A low‐toxic and efficient gene vector: Carboxymethyl dextran‐graft‐polyethylenimine

Abstract In this study, the low molecular weight branched polyethylenimine (PEI) (800 Da PEI) was grafted to the biodegradable and biocompatible carboxymethyl dextran (CMD) to obtain CMD‐g‐PEI, and the plasmid DNA was complexed with CMD‐g‐PEI polycation to form the polyion complex. The acid‐base titration profile showed that the CMD‐g‐PEI had endosomal disruption capacity, and the agarose gel electrophoresis suggested that the CMD‐g‐PEI could condense DNA efficiently. The transfection efficiency of CMD‐g‐PEI/DNA complexes was measured by luciferase and green fluorescent protein assay in HEK293 cells. The results revealed that the transfection efficiency of CMD‐g‐PEI at the N/P ratios over 30–70 was higher than or comparable to that of the 25 kDa PEI at optimal ratio (N/P = 10). The cytotoxicity of CMD‐g‐PEI as well as 25 kDa PEI was evaluated in NIH3T3 and HEK293 cells, respectively, and it was also found that the cytotoxicity of CMD‐g‐PEI was much lower than that of 25 kDa PEI. The resulted CMD‐g‐PEI with high transfection efficiency and low cytotoxicity have promising applications when used as gene vector. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008