Poly lactic acid-polyethylene glycol (PLA-co-PEG) copolyester was synthesized from oligomer of L-lactic acid and poly ethylene glycol (PEG) using stannous octoate as catalyst. 6-Thioguanine containing Poly lactic acid-polyethylene glycol (PLA-co-PEG) nanocapsules were prepared in the presence and absence of gold nanoparticles via the W/O/W emulsification solvent-evaporation method. The morphologies of prepared nanocapsules changed substantially because of the presence of gold nanoparticles. From SEM and TEM measurements, the average size of the polymer nanocapsules and gold nanoparticles were found to be in range of 230-260 nm and 18-20 nm, respectively. In general the drug release was quicker in Phosphate buffer saline (pH 7.4) compared to 0.1M hydrochloric acid and this may be due to higher solubility, higher swelling and penetration properties of PLA-co-PEG in PBS compared to HCl. Polymer nanocapsules with gold show a prolonged controlled release with higher encapsulation efficiency (75%) compared to that of polymer nanocapsules (45%) in the absence of gold nanoparticles. It may be due to the more entrapping efficiency of gold and less diffusivity of drugs from the nanocapsules. Application of in vitro drug release data to various kinetic equations indicated Higuchi model, indicating a uniform distribution of thioguanine in the nanocapsules.
©2012 Walter de Gruyter GmbH & Co. KG, Berlin/Boston