Intelligent peptide-nanorods against drug-resistant bacterial infection and promote wound healing by mild-temperature photothermal therapy

Due to the abuse of antibiotics, bacteria produce serious drug resistance, which makes the existing clinical antibiotic treatment scheme fail and seriously endangers human health. The construction of antimicrobial nanometer systems including antimicrobial peptides and antimicrobial nanomaterials has become the focus of research on new antimicrobial agents, and may significantly improve the antimicrobial efficiency. In this study, we successfully explored a novel antimicrobial nano-system Dap@Au/Ag nanorods (Dap@Au/Ag NRs) based on gold nanorods, and investigated the antimicrobial properties of this novel antimicrobial agent with methicillinresistant Staphylococcus aureus (MRSA) as the experimental strain. Under the action of H2O2, Dap@Au/Ag NRs can considerably release silver ions and antimicrobial peptides (Dap), destroying the integrity of the MRSA membrane and resulting in content leakage and bacterial death. Furthermore, in vivo and in vitro experiments showed that after a certain intensity of laser irradiation (808 nm, 0.8 W/cm(2), 40-60 s), the antibacterial properties of Dap@Au/Ag NRs were significantly improved by using gold nanorods with good photothermal effect. At the same time, compared with traditional photothermal therapy (PTT), we found that laser irradiation with the appropriate intensity was given at the initial stage of infection and controlled at a mild temperature (below 47 degrees C), it not only significantly inhibited the growth of MRSA, prevented large area of wound ulceration and promoted wound healing, but also had no obvious thermal damage to the wound surface and surrounding skin. The results showed that novel antibacterial nano-system Dap@Au/Ag NRs have significant bactericidal properties, and can be used as a potential promising antimicrobial agent, which provides a new strategy for facilitating and enhancing the effective antimicrobial efficiency to inhibit drug-resistant bacterial infection.