Release Mechanism and pH Responsiveness of Starch-Based Polymers

Amphiphilic polymer carriers (PEG-St-R) were prepared from cassava starch and their pH response was investigated. First, hydrophobic tapioca starch polymer (St-R) was prepared with octyl acyl as the hydrophobic group. The hydrophilic group polyethylene glycol (mPEG) was then introduced into the polymer by esterification to produce amphiphilic tapioca starch polymer (PEG-St-R). Its self-assembly behavior was characterized using fluorescent probes. The morphology of PEG-St-R was investigated by transmission electron microscopy (TEM). Loading of the anti-cancer drug curcumin was used to assess the delivery and slow-release performance of the amphiphilic tapioca starch polymer. Cumulative drug release was explored at various pH conditions, with the greatest release from drug-loaded micelles being observed under acidic conditions and stable in a neutral environment. These results provide a theoretical basis for the preparation of pH-responsive nanomicelle carriers, and a platform for the preparation of novel amphiphilic starch-based polymers.