A novel bacterial biofilms eradication strategy based on the microneedles with antibacterial properties

Bacterial biofilms possess high adaptive resistance to antimicrobials and human immune system, and it is extremely difficult to kill bacteria or remove biofilms from solid surfaces. Microneedles (MNs) can destroy the integrality of bacterial biofilms, and are helpful for bacterial biofilms eradication. In this study, we report dissolvable MNs composed of chitosan (CS) and zinc nitrate (CS-Zn2+ MNs), which combine the antimicrobial properties of CS and Zn2+ with the structural characteristics of MNs. The synergistic effect of CS and Zn2+ gives the CS-Zn2+ MNs fascinating antibacterial properties, and the microscale needle tips structure of MNs make the CS-Zn2+ MNs can puncture the bacterial biofilms delivery CS and Zn2+ to infection site. Counting the colony forming units assay shown that the antimicrobial properties of the CS-Zn2+ MNs was superior to CS MNs. Bacterial live/dead staining assay demonstrated that the CS-Zn2+ MNs exhibited better therapeutic effect to eradicate bacterial biofilms than membrane with same ingredient. Besides, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays confirmed the excellent cytocompatibility of the CS-Zn2+ MNs. Therefore, we believe the CS-Zn2+ MNs are promising for applications in bacterial biofilms contaminated sites.