In order to endue silk fibroin (SF) sponges with antibacterial function, positively charged poly(hexamethylene biguanide) hydrochloride (PHMB) was incorporated in SF through electrostatic interaction and by freeze-drying technique. The influence of PHMB on the structure and antibacterial activities of SF sponges was investigated. The zeta potential of SF was increased significantly when PHMB was incorporated in SF. The pores with size from 80 to 300 µm and the microscale holes in the pore walls within PHMB-loaded SF sponges provided the channels of PHMB release. The PHMB loaded in the porous sponges showed continuous and slow release for up to 20 days. Effective growth inhibition of both Escherichia coli and Staphylococcus aureus was achieved when the mass ratio of PHMB/SF was higher than 2/100. These results suggest that the porous PHMB/SF sponges have the potential to be used as a novel wound dressing for open skin wounds.

The construction of a targeted gene delivery system with low cytotoxicity to normal tissues is an urgent need for the clinical treatment of liver cancer. In this study, Antheraea pernyi silk fibroin (ASF) was cationized with low-molecular-weight polyethylenimine (PEI, 1.8 kDa) to synthesize a cationized Antheraea pernyi silk fibroin (CASF). The highly cancer-selective hepatoma targeted peptide, HCBP1 (sequence FQHPSFI), was coupled to the side chains of CASF to synthesize a hepatoma-targeted CASF (CASFP). CASFP relied on the positive charges of CASF could package the pDNA encoded the inhibitor of growth 4 (ING4) and interleukin-24 (IL-24) to form CASFP/pDNA complexes. The results showed that the zeta potential of ASF was reversed from –9.08 ± 0.20 to +11.33 ± 0.38 mV, and its isoelectric point significantly increased from 4.31 to 9.38 after PEI modification. The Fourier transform infrared spectroscopy results and the 1Hydrogen-nuclear magnetic resonance spectra demonstrated that HCBP1 could be coupled to the side chains of CASF under the action of the bifunctional reagent N-succinimidyl-3-(2-pyridyldithio) propionate (SPDP). In vitro, human hepatocellular carcinoma HepG2 cells and human normal hepatic L-02 cells were transfected with the CASFP/pDNA complexes. The results of confocal laser scanning microscope analysis and cell viability assays showed that the complexes were able to transfect HepG2 cells and effectively inhibit their proliferation but had no obvious cytotoxicity to L-02 cells. In this study, a new gene delivery system, constructed by using HCBP1-modified CASF and the ING4-IL-24 dual-gene co-expression plasmid, was able to inhibit the proliferation of hepatocellular carcinoma cells but had no obvious cytotoxicity to normal hepatic cells. Therefore, the gene delivery system has the potential for application as a gene therapy in liver cancer.