Gamma irradiation mediated synthesis of silver nanoparticles in mesoporous silica particles for combined antimicrobial action

Antimicrobial resistance (AMR) is a major global health challenge, driven by the increasing prevalence of multidrug-resistant microorganisms and the limited development of new antibiotics. Conventional antimicrobial therapy is often compromised by poor bioavailability, systemic toxicity, and inadequate drug concentrations at the infection site, highlighting the need for innovative delivery systems.

Mesoporous silica materials are promising nanocarriers due to their high surface area, tunable pore size, chemical stability, biocompatibility, and ability to provide controlled drug loading and release. In addition, silver nanoparticles (Ag NPs) exhibit broad-spectrum antibacterial activity through multiple mechanisms, including membrane disruption, reactive oxygen species generation, enzyme interference, and DNA damage. Their incorporation into mesoporous silica matrices may enhance nanoparticle stability and dispersion while enabling the simultaneous delivery of multiple antimicrobial agents. Radiation-induced synthesis provides a clean approach for the in situ formation of Ag NPs without additional reducing agents or high temperatures.

In this study, SBA-16 mesoporous silica was employed as a multifunctional carrier for the simultaneous incorporation of gamma-radiation-synthesized Ag NPs and two broad-spectrum antibiotics, chloramphenicol and bacitracin. The resulting systems were characterized by X-ray diffraction, nitrogen adsorption–desorption isotherms, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Their antimicrobial activity was evaluated using minimum inhibitory concentration and time-kill assays, while cytotoxicity assays were performed to assess biocompatibility.

Ag NPs were successfully synthesized and incorporated into the SBA-16 matrix. The combined Ag NPs/chloramphenicol/bacitracin systems demonstrated pronounced antimicrobial activity, as confirmed by MIC and time-kill assays, while cytotoxicity results supported their potential biocompatibility. Overall, these multifunctional systems represent a promising platform for enhanced antimicrobial therapy and an alternative strategy to address the growing challenge of AMR.