Gelatin-based sponge with Ag nanoparticles prepared by solution plasma: Fabrication, characteristics, and their bactericidal effect

A solution plasma process was established for fabrication of gelatin-based sponge incorporated with Ag nanoparticles (AgNPs) in this study. Without using any chemical reducing agent, colloidal AgNPs were formed in gelatin medium via the reduction reaction of Ag precursors (AgNO3) and the hydrogen radicals generated during discharge. The gelatin/AgNPs sponges fabricated by lyophilization had a 3D scaffold structure of micropores with diameters of about 20 μm. TEM analysis showed that the spherical AgNPs in the thin layer of gelatin were evenly well dispersed and had mean particle sizes of about 10–15 nm. The gelatin/AgNP solutions and sponges prepared in this study exhibited excellent bactericidal activity against two well-known bacteria, Escherichia coli and Staphylococcus aureus. All of them inhibited growth of E. coli more efficiently than that of S. aureus. Minimal inhibition concentration of gelatin/AgNP formed with 3% gelatin and 5 mM AgNO3 was <20 and 40 μg/ml for E. coli and S. aureus, respectively. The sponge of 3% gelatin and 5 mM AgNO3 discharged for 740 s showed the strongest bactericidal activity toward both bacteria.