Guanidinylated Polyethylenimine As A Nonviral Gene Vector

At present, poor cellular internalization has become the bottleneck of non-viral vector mediated gene delivery. Guanidinylated polyethylenimine(PEI) was synthesized by chemically modifying branched PEI in this work in order to design a nonviral vector which could effectively enhance the cellular uptake. The interaction between guanidinylated PEI with plasmid DNA and the complexes formed were physicochemically characterized by agarose retardation experiment, EB displacement assay, TEM and Zeta potential measurement. It was proven that the guanidinylated PEI could effectively condense DNA in spite of weaker DNA-binding strength relative to PEI. In TEM images, guanidinylated PEI/DNA complexes assumed spherical particles with size smaller than 150 nm at complexing ratio above critical value. The surface of guanidinylated PEI/DNA complexes retained positive charges, but zeta potential slightly decreased. Their transfection efficiency was also assessed employing COS-7 cell line - guanidinylated PEI was shown to have higher transfection efficiency and lower cytotoxicity compared to PEI. Drug inhibition assay showed that caveolin-dependent pathway was the main contributor to the transfection process of guanidinylated PEI. Furthermore, considering the characteristic of non-selective gating of nuclear pores by trans-cyclohexane-1,2-diol(TCHD), we examined the effect of TCHD on the transfection efficiency of guanidinylated PEI/DNA polyplexes. It was found that TCHD could further enhance the transfection efficiency of this nonviral vector system, predicting its possibility to improve transfection level of non-divided cells. In summary, guanidinylated PEIs may have a potential application as in vivo delivery vector with regard to their satisfactory transfection efficiency and cytotoxicity.