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A new class of twinned amphiphiles was developed by conjugating a pair of hydrophilic head groups from mPEG chains (Mn : 350 or 1000) and a pair of hydrophobic segments from linear alkyl chains (C11 or C18 ) through a novel spacer synthesized from glycerol and p-hydroxybenzoic acid. The aggregation phenomena of the amphiphiles were proven by DLS and fluorescence experiments, whereas size and morphology of the aggregates were evaluated by cryo-TEM. The measurements proved the formation of globular, thread-like or rod-like micelles as well as planar double-layer assemblies, depending on the amphiphile's molecular structure. The applicability of these non-ionic amphiphilic systems as nanocarriers for hydrophobic guest molecules was demonstrated by encapsulating a hydrophobic dye, Nile Red, and a hydrophobic drug, Nimodipine. The transport capacity results for both Nimodipine and Nile Red prove them as a promising candidate for drug delivery.

Enzymes, being remarkable catalysts, are capable of accepting a wide range of complex molecules as substrates and catalyze a variety of reactions with a high degree of chemo-, stereo- and regioselectivity in most of the reactions. Biocatalysis can be used in both simple and complex chemical transformations without the need for tedious protection and deprotection chemistry that is very common in traditional organic synthesis. This current review highlights the applicability of one class of biocatalysts viz. ‘‘lipases’’ in synthetic transformations, the resolution of pharmaceutically important small molecules including polyphenols, amides, nucleosides and their precursors, the development of macromolecular systems (and their applications as drug/gene carriers), flame retardants, polymeric antioxidants and nanocrystalline solar cells, etc.

Crosslinking of polymers using crosslinking agents has been widely utilized to further improve the mechanical and thermal properties of the polymers. We have explored various aliphatic and aromatic dicarboxylic acids such as malonic acid, glutaric acid, isophthalic acid, terephthalic acid and terephthaloyl chloride as crosslinking agents to crosslink polydimethylsiloxane copolymer [poly{poly(dimethylsiloxane-1000)-propylamine-5-aminoisophthaloyl}] to improve its flame retardant properties. We have also used nanoclays [Cloisite 20A, 2C18 MMT (dimethylditallowammonium-/ dimethyldioctadecylammonium-modified montmorillonite)] along with the crosslinker during crosslinking process to further reduce the flammability of the crosslinked polymers. Among all the crosslinkers investigated, isophthalic acid with the nanoclay was found to have the best performance for flame retardant applications. The present work provides a basis to further improve the performance of silicone-based polymers for the flame retardant ap...

Nano-particles with controllable particle size and shape are of great interest in biomedical applications (1). From the standpoint of drug carrier design with wide applicability to a variety of hydrophobic drugs, an effective strategy would be to prepare a simple copolymer having the property to form stable polymeric micelles which can entrap hydrophobic drugs in the core (2). In this study, we have attached saturated and unsaturated long chain acid chlorides to the copolymer of PEG and dimethyl-5-aminoisophthalate via an amide linkage in order to make the copolymers amphiphilic. Further, bioactive compounds like β-carotene, which has considerable double bond unsaturation and curcumin, which has considerable aromatic unsaturation, were encapsulated in these amphiphilic copolymers which successfully demonstrated their drug loading ability.

The chain-breaking antioxidant activities of eight coumarins [7-hydroxy-4-methylcoumarin (1), 5,7-dihydroxy-4-methylcoumarin (2), 6,7-dihydroxy-4-methylcoumarin (3), 6,7-dihydroxycoumarin (4), 7,8-dihydroxy-4-methylcoumarin (5), ethyl 2-(7,8-dihydroxy-4-methylcoumar-3-yl)-acetate (6), 7,8-diacetoxy-4-methylcoumarin (7) and ethyl 2-(7,8-diacetoxy-4-methylcoumar-3-yl)-acetate (8)] during bulk lipid autoxidation at 37 °C and 80 °C in concentrations of 0.01–1.0 mM and their radical scavenging activities at 25 °C using TLC–DPPH test have been studied and compared. It has been found that the o-dihydroxycoumarins 3–6 demonstrated excellent activity as antioxidants and radical scavengers, much better than the m-dihydroxy analogue 2 and the monohydroxycoumarin 1. The substitution at the C-3 position did not have any effect either on the chain-breaking antioxidant activity or on the radical scavenging activity of the 7,8-dihydroxy- and 7,8-diacetoxy-4-methylcoumarins 6 and 8. The comparison with DL-α-tocopherol (TOH), caffeic acid (CA) and p-coumaric acid (p-CumA) showed that antioxidant efficiency decreases in the following sequence: TOH > CA > 3 > 4 > 6 > 5 > 2 > 1 = 7 = 8 = p-CumA. Theoretical calculations and the “Lipinski’s Rule of Five” were used for explaining the structure–activity relationships and pharmacokinetic behavior. A higher TGSO oxidation stability was observed in the presence of equimolar (1:1) binary mixtures of coumarins with TOH (1 + TOH, 3 + TOH and 5 + TOH). However, the synergism (14%) was observed only for the binary mixture of 5 + TOH.