Quaternized amino poly(glycerol-methacrylate)s for enhanced pDNA delivery

Linear and 8-arm amino poly(glycerol methacrylate)s (PGOHMAs) were synthesized from poly(glycidyl methacrylate)s (PGMA)s via ring opening reactions with methylethylamine (MEA), diethylamine (DEA) and dipropylamine (DPA), respectively. Further modification of tertiary amine groups of amino PGOHMAs by quaternization reaction with methyl iodide resulted in partially quaternized PGOHMAs, namely, QPGOHMAs. QPGOHMA/plasmid DNA (pDNA) complexes at different nitrogen-to-phosphate (N/P) ratios were then prepared. In addition, eight-arm star-shaped MEA-modified PGMA (S8-MEA) was also used to complex with pDNA as a positive control to compare with QPGOHMA/pDNA complexes. QPGOHMA/pDNA complexes were spherical in shape as observed by scanning electron microscopy (SEM), and smaller in size than S8-MEA/pDNA complexes as suggested by dynamic light scattering (DLS). Interestingly, gel electrophoresis and ethidium bromide displacement assay indicated that QPGOHMAs could condense pDNA at lower N/P ratios than that of S8-MEA. In vitro experiments on Huh-7 cells showed that QPGOHMAs displayed lower cytotoxicity and better transfection efficacy compared to S8-MEA. The cellular uptake analysis revealed that QPGOHMAs enhanced the cellular uptake level of pDNA. Overall, amino PGOHMAs modified by quaternization were proved to be effective gene delivery systems for gene therapy.