Gold nanostars and nanourchins for enhanced photothermal therapy, bioimaging, and theranostics

Photothermal therapy (PTT), a recently emerging method for eradicating tumors, utilizes hyperthermia induced by photo-absorbing materials to generate heat within cancer cells. Gold nanoparticles (AuNPs) have gained reliability for in vitro and in vivo applications in PTT due to their strong light absorbance, stability, and biocompatibility. Yet, their potential is limited by their spherical shape, impacting their size capabilities, electromagnetic enhancement effects, and localized surface plasmon resonance (LSPR). Anisotropic shapes have been tested and implemented in this treatment to overcome the limitations of spherical AuNPs. Nanostars (AuNSs) and nanourchins (AuNUs) offer unique properties, such as increased local electron density, improved catalytic activity, and an enhanced electromagnetic field, which have proven to be effective in PTT. Additionally, these shapes can easily reach the NIR-I and NIR-II window while exhibiting improved biological properties, including low cytotoxicity and high cellular uptake. This work covers the critical characteristics of AuNS and AuNUs, highlighting rough surface photothermal conversion enhancement, significantly impacting recent PTT and its synergy with other treatments. Additionally, the bioimaging and theranostic applications of these nanomaterials are discussed, highlighting their multifaceted utility in advanced cancer therapies.