Antibacterial, antibiofilm and cytotoxic activity of synthesized metal-incorporated mesoporous silica nanoparticles.

Antibiotic misuse has triggered a global health crisis due to the rise of antimicrobial-resistant microorganisms. Recent studies suggest that nanoparticles (NPs), particularly silver nanoparticles, may provide a solution. However, their toxicity necessitates the development of novel carriers to enhance targeting while minimizing cytotoxicity. This study aimed to synthesize, characterize mesoporous silica nanoparticles (MSN) incorporated with silver alone or combined with zinc, and evaluate their antibacterial, antibiofilm, and cytotoxic properties. Characterization through X-ray diffraction (XRD) and scanning electron microscopy (SEM), revealed particle sizes between 413 and 560 nm. Antibacterial activity was assessed via the broth-dilution method against Staphylococcus aureus ATCC 25,923, Escherichia coli ATCC 25,922, Methicillin-resistant Staphylococcus aureus (MRSA) ATCC 33,591, and five multidrug-resistant pathogens (MDR). Two types of silver-incorporated mesoporous silica nanoparticles were synthesized: Ag/MCM-48 (10 mmol Ag) and Ag/Zn/MCM-48 (10 mmol Ag + 10 mmol Zn). The minimum inhibitory and minimum bactericidal concentrations ranged from 7.8 to 31.25 and 7.8 to 62.5 µg/mL, respectively. Ag/MCM-48 NPs exhibited 78% antibiofilm activity against MRSA ATCC 33,591, while Ag/Zn/MCM-48 NPs displayed up to 90% antibiofilm activity against MDR bacteria. Cytotoxicity assays revealed promising results, with CC₅₀ values of 169.16 ± 6.43 µg/mL and 19.95 ± 0.63 µg/mL for Ag/Zn/MCM-48 NPs and Ag/MCM-48 NPs against Vero cell line, respectively. The IC₅₀ values of Ag/Zn/MCM-48 and Ag/MCM-48 NPs were 62.17 ± 2.15 µg/mL and 3.58 ± 0.12 µg/mL against Caco-2 cell line, respectively. Accordingly, our synthesized silver/zinc incorporated mesoporous silica NPs present a safer antibacterial and antibiofilm agent with lower cytotoxicity than silver NPs, making them a promising alternative for combating MDR bacteria.