Gold nanoparticles (AuNPs) are widely used in nanomedicine because of their biocompatibility, stability, and ability to deliver drugs in a targeted manner. Gold, being inert and nontoxic, is ideal for clinical applications. Another aspect is their ease of functionalization, that is, the ability to easily bind biological molecules, such as proteins, nucleic acids, or polymers onto their surface. Because of their optical properties, AuNPs can be used as probes in advanced imaging techniques such as Point accumulation for Imaging in Nanoscale Topography (DNA-PAINT) microscopy. This technique consists of exploiting fluorescent molecules that temporarily bind to a target, producing intermittent signals to accurately determine the location of emitters.