Comprehensively Unveiling the Dual Antifungal and Antibacterial Activity of Ultra-small Pt Nanoclusters through Membrane Impairment Induced by Oxidative Stress

Microorganisms, including bacteria, fungi, and viruses, can invade the human body, disrupt normal physiological functions, and trigger a variety of infectious diseases, currently posing a significant global health issue. Silver (Ag), gold (Au), and titanium dioxide (TiO2) nanomaterials have already demonstrated exciting antimicrobial properties and promising therapeutic applications. However, the antibacterial performance of Pt nanomaterials, especially nanoclusters (NCs, <2 nm), has rarely been investigated. In this study, Pt NCs with an ultra-small size of 1.5 ± 0.5 nm were produced by a reduction method, and their structure presents a composite of fine atomic clusters. A series of bacteriostatic experiments proved that the sterilizing rates of Gram-negative bacteria Escherichia coli (E. coli) and Gram-positive bacteria Staphylococcus aureus (S. aureus) are 98.02 and 99.99%, respectively. In addition, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Pt NCs against Fusarium solani (F. solani) were determined to be as low as 0.8 and 1.7 μg/mL, and these Pt NCs exhibited fungicidal activity. The antibacterial and antifungal mechanisms were elucidated, showing that the oxidative stress generated via the excessive reactive oxygen species (ROS) induced by Pt NCs triggers the chain reaction of lipid peroxidation (LPO), consequently causing the structural degradation and functional impairment of membranes, ultimately resulting in the cytoplasmic contents leaking and bacterial/fungal death. Astonishingly, the wound healing rate for methicillin-resistant S. aureus (MRSA) infections was 98.90% at 10 days post treatment by Pt NCs, indicating significantly higher efficacy than that of the conventional broad-spectrum antibacterial fluoroquinolone drug ofloxacin. Furthermore, the antimicrobial gauze fabricated using these Pt NCs exhibited at least 99.75% inhibition of both E. coli and S. aureus within 24 h, suggesting their promising application prospects as a novel and safer antibacterial and antifungal agent.