Comprehensive comparison of two new biodegradable gene carriers.

Safety and high transfection efficiency are the prerequisites for an ideal gene vector. Polyethylenimine (PEI), especially PEI 25k (25 kDa), is a well-known cationic gene carrier with high transfection efficiency. However, the high toxicity, depended on its molecular weight, has limited its use as a potential gene carrier. In our research, for the purpose of reducing the toxicity and increasing the transfection efficiency and further to inspect where the degradation of these biodegradable polymers take place would be more beneficial, in cytoplasm or in endocytic vesicles, two kinds of degradable polymers were synthesized. One is an acid-liable PEI derivate (PEI-GA) which was cross-linked by PEI 2k with glutadialdehyde (GA) through imine linkages and the other one (PEI-TEG) was cross-linked PEI 2k with modified triethyleneglycol (TEG) through biscarbamate linkages and can be degraded at neutral environment. By the use of a series of assay methods both in vitro and in vivo, the results showed that PEI-TEG was found to be biodegradable at neutral environment and exhibit high transfection ability with low toxicity, which indicated its potential as a candidate carrier for gene therapy.