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International audience; A stable oil-in-water (O/W) magnetic emulsion was prepared by the emulsification of organic ferrofluid in an aqueous media, and its theranostic applications were investigated. The synthesis and characterization of the organic ferrofluid were carried out comprising of superparamagnetic maghemite nanoparticles with oleic acid coating stabilized in octane. Both exhibit spherical morphology with a mean size of 6 nm and 200 nm, respectively, as determined by TEM. Thermogravimetric analysis was carried out to determine the chemical composition of the emulsion. The research work described here is novel and elaborates the fabrication of thin-film gradients with 5, 10, 15, and 20 bilayers by layer-by-layer technique using polydimethyl diallyl ammonium chloride (PDAC) and prepared magnetic colloidal particles. The thin-film gradients were characterized for their roughness, morphology, and wettability. The developed gradient films and colloids were explored in magnetic resonance imaging (MRI) and hyperthermia. T1-and T2-weighted images and their corresponding signal intensities were obtained at 1.5 T. A decreasing trend in signal intensities with an increase in nanoparticle concentration in colloids and along the gradient was observed in T2-weighted images. The hyperthermia capability was also evaluated by measuring temperature rise and calculating specific absorption rates (SAR). The SAR of the colloids at 259 kHz, 327 kHz, and 518 kHz were found to be 156 W/g, 255 W/g, and 336 W/g, respectively. The developed magnetic combinatorial thin-film gradients present a significant potential for the future efficient simultaneous diagnostic and therapeutic bioapplications.

Gadolinium silicide (Gd5Si4) nanoparticles are an interesting class of materials due to their high magnetization, low Curie temperature, low toxicity in biological environments and their multifunctional properties. We report the magnetic and magnetothermal properties of gadolinium silicide (Gd5Si4) nanoparticles prepared by surfactant-assisted ball milling of arc melted bulk ingots of the compound. Using different milling times and speeds, a wide range of crystallite sizes (13–43 nm) could be produced and a reduction in Curie temperature (TC) from 340 K to 317 K was achieved, making these nanoparticles suitable for self-controlled magnetic hyperthermia applications. The magnetothermal effect was measured in applied AC magnetic fields of amplitude 164–239 Oe and frequencies 163–519 kHz. All particles showed magnetic heating with a strong dependence of the specific absorption rate (SAR) on the average crystallite size. The highest SAR of 3.7 W g−1 was measured for 43 nm sized nanoparticles of Gd5Si4. The high SAR and low TC, (within the therapeutic range for magnetothermal therapy) makes the Gd5Si4 behave like self-regulating heat switches that would be suitable for self-controlled magnetic hyperthermia applications after biocompatibility and cytotoxicity tests.

Aminodextran (AMD) coated magnetic cobalt ferrite nanoparticles are synthesized via electrostatic adsorption of aminodextran onto magnetic nanoparticles and their potential theranostic application is evaluated. The uncoated and aminodextran-coated nanoparticles are characterized to determine their hydrodynamic size, morphology, chemical composition, zeta potential and magnetization. The aminodextran containing cobalt ferrite nanoparticles of nanometer size are positively charged in the pH range from 3 to 9 and exhibit saturation magnetization of 50 emu/g. The magnetic resonance imaging (MRI) indicates capability for diagnostics and a reduction in intensity with an increase in nanoparticle amount. The hyperthermia capability of the prepared particles shows their potential to generate suitable local heat for therapeutic purposes. There is a rise of 7 &deg, C and 9 &deg, C at 327 kHz and 981 kHz respectively and specific absorption rates (SAR) of aminodextran-coated nanoparticles are calculated to be 259 W/g and 518 W/g at the given frequencies larger than uncoated nanoparticles (0.02 W/g). The development of novel aminodextran coated magnetic cobalt ferrite nanoparticles has significant potential to enable and improve personalized therapy regimens, targeted cancer therapies and ultimately to overcome the prevalence of nonessential and overdosing of healthy tissues and organs.

This current work deals with the study of the magnetic and biomedical characterization of La0.7Sr0.3Mn1-xBxO3 (B=Mo, Ti) nanoparticles for hyperthermia applications. Our nanoparticles were prepared through an aqueous combustion process (Glycine Nitrate Process, GNP), and are characterized with a mean crystallite size about 18 nm. The incorporation of Ti4+ and Mo6+ in Mn-site induced a structural transition from rhombohedral structure with R-3 C space group for La0.7Sr0.3MnO3 compound to orthorhombic one with Pnma space group for La0.7Sr0.3Mn0.95Mo0.05O3 and La0.7Sr0.3Mn0.95Ti0.05O3 compounds. The morphological properties indicated a variation in grain size ranging from 82 to 90 nm with doping extra element in manganese site. All samples exhibit a classical behavior from ferromagnetic (FM) to paramagnetic (PM) state as the temperature increases. A decrease in Curie temperature (TC) has been remarked from 84 °C to 70 °C and 82 °C for La0.7Sr0.3MnO3, La0.7Sr0.3Mn0.95Ti0.05O3, La0.7Sr0.3Mn0.95Mo0.05O3 respectively. According to the Arrott plots, the slopes of the curves of all the samples are positive, which is a signature of second order transition. The magnetic heating characteristics in AC field were measured in alternating magnetic fields of 23.89 mT at a fixed frequency of 518.7 kHz. The intrinsic loss power (ILP) has been calculated from SAR values. The different nanoparticles with a high ILP may be useful for the in situ hyperthermia treatment of cancer cells.

The structural, magnetic and thermal features of Strontium (Sr) and iron doped (LaMnO3) have been studied to optimize their Hyperthermia efficiency. Citrate-gel technique was employed to synthesize (La1-xSrxMnO3) (x = 0.27, 0.3& 0.33) and a new composite (La1-x Srx Mn1-yFeyO3) (x = 0.27, y = 0.03). XRD patterns showed good polycrystalline structures with crystallite size up to 16 nm. HRTEM was employed to study the morphology of nanoparticles (NPs). Sodium Poly-Styrene Sulfonate (PSS) was opted to attach with (NPs), as a novel attempt, for coating purpose and FTIR showed existence of diversified peaks. Differential scanning calorimetric (DSC) studies were employed to assess the phase changes through respective heat flow mechanisms. The magnetic parameters using super quantum interface device (SQUID) showed good magnetization till 50 kȎe. Radio frequency (RF) induced field studies were employed at three different values (259.7, 327 & 518 kHz), to display comparative heating aptitudes of LSMO for hyperthermia efficacy.

In this work we report detailed investigations of structural, ac transport and magnetotransport properties of composites of reduced graphene oxide (rGO) and magnetite nanoparticles measured in the frequency range 10 Hz–2 MHz and in static magnetic fields upto 500 mT. AC conductivity of composite samples was enhanced by a factor of ~3 over that of the pure rGO even though the conductivity of magnetite is five orders of magnitude lower than that of rGO. We attribute this to charge transfer effects between the magnetite nanoparticles and the rGO matrix. Evidence of this is also observed in detailed Raman analysis of all samples. Further, we find a giant magnetoconductivity in the ac transport behavior of the composite samples. The rGO sample showed a negative magnetoconductivity of ~−15% at room temperature, while all composite samples showed positive magnetoconductivity with weak frequency dependence between 10 Hz and 254 kHz. We report a room temperature ac magnetoconductivity of 57% (at f = 254 kHz) and 40% (at f = 10 Hz) in a magnetic field B = 500 mT for the sample with 40 wt% magnetite nanoparticles. This is much larger than that obtained in dc magnetotransport, where room temperature magnetoconductivities in similar composites are typically 10% or less in comparable magnetic fields.