Gene Expression of Aspect Ratio-Controlled Polyplexes Based on the Effect of Multi-Arm Poly(ethylene glycol)

Controlling the aspect ratio of polyplexes prepared by mixing pDNA with a polycation mixture of a poly(L-lysine) (PLL) homopolymer and PLL terminally bearing a multiarm poly(ethylene glycol) (PEG) part (maPEG-PLL) was examined. By varying the maPEG-PLL content in the polycation mixture, the condensation of pDNA accompanied by polyplex formation and the morphology of the polyplexes were evaluated by a dye exclusion assay and AFM observations, respectively. Increasing the maPEG-PLL content caused elongation of the polyplex, and polyplexes with aspect ratios from 2 to 10 were prepared successfully by controlling the maPEG-PLL content. The reactivity of pDNA in the polyplexes with varying aspect ratios against DNase I and polymerase were examined by agarose gel electrophoresis and real-time PCR measurements, respectively. Moreover, cellular uptake and transfection efficiency of the polyplexes by HeLa cells was evaluated. The results revealed that an increase in aspect ratio of the polyplexes caused an increase in PCR efficiency with a concomitant decrease in cellular uptake.