Nanospheres

An approach for enzyme therapeutics is elaborated with cell-implanted nanoreactors that are based on multiple enzymes encapsulated in hollow silica nanospheres (HSNs). The synthesis of HSNs is carried out by silica sol-gel templating of water-in-oil microemulsions so that polyethyleneimine (PEI) modified enzymes in aqueous phase are encapsulated inside the HSNs. PEI-grafted superoxide dismutase (PEI-SOD) and catalase (PEI-CAT) encapsulated in HSNs are prepared with quantitative control of the enzyme loadings. Excellent activities of superoxide dismutation by PEI-SOD@HSN are found and transformation of H2 O2 to water by PEI-CAT@HSN. When PEI-SOD and PEI-CAT are co-encapsulated, cascade transformation of superoxide through hydrogen peroxide to water was facile. Substantial fractions of HSNs exhibit endosome escape to cytosol after their delivery to cells. The production of downstream reactive oxygen species (ROS) and COX-2/p-p38 expression show that co-encapsulated SOD/CAT inside the ...

We present a novel approach for analysis of low-conductivity and insulating materials with conventional pulsed-voltage atom probe tomography (APT), by incorporating an ultrathin metallic coating on focused ion beam prepared needle-shaped specimens. Finite element electrostatic simulations of coated atom probe specimens were performed, which suggest remarkable improvement in uniform voltage distribution and subsequent field evaporation of the insulated samples with a metallic coating of approximately 10nm thickness. Using design of experiment technique, an experimental investigation was performed to study physical vapor deposition coating of needle specimens with end tip radii less than 100nm. The final geometries of the coated APT specimens were characterized with high-resolution scanning electron microscopy and transmission electron microscopy, and an empirical model was proposed to determine the optimal coating thickness for a given specimen size. The optimal coating strategy was ...

Anatase TiO2 displaying dual morphologies were synthesized with a simple chemical route via a single step. A strong correlation between the dye sensitized solar cell (DSSC) device performance and the obtained dual morphologies are highlighted using relevant evidences from UV-vis and diffuse reflectance spectroscopy (DRS), Raman analysis, field emission scanning electron microscope, high resolution transmission electron microscope, current-voltage characteristics and impedance analysis. Structural investigation revealed that the interested medium in this work employed for the synthesis of TiO2 produced different types of dual morphologies such as nanospheres with nanoparticles (NSNP), microsphere decorated with nanoparticles (μSNP) and nanoparticles with stone like features (NPS). UV-vis and DRS results indicated the ability of the materials to assist with diffused reflectance and optical absorption of the screen printed photoanodes. In addition, an investigation of Raman vibrational characteristics was carried out in detail using synchronous and asynchronous 2D correlation analysis. The high intense Eg anatase mode of Raman spectrum was simulated using a phonon confinement model and its normalised spectra are compared with an experimental data. The resultant performances in the DSSCs were not indicative by the material properties; so, the charge transfer resistance (Rct) and recombination properties of the photoanode were investigated. These results showed that the Nyquist plot of NSNP possesses the smallest diameter, which reveals that the device based on NSNP offers the lowest Rct value that accounts for the higher conversion efficiencies when compared with the DSSC device based on photoanodes μSNP and NSP. It can be concluded that the improved power conversion efficiency shown by photoanode fabricated using NSNP has the dual role of optimum surface area for dye loading and light scattering centres. These properties, when optimized along with the offered pathway for electrolyte diffusion to the dye degeneration with less Rct, could lead to better photoelectric conversion efficiency.

In the recent past, the targeted drug delivery has gained more attention for various advantages. Amongst the plethora of Avenues explored for targeted drug delivery. Nanoparticles are particulate dispersions or solid particles with a size in the range of 10-1000nm. The drug is dissolved, entrapped, encapsulated or attached to a nanoparticle matrix. Depending upon the method of preparation, nanoparticles, nanospheres or nanocapsules can be obtained. The major goals in designing nanoparticles as a delivery system are to control particle size, surface properties and release of pharmacologically active agents in order to achieve the site-specific action of the drug at the therapeutically optimal rate and dose regimen. Present review reveals the methods of preparation, characterization and application of several nanoparticulate drug delivery systems.

For the first time, uniform molecularly imprinted polymer (MIP) nanoparticles were prepared using dicamba as a template. The MIP nanoparticles were successfully synthesized by precipitation polymerization using methacrylic acid (MAA) as functional monomer, trimethylolpropane trimethacrylate (TRIM) as cross-linker and acetonitrile as porogen. The produced polymers were characterized by differential scanning calorimetry (DSC) and their morphology was precisely examined by scanning electron microscopy (SEM). The MIP nanospheres were obtained with the average diameter of 234 nm. Batch-wise guest binding experiments were carried out to determine the removal efficiency of the produced MIP nanoparticles towards the template molecule in aqueous solutions. The MIP showed outstanding affinity toward dicamba in aqueous solution with maximum removal efficiency of 87.5% at 300 mg.L-1 of dicamba solution. The MIP exhibited higher adsorption efficiency compared with the corresponding non-imprinted polymer (NIP) as well as outstanding selectivity towards dicamba relative to the template analog in an aqueous solution. Moreover, effects of pH on removal efficiency and selectivity of MIP were evaluated in detail.

Magnetic hydrogel κ-carrageenan nanospheres were successfully prepared via water-in-oil (w/o) microemulsions combined with thermally induced gelation of the polysaccharide. The size of the nanospheres (an average diameter (∅) of about 50 and 75 nm) was modulated by varying the concentration of surfactant. The nanospheres contained superparamagnetic magnetite nanoparticles (∅8 nm), previously prepared by co-precipitation within the biopolymer. Carboxyl groups, at a concentration of about 4 mmol g-1, were successfully grafted at the surface of these magnetic nanospheres via carboxymethylation of the κ-carrageenan. The carboxylated nanospheres were shown to be thermo-sensitive in the 37-45 °C temperature range, indicating their potential as thermally controlled delivery systems for drugs and/or magnetic particles at physiological temperatures. Finally, preliminary results have been obtained for IgG antibody conjugation of the carboxylated nanospheres and the potential of these systems for bio-applications is discussed.