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Mn1-xZnxFe2O4 (0 ≤ x ≤ 0.7) nanoparticles were synthesised by a hydrothermal process. X-ray diffraction patterns reveal that all samples have spinel crystalline structures. Scanning electron microscopy and X-ray diffraction patterns show that nanoparticles are near-spherical in morphology and their average size is 13–45 nm. The elemental analysis was carried out by energy dispersive X-ray analysis technique. The optical direct band gap of Mn1-xZnxFe2O4 nanoparticle decreases from 2.38 to 1.88 eV as the Zn content increases. Moreover, the saturation magnetisation at room temperature tends to decrease with increasing Zn content. The specific absorption rate (SAR) values were measured at a fixed frequency of 178 kHz with magnetic field amplitude of 80 Oe. The SAR initially decreases with the sample concentration and its decrease is attributed to the enhancement of dipolar interaction and agglomeration of the particles. The intrinsic loss power (ILP) value varies between 6.5 and 15 nHm2kg−1 in the biologically safe experimental limit of 1.13 × 109Am−1s−1. The high value of ILP makes these nanoparticles possible for potential candidates for treating magnetic hyperthermia.

In this study, the magnetic fluid with various concentrations of well-dispersed dextran coated Fe3O4 nanoparticles were synthesized for hyperthermia application. The dextran-coated colloidal suspension, in the form of clusters of several Fe3O4 nanoparticles, maintains superparamagnetic behavior of Fe3O4 with the saturation magnetization of 59 emu/g at room temperature. The coated nanoparticles dispersed in aqueous medium agglomerate to form a monodisperse system and its average polydispersity index is 0.096. The inter-particle interaction caused the large susceptibility (1239 emu/gT) in dextran coated Fe3O4 nanoparticles. Effect of magnetic dipole interaction between the clusters on magnetic properties and heat capacity was examined by comparing specific loss power (SLP) of magnetic fluids at different Fe3O4 concentration. The intrinsic loss power (ILP) parameter increases with decreasing concentration of the dextran coated Fe3O4 and reaches the value of 15.6 nHm2/kg, which is 35% better than the best commercial equivalents. This result clearly shows that magnetic interaction between coated particles strongly influences induction heating efficiency of magnetic fluid. The in vitro toxicity experiments of magnetic fluids with Madin Darby Canine Kidney cells prove that our obtained magnetic fluids are promising for the hyperthermia cancer treatment application.

In this paper, nanocomposites with core–shell structure of dextran coated Co0.2Fe0.8Fe2O4 nanoparticles (NPs) were synthesized by a facile sono-chemical method. The characterization of nanocomposites such as crystallinity, particle size, and the linking between coating layer and magnetic NPs (MNPs) were analyzed by X-ray diffraction, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis–differential thermal analysis. Using this method, the obtained colloidal composite NPs with size around 50 nm are well dispersed in aqueous solution at the highest concentration of 14.4 mg/mL. The MNPs present superparamagnetic behavior at high blocking temperature with saturation magnetization of 53 emu/g and coercivity of 120 Oe. The induction magnetic heating property of nanocomposite was determined by calorimetric measurements in alternating magnetic field of 390 kHz frequency and various amplitudes. The hysteresis loss of magnetic fluid containing nanocomposites strongly depends on the amplitude of the applied field while the heating capacity was enhanced by significant contribution of hysteresis loss. The nanocomposites show great potential in hyperthermia applications.

In this work, we developed a polymer encapsulation of Fe3O4 nanoparticles as a core–shell nanocluster with different sizes to investigate the cluster structure effect on their magnetic properties and magnetic heating behavior. Well-dispersed nanoclusters of O-carboxymethyl chitosan-coated Fe3O4 nanoparticles were synthesized by microwave-assisted co-precipitation. The cluster sizes were tunable by varying the concentration of polymers used during synthesis. Nanoclusters present superparamagnetic behavior at room temperature with a reduction in saturation magnetization as a consequence of coating layer. The shift of blocking temperature to the higher value with increasing clusters size shows the stronger magnetic interaction in larger magnetic clusters. In a low alternating magnetic field with frequency of 178 Hz and amplitude of 103 Oe, nanoclusters offer a high heating efficiency. A maximum specific absorption rate of 204 W/g is observed in the sample with hydrodynamic size of 53 nm. In vitro cytotoxicity analysis performed on HeLa cells verified that nanoclusters show a good biocompatibility and can be an excellent candidate for applications in hyperthermia cancer treatment.

In this study, we developed a green and easy to scale up approach for producing Au/g-C3N4 (Au/GCN) hybrid plasmonic photocatalyst without using the chemical reducing agents via the growing of Au nanoparticles (Au NPs) on the surface of GCN nanosheets under the photo-reduction of ultraviolet (UV)-radiation. Different characterization techniques were conducted for investigating the structure, morphology, surface chemistry and optical properties of the as-prepared catalysts. The scanning electron microscope image shows that the homogeneous Au NPs anchored on the surface of the GCN nanosheet increased with the UV illumination time. The x-ray photoelectron spectroscopy results prove the coexistence of GCN nanosheets with heptazine heterocyclic ring (C6N7) units and Au NPs in the Au/GCN. The photoluminescence intensity decreased sharply with the time of UV irradiation, indicating that the recombination rate of photogenerated electron–hole recombination decreased. The photocatalytic activity of the hybrid catalysts was evaluated by degrading rhodamine B (RhB) under simulated sunlight irradiation. The results show that the Au/GCN photocatalyst exhibits superior sunlight photocatalytic activity than that of bare GCN. The 6 h irradiated fabricating sample exhibited the strongest photocatalytic activity, completely decomposing the 10 ppm RhB in 30 min of irradiation. This report can provide the design of a simple and green synthesis method for the highly active Au/GCN photocatalyst.

The magnetic properties and heating capacity of cobalt ferrite (CoFe2O4) nanoparticles 13–24 nm in size were studied. Results showed that the specific absorption rate of the nanoparticles strongly depended on their magnetic properties and particle size. Specific absorption rate values decreased with increased particle size, and the smallest CoFe2O4 nanoparticles (13.5 nm) exhibited the highest specific absorption rate. The mechanism underlying the decrease in specific absorption rate of the CoFe2O4 nanoparticles with increased particle size was also discussed.

Monodispersed CoFe2O4 nanoparticles were synthesized by the thermal decomposition of Co and Fe acetylacetonate in octadecene, which contained oleic acid (OA) and oleylamine (OLA). The hydrophobicity of the CoFe2O4 nanoparticles was alleviated such that they were water dispersible by encapsulating them with poly(maleic anhydride-alt-1-octadecene) (PMAO). The heating ability of these magnetic fluids was assessed by calorimetry measurement of specific absorption rate under an alternating magnetic field of 300 Oe within the frequency interval of 290–450 kHz. The highest value of the specific absorption rate was 297.4 W g−1 for a sample concentration of 1 mg mL−1 under an applied field of 300 Oe and frequency of 450 kHz. Linear response theory was used to explain the results. The high specific absorption rate of the nanofluid based on PMAO-encapsulated CoFe2O4@OA/OLA showed that it may meet the requirements for practical applications in tumor-targeted hyperthermia treatment. In vitro cytotoxicity analysis was also performed on Sarcoma 180 cancer cells, and the results showed that these nanoparticles were nontoxic to cells.

In this work, we focus on synthesizing g-C3N4 nanosheets with a large surface area for enhanced solar light photocatalytic performance via a simple thermal polymerization of a low-cost urea precursor in enclosed conditions. The effects of annealing duration on the phase formation, structure, and optical and photocatalytic properties of the g-C3N4 nanosheets were investigated. The characterization analysis revealed that g-C3N4 nanosheets with different textures, including stacked-layer, porous and ultrathin morphologies, were obtained by controlling the annealing time. The prepared g-C3N4 samples offer a large specific surface area, narrow band gap and efficient separation of photogenerated electron-hole pairs with increasing annealing duration. The photocatalytic properties of the as-synthesized g-C3N4 samples were examined by measuring the degradation of rhodamine B (RhB) under simulated solar irradiation. With a 100% RhB solution (10 ppm) decomposed by exposure to solar irradiation for 60 min, ultrathin g-C3N4 shows considerable potential in practical applications concerning environmental remediation, especially in large-scale applications in industry.

In this paper, we elucidate several specific magnetic properties of Fe 3 O 4nanoparticles synthesized by coprecipitation method. The characterizations by X-ray diffraction technique (XRD) and scanning electron microscopy (SEM) showed the particles to be of spinel structure and spherical shapes whose diameter could be controlled in the range from 14 to 22 nm simply by adjusting the precursor salts concentration and coprecipitation temperature. Magnetic properties of the Fe 3 O 4 nanoparticles measured by using vibration sample magnetometer (VSM) indicated the saturation magnetization and blocking temperature to increase with the particles size. Fe 3 O 4 nanoparticles with crystal size smaller than 22 nm exhibits superparamagnetic behavior at room temperatures. Characteristic magnetic parameters of the particles including saturation magnetization, effective anisotropy constant, and magnetocrystalline anisotropy constant have been determined. The observed decrease of saturation magnetization was explained on the base of core-shell model. A simple analysis indicated that the shell thickness decreases with an increase in particle size.

Acute encephalitis syndrome (AES) is associated with high morbidity and mortality, and affects both children and adults. The main etiologic agent is Japanese encephalitis virus (JEV); however, there are also reports of Dengue virus (DENV) encephalitis. The objectives of this study were to determine the proportion of patients with encephalitis due to JEV during the 2014 outbreak in Son La Province in Vietnam and to explore the association of DENV in non-JEV viral encephalitis cases. Of 90 patients, 6 (6.7%) were positive for anti-JEV immunoglobulin M (IgM), 5 (5.6%) were positive for anti-DENV IgM, 30 (33.3%) were positive for both anti-JEV and anti-DENV IgM, and 56 (62.2%) were positive for flavivirus immunoglobulin G (IgG). In 5 patients with AES, who had positive anti-DENV IgM results in at least one of the paired serum samples, DENV was confirmed by neutralization testing. The incidence of JEV infection was high. There is still a need to maintain and strengthen the national JEV immunization program. This noticeable occurrence of DENV infection was not reported in Son La Province in 2013?2014. Our data suggested that in addition to JEV, DENV was also a causative agent of AES in 2014 in Son La Province, and this finding also confirmed the local occurrence of DENV infection., Japanese Journal of Infectious Diseases, 70(4), pp.357-361; 2017

In this paper, we report results on the fabrication and magnetic properties of spinel ferrite Mn1-xZnxFe2O4 (0 ≤ x ≤ 0.8) nanoparticles. The nanoparticles were synthesized by a co-precipitation method. The effects of substituting Zn for Mn on the magnetic properties and particles size were focused. It was found that the phase-formation temperature is 90OC and the average particle size decreases from 40 nm to 10 nm when increased Zn concentration from zero to 0.8. The Curie temperature TC strongly decreases from 585 K (x = 0) to 320 K (x = 0.8) concomitantly with a decrease of the saturation magnetization MS. With a TC of 320 K and MS of 17 emu/g, the x=0.8 sample could be a promising candidate for some biomedical applications.

This paper presents a summary of research on magnetic nanoparticles (MNPs) carried out recently at the Institute of Materials Science. Three families of oxide MNPs namely magnetite, manganite and spinel ferrite materials were prepared by several methods: co-precipitation, sol-gel and high-energy mechanical milling. Magnetite nanoparticles were encapsulated by two natural polymers, starch and chitosan. The structure of the prepared nanosystems was characterised by XRD, SEM, TEM techniques while their magnetisation was measured by VSM and PPMS. The magnetic heating (MH) of both naked and polymer-coated MNPs was studied. We also present two examples of researched applications that can be derived from this effect, namely the use of MH of magnetite NPs coated with starch to kill cancer cells, and the MH-assisted desorption of VOC from SBA/ferrite nanocomposite. Other research application examples include the use of magnetite MNPs to remove heavy toxic metals, such as arsenic, lead and nickel from contaminated water.

The paper presents results of research on preparing the magnetic fluid based on Fe3O4 nanoparticles and its potential hyperthermia application. Magnetic fluids were manufactured by dissolving superparamagnetic nanoparticles coated by suitable biocompatible starch layer during the co-precipitation processing. The coated particle size changes in range of 15÷17 nm were characterized by FESEM images. At room temperature, the samples exhibit super-paramagnetic behaviour with a saturation moment of 65 emu/g. The concentration of magnetic nanoparticles contained in carried liquid reach to 15 mg/ml. The magnetic fluid was used as a mediator for heating by an AC magnetic field with the frequency of 184 kHz and field strength of 12 kA/m. The dependence of heating on nanoparticle concentration was observed and it implied that the magnetic fluid is a suitable mediator for cancer treatment by hyperthermia application with appropriate controlling the heating temperature ranges from 45 to 50°C.

A Fe3O4 based magnetic fluid with different concentrations ranged between 0.15 ng/cell to 10 ng/cell (nano gram/cell) was used in the in vitro toxicity test on several cancer cell lines, Sarcoma 180, HeLa and H358. It shows that the fluid with a concentration of Fe3O4 below 1.2 ng/cell is completely non-toxic for these cell lines. Even through in the presence of the highest concentration of 10 ng/cell, the cell viability still reaches more than 60%. The magnetic fluid with Fe3O4 concentration of about 0.1 ng/cell was also used to search ex-vivo the possibility of Sarcoma 180 extermination by magnetic heating with an AC field of 120Oe and 184 KHz. The result shows that after a heat treatment for 30 min., 40% of Sarcoma 180 cells was killed.