Dielectric and Mechanical Properties of PDMS-La2Ba2XZn2Ti3O14 (X = Mg/Ca/Sr) Nanocomposites.

Flexible polydimethylsiloxane-La2Ba2XZn2Ti3O14 (X = Mg/Ca/Sr) [PDMS-LBT] nanocomposites with high permittivity (dielectric constant, k) are prepared through a room-temperature mixing process. The LBT nanoparticles used in this study are prepared through a high-temperature solid-state reaction. It is observed that LBT (X = Mg/Ca) nanoparticles are spherical in nature, with particle size ∼20 nm, as observed from the HRTEM images, whereas LBT (X = Sr) nanoparticles are cubical in nature with particle size ≥100 nm. These LBT (X = Mg/Ca/Sr) nanoparticles are crystalline in nature, as apparent from the XRD analysis and SAED patterns. The permittivity of LBT nanoparticles is higher when "Ca" is present in place of "X". These three oxides show a temperature-dependent dielectric behavior, where LBT nanoparticles with "Sr" show a sharp change in permittivity at a temperature of ∼105 °C. These kinds of oxide materials, especially LBT (X = Sr) nanoparticles/oxides, can be used in dielectric/resistive switching devices. The effect of LBT nanoparticle concentration on the dielectric and mechanical properties of PDMS-LBT nanocomposites is widely studied and found that there is a significant increase in dielectric constant with an increase in the concentration of LBT nanoparticles. There is a decrease in the volume resistivity with the increase in the LBT nanoparticle concentration. All the PDMS-LBT nanocomposites have low dielectric loss (ε″) compared to the dielectric constant value. It is found that both permittivity (ε') and AC conductivity (σac) of PDMS-LBT composites are increased with the temperature at a frequency of 1 Hz. The % elongation at break (% EB) and tensile strength (TS) decrease with the LBT nanoparticle concentration in the matrix PDMS, which is due to the non-reinforcing behavior of LBT nanoparticles. The distribution and dispersion of LBT nanoparticles in the matrix PDMS are observed through HRTEM and AFM/SPM.

Citric Acid Fuctionalized Magnetic Ferrite Nanoparticles for Photocatalytic Degradation of Azo Dye.

In this study different magnetic ferrite nanoparticles (MFe2O4, where M = Fe, Mn, Zn) were synthesized through an aqueous coprecipitation method and then functionalized with citric acid for the degradation of azo dye present in industrial waste water. Here we evaluated the role of citric acid for photocatalytic application. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and the catalytic activity in degradation of methyl orange (MO) was evaluated. The rate of MO degradation in different magnetic systems was determined by UV-Vis spectroscopy. The effect of active parameters (pH, initial MO concentration and effect of sunlight) on degradation performance was investigated. For the first time, citric acid chemistry is successfully exploited to develop a photocatalyst that can successfully degrade the dyes. This citric acid functionalized magnetic ferrite nanoparticles are very much effective for photocalytic degradation of dye and also these can be recollected with the help of permanent magnet for successive uses.

Nanoparticle and polysaccharide conjugate: a potential candidate vaccine to improve immunological stimuli.

Active polysaccharides isolated from various fungal sources have been implicated to stimulate immune response against various pathogens as well as self anomalies such as cancer. Therefore, the nuanced approach presented in our work was to blend polysaccharides derived from Pleurotus ostreatus with biocompatible ferrite nanoparticles and thereafter investigate the enhanced immune functionality of the polysaccharide-nanoparticle composite. A Schiff base reductive amination reaction occurred between the aldehyde group of the polysaccharide and the amine group of the nanoparticles in the presence of a strong reducing agent such as sodium cyanoborohydride to form a stable amide bond between the two conjugating molecules. The multifaceted conjugate was characterized by physiochemical techniques such as electron microscopy, FTIR, VSM and DLS measurements. This particulate form of the polysaccharide showed a marked escalation in the production of free radicals such as reactive oxygen and nitrogen species in murine macrophages as compared to the soluble form. Animal based experiments demonstrated a reduction in tumor volume and augmentation in the proliferation of splenocytes in particulate or conjugated polysaccharide treated mice. Furthermore, molecular signaling studies showed a high upregulation in p-p38 and p-MEK molecules in particulate polysaccharide treated RAW264.7 cells suggesting a cellular downstream mechanistic regulation behind the immunostimulative response.

Biocompatible mesoporous silica-coated superparamagnetic manganese ferrite nanoparticles for targeted drug delivery and MR imaging applications.

Multifunctional mesoporous silica-coated superparamagnetic manganese ferrite (MnFe2O4) nanoparticles (M-MSN) were synthesized and evaluated for targeted drug delivery and magnetic resonance imaging (MRI) applications. MnFe2O4 nanoparticles were prepared by solvothermal route and were silica-coated by surface silylation using sol-gel reactions. Subsequently, silylation was done using (3-aminopropyl)triethoxysilane in presence of a surfactant (CTAB), followed by selective etching of the surfactant molecules that resulted in amine-functionalized superparamagnetic nanoparticles (NH2-MSN). Further modification of the surface of the NH2-MSN with targeting (folate) or fluorescent (RITC) molecules resulted in M-MSN. The formation of the M-MSN was proved by several characterization techniques viz. XRD, XPS, HRTEM, FESEM, VSM, BET surface area measurement, FTIR, and UV-Vis spectroscopy. The M-MSN were loaded with anticancer drug Doxorubicin and the efficacy of the DOX loaded M-MSN was evaluated through in vitro cytotoxicity, fluorescence microscopy, and apoptosis studies. The in vivo biocompatibility of the M-MSN was demonstrated in a mice-model system. Moreover, the M-MSN also acted as superior MRI contrast agent owing to a high magnetization value as well as superparamagnetic behavior at room temperature. These folate-conjugated nanoparticles (FA-MSN) exhibited stronger T2-weighted MRI contrast towards HeLa cells as compared to the nanoparticles without folate conjugation, justifying their potential importance in MRI based diagnosis of cancer. Such M-MSN with a magnetic core required for MRI imaging, a porous shell for carrying drug molecules, a targeting moeity for cancer cell specificity and a fluorescent molecule for imaging, all integrated into a single system, may potentially serve as an excellent material in biomedical applications.

Heteroglucan-dendrimer glycoconjugate: a modulated construct with augmented immune responses and signaling phenomena.

BACKGROUND: Newer strategies for augmenting immune responses of pharmacologically active glucans may serve to improve the medicinal potential of these biomolecules. With this aim, the present work was focused on generating targeted high molecular size glucan particles with magnified immune response activity. METHODS: Heteroglucans were conjugated with PAMAM dendrimers using a Schiff base reductive amination reaction to generate a polytethered molecule with multiple glucan motifs. The modulated construct was characterized by FTIR, TEM, (1)H NMR and dynamic light scattering (DLS) methods. Effects of conjugated glucans were examined in RAW 264.7 macrophage cells as well as in S-180 murine tumor models. RESULTS: Dendrimer-conjugated glucans were found to exhibit a two-fold increase in immune stimulation in comparison to unconjugated glucans. This may be corroborated by the predominant enhancement in immunological functions such as nitric oxide production, ROS generation and immune directed tumor inhibition in murine models. Immune cell surface markers (CD4, CD8, CD19, MHC-II) and cytokine levels were also found to be highly up-regulated in the splenocytes of mice subjected to particulate glucan administration. Our study also demonstrated that conjugated glucan treatment to RAW 264.7 cells strongly enhanced the phosphorylation of two downstream signalling molecules of the mitogen activated protein kinase (MAPKs) family: p38 and MEK1/2 relative to single glucans thereby relating molecular mechanisms with enhanced immune stimulation. CONCLUSIONS AND GENERAL SIGNIFICANCE: The results obtained thus support that particulate format of soluble heteroglucan will thereby improve its functionality and identify leads in therapeutic competence.

Thermal and pH responsive polymer-tethered multifunctional magnetic nanoparticles for targeted delivery of anticancer drug.

Targeted and efficient delivery of therapeutics to tumor cells is one of the key issues in cancer therapy. In the present work, we report a temperature and pH dual responsive core-shell nanoparticles comprising smart polymer shell coated on magnetic nanoparticles as an anticancer drug carrier and cancer cell-specific targeting agent. Magnetite nanoparticles (MNPs), prepared by a simple coprecipitation method, was surface modified by introducing amine groups using 3-aminopropyltriethoxysilane. Dual-responsive poly(N-isopropylacrylamide)-block-poly(acrylic acid) copolymer, synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, was then attached to the amine-functionalized MNPs via EDC/NHS method. Further, to accomplish cancer-specific targeting properties, folic acid was tethered to the surface of the nanoparticles. Thereafter, rhodamine B isothiocyanate was conjugated to endow fluorescent property to the MNPs required for cellular imaging applications. The nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), zeta potential, vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS) measurements, and FTIR, UV-vis spectral analysis. Doxorubicin (DOX), an anticancer drug used for the present study, was loaded into the nanoparticles and its release behavior was subsequently studied. Result showed a sustained release of DOX preferentially at the desired lysosomal pH and temperature condition. The biological activity of the DOX-loaded MNPs was studied by MTT assay, fluorescence microscopy, and apoptosis. Intracellular-uptake studies revealed preferential uptake of these nanoparticles into cancer cells (HeLa cells) compared to normal fibroblast cells (L929 cells). The in vitro apoptosis study revealed that the DOX-loaded nanoparticles caused significant death to the HeLa cells. These nanoparticles were capable of target specific release of the loaded drug in response to pH and temperature and hence may serve as a potential drug carrier for in vivo applications.

Characterization and lectin microarray of an immunomodulatory heteroglucan from Pleurotus ostreatus mycelia.

Glucans isolated from various mushroom and mycelia sources are interestingly being studied nowadays as a potent therapeutic agent. The present work was focused on the isolation, characterization and immunomodulatory study of a novel water soluble glucan from the pure mycelia of Pleurotus ostreatus. The extracted glucan was found to have a high molecular weight of ∼2.7 × 10(6)Da and mainly comprised of glucose, mannose and fucose in a ratio of 3:2:1 with both ß and α linkages. Presence of terminal or interior glucose, mannose and fucose residues was also revealed using a high throughput miniaturized platform of lectin microarray. The heteroglucan folded into a triple helical conformation and exhibited enhanced immune cell activation and anti-tumor potential in tumor bearing mice model. Thus, potential biological functions incorporated in these glucan molecules acts in accord with its structural property and exploration of such structure-function relationship will unveil its diverse mechanism of action.

A novel approach for efficient immobilization and stabilization of papain on magnetic gold nanocomposites.

In the present study, a facile functionalization of magnetic nanoparticles has been described for the immobilization of enzyme that offers many advantages for reuse and excellent efficiencies. The magnetic gold nanocomposites have been fabricated for the successful immobilization of an industrially important enzyme "papain". For immobilization of papain on magnetic gold nanocomposites, magnetic nanoparticles were modified with 3-(mercaptopropyl) trimethoxy silane (MPTS). Further, the citrate stabilized gold nanoparticles were chemisorbed on these thiol coated magnetic nanoparticles to fabricate the desired magnetic gold nanocomposites. Papain containing net positive charge (isoelectric point of papain=8.75) in PBS buffer (pH 7.4) has immobilized on the surface of the negatively charged magnetic gold nanocomposites through the ionic or electrostatic interaction. The Michaelis-Menten kinetic constant (K(m)) and maximum reaction velocity (V(max)) for free papain were 0.236×10(5) g ml(-1) and 4.08 g ml(-1)/s respectively whereas for immobilized papain, K(m) and V(max) values were 0.308×10(5) g ml(-1) and 5.4 g ml(-1)/s respectively. The loading amount of papain on magnetic gold nanocomposites was 54 mg/g support and the activity recovery of the immobilized papain reached to 47 (±5)% compared to native papain. The main advantage of this papain nanobiocatalyst is the easy isolation of enzyme from the reaction medium.

Facile preparation of multifunctional hollow silica nanoparticles and their cancer specific targeting effect.

Efficient delivery of therapeutics to tumor cells is one of the key issues in cancer therapy. In the present work, we have established a facile and unique chemical strategy for fabrication of highly biocompatible and water-dispersible multifunctional hollow silica nanoparticles (HSNPs). These mesoporous silica nanoparticles, having ring-like morphology, were fabricated by the sol-gel method followed by selective etching of the inner inorganic core. Further, to accomplish cancer-specific targeting properties, folic acid was tethered to the surface of HSNPs through amide bond formation using the EDC/NHS coupling method. Thereafter, rhodamine B isothiocyanate (RITC) was conjugated to the HSNPs to endow the fluorescent property to the nanoparticles required for biological imaging applications. The successful formation of multifunctional HSNPs was confirmed by XRD, FTIR, zeta potential, TEM, FESEM, and BET surface area measurements. The average particle size of HSNPs was found to be 50 nm to 70 nm from TEM analysis, which is the desired size-range for drug-delivery vehicles. These HSNPs showed good mesoporous behavior and were found to be an excellent candidate for loading and releasing the anticancer drug doxorubicin (DOX). The bioactivity of the HSNPs was verified by biological assay including cell cytotoxicity by MTT assay, intracellular uptake by fluorescence microscopy, cell cycle analysis by fluorescence-activated cell sorting (FACS), and apoptosis study. Besides, the effect of salt concentration on the drug release performance was evaluated. An in vitro biological study revealed that these DOX-loaded folate-targeted HSNPs achieved excellent efficacy for simultaneously targeting and destroying cancer cells.