Evaluation of a smart nanoparticle system for potential use in anticancer drug delivery

A previously reported method of synthesis for hollow nanospheres has been successfully optimized in this project to produce polypyrrole-chitosan (ppy-chit) hollow nanospheres using low molecular weight chitosan. The product has been Characterized by several techniques, i.e transmission electron microscopy, powder x-ray diffractometry and UV-visible spectrophotometry.' The size and stability were assessed by using a Zetasizer, which has shown a high zeta potential value (>+30 mV), and the size was approximately 80' nm. These results would be favourable for biological purposes; the small size range of these nånospheres could transport a biorriolecule and could penetrate through the tumour vessels and target the tumour passively, and also the positively charged _ nanospheres could interact with negatively charged tumour membrane and could accumulate a loaded drug at the tumour site. Hence these nanospheres were loaded with calcein and nile blue chloride dyes as models for drug compounds. Nile blue chloride proved to be partially adsorbed onto the surface of ppy-chit hollow nanospheres. A release study was conducted on the polypyrrole-chitosan loaded with nile blue chloride in which 88% of the nile blue chloride was released from the hollow nanospheres, indicating that ppy-chit could be a potentially useful drug carrier. Chitosan was proven to release the drugs upon stimuli such as pH change, and polypyrrole could. stimulate the release of drug by inducing local pH lowering, which needs further investigation. It could be a useful drug carrier for treating solid tumours by passive targeting.