Polymer Anchored Gold Nanoparticles: Synthesis, Characterization and Antimicrobial Activities

Abstract

Background:: Gold nanoparticles (GNPs) have diverse optical and photo-thermal properties. It is used for diagnostic imaging because of their ability to absorb near infrared (NIR) and X-rays, and their surface enhanced Raman scattering properties. Recently they are used for drug delivery and more particularly photothermal treatment. Their ability to absorb NIR energy and convert it to heat by a Surface Plasmon Resonance mechanism has made these materials promising for the treatment of tumors. GNPs having diameter higher than 1.4-1.5 nm is found nontoxic to the environment. Methods:: In the present work, polymer anchored GNPs are synthesized by reducing AuIII to Au0 in presence of either chitosan or polyvinyl alcohol, which act as in situ reducers cum stabilizers. Microscopic techniques (TEM, SEM and DLS) are used to analyse the size, surface morphology and size distribution respectively. The unique mucoadhesive properties of chitosan particularly make the system promising with respect to antimicrobial (anti-bacteria as well as anti-fungus) activities. An attempt has been made to understand the mechanistic path involved in antimicrobial activities. Antimicrobial potential of chitosan anchored gold nanoparticles (GNPc) are noticed even at very low dose. Results:: The results of bio-chemical analysis (MDA, NBT, DNA fragmentation and overexpression of heat shock protein) clearly explain antimicrobial activities. Additionally, gold chitosan systems interact with microbial DNA and inhibit the action of DNA repair enzyme. Interestingly, in vitro (rat peritoneal MФ) or in vivo (Wistar rat) analysis exhibits negligible cytotoxicy. Conclusion:: Thus the synthesized material (particularly GNPc) is promising as an effective nano therapeutic agent.