Effective adsorption of nisin on the surface of polystyrene using hydrophobin HGFI

Herein, a new method was demonstrated for effective immobilization of the antibacterial peptide nisin on Grifola frondosa hydrophobin (HGFI), without the need of any additional complex reaction. Hydrophobin can self-assemble as a monolayer to form continuous negative-charged surfaces with enhanced wettability and biocompatibility. Adding nisin solution to such hydrophobin surface created antibacterial surfaces. The quantification analysis revealed that more nisin could be adsorbed on the HGFI-coated than to control polystyrene surfaces at different pH values. This suggested that electronic attraction and wettability may play important roles in this process. The transmission electron microscopy, atomic force microscopy and fourier transform infrared (FTIR) analysis indicated the adsorption mode of nisin on the HGFI film, i.e., hydrophobins served as an adhesive layer for binding charged peptides to interfaces. The antibacterial activity of the treated surface was investigated via counting, a nucleic acid release test, scanning electron microscopy, and biofilm detection. These results indicated the excellent antibacterial activity of nisin adsorbed on the HGFI-coated surfaces. The activity retention of adsorbed nisin was demonstrated by immersing the modified substrates in a flowed liquid condition.