Chitosan and its derivatives have been extensively utilized in gene delivery applications because of their low toxicity and positively charged characteristics. However, their low solubility under physiological conditions often limits their application. Glycol chitosan (GC) is a derivative of chitosan that exhibits excellent solubility in physiological buffer solutions. However, it lacks the positive characteristics of a gene carrier. Thus, we hypothesized that the introduction of oligoarginine peptide to GC could improve the formation of complexes with siRNA, resulting in enhanced uptake by cells and increased transfection efficiency in vitro. A peptide with nine arginine residues and 10 glycine units (R9G10) was successfully conjugated to GC, which was confirmed by infrared spectroscopy, 1H NMR spectroscopy, and elemental analysis. The physicochemical characteristics of R9G10-GC/siRNA complexes were also investigated. The size and surface charge of the R9G10-GC/siRNA nanoparticles depended on the amount of R9G10 coupled to the GC. In addition, the R9G10-GC/siRNA nanoparticles showed improved uptake in HeLa cells and enhanced in vitro transfection efficiency while maintaining low cytotoxicity determined by the MTT assay. Oligoarginine-modified glycol chitosan may be useful as a potential gene carrier in many therapeutic applications.
Keywords: gene therapy; glycol chitosan; oligoarginine; siRNA.