Synthesis and characterization of PEG-conjugated quaternized chitosan and its application as a gene vector

Poly(ethylene glycol)-conjugated N-(2-hydroxy) propyl-3-trimethyl ammonium chitosan chloride (PHTAC) derivatives were prepared by incorporating PEG molecules onto quaternized chitosan backbone. The copolymers were characterized by FTIR, 1H NMR and XRD. Agarose gel retardation assay indicated that PHTAC had good plasmid DNA (pDNA) binding capability and the particle sizes of PHTAC/pDNA complexes determined by DLS were about 200 nm. Cytotoxicity assays in HeLa and 293T cells showed that PHTAC had low cytotoxicity. In vitro luciferase assay showed that PHTAC with PEGylation degree of 9% (PHTAC-1) had good transfection efficiency about 5.3-fold higher than quaternized chitosan, which was comparable with PEI (25 kDa). These results suggest that PHTAC-1 is a promising candidate as an efficient nonviral gene vector.