Unveiling the antibacterial efficacy of gold nanoparticles: a critical review

The antibiotic exploitation has escalated the menace of drug-resistant bacteria, necessitating the development of powerful new drugs. Gold nanoparticles (Au NPs) are ideal bactericidal agents due to their unique physicochemical properties, non-toxicity, inertness, and biocompatibility. The surface properties of Au NPs have a critical role in their antibacterial activity. This review summarizes the data of published literature from 2001 to 2025 on the various physio-chemical and biological methodologies for synthesizing Au NPs and their antibacterial functions. The ability of the Au NPs to transform the near-infrared light into heat has demonstrated the photothermal-based bacterial death due to excessive heat generation. Engineering and functionalization of Au NPs with antibiotics/antimicrobial compounds/phages/enzymes have been shown to enhance antibacterial efficacy through targeted drug therapy by making the bacteria extremely vulnerable to these combinations. The complexity, cost-ineffectiveness, and lack of standardized protocols for Au NP synthesis can limit their adoption for antibacterial purposes. Resistant strains may develop from the prolonged and sublethal exposure of Au NPs. The in-vivo studies on animal models have confirmed the aggregation of Au NPs in the vital organs, bringing developmental, genotoxic, and cytotoxic effects. The unforeseen consequences on humans and the environment by long-term exposure to Au NPs have not yet been determined, thus restricting their applications for antibacterial therapy. Meticulous research on Au NPs and their combination therapy along with AI-driven approaches will promote the translation of Au NPs into clinical trials by uncovering their bioavailability, safety, distribution and mechanism before validating them for antibacterial therapy.