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

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