The effect of swelling and cationic character on gene transfection by pH-sensitive nanocarriers

We synthesized a series of pH-sensitive vehicles, composed of dimethylaminoethyl methacrylate (DMAEMA) and 2-hydroxyethyl methacrylate (HEMA), to optimize the triggered release of DNA for gene transfection. The purpose of this study was to assess the role of swelling and cationic character independently on transfection; both of which may affect DNA release. Gene transfection was performed by delivering plasmid DNA (pDNA) encoding for luciferase. DNA release was controlled via volumetric swelling by regulating the endosomal pH as a result of inhibiting V ATPases using bafilomycin A1. Increasing the cationic character from 10 to 30 mol% DMAEMA did not increase transfection when swelling was inhibited. Transfection was significantly affected by the rate of pDNA release. pH-sensitive nanocarriers were also compared to vehicles comprised of polyethyleneimine (PEI), dioleoyl triammonium propane (DOTAP), and poly(lactic-co-glycolic acid) (PLGA, 50:50). pDNA encapsulating DMAEMA/HEMA nanoparticles and PEI/pDNA complexes had reduced transfection when V ATPases were inhibited, whereas pDNA encapsulating PLGA nanoparticles showed no endosomal pH dependence. DMAEMA/HEMA nanoparticles cross-linked with 3 mol% tetraethylene glycol dimethacrylate (TEGDMA) reported equivalent or greater gene transfection relative to the nanocarriers tested at 24 and 48 h.