Spermine-modified Antheraea pernyi silk fibroin as a gene delivery carrier

Abstract

The development of a novel cationized polymer used as a gene delivery carrier that can conveniently and effectively transfect cells resulting in a stably expressed target gene remains a challenge. Antheraea pernyi silk fibroin (ASF) is a cytocompatible and biodegradable natural polymer, and it possesses Arg–Gly–Asp sequences but a negative charge. In order to render ASF amenable to packaging plasmid DNA (pDNA), spermine was used to modify ASF to synthesize cationized ASF (CASF), which was used as a gene delivery carrier. CASF was characterized using trinitrobenzene sulfonic acid assay, the zeta potential determination, and a Fourier transform infrared analysis, and the results of these characterizations indicated that the –NH₂ in spermine effectively reacts with the –COOH in the side chains of ASF. Spermine grafted to the side chains of ASF resulted in the conversion of the negative charge of ASF to a positive charge. CASF packaged pDNA and formed CASF/pDNA complexes, which exhibited spherical morphology with average particle sizes of 215–281 nm and zeta potential of approximately +3.0 mV to +3.2 mV. The results of the MTT assay, confocal laser scanning microscopy, and flow cytometry analysis in a human endothelial cell line revealed that CASF/pDNA complexes exhibited lower cytotoxicity and higher transfection efficiency compared to the pDNA complexes of polyethyleneimine. These results indicate that our synthesized CASF, a cationized polymer, is a potential gene delivery carrier with the advantages of biodegradability and low cytotoxicity.

Keywords:

• silk fibroin
• spermine
• cationized polymer
• gene delivery carrier

Acknowledgments

This work was supported by the National Natural Science Foundation of China (31370968, 51403146), the Natural Science Foundation of Jiangsu Province (BK20131177), the College Natural Science Research Project of Jiangsu Province (12KJA430003), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

Disclosure

The authors report no conflicts of interest in this work.