Enhanced antibacterial and anti-biofilm activities of antimicrobial peptides modified silver nanoparticles

Abstract

Background: The biofilms could protect bacteria from antibiotics and promote the produc-tion of drug-resistant strains, making the bacteria more difficult to be eradicated. Thus, we developed an AMP@PDA@AgNPs nanocomposite, which is formed by modifying silver nanoparticles (AgNPs) with antimicrobial peptides (AMP) modified nanocomposite to destroy biofilm in this study. Methods: The AMP@PDA@AgNPs nanocomposite was prepared with polymerization method and characterized by using ultraviolet-visible (UV-vis) spectroscopy, dynamic light scattering (DLS), Fourier transform-infrared spectroscopy (FT-IR), and transmission electron microscope (TEM). The antibacterial effects of the nanocomposite were investigated by using agar diffusion method and minimum inhibitory concentration (MIC) test. The quanti-tative analysis of the biofilm formation by the nanocomposite was conducted using crystal violet staining and confocal laser scanning microscope (CLSM). Results: The DLS and TEM analysis showed it was a spherical nanocomposite with 200 nm size and well dispersed . The results of UV-vis and FT-IR confirmed the presence of AMP and AgNPs. The nanocomposite had an excellent biocompatibility at 100 μg/mL. And the AMP@PDA@AgNPs nanocomposite showed superior antimicrobial activity against both Gram-negative (E. coli, P. aeruginosa) and Gram-positive (S. aureus) bacteria than AgNPs or AMP. Importantly, the mRNA expression of biofilm-related genes were decreased under the action of the nanocomposites. Conclusion: An AMP@PDA@AgNPs nanocomposite with good biocompatibility was successfully prepared. The nanocomposite could destruct bacterial biofilms by inhibiting the expression of biofilm-related genes. The synergistic strategy of AMPs and AgNPs could provide a new perspective for the treatment of bacterial infection.