2O4 nanoparticle have attracted a great deal of attention thanks to high anisotropy constant Therefore, this material has high SLP value Based on the above reasons, we chose the research project for thesis, namely: Study of Magnetic Induction Heating mechanisms of spinel ferrite nanoparticles M1-xZnxFe2O4 (M=Mn, Co) Research object of the thesis: Spinel ferrite nanoparticle M1-xZnxFe2O4 (M = Mn, Co; 0,0 ≤ x ≤ 0,7) Research targets of the thesis: Fabricating spinel ferrite nanoparticle M1-xZnxFe2O4 (M = Mn, Co; 0,0 ≤x≤0,7) with controlled parameters affecting to Hc, TC and D Establishing semi-experimental models based on experimental results to explain the correlation between SLP and (Keff, D) in order to figure out suitable mechanisms for calculating SLP value of CoFe2O4 nanoparticle Scientific and practical meaning of the thesis: Applying theoritical models (LRT and SW) to figure out physical mechanisms contributing to the formation of SLP which helps to more clearly understand about MIH in order to apply magnetic nanoparticle Research methodology: The thesis was carried out by practical experimental combining with numerical data process Random samples were fabricated by hydrothermal and thermal decomposition synthesis Samples were characterized by electron microscopes (FESEM and TEM) Magnetic properties of material were investigated by VibratingSample Magnetometer (VSM), PPSM, SQUID FTIR, TGA were used to evaluate the presence of functional groups on magnetic nanoparticles DLS was used to determind the hydrodynamic diameter and stability of magnetic fluid Magnetic Induction Heating was carried out on equipments: RDO-HFI- kW and UHF-20A- 20 kW Research contents of the thesis: Investigating the effect of fabrication parameters (reaction time, temperature, Zn content) on structure and magnetic properties of M 1-xZnxFe2O4 nanoparticles (M = Mn, Co; 0,0 ≤ x ≤ 0,7) Investigating the effect of particle size on structure and magnetic properties of CoFe2O4 nanoparticles Investigating the correlation between D, Keff for SLP Calculating and optimizing SLP based on particle size by numerical data process and experimental results Using critical parameters of LRT and SW models to evaluate physical mechanisms in formation of SLP of nanoparticles with different sizes Evaluating toxicity of magnetic fluid for hyperthermia testing on cancer cells Layout of the thesis: The contents of thesis were presented in chapters Chapter is review of spinel ferrite materials Chapter is about physical mechanisms and theoretical models applying in magnetic induction heating (MIH) Chapter presents experimental methods for fabricating nanoparticles Chapter is the results of fabrication of M1-xZnxFe2O4 (M=Mn, Co; 0,0 ≤ x ≤ 0,7) obtained by hydrothermal method Chapter is the results of fabrication of CoFe2O4 obtained by thermal decomposition method Research results of the thesis were published in 07 scientific reports including: 02 ISI reports, 03 national reports, 02 reports in national and international scientific workshop Main results of the thesis: Investigated effect of fabrication paramters on structure and magnetic properties of M1-xZnxFe2O4 (M=Mn, Co; 0,0 ≤ x ≤ 0,7) Fabricated CoFe2O4 nanoparticles with different size The effect of size on magnetic properties and SLP values was studied Applying numerical data process to find out the optimal size for magnetic induction heating Using critical parameters of LRT and SW models evaluate the mechanism contributing to formation of SLP Evaluated toxicity of magnetic fluid, carried hyperthermia experiment on cancer cell (Sarcoma 180) Chapter REVIEW OF SPINEL FERRITE MATERIALS 1.1 Structure and magnetic properties of spinel ferrite materials 1.1.1 Structure of spinel ferrite materials Ferrite spinel is term of materials which have structure containing crystal lattices The interaction between crystal lacttices is ferromagnetic interaction An unit cell of spinel ferrite crytal ( lattice constant – a ≈ 8,4 nm) is formed by 32 O2atoms and 24 cations (Fe2+, Zn2+, Co2+, Mn2+, Ni2+, Mg2+, Fe3+ and Gd3+) There are 96 positions for cations (64 octa-positions, 32 tetra-positions) 1.1.2 Magnetic property of spinel ferrite materials Based on molecular field theory, the origin of magnetic property of spinel ferrite material is the result of indirect interaction between metal ions (magnetic ions) locating in two lattices A and B through oxygen ions 1.2 Effecting factors on magnetic property of spinel ferrite nanoparticles Magnetic property of spinel ferrite nanoparticls is determined by factors including size, shape and content 1.3 Dynamic state of magnetic nanoparticles 1.3.1 Non-interacting magnetic nanoparticles Based on classical theory, spin- reversed speed of particle through potential energy depends on thermal energy and frequency according to Arrehenius law, calculating equation of relaxation time (τ0 ~ 10-9 - 10-13 s) for non-interacting magnetic nanoparticles 1.3.2 Weakly interacting magnetic nanoparticles Shtrikmann and Wohlfarth used mean field theory to establish the expression of releaxtion time of weaky interacting magnetic nanoparticles under Vogel-Fulcher law 1.3.3 Strong interacting magnetic nanoparticles By measuring the change of phase transition temperature by frequency in a wide range, the state of material could be determined whether spin glass or not when processing data by critical slowing down model 1.4 Biomedical application of magnetic nanoparticle Magnetic nanoparticle has been studying for medical applications including cell separation, drug delivery, MRI and magnetic hyperthermia Chapter PHYSICAL MECHANISMS AND THEORETICAL MODELS APPLIED IN MAGNETIC INDUCTION HEATING (MIH) 2.1 Induction heating mechanism of magnetic nanoparticls under AC magneitic field 2.1.1 Relaxation mechanism (Néel and Brown) In case of single domain size, anisotropic energy is smaller than heat energy, spin of nanoparticle could rotate every direction even without magnetic field If roating spin while keeping particle in one direction then after a period of time, spin will return to the original position That is Néel relaxtion time Néel relaxation is rotation of moment of magnetic nanoparticle Brown relaxation is the movement of magnetic nanoparticls in liquid 2.1.2 Hysteresis loss mechanism Hysteresis loss is energy loss in a magnetism process, determined by the area of hysteresis loop of material This process strongly depends on magnetic field intensity and intrinsic property of mangnetic nanoparticle 2.1.3 Other mechanisms Beside above mechanisms, induction heating of magnetic nanoparticle induces heat under AC magnetic field also happens by another mechanism That is the loss induced by friction in liquid 2.2 Theoretical models 2.2.1 Stoner-Wohlfarth (SW) model The SW model is a theoretical model use calculating the area energy of the delay of material when it magnetized to saturated LRT model is not suitable for materials without supperparamagnetism Accordingly, SW model is used Theoretically, some authors calculated magnetic resistance force by following equation: [ ] (2.16) 2.2.2 LRT model LRT model describes the linear reponse of magnetic moments under magnetic field The simulation result of magnetism process by magnetic field shows the linearity with magnetic field at  < This is the condition for application of LRT model 2.3 Calculation methods of Specific Loss Power (SLP) 2.3.1 Theoretical calculation of SLP For non-interacting superparamagnetic nanoparticle under AC magnetic field, maximum SLP is calculated by following equation: (2.21) 2.3.2 Experimental calculation of SLP a) Heat measurement method This is the most common method for determining heat induction capacity of magnetic liquid SPL value is calculated by the rate of increasing temperature: (2.24) b) Hysteresis loop measurement method SLP is calculated from hysteresis loop corresponding to applied magnetic field: ∮ (2.27) 2.4 State of art of Magnetic Heat Induction study Studies of MHI used many materials such as single nanoparticle, exchangecoupled materials, core-shell materials Supperparamagnetic nanoparticles, Fe3O4 and γ-Fe2O3, are most common studied thanks to good biocompatibility, specially success in MRI apllication Chapter EXPERIMENTAL METHODS 3.1 Fabrication of M1-xZnxFe2O4 (M = Mn, Co; 0,0 ≤ x ≤ 0,7) nanoparticle by hydrothermal method M1-xZnxFe2O4 (M = Mn, Co; 0,0 ≤ x ≤ 0,7) nanoparticles were fabricated by hydrothermal method described in the following diagram (Figure 3.1.) Figure 3.1 Fabrication process of M1-xZnxFe2O4 (M = Mn, Co; 0,0 ≤ x ≤ 0,7) nanoparticles 3.2 Fabrication of CoFe2O4@OA/OLA nanoparticles by thermal decomposition method CoFe2O4@OA/OLA nanoparticles were fabricated by thermal decomposition method described in the following diagram (Figure 3.2.) : Figure 3.2 Fabrication process of Figure 3.2 PMAO encaosulation CoFe2O4 @OA/OLA nanoparticles process 3.2.3 Phase transition of magnetic nanoparticle from organic solvent to water Phase transition process of magnetic nanoparticle from organic solvent to water was performed in the following diagram (Figure 3.5.) 3.3 Characterization methods Samples were characterized by electron microscopes (FESEM and TEM) Magnetic properties of material were investigated by Vibrating-Sample Magnetometer (VSM), PPSM, SQUID FTIR, TGA were used to evaluate the presence of functional groups on magnetic nanoparticles DLS was used to determind the hydrodynamic diameter and stability of magnetic fluid Magnetic Induction Heating was carried out on equipments: RDO-HFI- kW and UHF-20A- 20 kMaterial structure was studied by X-ray diffraction, electron microscopy 3.4 Toxicity evaluation of magnetic fluid on cancer cell Evaluating cancer cell killing ability of magnetic fluid on cancer cell 3.5 Magnetic hyperthermia of magnetic fluid on cancer cell Evaluating death ratio of cancer cell after magnetic hyperthermia by changing temperature and magnetic fied application time Chapter STRUCTURE, MAGNETIC PROPERTY AND MAGNETIC INDUCTION HEATING OF M1-xZnxFe2O4 (M = Mn, Co; 0,0 ≤ x ≤ 0,7) NANOPARTICLES FABRICATED BY HYDROTHERMAL METHOD 4.1 Effect of reaction temperature on structure and magnetic property MnFe2 MnFe3 25 30 35 40 45 50 (440) (511) CoFe2 CoFe3 CoFe4 MnFe4 55 60 25 (b) 65 2(®é) (a) CoFe1 (422) (400) (311) (222) (220) (440) (511) C-êng ®é (®.v.t.y) MnFe1 (422) (400) (311) (222) C-êng ®é (®.v.t.y) (220) 4.1.1 Effect of reaction temperature on structure 30 35 40 45 50 55 60 65 2(®é) Figure 4.1 X-ray diffraction of samples: MnFe2O4 (a) and CoFe2O4 (b) at different temperatures in 12 hours Figure 4.1a and 4.1b are the X-ray diffraction of MnFe2O4 and CoFe2O4 nanoparticles fabricated by hydrothermal method at different temperatures, coded: 120oC (MnFe1, CoFe1), 140oC (MnFe2, CoFe2), 160oC (MnFe3, CoFe3) and 180oC (MnFe4, CoFe4) with reaction time of 12 hours It was showed that both kinds of sample are single crystal expressed at characteristic peaks (220), (311), (222), (440), (442), (511), (440) When increasing temperature reaction, particle size of two kinds of sample increases 4.1.2 Effect of reaction temperature on magnetic property Saturation magnetism Ms increases from 31,1 emu/g (MnZn1) to 66,7 emu/g (MnZn4) (Figure 4.4a) and from 59,3 emu/g (CoZn1) to 68,8 emu/g (CoZn4) when changing reaction temperature from 120oC to 180oC (Figure 4.4b) force Hc for both kinds of samples changed but it did not follow the law of Herzer which is that Hc decreases when particle size decreases only in single domain size range 4.3 Effect of Zn2+ content on structure and magnetic property 4.3.1 Effect of Zn2+ content on structure With the aim of fabricating materials possessing Curie temperature lower than 42oC-46oC (temperature kills cancer cell), we studied effect of Zn 2+ on structure and magnetic property of Mn1-xZnxFe2O4 Co1-xZnxFe2O4 (x = 0,0; 0,1; 0,3; 0,5 0,7) nanoparticles, coded: MnZn0, MnZn1, MnZn3, MnZn5 MnZn7; CoZn0, CoZn1, CoZn3, CoZn5 CoZn7 All samples were fabricated at 180oC in 12h X-ray diffraction in figure 4.9 show that both kinds of sample are single phase spinel structure However, diffraction peaks of Mn1-xZnxFe2O4 are sharper than that of Co1xZnxFe2O4, meaning that the size of Mn1-xZnxFe2O4 nanoparticle is bigger than that of Co1-xZnxFe2O4 nanoparticle In one kind of sample, increasing Zn2+ leads to MnZn5 MnZn3 MnZn1 30 35 40 45 50 (440) (511) CoZn5 CoZn3 CoZn1 CoZn0 MnZn0 25 (a) CoZn7 (422) (400) (311) (222) (220) C-êng ®é (®.v.t.y) (440) (511) MnZn7 (422) (400) (311) (222) (220) C-êng ®é (®.v.t.y) decreasing intensity of diffraction peaks showing that the particle size decreases 55 60 25 65 2(®é) (b) 30 35 40 45 50 55 60 65 2(®é) Figure 4.9 X-ray diffractions of Mn1-xZnxFe2O4 nanoparticles (x = 0,0; 0,1; 0,3; 0,5 and 0,7) (a) and Co1-xZnxFe2O4 nanoparticles (x = 0,0; 0,1; 0,3; 0,5 0,7) (b) 4.3.2 Effect of Zn2+ content on magnetic property Figure 4.14 shows hysteresis loops of Mn1-xZnxFe2O4 nanoparticles (x = 0,0; 0,1; 0,3; 0,5 0,7) measured at room temperature Compared to MnZn0 sample without Zn, Ms achieved the highest values at 66,7 emu/g and gradualy decreased when increased Zn2+ content MnZn7 sample had the lowest value at 29,8 emu/g Temperature dependence of magnetism of samples measured at 100 Oe, in Field Cooled manner was showed in figure 4.15 Samples exhibited the ferromagnetic10 paramagnetic phase transition at differrent TC TC values of MnZn0, MnZn1, MnZn3, MnZn5 MnZn7 were 620 K, 560 K, 440 K, 350 K 330 K 14 80 20 10 -20 M (emu/g) M (emu/g) 40 -40 -60 -80 -1 104 MnZn0 MnZn1 MnZn3 MnZn5 MnZn7 H (Oe) 2 0-80 -5000 MnZn0 MnZn1 MnZn3 MnZn5 MnZn7 12 M (emu/g) 60 MnZn0 MnZn1 MnZn3 MnZn5 MnZn7 -60 -40 -20 H (Oe) 5000 0 100 10 200 300 400 500 T (K) 600 700 Figure 4.14 Hysteresis loops of Figure 4.15 Temperature Mn1-xZnxFe2O4 (x = 0,0; 0,1; 0,3; 0,5 dependence of magnetism of and 0,7) Smaller figure is hysteresis Mn1-xZnxFe2O4 (x = 0,0; 0,1; 0,3; 0,5 loop at low magnetic field and 0,7) measured at 100 Oe For Co1-xZnxFe2O4 nanoparticles (x = 0,0; 0,1; 0,3; 0,5 and 0,7), the change of Ms was similar to Mn1-xZnxFe2O4 nanoparticles Ms decreased when increasing Zn2+ content, achieving the highest value at 68,8 emu/g at x = 0,0 The reduction of saturation magnetism of Co1-xZnxFe2O4 nanoparticels could be explained by coreshell structure In this structure, the core has magnetism, shell is considered as nonmagnetism because of that spin on the surface of shell arrange disorderly Temperature dependence of magnetism of Co1-xZnxFe2O4 (x = 0,0; 0,1; 0,3; 0,5 and 0,7) measured in FC and ZFC (Zero Field Cooled - ZFC) manners at 100 Oe was showed in figure 4.17 From the results, TC and Blocking temperaute (TB) were determined Below TB , randomly orriented spins are “locked” at non-stable state This state is gradually lost when temperature increase to TB Under magnetic field, spins are oriented in the direction of magnetic field Thus, magnetism value measured in FC manner is higher than that in ZFC manner and little changes at T < TB 11 ⁄ 12 FC ZFC 10 T B M (emu/g) 4.4 Interaction betwwen magnetic nanoparticles Some studies demonstrated that at nano scale, materials have some differents properties compared to bulk materials When the size of material is smaller than the critical size CoZn0 CoZn1 CoZn3 CoZn5 ( (magnitude of CoZn7 exchange interaction, K- anisotropy constant, 200 300 400 500 600 700 M- Spontaneous magnetism), each nanoparticle T (K) is single domain with spin about 10 Bohr Figure 4.17 Temperature magneton and called “super spin” There are dependence of Co1-xZnxFe2O4 kinds of super spin: non/weakly interacting nanoparticles (x = 0,0; 0,1; 0,3; super spin (inducing superparamagnetim) and 0,5 and 0,7) measured in FC and strongly interacting super spin (inducing spin ZFC manners at 100 Oe glass state) Both cases are not same and verry difficult to distinguish There are some measurements and theoretical models to study intrinsic magnetic property of nanoparticles In case of strongly interacting magnetic nanoparticles, critical slow model is the best to study this case In case of non interacting magnetic nanoparticles, Néel-Brown model is suitable for studying experimental data In other way, if there is interaction between nanoparticles but not enough to induce spin glass state, Vogel-Fulcher model will be used to study the magnetic property Based on these information, we chose these theoretical models along with our experimental data to figure out magnetic interaction of MnZn7 and MnZn5 samples The obtained results showed that these samples fit the critical slow model 4.5 Self-regulated Magnetic Induction Heating 4.5.1 MnZn7 and MnZn5 nanoparticles Figure 4.31 is the magnetic induction heating of MnZn7 nanoparticle at different concentrations: mg/ml, mg/ml, 10 mg/ml 15 mg/ml under different magnetic fields (50-80 Oe, 236 kHz) It was showed that the magnenetic induction heating increases along with the increase of magnetic field Temperature increases linearly at the fist stage from bigining to 250s After that temperature increases slower and reaches almost saturation at 1500s Moreover, Tb at 1500s are alway lower than 48oC and TC (55oC) when increasing both magnetic field intensity and 12 concentration of magnetic nanoparticles This could be explained by the escapse of a part of heat to outside Therefore, Tb in all experimental conditons are alway smaller than TC 55 55 80 70 60 50 mg/ ml 60 Oe 40 35 35 30 300 600 (a) 900 t (s) 1200 1500 50 45 Oe Oe Oe Oe 600 900 1200 1500 t (s) 80 70 60 50 15 mg/ml 50 T (oC) T (oC) 300 55 80 70 60 50 10 mg/ml 40 45 Oe Oe Oe Oe 40 35 35 (c) (b) 55 30 50 Oe 45 40 70 Oe 50 45 30 80 Oe mg/ml T (oC) T (oC) 50 Oe Oe Oe Oe 30 300 600 900 1200 1500 (d) t (s) 300 600 900 1200 1500 t (s) Figure 4.31 Magnetic induction heating of MnZn7 at different magnetic field intensities,236 kHz, concentrations: 3mg/ml (a), mg/ml (b), 10 mg/ml (c) and 15 mg/ml (d) The fast increase of temperature at the first stage is the result of hysteresis loss, relaxation loss (Néel, Brown) and vortex current loss Other way, superparamagnetic state at room temperature was obseverd on MnZn7 sample Therefore, the Magnetic induction heating of MnZn7 is the result of relaxation loss (Néel, Brown) H2 dependence of SLP at different concentrations is showed in figure 4.32 SLP depends linearly with H2 at determined concentrations Therefore, the obtained results fit with LRT model, meaning that the obtained SLP is only the result of relaxation mechanism (Néel, Brown) Calculated SLP of MnZn5 shows that when concentration of magnetic nanoparticles increases from 3mg/ml to mg/ml, SLP decreases from 28,38 W/g to 25,52 W/g at 80 Oe The increase of magnetic 13 SLP (W/g) nanoparticle concentration increases the aggregation of nanoparticles in liquid leading to the increase of dipole-dipole interaction 25 and the reduction of inducting heat The result 15 mg/ml demonstrated that concentration increase is not 10 mg/ml 20 mg/ml the reason for high SLP mg/ml 4.5.2 CoZn7 and CoZn5 nanoparticles Figure 4.36 is the magnetic induction heating of CoZn7 and CoZn5 at different magnetic fields from 50-80 Oe with the mangnetic concentrations of mg/ml and mg/ml At the first stage from the beginning to 350s, temperature increases linearly in all experimental conditions 48 0 10 20 30 40 50 H2 (kA/m)2 Figure 4.32 H2 denpendence of SLP at different concentrations of magnetic nanoparticles 80 Oe mg/ml 44 T (oC) 40 36 36 32 32 300 600 60 Oe 50 Oe 40 (a) mg/ml 70 Oe o T ( C) 10 48 80 Oe 70 Oe 60 Oe 50 Oe 44 900 1200 1500 300 600 (b) t (s) 52 900 t (s) 1200 1500 65 80 Oe 70 Oe 60 Oe 50 Oe 48 mg/ml 80 Oe 70 Oe 60 Oe 50 Oe 60 55 mg/ml 50 o T ( C) 44 T (oC) 15 40 45 40 36 35 32 (c) 300 600 900 1200 1500 (d) t (s) 300 600 900 1200 1500 t (s) Figure 4.36 Magnetic induction heating of CoZn7 at concentrations of mg/ml (a), mg/ml (b); CoZn5 at concentrations of mg/ml (c), mg/ml (d), measured under different magnetic fields from 50 to 80 Oe, frequency 178 kHz 14 After the first stage, temperature increases slower and reaches almost saturation at 1500s Induced heat depends on magnetic field intensity at the same frequency (178 kHz) Increasing magnetic field intensity leads to increase of Tb In addition, (ΔT) of CoZn7 and CoZn5 at different concentrations at the beginning to the end of applying magnetic field increases when increasing magnetic field intensity from 50 to 80 Oe It is showed that when increasing magnetic field intensity, SLP of CoZn7 increases for both concentrations (1 mg/ml and mg/ml) SLP of CoZn7 (1 mg/ml) are 20,48 W/g (50 Oe) and 64,37 W/g (80 Oe) Obtained experimental SLP was fit by SLP  Hα law with α > at different concentrations Therefore, SLP does not fit with LRT model (SLP  H2) 4.5.3 Comparition of SLP between experimental data and LRT model using size distribution In theoretical study, size (D) of nanoparticle is often used with σ = In fact, for any synthesis method, size of obtained nanoparticle always has σ > The obtained results showed that MnZn5 and MnZn7 is suitable with LRT model, meaning that the mechanism of formation of SLP is only (Neél and Brown) relaxation loss In contrast, for CoZn5 and CnZn7 samples, SLPHC is higher than SLPLRT It is said that hysteresis loss happens in these two samples This result fits with experimental data (SLP does not fit with LRT model (SLP  H2)) In conclusion, changing temperature, time and Zn2+ content lead to change of size and magnetic property Study of magnetic induction heating of MnZn7, MnZn5, CoZn7, CoZn5 nanoparticles shows that SLP increases when increasing magnetic field intensity and decreases when increasing magnetic nanoparticle concentration In case of MnZn7 and MnZn5 samples, SLP depends linearly with H and follows H2 law However, in case of CoZn7 and CoZn5 samples, SLP depends linearly with H bit does not follow H2 law with α > Chapter MAGNETIC INDUCTION HEATING, TOXICITY AND CANCER HYPERTHERMIA OF MANGNETIC NANOPARTICLE ( CoFe2O4@OA/OLA-PMAO) FABRICATED BY THERMAL DECOMPOSITION 5.1 Structure and magnetic property of CoFe2O4@OA/OLA nanoparticle 5.1.1 Structure and morphology of CoFe2O4@OA/OLA nanoparticle 15 Figure 5.1 shows X-ray diffraction of CF1, CF2, CF3 and CF4 samples 6,3 nm, 8,6 nm, 10,6 nm 20,6 nm, standard deviations calculated by CF2 CF3 CF4 LogNormal are ± 0,8 nm (12,6%), ± 1,3 nm (15%), ± 1,5 nm (15%) ± 2,4 nm 10 20 30 40 50 60 70 2(®é) (11,2%) 5.1.2 (440) C-êng ®é (®.v.t.y) spinel structure with the mean size of (400) CF1 method All samples are single phase (422) (511) decomposition (311) thermal (222) by (220) fabricated Magnetic property Hình 5.1 Giản đồ nhiễu xạ tia X mẫu of CF1, CF2, CF3 CF4 tổng hợp CoFe2O4@OA/OLA nanoparticles phương pháp phân hủy nhiệt Figure 5.3 shows hysteresis loops of samples measured at 300 K CF4 sample has highest saturation magnetism of 70 emu/g, (smaller than saturation magnetism of bulk material: 80 emu/g) Sizes of CF1 and CF2 samples are smaller than 10 nm and their Hcs are nearly zero, meaning that they exhibit superparamagnetic state at room temperature CF4 60 CF3 40 CF2 CF1 M (emu/g) 20 50 CF4 -20 M (emu/g) M (emu/g) 80 -40 CF3 FC CF2 CF1 -60 TB -50 -500 ZFC 500 H (Oe) -80 -1 10 -5000 H (Oe) 5000 10 100 150 200 250 300 350 400 450 T (K) Figure 5.3 Hysteresis loops o CF1, Figure 5.4 Temperature dependene CF2, CF3 and CF4 samples Smaller of magnetism of CF1, CF2, CF3 and figure is hysteresis loop at low CF4 samples measured in FC-ZFC magnetic field manner under mangetic field of 100 Oe Ferromagnetism is exhibited on CF3 (Hc = 40 Oe) and CF4 (Hc = 480 Oe) and particle size beyond the critical size range of superparamagnetism Both Ms and Hc 16 increases when particle size increases Ms is low with small size and reaches highest value at size of 20,6 nm Figure 5.4 shows temperature denpendence of magnetism measured in FC and ZFC manners under 100 Oe CF1, CF2 and CF3 samples have maximum points (TB) on ZFC line 5.2 Phase transfer of CoFe2O4@OA/OLA nanoparticle using PMAO For biomedical applications, one of essential requirements is aqueous dispersion Figure 5.7 is the images of CF3 sample before and after encapsulation of PMAO (which is an amphiphilic polymer) in hexan and water It is seen that before encapsulation of PMAO, the nanoparticles is well-dispersed in hexan and absolutely can not disperssed in water (Figure 5.7a and 5.7b) After encapslutated by PMAO, surface of CoFe2O4 becomes hydrophylicity and well-dispersed in water (figure 5.7c and 5.7d) Furthermore, magentic nanparticles after encapsulated by PMAO still have strong magnetism (figure 5.7e) Hình 5.7 CoFe2O4 nanoparticle before and after encapsulating PMAO in hexane (a) in in mixture of hexane and water (b); CoFe2O4 nanoparticle encapsulated by PMAO in water (c) and in mixture of hexane and water (d).CoFe2O4 encapsulated by PMAO in mixture of hexane and water under application of magnet (e) For mixture of hexane and water, the upper part is hexane,the under part is water 5.3 Magnetic induction heating of CoFe2O4@OA/OLA-PMAO nanoparticle 5.3.1 Heat inducing capacity of o CoFe2O4@OA/OLA-PMAO nanoparticle To understand effect of magnetic field parameters (H,f) to heat inducing process of magnetic liquid (CF1, CF2, CF3, and CF4 transfered to aqueous environment with the magnetic nanoparticle concentration of mg/ml, magnetic induction heating was carried out at H (100-300 Oe) and f (290-450 kHz) with the 17 rule that when H changes, f is fixed and reverse Based on experimental data, SLP value was calculated The obtained results showed that there are changes at different H and f for all samples This trend demonstrated that the temperature changing process at the beginning stage of magnetic induction heating process in fist 300s From the calculated results, maximum SLP (297,4 W/g, 300 Oe, 450 kHz) was reached at particle size of 10,6 nm 5.3.2 Contributing mechansims and Specific Loss Power, Neél and Brown 250 300 SLP hys SLPB SLP 150 N 100 50 SLPN 150 SLP 100 100 150 200 250 300 100 150 (b) H (Oe) 200 250 300 H (Oe) 300 300 CF3 SLPhys SLP 200 SLP SLP B N SLP 150 150 SLP 50 50 150 200 H (Oe) 250 B SLPN 100 CF4 hys 200 100 100 SLP 250 SLP (W/g) 250 SLP (W/g) 200 50 (a) (c) CF2 hys SLPB SLP SLP 250 SLP (W/g) SLP (W/g) 200 CF1 300 (d) 100 150 200 250 300 H (Oe) Figure 5.22 SLPhys, SLPB, SLPN and SLP depend on magnetic field of different magnetic liquids Early studies suggested that SLP of superparamagnetic nanoparticle only depends on Néel and Brown relaxation The interference of two processes depends on anisotropic constant Keff and particle volume V Néel relaxation time τN depends on (eα) of Keff and V, meanwhile, Brown relaxation time (τB ) changes linearly with V and viscosity (η) of solvent Suggesting that viscosity of magnetic nanoparticle is similar to water η =1,01x10-3 Pa.s = 1,01x10-3 kg.m-1.s-1 Neél and Brown relaxation 18 time will be calculated When two losses happen at the same time, sorter relaxation time will predominate In magnetic induction heating, there are main mechanisms including hysteresis loss (SLPhys), Neél relaxation loss (SLPN) and Brown relaxation loss (SLPB) The constribution of each mechanism on the formation of SLP is different depending on Keff and D Therefore, the estimation of each mechanism on SLP is very difficult For estimating Brown relaxation, 1mg/ml of CF1, CF2, CF3 and CF4 encapsulated by PMAO were dispersed in agar solution (2%), SLPhys of samples are showed in figure 5.22 5.3.3 Theoretical and experimental optimal size LRT model was used to optimize experimental paramters in magnetic induction heating In this model, optimal particle volume (Vopt) is determinded by following equation: ⁄ ( (5.3) ) kB – Boltzmann constant (1,38 x 10-23 J.K-1), T - (300 K), f -frequency (kHz), τo – standard relaxation time (10-9 s), Keff –anisotropic constant ((1,8-3,0) x 105 J.m-3), μoHmax – applied magnetic field (4 x 10-7 H.m-1 x μoHmax A.m-1) and Ms –saturation magnetism (336 kA.m-1) f = 450 kHz, Hmax = 24 kA.m-1, Dopt = [6x(V/)]1/3 = nm, Keff = 3,0x105 J.m-3 and 14 nm, Keff = 1,8x105 J.m-3 For this calculation, optimal size is in the range of nm - 14 nm 5.3.4 SW and LRT theoretically model Theoretically, SLP is an important parameter to evaluate heat inducing capacity of magnetic liquid and determined by the following equation: (5.5) A3 is calculated by quation 5.6 or 5.7 depeding on  = KeffV/kBT (ratio of anisotropic energy and heat energy): * + (5.6) * + (5.7) or 19 is a multivariable function It is difficult to calculate SLP of material To understand clearly the effect of anistropic constant on SLP, LRT model was used to calculate SLP of CF1, CF2, CF3 and CF4 by using experimental data in case of with: (5.8) Other way, SW model showed good results for multi domain nanoparticles when k < 0,7: ( ) (5.9) To determine which model is the most suitable, experimental data was used to calculate The obtained results showed that CF1, CF2 and CF3 have CF4 has < 1, k > 0,7, , not suitable with LRT model 5.4 Stability and toxicity of CoFe2O4@OA/OLA-PMAO magnetic fluid Stability of magnetic fluid in 120 physiological environment is an important body, salt concentration is in the range of 165 ÷ 180 mM, pH 7,5 Therefore, the Tỷ lệ tăng sinh (%) requirement for biomedical application In 100 80 60 40 stability of magnetic fluid was examinded in 20 aqueous solution with the salt concentrations of 165 mM, 180 mM, 200 mM, 220 mM 1.56 3.152 6.25 12 25 50 Nång ®é g/ml) 100 250 mM and pH: 1, 2, 4, 5, 7, and 11 The Figure 5.32 Proliferation of results Sarcoma 180 cell at different showed that magnetic fluid containing CoFe2O4@OA/OLA-PMAO is magnetic nanoparticle concentration stable enough for biomedical application CF3 sample was test toxicity on cancer cell (Sarcoma 180) Cells were cultured in 96-well plate with density of 2000 cells/well before adding CF3 magnetic nanoparticle at concentrations of 100 µg/ml (C1), 50 µg/ml (C2), 25 µg/ml (C3), 12,5 µg/ml (C4), 6,25 µg/ml (C5), 3,125 µg/ml (C6) 1,56 µg/ml (C7) The proliferation of Sacroma 180 cell was different at different concentrations of CF3 (Fiugre 5.32) The results showed that CF3 magnetic fluid is not toxic on Sacroma 180 at studied concentrations 20 5.5 Hyperthermia on Sacomar 180 cell CF3 magnetic concentration of fluid 100 with the 100 µg/ml 80 Tû (%) (corresponding to 0,04 ng/cell) was selected for hyperthermia experiment on Sacomar 180 cell Two hyperthermia 60 40 methods were carried out: method 1: 20 appling magnetic field to induce heat T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 from magnetic nanoparticle, method 2: using magnetic stirrer to heat the sample Figure 5.37 Cell death (%) at different (MHT) Figure 5.37 shows the cell death experimental conditions at different experimental conditions (EHT): T1: cancer cell control, cell death: 9,3%; T2: magnetic nanoparticle control, cell death: 10,6%; T3: magnetic field control, cell death: 10,4%; T4: magnetic hyperthermia at 40oC, 10 min, cell death: 10,5%; T5: magnetic hyperthermia at 42oC, min, cell death: 14,8%; T6: magnetic hyperthermia at 42oC, min, cell death 73,5%; T7: magnetic hyperthermia at 42oC, min, cell death: 93,7%; Exogenous heating at 42oC, min, cell death 17,1%; T9: Exogenous heating at 42oC, min, cell death 19,4%; T10: Exogenous heating at 42oC, min, tế cell death 23,2%; T11: cell death, after 15 minutes (at T7), cell death 98,7% Magnetic hyperthermia induced 90% cell death at 42oC in In conclusion, SLP value of CoFe2O4 magnetic fluid increases linearly with H and f CF1, CF2, CF3 sample is suitable with LRT model, SW model is suitable for CF4 sample Toxicity of magnetic fluid was evaluated on Sacomar 180 cancer cell The result showed that at the highest concentration of 100 µg/ml, cell death is smaller than 50%, meaning safety to cell For hyperthermia experiment, MHT method induced 90% cell death at 42oC in min, meanwhile, at the same condition, EHT induced only 23,7% cell death This result demonstrated the efficacy of magnetic hyperthermia method 21 CONCLUSION Success in fabrication of M1-xZnxFe2O4 (M = Mn, Co; 0,0 ≤ x ≤ 0,7) with single phase spinel structure, spherical shape by hydrothermal method Optimal fabricating conditions for maximum saturation magnetism are: reaction temperature- 180oC, reaction time- 12h Increase of Zn2+ content leads to decrease of Ms, Hc, TC of Mn1-xZnxFe2O4, Co1xZnxFe2O4 MnZn7 has TC = 330 K, CoZn7 has TC = 380 K Although these values are higher than temperature killing cancer cell, magnetic resistance force Hc achieves requirement for hyperthermia Specific Loss Power (SLP) of MnZn7, MnZn5, CoZn7, CoZn5 and CoFe2O4 nanoparticles increases when increasing magnetic field intensity and decreases when increasing nanoparticle concentration For MnZn7 and MnZn5, SLP is proportional to H2 However, SLP of CoZn7 and CoZn5 increases with increase of H but is not proportional to H2 CoFe2O4 fabricated by thermal decomposition method was transferred to aqueous phase by using PMAO The obtained samples are very stable in different salt concentrations and pHs with zeta potential in range of - 60 mV to 60 mV CF3 sample is stable at pH ≥ and salt concentration ≤ 230 mM Magnetic induction heating was examined under different magnetic field (100300 Oe and 290-450 kHz) SLP increases linearly with H and f In case of CF3, maximum SLP is 297,4 (W/g) under 300 Oe, 450 kHz For CF and CF2, Neél mechasnim contributes mainly to the formation of SLP For CF3 and CF4, which mechanism for the formation of SLP is not clearly understood Size of maximum SLP of CF3 is 10,6 nm Heat inducing mechanism of CF1, CF2, CF3 magnetic fluid is in good agreement with LRT model, meanwhile, SW model is suitable for CF4 Toxicity of magnetic fluid was evaluated on Sacomar 180 cell At the highest concentration of 100 µg/ml, cell proliferates above 50% Therefore, the magnetic fluid does not induce toxicity on cancer cell 22 MHT and EHT are two methods applied for cancer hyperthermia In case of MHT,there is 90% cell death at 42oC in Meanwhile, in case of EHT, at the same conditions, there is 23 only 23,7% cell death PUBLISHED REPORTS USED IN THIS THESIS Pham Thanh Phong, P.H Nam, Do Hung Manh, D.K Tung, In-Ja Lee & N.X Phuc, Studies of the Magnetic Properties and Specific Absorption of Mn0.3Zn0.7Fe2O4 Nanoparticles, Journal of Electronic Materials, 44 (2015) 287294 P.T Phong, P.H Nam*, D.H Manh, In-Ja Lee, Mn0.5Zn0.5Fe2O4 nanoparticles with high intrinsic loss power for hyperthermia therapy, Journal of Magnetism and Magnetic Materials, 433 (2017) 76-83 Phạm Hồng Nam, Trần Đại Lâm, Nguyễn Xuân Phúc, Đỗ Hùng Mạnh, Ảnh hưởng nồng độ Zn tới tính chất từ đốt nóng cảm ứng từ hệ hạt nano Mn 1XZnXFe2O4, Tạp chí Khoa học Cơng nghệ 52 (3B) (2014) 136-143 Phạm Hồng Nam, Phạm Thanh Phong, Đỗ Hùng Mạnh, Nghiên cứu cấu trúc tính chất từ hệ hạt nano Co1-xZnxFe2O4 (x = 0-0,7) chế tạo phương pháp phân hủy nhiệt, Tạp chí Khoa học Công nghệ 54 (1A) (2016) 25-32 P.H Nam, L T Lu, V.T.K Oanh, D.K.Tung, D.H Manh, P.T Phong, N.X Phuc, Magnetic heating of monodisperse CoFe2O4 nanoparticles encapsulated by poly(maleic anhydride-alt-1-octadecene), Proceedings of The 8th International Workshop on Advanced Materials Science and Nanotechnology, Ha Long City, Vietnam, 8-12 November (2016) 171-182 Phạm Hồng Nam, Nguyễn Thị Thảo Ngân, Đỗ Hùng Mạnh, Lê Trọng Lư, Phan Mạnh Hưởng, Phạm Thành Phong, Nguyễn Xuân Phúc, Nghiên cứu so sánh công suất tổn hao riêng xác định từ đường cong từ trễ từ trường xoay chiều lý thuyết đáp ứng tuyến tính, Tuyển tập báo cáo Hội nghị vật lý chất rắn toàn quốc lần thứ X, TP Huế, Việt Nam, 19-21, tháng 10 (2017), 64-67 Pham Hong Nam, Luong Le Uyen, Doan Minh Thuy, Do Hung Manh, Pham Thanh Phong, Nguyen Xuan Phuc, Dynamic effects of dipolar interactions on the specific loss power of Mn0.7Zn0.3Fe2O4, Vietnam Journal of Science and Technology 56 (1A) (2018) 50-58 ... Chapter REVIEW OF SPINEL FERRITE MATERIALS 1.1 Structure and magnetic properties of spinel ferrite materials 1.1.1 Structure of spinel ferrite materials Ferrite spinel is term of materials which... study intrinsic magnetic property of nanoparticles In case of strongly interacting magnetic nanoparticles, critical slow model is the best to study this case In case of non interacting magnetic nanoparticles, ... tetra-positions) 1.1.2 Magnetic property of spinel ferrite materials Based on molecular field theory, the origin of magnetic property of spinel ferrite material is the result of indirect interaction between