A combined experimental and quantum chemical analysis to explore the nonlinear optical activity of guanidinium L-monohydrogen tartrate.

Single crystal of guanidinium l-monohydrogen tartrate (GuHT) was grown by slow evaporation technique and was characterized by single crystal X-ray diffraction to confirm its crystal structure. UV-vis spectral study reveal that the GuHT crystal is optically transparent and its band gap was estimated from the transmittance data. The laser induced surface damage threshold study was carried out for the grown crystal using Nd:YAG laser. The second harmonic generation (SHG) nonlinearity of the grown crystalline sample was measured by Kurtz and Perry powder technique. The optimized molecular geometry, first order hyperpolarizability, dipole moment and polarizability of GuHT were obtained by density functional theory (DFT) using B3LYP/6-31G (d,p) level of basis set. The thermodynamic functions of the title compound was computed. The HOMO-LUMO energy gap explains the charge transfer interactions that take place within the molecule.

Bioreducible core-crosslinked hyaluronic acid micelle for targeted cancer therapy.

For drug delivery nanocarriers to be a safe and effective therapeutic option, blood stability, tumor-targetability, and intracellular drug release features should be considered. In this study, to develop a potent drug delivery carrier that can meet the multiple requirements, we engineered a bioreducible core-crosslinked polymeric micelle based on hyaluronic acid (CC-HAM) by a facile method using d,l-dithiothreitol in aqueous conditions. The CC-HAM exhibited enhanced structural stability under diluted conditions with PBS containing FBS or sodium dodecyl sulfates. We also successfully encapsulated doxorubicin (DOX), chosen as a hydrophobic anti-cancer drug, in CC-HAMs with high loading efficiency (>80%). The drug release rate of CC-HAMs was rapidly accelerated in the presence of glutathione, whereas the drug release was significantly retarded in physiological buffer (pH7.4). An in vivo biodistribution study demonstrated the superior tumor targetability of CC-HAMs to that of non-crosslinked HAMs, primarily ascribed to robust stability of CC-HAMs in the bloodstream. Notably, these results correspond with the improved pharmacokinetics and tumor accumulation of DOX-loaded CC-HAMs as well as their excellent therapeutic efficacy. Overall, these results suggest that the robust, bioreducible CC-HAM can be applied as a potent doxorubicin delivery carrier for targeted cancer therapy.

Experimental and theoretical investigations on N,N'-diphenylguanidinium dihydrogen phosphite - a semi-organic nonlinear optical material.

Single crystal of N,N'-diphenylguanidinium dihydrogen phosphite (DPGP) was grown by a slow evaporation technique and was characterized by single crystal X-ray diffraction and powder X-ray diffraction to confirm the structure and crystalline nature of DPGP crystal. UV-vis spectral study revealed that the DPGP crystal is optically transparent. The chemical bonding and presence of various functional groups were confirmed by the FT-IR and FT-Raman spectral studies. The thermal behavior of DPGP crystal was analyzed by simultaneous TG-DTA studies. The laser induced surface damage threshold study was carried out for the grown crystal using Nd:YAG laser. The second harmonic generation (SHG) nonlinearity of the grown crystalline sample was measured by the Kurtz and Perry powder technique. The quantum chemical analyses were performed by density functional theory (DFT) using B3LYP/6-31G (d,p) basis set.

A polymeric conjugate foreignizing tumor cells for targeted immunotherapy in vivo.

Antigen-specific CD8(+) cytotoxic T lymphocytes (CTLs) are key elements of immunological rejection in transplantation as well as cancer immunotherapy. Most tumors, however, are not immunologically rejected because they have self antigens, which are not recognized as the foreigner by CTLs. In this study, we hypothesized that "foreignizing" tumor cells by delivering non-self foreign antigens into the tumors would result in rejection by foreign antigen-reactive CTLs. As the model system to foreignize the tumors, we prepared a polymeric conjugate consisting of hyaluronic acid as the CD44(+) tumor-targeting ligand and ovalbumin (OVA) as a foreign antigen. When the conjugate was treated with CD44(high) TC-1 tumor cells, it was effectively taken up and allowed for displaying of antigenic OVA257-264 peptide at MHC class I on the surface of the cells. In addition, the conjugate was effectively accumulated into tumor tissue after its systemic administration to mice which are immunized with a vaccine for a vaccinia virus expressing OVA to generate OVA257-264 specific CTLs, resulting in substantial inhibition of tumor growth. Overall, these results suggest that the polymeric conjugates bearing foreign antigens may be innovative and promising cancer immunotherapeutic agents by foreignizing tumor cells, leading to immunological rejection.

Polysaccharide-based nanoparticles: a versatile platform for drug delivery and biomedical imaging.

Polysaccharide-based nanoparticles have attracted interest as carriers for imaging and therapeutic agents because of their unique physicochemical properties, including biocompatibility and biodegradability. In addition, the functional groups of the polysaccharide backbone allow facile chemical modification to develop nanoparticles with diverse structures. Some polysaccharides have the intrinsic ability to recognize specific cell types, facilitating the design of targeted-drug delivery systems through receptor-mediated endocytosis. The main objective of this review is to provide an overview of various polysaccharide-based nanoparticles and to highlight the recent efforts that have been made to improve the characteristics of polysaccharide-based nanoparticles for drug delivery and biomedical imaging.

Hydrotropic oligomer-conjugated glycol chitosan as a carrier of paclitaxel: synthesis, characterization, and in vivo biodistribution.

Development of successful formulations for poorly water-soluble drugs remains a longstanding critical and challenging issue in cancer therapy. As a potential drug carrier of paclitaxel, hydrotropic oligomer-glycol chitosan (HO-GC) was synthesized by chemical conjugation of the N,N-diethylnicotinamide-based oligomer, uniquely designed for enhancing the aqueous solubility of paclitaxel, to the backbone of glycol chitosan. Owing to its amphiphilicity, the conjugate formed self-assembled nanoparticles with a mean diameter of 313+/-13nm in a phosphate-buffered saline (PBS, pH 7.4 at 37 degrees C). HO-GC nanoparticles maintained their structure for up to 50days in PBS. They could encapsulate a high quantity (20wt.%) of paclitaxel (PTX) with a maximum drug-loading efficiency of 97%, due to the presence of hydrotropic inner cores. When HO-GC-PTX particles were exposed to the 0.1M sodium salicylate solution in PBS (pH 7.4), PTX was released from nanoparticles in a sustained manner. From the cytotoxicity test, it was confirmed that HO-GC-PTX nanoparticles showed lower cytotoxicity than free PTX formulation in 50%/50% Cremophor EL/ethanol mixture. The optical imaging results indicated that near-infrared fluorescence dye (Cy5.5)-labeled HO-GC-PTX showed an excellent tumor specificity in SCC7 tumor-bearing mice, due to the enhanced permeation and retention effect. Overall, HO-GC-PTX nanoparticles might be a promising carrier for PTX delivery in cancer therapy.

A modified catalytic-photometric method for the determination of vanadium in chloride rich hydro-geochemical samples.

The vanadium content in chloride rich hydrogeochemical samples has been determined through a modification in the existing standard gallic acid oxidation method which has severe interference problem from halides. The modification incorporates a preliminary fume-drying of the sample aliquot with a mixture of perchloric and sulphuric acids. This ensures total removal of halides and hence their interference. The estimation is completed as per the standard method after taking the sample in 10 ml of 1% nitric acid. Also mercuric nitrate addition which forms a part of the standard procedure to prevent halide interference, is also dispensed with keeping in view the toxic nature of mercury. The method has been tried on a number of samples having varying chloride content. The results obtained compare well with the standard PAR method. The method can be used to determine vanadium down to 1 ppb. The relative standard deviation obtained for vanadium contents in the range 400-10 ppb is in the range 4-8.2%.