Effect of acyl chain length and unsaturation on physicochemical properties and transfection efficiency of N-acyl-substituted low-molecular-weight chitosan.

The effects of acyl chain length and unsaturation on physicochemical characteristics and transfection efficiency of novel nanomicelles of N-acyl-substituted low-molecular-weight chitosan (N-acyl LMWC) were studied. After transfection optimization, 18-carbon chain length grafts were selected, and N-acyl LMWCs were prepared with increasing unsaturation (18:1-18:3 carbon acyl grafts). N-acyl LMWCs were characterized using infrared spectroscopy and elemental analysis. The effect of DNA addition on size and zeta potential of N-acyl LMWCs was determined by dynamic light scattering. N-acyl LMWC-plasmid DNA (pDNA) polyplex stability was confirmed using gel electrophoresis. Transfection efficiency of the derivative polymers was visualized in human embryonic kidney cells using a plasmid encoding green fluorescent protein by confocal fluorescence microscopy and was quantified using therapeutic plasmids encoding for interleukin-4 and interleukin-10. N-acyl LMWCs could form cationic nanomicelles with average hydrodynamic size between 73 and 132 nm. DNA addition to nanomicelles led to minimal increase in the size. N-acyl LMWC-pDNA polyplexes showed excellent stability on storage and could protect DNA from enzymatic degradation. The transfection efficiencies of N-acyl LMWCs with 18:1 and 18:2 grafts were comparable with FuGENE® HD but were approximately eightfold and 35-fold greater as compared with LMWC and naked DNA, respectively.