Differential scanning calorimetry studies of crystalline morphology in bioerodible polyanhydrides for drug delivery

Abstract

The overall goal of the research project is to design drug delivery systems with specifically tailored time-release profiles. The polymers of interest are polyanhydrides composed of 1,6-bis- (p-carboxyphenoxy) hexane-co-sebacic anhydride, which are referred to as CPH:SA throughout the document. In order to design these drug delivery systems, we need to understand the morphology of the polymers, the polymer-drug interactions, and the polymer degradation kinetics. We investigate the thermal properties, degree of crystallinity, and crystal lamellar thickness of various compositions of CPH:SA using differential scanning calorimetry (DSC). Our results indicate that as the CPH content in the polymer increases, the crystal lamellar thickness increases and degree of crystallinity decreases. In addition, DSC studies of polymer/drug systems were performed using brilliant blue & p-nitroaniline as model compounds. The studies indicated that hydrophilic compounds (brilliant blue) are dispersed as particles while hydrophobic compounds (p-nitroaniline) form a solid solution with the polymer, leading to melting point depression.