A diaminoethane motif bearing low molecular weight polymer as a new nucleic acid delivery agent

Among polymer-based gene delivery systems, poly(ethylene imine) (PEI) stands out as an effective polycation. However, the toxic effects of PEI especially at higher molecular weights limit its usage. Although the effects of PEI's architecture and molecular weight on gene delivery is controversial in literature, low molecular weight PEI appears to be efficient at transfection while having lower toxicity. Herein, as an alternative to low molecular weight, linear PEI, a methacrylate polymer bearing diamimoethane motifs, poly(2-((2-aminoethyl)amino)ethyl methacrylate) (P(AEAEMA)), was evaluated in vitro as a new nucleic acid delivery agent. P(AEAEMA) (8 kDa) showed low toxicity on Skov-3-luc and NIH/3T3 cell lines at polymer concentrations where PEI (8 kDa) was highly toxic. P(AEAEMA) could efficiently form complexes with siRNA at an N/P ratio of 2 as shown by gel electrophoresis. The diameter of P(AEAEMA)-siRNA complexes was found to be significantly lower than PEI-siRNA complexes almost at all tested N/P ratios. P(AEAEMA) could improve the stability of siRNA in serum containing media by protecting the siRNA against serum nucleases. siRNA and pDNA transfection efficiency of P(AEAEMA) on luciferase expressing Skov-3-luc cell line and HEK 293T cell line, respectively was found to be comparable to well-known nucleic acid carrier, PEI. The transfection efficiency of both P(AEAEMA) and PEI was found to be cell-type-dependent. None of the polymers were able to transfect MDA-MB-231 cells with siRNA or pDNA.