Poly-amine based tailored made ordered nanocapsule :preparation fluorescence study and application -

Abstract

Various studies have proven the significance of curcumin as an antioxidant, anti inflammatory, anti-amyloid, anti-HIV, anti-microbial, and anti-tumor agent. Curcumin exists in its enole form and undergoes Excited State Intra-molecular Hydrogen Transfer (ESIHT) during deactivation process. Hence understanding ESIHT of curcumin adds to its medicinal values. At the same time delivery of curcumin has been a major challenge in the drug delivery field due to its poor water solubility and low bioavailability. These two problems can be overcome by applying an approach based on nanotechnology. Chapters II and III report on curcumin associated poly (allylamine hydrochloride) (PAH) crosslink with dipotassium phosphate and subsequently congregates ~24 nm silica nanoparticles to form hierarchically ordered nanocapsule structures. The capsule sizes are in the range of 100 – 1000 nm depending on concentration of dipotassium phosphate. The fluorescence images confirm that curcumin is present all over the capsules. These nano-structures alter the optical behavior by reversing the excited state intra-molecular hydrogen transfer in curcumin depending on the size of nanocapsules. pH triggers the release of curcumin from the capsule where by a basic environment triggers the maximum release compared to acidic and neutral conditions. The drug release profile of curcumin in nanocapsule follows Higuchi model and depends on the size of nanocapsules. Apart from drug delivery, the biological activity of curcumin within the capsule is important. The researcher studies the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of curcumin by simply measuring the change in DPPH absorbance at 520 nm. Results show that the scavenging activity of the encapsulated curcumin is lower than that of curcumin alone; as well it decreased exponentially with the size of the capsule. Chapter IV examines the preparation of poly(9-(2-diallylaminoethyl) adenine.HCl-co-sulfur dioxide) (Poly A)-silica nanoparticles based capsules. The dynamic light