Mesoporous silica nanostructures embedding NIR active plasmonic nanoparticles: Harnessing antimicrobial agents delivery system for photo-assisted eradicating Gram-positive bacteria

Implant-associated bone infection is increasingly emerging as a serious threat due to the high demand for orthopedic implants in our ageing society. Bacteria adhering to the surface of implants are highly resistant to conventional antibiotics and increasingly difficult to kill. In the quest for new antimicrobial strategies, multifunctional antimicrobial nanosystems offer new promise in the treatment of such infections. Herein, the development of mesoporous silica-coated plasmonic nanostructures for the delivery of antimicrobial drug for lightassisted therapy for bone infections is reported. Core@shell structures featuring Cu2-xS facet triangular nanoplates (NPL) core and a mesoporous silica shell (Cu2-xS@MSS) were synthesized. Further loading with antimicrobial molecules, such as levofloxacin (Levo) o rifampicin (Rif), allowed to synergistically combine the Cu2-xS NPL inherent antibacterial photoactivity with the pharmacological effects of the drug. The silica-based nanostructures, synthesized using a microemulsion approach, were thoroughly characterized, and their antibacterial activity explored in terms of inhibition of bacteria growth against Staphylococcus aureus. These results outline future applications of these nanoformulations for the management of bone implant-associated bacterial infections.