Summary of chemistry doctoral thesis: Study on the fabrication of magnetic fluids based on superparamagnetic iron oxide nanoparticles (SPIONs) applied to magentic resonance imaging (MRI)

The goad of the thesis is to build the manufacture process of nano-sized magnetic fluids based on iron oxide (uniform particle size and high magnetic saturation) with stable technology; Characteristic research of magnetic properties of magnetic nanoparticles; assessment of toxicity and test of effects on cells, aiming to make contrast medicine in imaging diagnosis by magnetic resonance imaging (MRI), application on accurately identifying cancer.

MINISTRY OF EDUCATION AND TRAINING VIETNAM ACADEMY OF SCIENCE AND TECHNOLOGY GRADATE UNIVERSIY OF SCIENCE AND TECHNOLOGY  LE THE TAM STUDY ON THE FABRICATION OF MAGNETIC FLUIDS BASED ON SUPERPARAMAGNETIC IRON OXIDE NANOPARTICLES (SPIONs) APPLIED TO MAGENTIC RESONANCE IMAGING (MRI) APPLICATION Major: Inorganic chemistry Code: 9.44.01.13 SUMMARY OF CHEMISTRY DOCTORAL THESIS Ha Noi - 2019 This thesis was done at: Laboratory of Biomedical Nanomaterials, Institute of Materials and Sciene, Vietnam Academy of Science and Technology Laboratory of Electronic-Electrical Engineering, Institute for tropical technology, Vietnam Academy of Science and Technology Centre for Pratices and Experimences, Vinh University Supervisor: Prof., Dr Tran Dai Lam Assoc.Prof., Dr Nguyen Hoa Du 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: ., , 2019 This thesis could be found at National Library of Vietnam, Library of Graduate University of Science and Technology, Library of Chemistry, Library of Vietnam Academy of Science and Technology INTRODUCTION Recent applications of magnetic nanoparticles in biomedical applications, especially in imaging diagnostics using MRI Magnetic Resonance Imaging engineering have attracted the attention of scientists around the world Currently in imaging diagnostics using MRI magnetic resonance imaging, Tl contrast agents have become a traditional commodity, which is a complex of paramagnetic ions with a large torque value like Gd3+ (7 unpaired electrons) These Gd3+ ions are combined with molecules such as DTPA (diethylentriamine penta acetic acid) and create Gd-DTPA chelate round complex structures During the recovery process, the interaction between the magnetic moment of the proton and the magnetic moment of the paramagnetic ions causes the T1 time to be reduced, so the recovery rate R1 increases The concentration of agents is different in each cell tissue region, thus providing an effective contrasting on MRI images For nearly 10 years now, along with the development of nanotechnology iron oxide (IO) nanoparticle having been strongly researched and actual many commercial products that increase MRI contrast levels using this iron oxide material, proving that iron oxides-MRI can give better quality of contrast level than Gd-DTPA because iron oxide particles have a higher magnetic induction coefficient IO-MRI substances can reduce both T1 and T2, increasing MRI recovery rates in both Tl and T2 MRI modes The important requirements for MRI contrast increasing products are that magnetic nanoparticles must have a relatively uniform particle distribution and magnetic saturation enough large, and the coating materials must have good biological compatibility While some commercial products in the world, such as Resovist, use dextran as a coating material, with a 65 nm core particle created from saturation of about 65 emu/g Products with particle sizes in the 2040nm region such as AMI-227: Sinerem/Combidex are suitable for lymph and bone In the last 10 years, people have been studying to create superparamagnetic nanoparticles with a particle size smaller than 20 nm (also known as microscopic if the particle size is D F Model 35.75 0,0068a 0.03 A 10.64 0,0038a B 7.31 0,0457b 0.02 C 30.64 0,0116b AB 9.27 0,0308b 0.01 AC 76,96 0,0031a BC 5,83 0,0346b A 33,46 0,0103b B2 21,85 0,0185b C2 107,69 0,0019a Variable R =0,9908 Figure 3.2 Analysis of variance (ANOVA) for full quadratic model and Model coefficient estimated by linear regression (asignificant at 1% level; bSignificant at 5% level) Giá trị F C2 BC A A2 C B2 AB AC B p-value Factor Figure 3.3 Surface plot and contour plot of the combined effects of A and B (a); A and C (b) on the yield of Ms at another coded level of zero Figure 4.1 TEM images of Fe3O4 synthesized at different reactions solvent and temperature of hours By surveying the effect of temperature, it was found that the sample was made at a temperature lower than the solvent temperature for particles of small, uneven, and grainy size Dibenzyl ether solvents give heterogeneous particles in shape, uneven size compared to octadecene solvents Particles of uniform size with grain boundaries are more clear when the reaction temperature is increased to 300 to 310 oC and 320 oC This indicates that the temperature and nature of the solvents are important factors in the formation and development of particles Figure 4.1 The M(H) curves of Fe3O4 synthesized at different reactions solvent (inset is the enlarged hysteresis curve) The value from Ms saturation increased from 51 emu/g (OIO-DIO1) to 59 emu/g (OIODIO2) and 62 emu/g (OIO-DIO3) when changing the reaction temperature from 270oC đến 310oC (Figure 4.1c) 4.2 Effect of reaction time on magnetic structure and properties Figure 4.2 TEM images of Fe3O4 synthesized at different reaction times Figure 4.2 shows that all models are composed of cubic and spherical particles with relatively uniform dimensions The average particle size (DXRD) of samples increased from 5.2 nm to 11.2 nm corresponding to reaction time increased from: 0.5 hours to hours Looking at TEM images, we find that grain boundaries become more pronounced when reaction time increases Figure 4.3 shows the magnetization curves of fabricated Fe3O4 samples with different reaction times Thus, by changing the reaction time, the single-phase Fe3O4 nanoparticles samples have the size from 7.52 nm to 13.15 nm correspond to the price magnetic values increased from 53 emu/g to 65 emu/g However, prolonged time can lead to large particle size so that the value of magnetic coercivity is large and may not reach superparamagnetic state Figure 4.3 The M(H) curves of Fe3O4 synthesized at different reactions times (inset is the enlarged hysteresis curve) (a) and HRTEM images of OIO-DIO5 samples (b) 4.3 Manufacturing magnetic fluids containing Fe3O4 magnetic nanoparticles coated with PMAO F e 3O F e 3O F e 3O (b) (a) Figure 4.4 Fe3O4 nanoparticle before and after encapsulating PMAO in hexane and water (a); HRTEM images of Fe3O4 nanoparticles before and after encapsulating PMAO (b) Figure 4.4a is a photograph of the sample before and after the phase transfer with PMAO in n-hexane and water solvent It can be seen that the sample before coating PMAO is dispersed very well in hexane and completely not dispersed in water After coating PMAO, the surface of Fe3O4 particles becomes hydrophilic and disperses well in water, not dispersed in hexane Thus, it can be determined that the polymer layer has covered the surface of the particles and helps them stabilize and disperse well in water Hình 4.5 TEM images of Fe3O4 nanoparticles encapsulating PMAO after dilution solvent Observation of TEM and HR-TEM images in Figure 4.4 and Figure 4.5 showed that the coated samples still have spherical shape, with uniform- distributed particle size The particle size of the coated samples is larger than the particle size of the original sample, corresponding to the average size of 9.6 nm and 12.1 nm Figure 4.6 The M(H) curves of Fe3O4, Fe3O4@PMAO samples (a); FTIR spectrum of Fe3O4, Fe3O4@OA, OLA and Fe3O4@PMAO (b) From Figure 4.6, it can be seen that the experimental data on the M(H) base line of the uncoated sample (Fe3O4) and the fluid sample contains of Fe3O4@PMAO particles completely follow Langevin function, it can be assumed that these magnetic fluid samples is superparamagnetic at room temperature Figure 4.7 The zeta potential scanning of the nanoparticles dispersed in fluids at different times: for day (a), months (b), months (c) of the Fe3O4@PMAO MNPs The responsiveness on durability in body physiology environment is also one of the requirements for magnetic nanoparticles for biomedical applications As we know, the salt concentration in the body remains in the range of 165 ÷ 180 mM, pH ~ 7.5 Therefore, we investigated the strength of the phase-transferred samples in physiological salt medium with concentrations of 100 mM, 200 mM, 250 mM and 300 mM, respectively, with a pH of 7.5 The survey results show that synthetic PMAO coated particles completely meet the durability requirements for biomedical purposes Figure 4.8 The Zeta potential of PMAO coated Fe3O4 NPs dispersed in fluids at different NaCl concentrations 4.4 Test and evaluation of the toxicity of Fe3O4 phase-transferred and PMAO coated fluid system Figure 4.9 The toxicity of Fe3O4 phase-transferred and PMAO coated fluid system to cells line Hep-G2, MCF-7 and RD The cells incubated with Fe3O4 25 µg/ml Objective lens: 40X Cellular toxicity of the PMAO magnetic nanomaterials system is assessed on three human cancer cell lines Hep-G2, MCF-7, RD and a healthy cell line from Vero using the Sulforhodamine B (SRB) method Results of SRB analysis on the four cell lines shown in Figure 4.9 showed that DMSO at the test concentration did not have a toxic effect on the cell with 100% of proliferating cells while the standard matter in the positive check sample is nearly exterminated all cancer cells rightly after 72 hours and inhibit strong overgrowth for healthy cells Compared with the results of incubation disc and Fe3O4@PMAO magnetic nanoparticles, the values were almost unchanged against solvent control with the rate of overgrowth cells on the cell lines Hep-G2, MCF-7, RD and Vero are 95.45%, 99.64%, 99.63% respectively in 100% Thereby, it was concluded that the Fe3O4@PMAO system has absolutely no toxic effect on these four cell lines This shows that Fe 3O4@PMAO materials have great potential in image diagnosis and cancer treatment applications CHAPTER 5: REHABILITATION CHARACTERISTICS R1, R2, TOXIC TEST AND EVALUATION OF IMAGE CONTRAST WITH MRI MAGNETIC RESONANCE IMAGING 5.1 Evaluation of the recovery rate r1, r2 of the magnetic fluid system Figure 5.1 and Figure 5.2 are magnetic resonance images of Fe3O4@PMAO fluid samples at concentrations of 2.5 µg/ml, 5.0 µg/ml, 10 µg/ml, 15 µg/ml, 25 µg/ml and 30 µg/ml in T1, T2 mode in different shooting conditions of TR and TE values TE = 12; TR = 100 TE = 12; TR = 200 TE = 12; TR = 400 Figure 5.1 MRI images of the magnetic fluids samples by different concentrations taken by the T1W status, TR= 100 ms (a), TR =200 ms (b), TR =400 ms (c), TE =12 ms with (A) Fe3O4@PMAO, (B) Fe3O4@CS The sample magnetic fluids prepared by different concentrations of (1) 2,5 µg/ml, (2) 5,0 µg/ml, (3) 10,0 µg/ml, (4) 15,0 µg/ml, (5) 25,0 µg/ml and (6) 30,0 µg/ml TE = 11; TR = 3970 TE = 23; TR = 3970 TE = 57; TR = 3970 TE = 91; TR = 3970 TE = 34; TR = 3970 TE=113; TR=3970 TE = 91; TR = 3970 Figure 5.2 MRI images of the magnetic fluids samples by different concentrations taken by the T2W status, TE =11 ms (a), TE =23 ms (b), TE = 34 ms (c), TE= 57 ms (d), TE =91 ms (e), TE =113 ms (f), TR =4000 ms with (A) Fe3O4@PMAO, (B) Fe3O4@CS in agarose media 2%% The sample magnetic fluids prepared by different concentrations of (1) 2,5 µg/ml, (2) 5,0 µg/ml, (3) 10,0 µg/ml, (4) 15,0 µg/ml, (5) 25,0 µg/ml and (6) 30,0 µg/ml From Figure 5.1 and Figure 5.2, we see that agar 2% check sample with white image has a concentration of C = µg/ml (there is no concentration of the fluid sample Fe3O4@PMAO) Six white to black order images placed in the wells from left to right are samples with corresponding concentrations: 2.5; 5; 10; 15; 25; and 30 µg/ml The contrast changes very clearly when changing a small amount of concentration of the sample Fe3O4@PMAO MRI image contrast agents have the same effect increasing the signal value of T1 imaging mode (increasing the recovery speed along R1) and reducing the T2 signal imaging mode (reducing the horizontal relaxation rate R2) The inverse of the recovery times T1 and T2 is the recovery rate R1, R2 However, the increase or decrease ability of this signal depends on the reversibility of ri (i = 1,2, corresponding to vertical recovery and horizontal recovery) of each specific magnetic fluid The reversibility of ri of magnetic fluids can be determined from a linear relationship between Rx relaxation rate: R1,2 = 1/T1,2 = Ro1.2 + r1.2.C (5.1) Figure 5.3 Exponential decay curve for T2 signal intensity with increasing concentration of Fe3O4@PMAO (a) Fe3O4@CS (b) (a) (b) Figure 5.4 The plot of T2 relaxation rate (1/T2) (a); (b) T1 relaxation rate of Fe3O4@CS nanoparticles at 1.5 T for different Fe concentration Figure 5.1 Matching the dependent function of R1 and R2 to the fluid sample concentration according to the expression (5.1) shows that this dependence is linear From Figure 5.1, we see that our phase-transferring magnetic fluid samples, coated with PMAO and CS give a horizontal recovery much higher than the value of Resovist and some commercial products Thus, as expected, the fluid from superparamagnetic particles based on our Fe3O4 can be used as a MRI imaging contrast enhancer under a good T2 regime 5.2 Evaluation of the in vitro magnetic resonance imaging contrast ability in different environments 5.2.1 Evaluate the contrast ability in the water environment of magnetic fluids and Resovist commercial products (a) (b) Figure 5.5 MRI images of the magnetic fluids samples by different concentrations taken by the T2W status, TE= 62 ms (a), TE =75 ms (b), TR =4000 ms with (A) Fe3O4@PMAO in water, (B) Fe3O4@Dextran (Resovist) in water, (C) Fe3O4@CS, (D) control with water (with the concentration C=0 µg/mL) The sample magnetic fluids prepared by different concentrations of (1) 5,0 µg/ml, (2) 10,0 µg/ml, (3) 15,0 µg/ml, (4) 30,0 µg/ml, (5) 45,0 µg/ml When removing affect of factors such as protein and lipid from the cells, MRI image in the water shows PMAO polymer coating Fe3O4 gives better contrast than T2, resovist give better contrast than T1 TE=15; TR=100 (a) TE=15; TR=400 (b) Figure 5.6 MRI images of the magnetic fluids samples by different concentrations taken by the T1W status, TR= 100 ms (a), TR =400 ms (b), TE =15 ms with (A) Fe3O4@PMAO in water, (B) Fe3O4@Dextran (Resovist in water, (C) Fe3O4@CS; (D) control with water (with the concentration C=0 µg/mL) The sample magnetic fluids prepared by different concentrations of (1) 5,0 µg/ml, (2) 10,0 µg/ml, (3) 15,0 µg/ml, (4) 30,0 µg/ml, (5) 45,0 µg/ml From Figure 5.5, we see that the distilled water check sample in the final well series (vertical column) with a white image has concentration of C = µg/mL (no concentration of fluid samples Fe3O4@CS, Fe3O4@PMAO, Resovist) Three ranges of top-down horizontal wells were prepared in accordance with the concentrations of Fe3O4@PMAO, Resovist and Fe3O4@CS hydrothermal samples with respective concentrations: 5, 10, 15, 30 and 45 µg/ml The contrast changes very clearly when changing a small amount of concentrations of Fe3O4@CS, Fe3O4@PMAO as well as Resovist commercial products The difference in contrast in the T2W shooting mode (Figure 5.5) is very clear It is shown that the dark signal gradually increases with the concentration of nanomaterials in the wells compared to biological control (well 6) as well as comparison between different samples At high concentrations such as 30 µg/ml of the Fe3O4@PMAO fluid sample, the dark signal almost occupies the entire well, even if there is no bright signal (well No 4) when shooting in TE, TR mode appropriately, it shows that the Fe3O4@PMAO magnetic fluid system has a higher saturation value, which gives better image contrast Between two samples Fe3O4@CS fabricated by hydrothermal and Resovist method, when shooting in T2W mode, the contrast is compared to the check sample, the contrast image is similar 5.2.2 Evaluation of contrast ability in changed pH environment of manetic fluid system and Resovist commercial product TE=34; TR=3970 (c) TE=57; TR=3970 (d) Figure 5.7 MRI images of the magnetic fluids samples by different concentrations taken by the T2W status, TE= 11 ms (a), TE = 23 ms (b), TE =34 ms (c), TE =57 ms (d) with (A) Fe3O4@PMAO in water, (B) Fe3O4@Dextran (Resovist in water The sample magnetic fluids prepared by the concentration incubated with Fe3O4 45.0 µg/ml of (1) pH =2, (2) pH =3, (3) pH =7, (4) pH =9, (5) pH =12 MRI images on different pH environments showed polymer-coated Fe3O4 gave better contrast at T2 and the signal strength decreased sharply at pH = 7, resovist samples gave good contrast at T2, lower signal strength (well No 3) TE=12; TR=100 (a) TE=12; TR=200 (b) TE=12; TR=400 (c) Hình 5.8 MRI images of the magnetic fluids samples by different concentrations taken by the T1W status, TR= 100 ms (a), TR = 200 ms (b), TR =400 ms (c), TE =12 ms (d) with (A) Fe3O4@PMAO in water, (B) Fe3O4@Dextran (Resovist in water The sample magnetic fluids prepared by the concentration incubated with Fe3O4 45.0 µg/ml of (1) pH =2, (2) pH =3, (3) pH =7, (4) pH =9, (5) pH =12 The difference in image contrast in the T2W shooting mode (Figure 5.7) is shown more clearly than in T1 mode (T1W) (Figure 5.8) It can be clearly seen that the signal the is almost unchanged when increasing the pH value of the environment from to 12 In the physiological environment of the Fe3O4@PMAO fluid sample, the dark signal almost occupies the entire well, even not also see a light color signal (well No 3) when shooting in the appropriate TE, TR mode, which shows that the Fe3O4@PMAO magnetic fluid system provides good image contrast, equivalent to the suitable Resovist commercial product according to MRI application 5.2.3 Evaluation of contrast ability in environment with changing salt concentration of magnetic fluid system and Resovist commercial product TE=57; TR=3970 (a) TE=75; TR=3970 (b) TE=87; TR=3970 (c) Figure 5.9 MRI images of the magnetic fluids samples by different NaCl concentrations taken by the T2W status, TE =57 ms (a), TE =75 ms (b), TE 87 ms (c), TR =3970 ms with (A) Fe3O4@Dextran (Resovist in water), (B) Fe3O4@PMAO in water, (C) control with water The sample magnetic fluids prepared by the concentration incubated with Fe3O4 45.0 µg/ml of (1) 50 mM, (2) 100 mM, (3) 150 mM, (4) 200 mM MRI images on the environment with different concentrations of salt showed that polymer-coated Fe3O4 and resovist samples gave better contrast at T2 and good signal strength even at high salt concentration environment (200 Mm) This shows that Fe3O4@PMAO fluid samples have suitable properties in biomedical conditions TE=12; TR=100 (a) TE=12; TR=400 (b) Figure 5.10 MRI images of the magnetic fluids samples by different NaCl concentrations taken by the T1W status, TR= 100 ms (a), TR =400 ms (b), TE =12 ms with (A) Fe3O4@Dextran (Resovist in water), (B) Fe3O4@PMAO in water, (C) control with water The sample magnetic fluids prepared by the concentration incubated with Fe3O4 45.0 µg/ml of (1) 50 mM, (2) 100 mM, (3) 150 mM, (4) 200 mM 5.3 Survey of applicability of magnetic fluids on laboratory animals 5.3.1 In-vivo test assesses the applicability of nanomagnetic Fe3O4 fluid system as a contrast drug in MRI magnetic resonance imaging technique in animals MRI images on rabbits before and after injecting magnetic fluids were taken in different types of shooting (SAGITAL and CORONAL), taken in T1 mode (vertical recovery) and taken in T2 mode (horizontal recovery) shown in Figure 5.11 to Figure 5.12 Hình 5.11 T1 weighted (Sagital) MR images showing rabbit liver (A) before injection of contrast agent (B) after injection of contrast agent with TE= 9,2 ms, TR =659 Figure 5.11 and Figure 5.12 show that the image of rabbit parts before injection almost are gray, not clearly distinguish the boundary of the internal organs of Rabbit After injecting Fe3O4@PMAO magnetic fluid, it shows that image in T1 ode has a slight change in contrast intensity Figure 5.12 T2 weighted (Sagital) MR images showing rabbit liver (A) before injection of contrast agent (B) after injection of contrast agent with TE= 94 ms, TR =3571 ms The results showed that after 10 minutes of injection (the Fe3O4@PMAO magnetic fluid sample) the internal organs of rabbits on MRI images showed more clearly than the MRI images before injecting drugs Compared to MRI images taken in T1 mode, MRI images taken in T2 mode give much clearer contrast At liver tissue position, when taking T1 mode with TR = 659 ms, TE = 9.2 ms with spin-echo impulse, the brightness and darkness of images in liver tissue are almost unchanged with the intensity ratio signal before injection Ia = 325 and signal strength after injection Ib = 369 While taking image under T2 mode (TR = 3571 ms, TE = 94 ms with turbo spin echo - TSE impulse sequence), the brightness and darkness of the image at the liver tissue changes with the decreased ratio of signal strength Ia/Ib = 2.3 times Hình 5.13 T2 weighted (Coronal) MR images showing rabbit (A) before injection of contrast agent (B) after injection of contrast agent (a) for minute (b)for 30 minutes (c) for 60 minutes with TE= 112 ms, TR =7500 ms From Figure 5.13 shows that, after 30 minutes of injection (Fe3O4@PMAO magnetic fluid sample) image (B), the rabbit's internal organs on MRI images have been shown more clearly than MRI images before injection (Figure A) Specifically when taking an area in liver tissue before and after the injection is 1.6 -1.8 cm2 respectively, the signal strength decreases from 88.1 to 35.8 (corresponding to decrease 2.46 times compared with before injection This shows that magnetic fluids have the ability to change the contrast very strongly With MRI images taken at 60 minutes (C), the images are as clear as MRI images at time of 30 minutes (B) 5.3.2 In-vivo test assesses the applicability of nanomagnetic fluid system Fe3O4 as a contrast drug in cancer diagnosis using MRI magnetic resonance technique in animals Solid tumor under the skin 15 days old in the thighs of mouse The tumor is thick, not necrotic and has a relatively homogeneous structure We performed an MRI scan and obtained images at the time immediately after direct injection of Fe3O4@PMAO magnetic fluid system into mouse tumors and injecting intravenously (Figure 5.14 and Figure 5.15) To assess the distribution of the Fe3O4@PMAO nano system in solid tumors under mouse skin, the tumor after injection of the magnetic nanoparticle will be monitored over time under a 90° imaging angle under Axial and Coronal style In Figure 3.9, the tumor of mouse C, F, G The tumor of mouse C, E, F, and G show a much higher contrast (darker) than the tumor of mouse B Signal strength in the tumor varies from 284.6 to 249, corresponding to mouse F and G This indicates that the magnetic fluid began to spread evenly throughout the tumor and changed the signal strength While for mouse C, although the intravenous fluids also had a signal change in the tumor clearly, specifically the signal strength in mouse treated with cancer B was 296.5 downed 226.8 Figure 5.14 T2 weighted (Coronal)MR images showing solid tumor mice with TE= 91 ms, TR =3970 ms With an average bidirectional size of about 15x10 mm, under normal conditions, there is almost no observation of the tumor on the mousebody However, after injecting the nanomagnetic system of Fe3O4@PMAO, it can be seen that a dark area with a shape similar to the tumor appears on the image (Figure 3.9) Thus, the presence of magnetic nanoparticles supported 1.5T magnetic resonance imaging system to detect tumors at low material concentrations (magnetic particles 0.18 mg) (Figure 3.10) Thus, the amount of 0.18 mg of magnetic particles allows to detect the tumor in the image but not enough for the nano-system can be spread to the entire tumor within 15 minutes, the shooting signal shows that nanomaterials are almost covered the entire tumor at 30 minutes after injecting and maintaining continuously for nearly hour afterwards (Figure 3.10) Figure 5.15 T2 weighted (Axial) MR images showing solid tumor mice (a) before injection of contrast agent; (b) after injection of contrast agent; (c) for 15 minutes; (d) for 30 minutes with TE= 91 ms, TR =3970 ms With the amount of magnetic nanoparticles injected into the tumor, the image shows a spread of the material over time (Figure 5.15) The results obtained on MRI images showed that after the direct injection of the fluid into the tumor, there was a clear dark area, different from the non-injected cancer checking mouse, and clearly saw the contrast of the tumor area after 30 minutes of injection To demonstrate the concentration of magnetic particles at tumors, Figure 3.9 and Figure 5.15 in the form of color figure shown the occurrence of purple corresponding to reduced signal strength that allows the use of magnetic fluid system applied in diagnostic of cancer and support of treatment After 30 minutes of injection of magnetic particles into the tumor, the black area in the tumor of mouse D and F is much wider than the time immediately after injection (Figure 5.15) The magnetic nanoparticles after being injected into the tumor tend to spread to the whole tumor When taking magnetic fluid in the tumor of mouse through the intravenous injection of mouse Figure 5.16 T2 weighted (Axial) MR images showing solid tumor mice (a) before injection of contrast agent; (b) after injection under the tail vein of contrast agent for hours; (c) for 12 hours; (d) for 24 hours with TE= 91 ms, TR =3970 ms In Figure 5.16, we see that the contrast of images when taking MRI of tumors in mouse has not much difference The results obtained on MRI images showed that after hours of injecting magnetic fluids in the mouse under the tail vein, clear dark areas were not observed, which showed that the amount of nanoparticles is to the solid tumor very less after vein injection after a short time This can be explained by the intravenous injection, the magnetic nanoparticles will follow the circulatory system to organs considered as the target of iron in the body like liver, kidney, spleen and lymph, specifically at these tissues show a marked signal reduction after injection of magnetic fluids (Figure 5.16), while other tissues and organs such as tumors without targeted molecules will require a longer time for magnetic fluids to circulate from the blood However, 12 hours after the injection, there were black points in the tumor area of mouse D, and is almost dark in tumor area of mouse E after 24 hours This suggests that there is a very small amount of magnetic particles reaching the mouse tumor position after briefly injecting the magnetic particles through the mouse vein The black area of the tumor obtained after 12 hours or more allows to clearly define the tumor area, the rim of the tumor and the depth structure of the tumor → this allows the use of magnetic fluid system applied in diagnostic of cancer and support in treatment However, when the magnetic fluid is directly inserted into the tumor, the contrast of the tumor in the MRI images is higher than that of taking the magnetic fluid into the vein in a short time GENERAL CONCLUSIONS Through the detailed research results and appropriate discussions, some key conclusions are drawn as follows: Successfully fabricated magnetic fluids based on Fe3O4 particles by hydrothermal method coated by chitosan natural polymer (CS) Optimized factors affecting magnetic properties Fe3O4@CS fluid sample has high durability in physiological environment Successfully fabricated magnetic fluids based on Fe3O4 particles by thermal decomposition method by transferring phase and coating with PMAO polymer Fe3O4@PMAO fluid samples are highly durable in different conditions, single-dispersed, uniform particles Examination of toxicity found that the Fe3O4@CS, Fe3O4@PMAO systems gave good IC50 index The fabricated fluid sample are not capable of cytotoxicity Determined the nuclear magnetic resonance imaging relaxation rate of systems Fe3O4@CS, Fe3O4@PMAO found that the fabrication systems have high r2 values of over 150 mM-1s-1 for samples of Fe3O4@PMAO, higher than the Resovist commodity These substances, when given MRI imaging tests, they appear good potential for applications increasing contrast In-vitro, ex-vivo and in-vivo studies of MRI contrast enhancement showed that many of the magnetic fluids of the manufacturing topic group showed good contrast enhancement Applying Fe3O4@PMAO system to solid tumors under the skin and liver tumors, found the potential for observing the shape and structure of tumor details in stages, support for diagnosis and treatment The research results have been presented and published in 09 scientific articles (02 articles in ISI magazine, in which 01 article has been published and 01 article is being submitted for criticism, 08 in specialized journals and National Conferences) An intellectual property license was registered (accepted for application, published in Intellectual Property Gazette Episode A No 365) on the manufacturing and testing technology of magnetic fluids in MRI PUBLISHED REPORTS USED IN THIS THESIS Vu Thi Thu, An Ngoc Mai, Le The Tam, Hoang Van Trung, Phung Thi Thu, Bui Quang Tien, Nguyen Tran Thuat, Tran Dai Lam Fabrication of PDMS-Based microfluidic devices: Appliaction for synthesis of magnetic nanoparticles Journal of electronic materials (SCI), Q2, IF2017 1.579 Vol 45, Issue 5, 2016, pp 2576-2581 DOI 10.1007/s11664-016-4424-6 Le The Tam, Nguyen Hoa Du, Le Trong Lu, Phan Thi Hong Tuyet, Nguyen Quoc Thang, Nguyen Thi Ngoc Linh, Nguyen Thi Hai Hoa, Tran Dai Lam Magnetic Fe3O4 nanoparticle imaging T2 contrast agent synthesized by optimized hydrothermal method Submited to Royal Society of Chemistry Advances (SCI), 2019, Q1, IF2017 2.936 (Under Review) Trần Đại Lâm, Lê Thế Tâm, Lê Trọng Lư, Vương Thị Kim Oanh, Đỗ Hùng Mạnh, Nguyễn Xuân Phúc, Phạm Hồng Nam, Trần Đại Lâm Quy trình chế tạo hệ chất lỏng từ tính nano Fe3O4 để làm thuốc tương phản chẩn đốn hình ảnh kỹ thuật cộng hưởng từ MRI Sở hữu trí tuệ (Sáng chế) Số đơn SC 1-2018-01215 Đã chấp nhận đơn hợp lệ công bố công báo sở hữu công nghiệp số 365/T8, tập A: 58762 Le The Tam, Nguyen Hoa Du, Tran Dai Lam, Le Thi Nhan, Nguyen Van Toan Study on some factor of magnetic fluid chitosan-coated Fe3O4 nanoparticles fabrication via hydrothermal method for Biomedicine, 2016 Viet Nam Journal of science and technology, Vol 54, 2C, 2016, pp 341-347 Le The Tam, Vuong Thi Kim Oanh, Nguyen Hoa Du, Tran Dai Lam Optimization of coprecipitation reaction involving main experimental factors on crystallite size of chitosancoated magnetic nanoparticles Fe3O4 by response surface method with central composite designs Vietnam Journal of Chemistry, No 5e1,2 (54), 2016, 207-211 Nguyen Hoa Du, Le The Tam, Tran Dai Lam, Phan Thi Hong Tuyet, Tran Thi Huong Optimization factors affected saturation Magnetic fluid Chitosan-coated Fe3O4 in coprecipitation reaction by Response surface method with central composite designs, 2016 Viet Nam Journal of science and technology, Vol 54, 2B, 2016, pp 142-148 Le The Tam, Vuong Thi Kim Oanh, Nguyen Hoa Du, Le Trong Lu, Le Hai Dang, Nguyen Thi Hai Hoa, Le Ngoc Tu, Tran Dai Lam Magnetic resonance imaging (MRI) application of Fe3O4 based ferrofluid synthesized by thermal decomposition using poly (maleic anhydride alt-1-octadecene) (PMAO) Viet Nam Journal of Science and Technology, Vol 56, 1A, 2018, pp 174-182 Le The Tam, Tran Dai Lam, Nguyen Hoa Du, Phan Thi Hong Tuyet, Nguyen Quoc Thang Synthesis, characterization and MRI application of Fe3O4 liquid was synthesized by hydrothermal with using Sodium Alginate Proceedings of the the Scientific Conference Chemical, Material and Environmental Engineering for Sustainable Development (CME2018), in Quy Nhon City Vietnam, pp 49-56 Lê Thế Tâm, Nguyễn Hoa Du, Nguyễn Quốc Thắng, Phan Thị Hồng Tuyết, Lê Trọng Lư, Nguyễn Thị Ngọc Linh, Võ Kiều Anh, Phạm Hồng Nam, Trần Đại Lâm Chế tạo chất lỏng từ tính chứa Fe3O4@PMAO cho ứng dụng MRI điều chế phương pháp phân hủy nhiệt Tạp chí Hóa học, Viện Hàn lâm KHCN Việt Nam (2018) Vol 56(6e2), pp 63-69 ... select the topic "Study on the fabrication of magnetic fluids based on superparamagnetic iron oxide nanoparticles (SPIONs) applied to magentic resonance imaging (MRI) application" to make this thesis... content Research object of the thesis: Magnetic fluid system based on superparamagnetic iron oxide Research targets of the thesis: The goad of the thesis is to build the manufacture process of. .. addition, the such unevenness even affects the research results of their magnetic properties Therefore, up to now, the selection of conditions in the fabrication of Fe3O4 nano magnetic fluid to