S.D. Dhole

Protein and polymer immobilized La0.7Sr0.3MnO3 nanoparticles for possible biomedical applications

La0.7Sr0.3MnO3 (LSMO) is a mixed-valent room temperature ferromagnet with properties that are attractive for their applicability in biomedicine. We report, for the first time, immobilization of commonly used biocompatible molecules on LSMO nanoparticles, namely bovine serum albumin and dextran. The former was conjugated to LSMO using 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide (CDI) as a coupling agent while the latter was used without any coupler. These bioconjugated nanoparticles exhibit several properties that suggest their applicability in the field of biomedicine, namely (a) no changes in the Curie temperature at ~360 K after conjugation with biomolecules, (b) rapid attainment of the desired temperature (48 °C) at low concentration (e.g. fluidized dextran-coated system at 80 µg ml−1) upon exposure to 20 MHz radio-frequency, (c) extremely low cytotoxicity in skin carcinoma, human fibrosarcoma and neuroblastoma cell lines and (d) high stability of the LSMO system with negligible leaching of ionic manganese into the delivery medium, indicating their safety in possible human applications.

Photocatalytic degradation of methyl orange using ZnO nanorods

Nanosized ZnO rods were synthesized using a microwave-assisted aqueous method. High molecular weight polyvinyl alcohol was used as a stabilizing agent. Size, surface morphology, and structure were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). SEM and TEM images show that ZnO nanorods have diameters of about 50 nm and lengths of a few micrometers. The XRD pattern reveals that ZnO nanorods are of hexagonal wurtzite structure. The average crystallite size calculated from Scherrers relation was found to be 40 nm. The effects of catalyst loading, pH value, and initial concentration of methyl orange on the photocatalytic degradation efficiency using ZnO nanorods as photocatalyst were discussed. The results revealed that ZnO nanorods with a diameter of 50 nm showed the highest photocatalytic activity at a surface density of 0.2 g dm−3.

Synthesis, characterization and in vitro study of biocompatible cinnamaldehyde functionalized magnetite nanoparticles (CPGF Nps) for hyperthermia and drug delivery applications in breast cancer.

Cinnamaldehyde, the bioactive component of the spice cinnamon, and its derivatives have been shown to possess anti-cancer activity against various cancer cell lines. However, its hydrophobic nature invites attention for efficient drug delivery systems that would enhance the bioavailability of cinnamaldehyde without affecting its bioactivity. Here, we report the synthesis of stable aqueous suspension of cinnamaldehyde tagged Fe3O4 nanoparticles capped with glycine and pluronic polymer (CPGF NPs) for their potential application in drug delivery and hyperthermia in breast cancer. The monodispersed superparamagnetic NPs had an average particulate size of ∼20 nm. TGA data revealed the drug payload of ∼18%. Compared to the free cinnamaldehyde, CPGF NPs reduced the viability of breast cancer cell lines, MCF7 and MDAMB231, at lower doses of cinnamaldehyde suggesting its increased bioavailability and in turn its therapeutic efficacy in the cells. Interestingly, the NPs were non-toxic to the non-cancerous HEK293 and MCF10A cell lines compared to the free cinnamaldehyde. The novelty of CPGF nanoparticulate system was that it could induce cytotoxicity in both ER/PR positive/Her2 negative (MCF7) and ER/PR negative/Her2 negative (MDAMB231) breast cancer cells, the latter being insensitive to most of the chemotherapeutic drugs. The NPs decreased the growth of the breast cancer cells in a dose-dependent manner and altered their migration through reduction in MMP-2 expression. CPGF NPs also decreased the expression of VEGF, an important oncomarker of tumor angiogenesis. They induced apoptosis in breast cancer cells through loss of mitochondrial membrane potential and activation of caspase-3. Interestingly, upon exposure to the radiofrequency waves, the NPs heated up to 41.6°C within 1 min, suggesting their promise as a magnetic hyperthermia agent. All these findings indicate that CPGF NPs prove to be potential nano-chemotherapeutic agents in breast cancer.

Diffusion mediated growth of (111) oriented silver nanoparticles in polyvinyl alcohol film under 6MeV electron irradiation

Silver (111) nanoparticles were synthesized by diffusing silver from a solution into polyvinyl alcohol (PVA) films under 6MeV electron irradiation at room temperature (∼25°C). The diffusion of silver in the PVA was confirmed by the Rutherford backscattering spectroscopy and scanning electron microscopy techniques. The plasmon absorption peak at ∼426nm was an evidence for the initiation of the diffusion mediated growth of silver nanoparticles. The x-ray diffraction results and the blueshift in the plasmon absorption peak reveal that the size of silver nanoparticles could be tailored in the range from 35to15nm by varying the electron fluence over the range of 1014–1015e∕cm2.

Reduction of graphene oxide by 100 MeV Au ion irradiation and its application as H2O2 sensor

Graphene oxide (GO) synthesized from a modified Hummers method was reduced (referred, rGO) by using 100 MeV Au ion species and its response to the sense H2O2 was investigated. The changes in the atomic composition and structural properties of rGO after irradiation were studied using x-ray diffraction, Fourier transform infrared spectroscopy and x-ray photo-electron spectroscopy. These results suggested that the removal of the oxygen-containing functional groups and the improvement of the electrochemical performance of reduced graphene oxide (rGO) after ion irradiation. Raman spectroscopic results revealed the increase in the disorder parameter (I D/I G) after Au ion irradiation and also the formation of a large number of small sp2 domains due to the electronic energy loss of ion beam. The resultant rGO was investigated for H2O2 sensing using electrochemical techniques and it showed a good response.

Synthesis and characterization of Nd2O3 nanoparticles in a radiofrequency thermal plasma reactor

The synthesis of nanocrystalline Nd2O3 through an inductively coupled radiofrequency thermal plasma route is reported. Unlike in conventional synthesis processes, plasma-synthesized nanoparticles are directly obtained in a stable hexagonal crystal structure with a faceted morphology. The synthesized nanoparticles are highly uniform with an average size around 20 nm. The nanoparticles are characterized in terms of phase formation, crystallinity, morphology, size distribution, nature of chemical bonds and post-synthesis environmental effects using standard characterization techniques. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy are used for structural and morphological studies. The thermo-gravimetric technique, using a differential scanning calorimeter, is used to investigate the purity of phase. Fourier transform infrared spectroscopy is used to investigate the nature of existing bonds. The optical response of the nanoparticles is investigated through the electronic transition of Nd(3+) ions in its crystalline structure via UV-visible spectroscopy. The presence of defect states and corresponding activation energies in the nanocrystalline Nd2O3 compared to those of the precursors are studied using thermoluminescence.

Radiation damage and minority carrier lifetime in crystalline silicon

Abstract The lifetime of the minority carriers in p and n type crystalline silicon was measured with 1 MeV pulsed electron beam. Silicon samples were exposed to different fluences of 1 and 6 MeV electron, 14 MeV neutrons, thermal neutrons and 60Co gamma rays and the value of the radiation damage coefficient for each sample was estimated by monitoring variations in the minority carrier lifetime with radiation fluence. It is found that 14 MeV neutrons can be effectively used in reducing the lifetime of minority carriers in silicon and therefore have potential in controlling parameters of semiconductor devices.

Defect studies in oxygen‐ion‐irradiated silicon‐based metal‐insulator‐semiconductor structures

Damages induced by 69 MeV oxygen ions (fluence: 1.3×1014 ions cm−2) in gold–silicon‐nitride–silicon metal‐insulator‐semiconductor (MIS) structures were studied by measuring the pre‐ and postirradiation junction and interface characteristics. Amount of the space‐charge produced at the silicon–silicon‐nitride interface was estimated by measuring capacitance‐voltage characteristics and the energies of the defects were measured with the technique of deep‐level transient spectroscopy. Two new defect levels having energies (Ec−0.34) eV and (Ec−0.63) eV were found in addition to the defects detected in the unirradiated devices. The values of the surface recombination velocities, measured with a variable‐energy electron beam, indicate that the radiation‐induced defect concentration on the surface was negligible; however, about 7% degradation in the lifetime of minority carriers in the bulk was observed. The results indicate that oxygen ions can be used to modify the junction characteristics of MIS structures whil...

Design of 6Mev linear accelerator based pulsed thermal neutron source: FLUKA simulation and experiment.

The 6MeV LINAC based pulsed thermal neutron source has been designed for bulk materials analysis. The design was optimized by varying different parameters of the target and materials for each region using FLUKA code. The optimized design of thermal neutron source gives flux of 3×10(6)ncm(-2)s(-1) with more than 80% of thermal neutrons and neutron to gamma ratio was 1×10(4)ncm(-2)mR(-1). The results of prototype experiment and simulation are found to be in good agreement with each other.

Comparison of 14 MeV neutron-induced and 1 MeV electron-induced radiation damage in crystalline silicon

A comparative study is made on the radiation damage caused by 14 MeV neutrons and 1 MeV electrons in crystalline silicon by measuring Hall mobility, carrier concentration, energies of defect centres and minority carrier lifetime. For both electrons and neutrons the energies of defect centres are found to be almost identical but the observed degradation in Hall mobility is large in neutron-irradiated and marginal in electron-irradiated silicon. The coefficient of radiation damage for 14 MeV neutrons is higher by almost three orders of magnitude compared with that for 1 MeV electrons.