Maleimide-Functionalized PEI600 Grafted Polyurethane: Synthesis, Nano-Complex Formation with DNA and Thiol-Conjugation of the Complexes for Dual DNA Transfection

A polyurethane (PU) grafted with small molecular weight polyethylenimine (PEI600) was synthesized. This PU-PEI600 can assemble DNA via electrostatic interactions into nano-sized polymer/DNA complexes. The complexes exhibited great transfection efficiency in delivering DNA along with a reduced cell toxicity comparing to commercial PEI25k (M-w similar to 25,000). In order to establish a system for concurrently delivering two different DNA or RNA molecules for cell reprogramming (e.g., induced pluripotent stem cells) or the necessity of multi-expression (e.g., double knock down), the PU-PEI600 was further functionalized with maleimide molecules. The novel PU-PEI600-maleimide would still effectively interact with assigned DNA and different functions of PU-PEI600-maleimide/DNA complexes were self-conjugated in presence of a dithiol molecule (1,6-hexanedithiol). In this study, two reporter genes (pEGFP-C2 and pLanRFP-N) were used and evidence of green/red fluorescence co-expression in cells was observed. This article brings a new concept and a practical method for a plurality of different DNA molecules that are more efficient to be concurrently delivered and co-expressed. This method is very helpful in studying cellular multi-regulation or in the treatment of disease with multiple gene defects in vivo.