Magnetic hyperthermia with biphasic gel of La₁₋<i>_x</i>Sr<i>_x</i>MnO₃ and maghemite

Magnetic hyperthermia experiments were carried out using a biphasic gel of La1−xSrxMnO3(LSMO) and γ-Al0.07 Fe1.93O3 with an AC magnetic field of amplitude 88 mT and a frequency of 108 kHz. Specific absorption rate (SAR) increases with the increased ratio of Al-substituted maghemite. The Tmax value for the gels prepared by the mixture of LSMO and Al-substituted maghemite can be adjusted to suit therapeutic temperature. The time required to reach optimum temperature decreased with the increased ratio of later. Such biphasic gel could be very useful for magnetic hyperthermia with in vivo control of temperature

Novel facets of multifunctional Ag@Fe3O4 core-shell nanoparticles for multimodal imaging applications

Biocompatible nanoparticles, with magnetic cores and optically active shells, acting as multifunctional materials with a core size of 6 nm encapsulated in silver shells of varying thickness were synthesized through a novel single phase microemulsion method. Incorporation of silver shells onto the magnetite core enhances the intensity of the highest luminescence peak observed for magnetite by a significant luminescence enhancement factor. A blue photoluminescence peak observed in the visible region of spectrum brightens further with the increase in the thickness of silver shell. The magnetic properties of these core-shell nanomaterials show superparamagnetic behavior at room temperature, which is a mandatory criterion for MRI contrast enhancement agents. The hyperthermic response of synthesized magnetite nanoparticles elevates its temperature to 43 degrees C in a sharp span of time, which is above the desired temperature for the therapeutic application of these multifunctional nanomaterials. These excellent optical and magnetic properties, of the material having a size range suitable for cellular uptake, make it a potential candidate for both diagnostic and therapeutic uses in biomedical applications

Effect of Gd3+ substitution on proton relaxation and magnetic hyperthermia efficiency of cobalt ferrite nanoparticles

In this study, Gadolinium substituted Cobalt Ferrite nanoparticles (CoFe _2-x Gd _x O _4 , 0 ≤ x ≤ 0.4) were prepared via hydrothermal route using triethylamine as reducing agent at 180°C for 12 h. X-ray diffraction studies revealed the single phase cubic spinel structure for both Cobalt ferrite (CF) and Gadolinium substituted Cobalt Ferrite (CFG) nanoparticles (x ≤ 0.24). An increase in the Specific absorption rate (SAR) was observed with increase in Gd concentration. Further with increase in the molar concentration (x > 0.24), gadolinium hydroxide was observed as the secondary phase, which was also confirmed by the Gd–O stretching vibrations observed in Fourier transform Infrared spectroscopy. The evolution of Gadolinium hydroxide showed a strong influence in the relaxivity ( r _1 ) and hype r thermia potential. Field emission scanning electron microscopy revealed that CF and CFG (x ≤ 0.24) nanoparticles were spherical in nature with particle size ranging from 10 to 25 nm, whereas the particle size increases above 30 nm for CFG (0.3 ≤ x ≤ 0.4) nanoparticles along with the presence of columnar shaped particles. Magnetic measurements confirmed the pseudo single domain, ferri-magnetic nature of CF and CFG nanoparticles. The magnetization data revealed a change in direction of magnetization towards easy axis with increasing Gd concentration. The orientation of magnetization direction towards easy axis had induced change in the hyperthermia potential. Proton relaxation studies of CF and CFG nanoparticles revealed that there is a strong interaction between the relaxivities r _1 and r _2 . The specific absorption rate of CF and CFG nanoparticles were observed to be in the range from 91.49 W g ^−1 to 232.17 W g ^−1 at applied Hf of 4.19 × 10 ^9 Am ^−1 s ^−1

The effect of Mn on the structural and magnetic behaviour of Fe–6Si–8B alloy produced by high energy ball milling

The alloys of Fe–6Si–8B and Fe–6Si–8B–1Mn were prepared using high energy planetary ball mill. X-ray diffraction patterns of the milled samples confirmed the formation of the alloys by dissolution of Si in Fe after 30 and 24 h of milling for the Fe–6Si–8B and Fe–6Si–8B–1Mn samples respectively. The lattice parameter was found to increase continuously with milling time and the rise was steeper for the quaternary alloy. After 36 h of milling, the crystallite size for the two samples were reduced to 98 and 86 nm respectively. Mossbauer spectra suggested the formation of minor amount of α-Fe2O3. The value of saturation magnetization was 162 Am2/kg for Fe–6Si–8B alloy obtained after 18 h of milling. However, the value decreased with increased milling time as well as with Mn-addition. The remanance value showed similar tendency as that for saturation magnetization. In contrast, the coercivity value was found to be increasing with milling time and with Mn-addition