Sizing nanoparticle-covered droplets by extrusion through track-etch membranes

Interfacial segregation of nanoparticles on droplets, such as water droplets in oil, is achieved by mixing or shaking organic solutions of the nanoparticles with water. This typically results in the formation of droplets with a large distribution of sizes, ranging from 10 microm to greater than 200 microm in diameter. Here we describe the application of track-etch membranes to control the size of these nanoparticle-coated droplets. Passing nanoparticle-coated droplets through the membranes substantially reduces their size by breaking up the droplets during the extrusion process and reforming droplets of comparable size to the membrane pore diameter. When the nanoparticles used in these sizing procedures are covered with functional ligands, stabilization of the post-extrusion diameter is achieved by polymerization/cross-linking of the ligand periphery.     

L‐Proline–H2O2: A New Chemoselective Approach for Oxidation of Sulfides to Sulfoxides

A facile and selective oxidation of sulfides to sulfoxides using an L‐proline–H₂O₂ system for structurally divergent sulfide substrates with excellent yields at ambient conditions is reported.     

An efficient and sustainable protocol for oxidation of alcohols to carbonyl compounds

A simple and extremely efficient protocol is developed for oxidation of alcohols to carbonyl compounds at room temperature by using green solvent lactic acid and green oxidant H₂O₂. This protocol provides high conversion under catalyst free conditions. The easy work up procedure allows high selectivity and good to excellent yields of carbonyl compounds with purity. We have performed wide range of substrates in present study with primary focus on reusability of lactic acid.     

Rationalisation of extractive protocol by high-performance thin-layer chromatographic–densitometric quantification of berberine in multiple hydroalcoholic extract of Tinospora cordifolia stem

JPC – Journal of Planar Chromatography – Modern TLC - Drug development from medicinal plants by using various hydroalcoholic solvents has been an emerging trend in the last few decades....     

Rapid Biosynthesis of Silver Nanoparticles Using Areca Nut (Areca catechu) Extract Under Microwave-Assistance

In this research paper, we report on the rapid synthesis of silver nanoparticles using dried areca nut (Areca catechu). The microwave exposed aqueous areca nut powder when treated with the aqueous silver salt solution yielded irregular shaped silver nanoparticles. The formation and morphology of the nanoparticles are studied using UV–visible spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The X-ray diffraction studies and energy dispersive X-ray analysis indicate that the particles are crystalline in nature. The understanding of capping of biological moiety is derived from Fourier transform infrared spectroscopy and the thermogravimetric analysis. The green chemistry approach for the synthesis of silver nanoparticles is modest, amenable for large scale commercial production. Further the biologically synthesized silver nanoparticles are known for their potential antibacterial activity.     

Production, Purification, and Biochemical Characterization of a Fibrinolytic Enzyme from Thermophilic Streptomyces sp. MCMB-379

Production of the fibrinolytic enzyme was carried out using 2.5-L glass fermentor, culture of thermophilic Streptomyces sp., and glucose yeast extract peptone medium of pH 8.0. Five successive batches were carried out under controlled fermentation conditions viz., agitation 140 rpm, aeration 0.5 vvm, 55 °C, and 18 h. The total protein extracellularly produced in the cell-free broth was ~300-500 mg/L. The enzyme belongs to serine endopeptidase type. Studies on the fibrin degradation indicate that the enzyme degrades the fibrin into small molecular weight products as seen from HPLC profile. Phase-contrast microscopic structure of fibrin showed that enzyme cleaves the fibrin filaments. The ex vivo activity of the actinokinase was compared with 500 IU of urokinase and 350 IU of streptokinase. The ex vivo clot lysis was found to be faster as compared to the commercial available enzymes.     

Preparation and physicochemical characterization of carbamazepine (CBMZ): para-sulfonated calix[n]arene inclusion complexes

The formation of inclusion complexes with para-sulfonated calix[n]arene (PSC[n]A) was studied for carbamazepine (CBMZ), a poorly water soluble anticonvulsant drug. The effect of PSC[4]A and PSC[6]A on aqueous solubility of carbamazepine was studied extensively. The complete complexation of the drug was achieved after 48 h of shaking with PSC[n]A in water and evaporation of water to get solid complex. The interaction between PSC[n]A and CBMZ in solid state inclusion complexes was accomplished by aqueous phase solubility studies, HPLC, DSC, PXRD, FTIR, UV–Vis, and FT-Raman spectroscopy. The solubility of CBMZ increases as a function of PSC[n]A concentration. The results of the two phase solubility experiments are in good conformity to signify the formation of 1:1 (PSC[6]A:CBMZ) and 2:1 PSC[4]A:CBMZ complexes. The order of dissolution rate of CBMZ is inclusion complex > physical mixture > drug alone. The purpose of this study was to enhance solubility resulting in high dissolution rate and bioavailability of this essentially water insoluble drug.     

Liquid crystals based on calix[4]arene Schiff bases

New liquid crystals based on calix[4]arene Schiff base were prepared by the reaction of tetraamino-calix[4]arene with aldehydes (4-hydroxy benzaldehyde, 2-vanillin, 4-vanillin and 2-hydroxy naphthaldehyde). Dielectric investigations on a magnetically oriented sample forming N, SmA, and SmC phases were carried out. The dielectric constant (ε’ and ε”) and dielectric loss (tan δ) have been determined as a function of frequency (20 Hz–2 MHz). The synthesized derivatives were purified and characterized by FT-IR, ¹H-NMR, ¹³C-NMR and MALDI-TOF MS. All the synthesized compounds were investigated for liquid crystalline properties using DSC (Differential Scanning Calorimetry), DTA (Differential Thermal Analysis) and POM (Polarizing Optical Microscopy) attached with a hot stage. They generally exhibited nematic and typical fanlike or mosaic texture, which suggest the ordered smectic mesophases. Compounds were found to adopt a specific molecular structure due to the rigid bowl like calix[4]arene core, i.e., a cone-like structure with mesogenic units aligned within the molecule.     

Trimethylsilylethynyl ketones as surrogates for ethynyl ketones in the double Michael reaction

Trimethylsilylethynyl ketones can be desilylated in the presence of a tethered carbon diacid and induced to undergo a double Michael reaction in situ. The trimethylsilylethynyl ketones can serve as surrogates of ethynyl ketones that are difficult to prepare or isolate.     

Studies on Curcumin Loaded Poly(N-isopropylacrylamide) Silver Nanocomposite Hydrogels for Antibacterial and Drug Releasing Applications

Design of silver nanoparticles containing poly(N-isopropylarclamide) (PNIPAAm) hydrogels were prepared by free-radical polymerization of N-isopropylarclamide as an environmentally sensitive monomer and MBA as a crosslinker in an aqueous medium. The embedded silver nanocomposite hydrogels (AgNCH) structure were characterized by, UV-Vis, FTIR, DLS, TEM and X-ray analysis. Curcumin loading and release characteristics were performed for PNIPAAm hydrogel, silver ions loaded hydrogels as well as silver nanocomposite hydrogels. These curcumin loaded silver nanocomposite hydrogels exhibit excellent antibacterial action on Escherichia coli (E. coli). Therefore, the present study clearly provides novel antimicrobial hydrogels which are potentially useful in biomedical applications.