Engineered polymeric amphiphiles self-assembling into nanostructures and acting as efficient gene and drug carriers

Nonviral gene delivery systems are finding widespread use due to their safety, rapid and economical production, and ease of modification. In this work, series of N-alkyl-substituted linear polyethylenimine (CP) polymers have been synthesized, characterized, and investigated about how degree of substitution (hydrophobic-hydrophilic balance) (i.e. N-alkylation) influenced the transfection efficiency. Mobility shift assay demonstrated efficient binding of plasmid DNA (pDNA). Transfection efficiency and cytotoxicity of CP polymers were assessed in vitro, which revealed that all the formulations exhibited higher transfection activity than linear polyethylenimine (lPEI) and commercial transfection reagents, Lipofectamine and Superfect, with negligible toxicity (MTT assay). In the projected series, one of the formulations, CP-3-pDNA complex, displayed the highest transfection efficiency (∼1.6-12 folds vs. lPEI and commercial transfection reagents) and effectively carried GFP-specific siRNA inside the cells as monitored by measuring the suppression in the gene expression of the target gene. Further, flow cytometry experiments confirmed that CP-3-pDNA complex transfected the highest number of cells. Besides, CP-3 was also evaluated in terms of its capability to entrap hydrophobic drug molecules. The results showed that it efficiently encapsulated an anti-cancer drug, etoposide, and released it in a controlled fashion over a period of time. Altogether, the data support that CP-3 is a promising vector for nucleic acid as well as hydrophobic drug delivery.