Abdullah Khan

Aggregation behaviour of non‐ionic twinned amphiphiles and their application as biomedical nanocarriers

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 amphiphiles 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.

Amphiphilic Copolymers having Saturated and Unsaturated Aliphatic Side Chains as Nano Carriers for Drug Delivery Applications

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.

Crosslinking of Biocatalytically Synthesized Organosilicone Copolymers for Flame Retardant Applications

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 applications.

Study of Intermacromolecular Complex Formation Between Acrylamide—Vinyl Alcohol Graft Copolymer and Poly[Methacrylic Acid]

Abstract Acrylamide‐vinyl alcohol (AAm/VA) graft copolymer was prepared and characterized. The interaction of the graft copolymer with poly‐(methacrylic acid) (PMAA) in water was studied by several experimental techniques, such as viscometry, potentiometry, conductometry, IR spectra, and transmittance measurements. PMAA was found to interact with the graft copolymer in two distinct steps. The relative complexation ability of PAAm and PVA with respect to PMAA does not change when these polymers are present as parts of a graft copolymer chain.