Self-assembly of poly(l-glutamate)-block-poly(2-(diethylamino)ethyl methacrylate) in aqueous solutions

Abstract

The self-assembly and gene delivery applications of poly(l-glutamate)- block-poly(2-(diethylamino)ethyl methacrylate) (PLG18-b-PDEAEMA 37) were investigated. Owing to the functional groups on the polymer, an amine and a carboxylic acid group, the self-assembly process is dependent on the solution pH, where the critical micelle concentration was determined to be 61 and 320 μgmL-1 at high and low pH, respectively. The block copolymer forms positively charged vesicles at low pH with a hydrodynamic radius of 90nm and negatively charged vesicles at high pH with a hydrodynamic radius of 50nm. At the isoelectric point of 4.9, PLG-b-PDEAEMA was found to form larger micellar aggregates with a hydrodynamic radius of 180nm because of the presence of both positive and negative charges. The complexation between PLG-b-PDEAEMA and DNA was studied at physiological pH as well as at low and high pH. DNA is condensed most effectively at pH 3, at an N/P ratio of 5, whereas at pH 7 and 10, an N/P ratio of 20 is required. However, in-vitro studies at physiological pH using neuroblastoma cells did not show substantial gene expression. © 2011 CSIRO.