Polypeptide hydrogel loaded with conducting polymer nanoparticles as electroresponsive delivery system of small hydrophobic drugs

Abstract

A hydrogel/nanoparticle-loaded system for the controlled delivery of small hydrophobic drugs has been prepared using poly(γ-glutamic acid) (PGGA), a naturally occurring biopolymer made of glutamic acid units connected by amide linkages between α-amino and γ-carboxylic acid groups, and poly(3,4-ethylenedioxythiophene) (PEDOT), a very stable conducting polymer with excellent electrochemical response. Specifically, curcumin (CUR)-loaded PEDOT nanoparticles (PEDOT/CUR) were incorporated to the PGGA hydrogel during the crosslinking reaction. After chemical, morphological and electrochemical characterization, the release profiles of PEDOT/CUR and PGGA/PEDOT/CUR system have been compared in absence and presence of electrical stimuli, which consisted on the application of a voltage of –0.5 V for 15 min every 24 h. Results show that the release is higher for electrically stimulated systems by more than twice, even though due to its hydrophobicity and poor solubility in water the release was relatively slow in both cases. This feature could be advantageous when the therapeutic treatment requires slow, controlled and sustained CUR release.