Antibacterial Activity of Solid-Supported Gold Nanorods Combined with Antimicrobial Peptides

In response to the growing clinical challenge of combating biomaterial-associated infections (BAIs), antibacterial modifications of biomaterials have emerged as a promising alternative. One approach harnesses the photothermal properties of plasmonic nanoparticles to achieve a light-activated antibacterial activity through localized heating. This study evaluates a combined antibacterial strategy based on the photothermal heating of solid-supported gold nanorods and the antimicrobial peptide (AMP) RRPRPRPRPWWWW-NH₂. The antibacterial activity of the solid-supported gold nanorods under near-infrared (NIR) irradiation and of the AMP was evaluated individually and in combination against Staphylococcus aureus. Combining the photothermal heating of the gold nanorods with the AMP resulted in an enhanced antibacterial efficacy, achieving 98% reduction compared to the untreated control. Interestingly, the material characteristics and irradiation parameters governing the photothermal heating strongly influenced the activity of the combined system. This effect was observed even at low gold nanorod surface coverage (∼15%), largely preserving the inherent surface properties of the biomaterial. Additionally, bacterial cytological profiling provided insight into the mode of action of the solid-supported gold nanorods and the AMP. The findings highlight key characteristics of this combined antibacterial strategy that are relevant for the development of improved biomaterials to combat BAIs.