To improve the cytotoxicity and biocompatibility of cationic polymers used as gene carriers, new cationic poly(ester-anhydride) copolymers (Pea-PAs) bearing a quaternary ammonium group in the backbone were synthesized through a reaction between an aminoester dicarboxylic acid with a tertiary amine in the backbone and excess acetyl chloride. Their structure was characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectrometry (FTIR), and gel permeation chromatography (GPC). They degraded hydrolytically in 20 mM HEPES buffer at pH 7.4 at 37A degrees C with a half-life of more than 70 h. Their cytotoxicity was substantially lower than that of PEI. The blood clotting index (BCI) and haemolysis ratio (HR) also showed that these newly synthesized Pea-PA polymer are biopolymers with good blood compatibility.
