In vitro hyperthermia with improved colloidal stability and enhanced SAR of magnetic core/shell nanostructures.

Magnetic core/shell nanostructures of Fe3O4 nanoparticles coated with oleic acid and betaine-HCl were studied for their possible use in magnetic fluid hyperthermia (MFH). Their colloidal stability and heat induction ability were studied in different media viz. phosphate buffer solution (PBS), saline solution and glucose solution with different physiological conditions and in human serum. The results showed enhanced colloidal stability in these media owing to their high zeta potential values. Heat induction studies showed that specific absorption rates (SAR) of core/shells were 82-94W/g at different pH of PBS and concentrations of NaCl and glucose. Interestingly, core/shells showed 78.45±3.90W/g SAR in human serum. The cytotoxicity of core/shells done on L929 and HeLa cell lines using 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide and trypan blue dye exclusion assays showed >89% and >80% cell viability for 24 and 48h respectively. Core/shell structures were also found to be very efficient for in vitro MFH on cancer cell line. About 95% cell death was occurred in 90min after hyperthermia treatment. The mechanism of cell death was found to be elevated ROS generation in cells after exposure to core/shells in external magnetic field. This study showed that these core/shells have a great potential to be used in in vivo MFH.

Intracellular synthesis of silver nanoparticle by actinobacteria and its antimicrobial activity.

Intracellular synthesis of silver nanoparticles (AgNPs) using Rhodococcus spp. is demonstrated. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier trans-form infrared spectroscopy, and transmission electron microscopy. Transmission electron microscopy study of microorganisms' revealed synthesis of nanoparticle was occurring inside the cell, in the cytoplasm. AgNPs ranged from 5 to 50 nm. Formed nanoparticles were stable in the colloidal solution due to presence of proteins on the surface. AgNPs showed excellent bactericidal and bacteriostatic activity against pathogenic microorganisms.

Synthesis, characterization and biocompatibility of chitosan functionalized superparamagnetic nanoparticles for heat activated curing of cancer cells.

Surface functionalization, colloidal stability and biocompatibility of magnetic nanoparticles are crucial for their biological applications. Here, we report a synthetic approach for the direct preparation of superparamagnetic nanoparticles consisting of a perovskite LSMO core modified with a covalently linked chitosan shell that provides colloidal stability in aqueous solutions for cancer hyperthermia therapy. The characterization of the core-shell nanostructure using Fourier transform infrared spectroscopy; thermo-gravimetric analysis to assess the chemical bonding of chitosan to nanoparticles; field-emission scanning electron microscopy and transmission electron microscopy for its size and coating efficiency estimation; and magnetic measurement for their magnetization properties was performed. Zeta potential and light scattering studies of the core shell revealed it to possess good colloidal stability. Confocal microscopy and MTT assay are performed for qualitative and quantitative measurement of cell viability and biocompatibility. In depth cell morphology and biocompatibility is evaluated by using multiple-staining of different dyes. The magnetic@chitosan nanostructure system is found to be biocompatible up to 48 h with 80% cell viability. Finally, an in vitro cancer hyperthermia study is done on the MCF7 cell line. During in vitro hyperthermia treatment of cancer cells, cell viability is reduced upto 40% within 120 min with chitosan coated nanoparticles. Our results demonstrate that this simplified and facile synthesis strategy shows potential for designing a colloidal stable state and biocompatible core shell nanostructures for cancer hyperthermia therapy.

Structured superparamagnetic nanoparticles for high performance mediator of magnetic fluid hyperthermia: synthesis, colloidal stability and biocompatibility evaluation.

Core-shell structures with magnetic core and metal/polymer shell provide a new opportunity for constructing highly efficient mediator for magnetic fluid hyperthermia. Herein, a facile method is described for the synthesis of superparamagnetic LSMO@Pluronic F127 core-shell nanoparticles. Initially, the surface of the LSMO nanoparticles is functionalized with oleic acid and the polymeric shell formation is achieved through hydrophobic interactions with oleic acid. Each step is optimized to get good dispersion and less aggregation. This methodology results into core-shell formation, of average diameter less than 40 nm, which was stable under physiological conditions. After making a core-shell formulation, a significant increase of specific absorption rate (up to 300%) has been achieved with variation of the magnetization (<20%). Furthermore, this high heating capacity can be maintained in various simulated physiological conditions. The observed specific absorption rate is almost higher than Fe3O4. MTT assay is used to evaluate the toxicity of bare and core-shell MNPs. The mechanism of cell death by necrosis and apoptosis is studied with sequential staining of acridine orange and ethidium bromide using fluorescence and confocal microscopy. The present work reports a facile method for the synthesis of core-shell structure which significantly improves SAR and biocompatibility of bare LSMO MNPs, indicating potential application for hyperthermia.

Functionalization of La(0.7)Sr(0.3)MnO3 nanoparticles with polymer: studies on enhanced hyperthermia and biocompatibility properties for biomedical applications.

Now-a-days surface functionalized La(0.7)Sr(0.3)MnO(3) (LSMO) nanoparticles by different biocompatible polymers are attracted considerable interest in various biomedical applications in general and magnetic fluid hyperthermia treatment of cancer in particular. In this paper La(0.7)Sr(0.3)MnO(3) nanoparticles are synthesized and functionalized with polymer (dextran, with mean particle size ~25 nm). Magnetic measurements of both coated and uncoated particles reveal the superparamagnetic nature at room temperature. The resulting coated particles form a stable suspension in an aqueous environment at physiological pH and possess a narrow hydrodynamic size distribution. In vitro cytotoxicity of the MNPs has been assessed under Trypan blue dye exclusion and MTT assay on HeLa and L929 cell lines. The results demonstrate that dextran functionalized nanoparticles have no significant effect on cell viability within the tested concentrations (0.2-1 mg/mL) as compared to bare LSMO. Magnetic fluid hyperthermia studies have been done in detail; the influence of an applied alternating current (AC) magnetic field on heat generation is presented in brief. Dextran functionalized LSMO has the higher Specific absorption rate (SAR) value than the bare LSMO. After functionalization with dextran the SAR values of LSMO nanoparticles increased from 25 to 51 W/g. The study shows that the rise in temperatures by these nanoparticles could be safely controlled around Curie temperature (T(c)).

Induction heating studies of dextran coated MgFe2O4 nanoparticles for magnetic hyperthermia.

MgFe(2)O(4) nanoparticles with sizes around 20 nm have been prepared by a combustion method and functionalized with dextran for their possible applications in magnetic particle hyperthermia. The induction heating study of these nanoparticles at different magnetic field amplitudes, from 6.7 kA m(-1) to 26.7 kA m(-1), showed self-heating temperature rise up to 50.25 °C and 73.32 °C (at 5 mg mL(-1) and 10 mg mL(-1) concentrations in water respectively) which was primarily thought to be due to hysteresis losses activated by an AC magnetic field. The dextran coated nanoparticles showed a maximum specific absorption rate (SAR) of about 85.57 W g(-1) at 26.7 kA m(-1) (265 kHz). Dextran coated nanoparticles at concentrations below 1.8 mg mL(-1) exhibit good viability above 86% on mice fibroblast L929 cells. The results suggest that combustion synthesized MgFe(2)O(4) nanoparticles coated with dextran can be used as potential heating agents in magnetic particle hyperthermia. Uncoated and dextran coated samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric-differential thermal analysis (TG-DTA) and zeta potential-DLS studies.

Natural radioactivity study in soil samples of South Konkan, Maharashtra, India.

This study assesses the level of natural radioactivity due to radionuclides, ²³8U, ²³²Th and 4°K, in 50 soil samples collected from South Konkan, Maharashtra, India. The mean activity concentrations of ²³8U, ²³²Th and 4°K are 44.97 ± 1.22 Bq kg⁻¹, 59.70 ± 2.17 Bq kg⁻¹ and 217.51 ± 8.75 Bq kg⁻¹, respectively, measured from all the soil samples studied. The good correlation between activity concentration of U-238 and Th-232; U-238 and K-40 as well as between activity concentration of Th-232 and K-40 was observed. The average calculated absorbed dose rate in air (68.08 nGy h⁻¹) was found to be higher than the world average of 57 nGy h⁻¹ (UNSCEAR 2000). Radium equivalent activity for all the villages was found to be lower than the worldwide value. The values of external hazard index and internal hazard index determined from all the soil samples were found to be within recommended limit. The calculated average annual effective dose was found to be 0.42 mSv y⁻¹, and it is lower than the worldwide value of 0.46 mSv y⁻¹.The annual effective dose values calculated from present study were comparable with previous studies carried out in other countries and in India. The data established from the study can be useful as baseline information on natural radioactivity in South Konkan, Maharashtra, India.

Enhanced colloidal stability of polymer coated La0.7Sr0.3MnO3 nanoparticles in physiological media for hyperthermia application.

Surface of La(0.7)Sr(0.3)MnO3 (LSMO) magnetic nanoparticles (MNPs) is functionalized with polymer (dextran) and their colloidal stability in various mediums is carried out. The influence of the surface functionalization of LSMO MNPs on their colloidal stability in physiological media is studied and correlated with their hyperthermia properties. Many studies have concerned the colloidal stability of MNPs coated with polymer, but their long-term stability when such complexes are exposed to physiological media is still not well understood. After zeta potential study, it is found that the dextran coating on MNPs improves the colloidal stability in water as well as in physiological media like PBS. The specific absorption rates (SAR) of these MNPs are found to be in 50-85 W/g in different concentrations of glucose and NaCl; and there values are suitable for hyperthermia treatment of cancer cells under AC magnetic field. After incorporation of MNPs up to 0.2-1mg/mL in 2 × 10(5)cells/mL (L929), the apoptosis and necrosis studies are carried out by acridine orange and ethidium bromide (AO and EB) staining and followed by visualization of microstructures under a fluorescence microscope. It is found that there are no morphological changes (i.e. no signs of cell rounding, bubble formation on the membrane and nuclear fragmentation) suggesting biocompatibility of dextran coated LSMO nanoparticles up to these concentrations.

Polyvinyl alcohol: an efficient fuel for synthesis of superparamagnetic LSMO nanoparticles for biomedical application.

La(0.7)Sr(0.3)MnO(3) (LSMO) nanoparticles have been prepared using glycine and polyvinyl alcohol (PVA) as fuels. Their crystal structure, particle morphology and compositions are characterized using X-ray diffraction, transmission electron microscopy, field-emission electron microscopy and energy dispersive analysis of X-ray. They show a pseudo-cubic perovskite structure. The spherical particle sizes of 30 and 20 nm have been obtained from samples prepared by glycine and PVA respectively. The field cooled (FC) and zero field cooled (ZFC) magnetizations have been recorded from 5 to 375 K at 500 Oe and superparamagnetic blocking temperatures (T(B)) of 75 and 30 K are obtained from samples prepared by glycine and PVA respectively. Particle size distribution is observed from dynamic light scattering measurements. Dispersion stability of the particles in water is studied by measuring the Zeta potential with varying the pH of the medium from 1 to 12. Under induction heating experiments, a hyperthermia temperature (42-43 °C) is achieved by both the samples (3-6 mg mL(-1)) at magnetic fields of 167-335 Oe and at a frequency of 267 kHz. The bio-compatibility of the LSMO nanoparticles is studied on the L929 and HeLa cell lines by MTT assay for up to 48 h. The present work reveals the importance of synthesis technique and fuel choice on structural, morphological, magnetic, hyperthermia and biocompatible properties of LSMO and predicts the suitability for biomedical applications.