Recent advances in smart gold nanoparticles for photothermal therapy

Gold nanoparticles (AuNPs) possess unique properties, including low toxicity and excellent optical characteristics, making them highly appealing for biomedical applications. The plasmonic photothermal effect of AuNPs has been explored to trigger localized hyperthermia. Four commonly explored gold nanoparticles (spheres, rods, stars, and cages) are produced and optimized to present the localized surface plasmon resonance effect in the near-infrared region, exploiting the increased penetration in the human body. Additionally, the production of hybrid AuNPs, combining them with other materials, such as silica, graphene, zinc oxide, polymers, and small molecules has been explored to amplify the photothermal effect (T ≥ 45ºC). This review provides an overview of AuNPs' application in photothermal therapy, describing the general synthesis processes and the main particle parameters that affect their application in photothermal therapy, including the hybrid nanomaterials. Associated with this rapid progress, surface functionalization can also improve colloidal stability, safety, and therapeutic outcomes. In this regard, we also highlight the emerging trend of applying cell-derived vesicles as biomimetic coatings, capable of evading immune recognition, increasing blood circulation, and targeting specific tissues. In addition, the challenges and future developments of AuNPs for accelerating the clinical translations are discussed in light of their therapeutic and theragnostic potential.