Nanoparticle-free synthesis of fluorescent gold nanoclusters at physiological temperature

Few-atom gold nanoclusters exhibit strong size-dependent fluorescence emission. For many applications, these clusters are preferable to quantum dots or organic fluorophores as fluorescent labels. However, the published synthetic procedures to create these nanoclusters involve toxic chemicals, are of low synthetic yield, and concurrently produce large nanoparticles. Here, we report two methods for high-yield synthesis of gold nanoclusters, utilizing physiological temperature and green chemistry. Blue, green, and red emissive nanoclusters with pH stability in a range of 6-8 were produced.