A synergistic photothermal antibacterial system based on silver-infused functionalized mesoporous carbon nanospheres

The emergence of antibiotic-resistant strains seriously reduces the efficiency of traditional antibiotic therapy. The development of a new alternative antibiotic method to effectively eliminate this bacterial infection has become a critical issue. Photothermal therapy (PTT) has shown many advantages in tissue penetration, spatiotemporal specificity, no drug resistance and broad-spectrum antimicrobial ability. However, extremely high temperature (55-65℃) is needed to achieve highly efficient bactericidal effect during PTT treatment process. Thus, this procedure will inevitably cause collateral damage to normal tissues. Silver nanoparticles (AgNPs) are one of the most commonly used broad-spectrum antimicrobial agents. Its antimicrobial activity is mainly derived from the release of silver ions (Ag⁺). However, excessive AgNPs not only would cause toxic to the body, but also waste precious metals. In this study, oxidized mesoporous carbon nanospheres (OMCN) were used as photothermal materials to prepare OMCN-Ag⁺ composites. The composite material can improve the antibacterial activity, reduce the waste of metal Ag and decrease the toxic and side effects. Moreover, the precisely controlled mild heat can overcome the shortcoming such as the damage to normal tissue caused by the excessive temperature during traditional photothermal antimicrobial process. The antimicrobial treatment system exhibits a good biocompatibility both in vitro and in vivo. Specially, the designed nanosytem can effectively eliminate the bacteria from the infected wound, subsequently promoting the process of wound healing. All animal experiments were carried out with approval of the Animal Experiment Ethics Committee of Henan University.