A new biodegradable poly-amino acid: alpha,beta-poly[(N-hydroxypropyl/aminoethyl)-DL-aspartamide-co-L-lysine], a potential nonviral vector for gene delivery.

A new class of biodegradable poly-amino acid, alpha,beta-poly[(N-hydroxypropyl/aminoethyl)-DL-Aspartamide-co-L-Lysine] (PHAAL), was synthesized by ring-opening of poly[succinimide-co-lysine](PSL) with n-propanolamine and ethylene diamine after thermal copolycondensation of DL-Aspartic acid and L-lysine under reduced pressure. Different ratio feeds of PSL were obtained and characterized by 1H-NMR, Fourier transformed infrared spectroscopy, X-ray, thermogravimetric analysis and gel permeation chromatography experiments. As one of the polycationic materials, performed for gene delivery carrier, the PHAAL degradation experiment was carried out in PBS (10 mM, pH =7.4) and enzyme (papain, trypsine 1 mg/ml, 37 +/- 0.1 degree C) solution. PHAAL had lower cytotoxicity than polyethylenimine (25KDa) and poly-L-Lysine (30 KDa), in Hela, E.C.V.-304, Bcap 37 cell lines. Particle size and zeta, potential of PHAAL/DNA complexes were measured. Sizes ranged from 300-500 nm and zeta potentials were at -20 to 2,5 mV. The condensation ability of PHAAL for DNA was evaluated by agarose gel electrophoresis. The PHAAL could completely neutralize DNA at N/P ratio (w/w) 150:1.