RESUMO
A new derivative of polyamidoamine and polyethylenimine, G2.5-PEI 423 or G1.5-PEI 423, is prepared by an amidation reaction of PAMAM G2.5 or PAMAM G1.5 using PEI 423. The polycations show a great ability to combine with pDNA to form complexes, which protect the pDNA from nuclease degradation. The polymers display stronger buffer capacity and lower cytotoxicity. The complexes have particle sizes of 120-180 nm and zeta potentials of 20-40 mV. The G2.5-PEI 423 complexes display much higher transfection efficiencies than PAMAM G5 and Lipo-2k, and the G1.5-PEI 423 complexes display higher transfection efficiencies than PAMAM G4 and PEI-25k. The complexes possess better serum-resistant capacity. The G2.5-PEI 423 has a great potential to be used as a serum-resistant gene vector.