Biomimetic preparation of polymer-supported free radical scavenging, cytocompatible and antimicrobial "green" silver nanoparticles using aqueous extract of Citrus sinensis peel

In the pursuit of making the nanoscale-research greener, the utilization of the reductive potency of a common byproduct of food processing industry i.e. orange peel is reported here to prepare biopolymer-templated "green" silver nanoparticles. Aqueous extract of orange peel at basic pH was exploited to prepare starch supported nanoparticles under ambient conditions. The compositional abundance of pectins, flavonoids, ascorbic acid, sugars, carotenoids and myriad other flavones may be envisaged for the effective reductive potential of orange peel to generate silver nanoparticles. The nanoparticles were distributed within a narrow size spectrum of (3-12 nm) with characteristic Bragg's reflection planes of fcc structure, and surface plasmon resonance peak at 404 nm. Anti-lipid peroxidation assay using goat liver homogenate and DPPH scavenging test established the anti-oxidant potency of the silver nanoparticles. Their synergy with rifampicin against Bacillus subtilis MTCC 736 and cytocompatibility with the human leukemic monocytic cell line, THP-1 were also investigated. Thus, the present work deals with the preparation of starch assisted anti-microbial, cytocompatible and free radical scavenging "green" silver nanoparticles.     

MICROWAVE INDUCED DRY-MEDIA SYNTHESIS OF SPIRO[INDOLE-THIAZOLIDINONES/ THIAZINONES] AS POTENTIAL ANTIFUNGAL AND ANTITUBERCULAR AGENTS AND STUDY OF THEIR REACTIONS

A series of new spiro[3H-indole-3,2′-thiazolidine]-2,4′(1H)-diones (IV) and spiro[3H-indole-3,2′-tetrahydro-1,3-thiazine]-2,4′(1H)-diones (V) have been synthesized in 85–93% yield by the one-pot environmentally benign microwave induced technique involving the cyclocondensation of 3-arylimino-2H-indol-2-ones (III) with thioacids viz. mercapto aceticacid (a)/3-mercapto propionicacid (b) using montmorillonite KSF as inorganic solid support. Intermediates (III) were synthesized in situ by the reaction of indole-2,3-diones (I) and substituted anilines (II). The spiro compounds have been further subjected to solvent-free acetylation, aminoalkylation and thiation under microwave irradiation using solid supports. The synthesized compounds have been screened in vitro for antifungal activity against Rhizoctonia solani, Fusarium oxysporum, and Collectotrichum capsici, and antitubercular acivity against Mycobacterium tuberculosis.     

Carbonated ferric green rust as a new material for efficient phosphate removal

Novel TiO(2)/carbon nanocomposites were prepared through the pyrolysis of TiO(2)/poly(furfuryl alcohol) hybrid materials, which were obtained by the sol-gel method, starting from titanium tetraisopropoxide (TTIP) and furfuryl alcohol (FA) precursors. Six different TiO(2)/C samples were prepared based on different TiO(2) nanoparticle sizes and TiO(2)/FA ratios. All of the samples were characterized using X-ray diffraction, infrared, and Raman spectroscopy. The results indicated effective FA polymerization onto the TiO(2) (anatase) nanoparticles, polymer conversion to disordered carbon following the pyrolysis, and a simultaneous TiO(2) anatase-rutile phase transition. The resulting TiO(2)/carbon composites were used as photocatalysts in the advanced oxidative process (AOP) for the degradation of reactive organic dyes in aqueous solution. The results indicate excellent photocatalytic performance (degradation of 99% of the dye after 60 min) with several advantages over traditional TiO(2)-based photocatalysts.     

Targeted delivery to single cells in precisely controlled microenvironments

The heterogeneous nature of cells can be an issue for in vitro analysis of cell function due to cell type differences within a population. Observations are most often averaged and dependent on the homogeneity or lack thereof for most cell types. Patterning of features at the sub-cellular scale (< 10 μm) allows for single cell manipulation. Additionally, the ability to pattern multiple materials simultaneously with nanoscale precision enables facile fabrication of multiplexed cellular microenvironment arrays. Here we use this ability to deliver different materials to single or few cells within hundreds of microns of each other on the same substrate. Calcein AM, Calcein Red AM and quantum dots are delivered to live single or few cells. This allows for exposing limited cell numbers to many well defined conditions, thus opening the possibility of single cell based assays.     

Volume exclusion and H-bonding dominate the thermodynamics and solvation of trimethylamine-N-oxide in aqueous urea

Trimethylamine-N-oxide (TMAO) and urea represent the extremes among the naturally occurring organic osmolytes in terms of their ability to stabilize/destabilize proteins. Their mixtures are found in nature and have generated interest in terms of both their physiological role and their potential use as additives in various applications (crystallography, drug formulation, etc.). Here we report experimental density and activity coefficient data for aqueous mixtures of TMAO with urea. From these data we derive the thermodynamics and solvation properties of the osmolytes, using Kirkwood-Buff theory. Strong hydrogen-bonding at the TMAO oxygen, combined with volume exclusion, accounts for the thermodynamics and solvation of TMAO in aqueous urea. As a result, TMAO behaves in a manner that is surprisingly similar to that of hard-spheres. There are two mandatory solvation sites. In plain water, these sites are occupied with water molecules, which are seamlessly replaced by urea, in proportion to its volume fraction. We discuss how this result gives an explanation both for the exceptionally strong exclusion of TMAO from peptide groups and for the experimentally observed synergy between urea and TMAO.     

Microfluidic production of biopolymer microcapsules with controlled morphology

We report a microfluidic approach to generating capsules of biopolymer hydrogels. Droplets of an aqueous solution of a biopolymer were emulsified in an organic phase comprising a cross-linking agent. Polymer gelation was achieved in situ (on a microfluidic chip) by diffusion-controlled ionic cross-linking of the biopolymer, following the transfer of the cross-linking agent from the continuous phase to the droplets. Gelation was quenched by collecting particles in a large pool of cross-linking agent-free liquid. The structure of microgels (from capsules to gradient microgels to particles with a uniform structure) was controlled by varying the time of residence of droplets on the microfluidic chip and the concentration of the cross-linking agent in the continuous phase. We demonstrated the encapsulation of a controlled number of polystyrene beads in the microgel capsules. The described approach was applied to the preparation of capsules of several polysaccharides such as alginate, kappa-carrageenan, and carboxymethylcellulose.     

Synthesis of 1D β-MnO2 for high-performance supercapacitor application

Journal of Solid State Electrochemistry - Electrochemical supercapacitors (ESs) still need to overcome development obstacles in order to realize their full potential while being acknowledged as a...