Subtle changes to polymer structure and degradation mechanism enable highly effective nanoparticles for siRNA and DNA delivery to human brain cancer

摘要

Polymeric materials can be used to deliver nucleic acids such as DNA plasmids and siRNA, but often have low efficacy in human cells. To improve gene delivery, we synthesized an array of over 70 hydrolytically degradable and bioreducible poly(beta-amino ester)s and evaluated properties of over 200 nanoparticle formulations fabricated from these biomaterials. We determined the effect of different polymer structures on the delivery of nucleic acids of different structures and sizes, including siRNA, linear DNA, and circular DNAs (1.8–26 kb). Significantly, leading hydrolytically degradable polymeric nanoparticles delivered DNA to 90±2% of primary human glioblastoma cells with <10% nonspecific cytotoxicity, better than leading commercially available reagents (p<0.01). Bioreducible polymeric nanoparticles optimized for siRNA delivery caused up to 85±0.6% knockdown in these cells as well while maintaining high viability. From a single dose, knockdown was higher than for Lipofectamine^™ 2000 (p<0.01) and persisted one month. Polymer molecular weight was a driving factor of transfection efficacy for some polymer structures (correlation of r²=0.63) but had no influence on transfection for other structures (r²=0.01). Polymers with a reducible cystamine functional group dramatically improved siRNA delivery by facilitating quick release while generally decreasing DNA delivery compared with non-reducible counterparts (p<0.01). Other material properties facilitated DNA delivery compared to siRNA delivery or increased delivery of both DNA and siRNA.