NIR-responsive gold nanomaterials in photothermal antibacterial therapy: From morphological design to multifunctional platforms

The prevailing strategies for treating bacterial infections predominantly utilize traditional antibiotics, leading to the proliferation of drug-resistant bacteria. These bacteria significantly undermine the efficacy of antimicrobial therapies and adversely impact the human immune system. Consequently, the development of novel antimicrobial approaches has become critically important. Recently, photothermal antimicrobial techniques, particularly those utilizing near-infrared (NIR) light, have garnered increasing attention for their deep tissue penetration and minimal side effects. Among NIR-responsive photothermal materials, gold nanoparticles (GNPs) have been extensively investigated for their superior photothermal properties, straightforward synthesis, and broad-spectrum antimicrobial capabilities, making them pivotal in developing antimicrobial nanocomposite platforms. This review examines the antimicrobial effects of GNPs and their NIR-responsive functionalized nanocomposites, discussing the morphology of GNPs, the underlying principles of NIR responsiveness, and their photothermal conversion efficiency. It highlights traditional and emerging gold nanostructures, including gold nanobipyramids and nanoclusters, and outlines strategies for leveraging the photothermal properties of gold-based nanoplatforms in antimicrobial applications. The paper concludes with an overview of current challenges and future directions in the field.