Biosynthesis of fluorescent gold nanoclusters for in vitro and in vivo tumor imaging

•Fluorescent gold nanoclusters (AuNCs) were synthesized with nature biomass as ligands.•The biosynthesis method was facile, scalable, cost-effective and environmentally benign.•The AuNCs had good biocompatibility in vitro and in vivo.•The AuNCs were used for tumor imaging in vitro and in vivo.

Recently, fluorescent metallic nanoclusters with sizes in the few-nanometer range have showed great potentials in biomedical applications for their stable and tailorable fluorescence. Although many studies have focused on fabricating these kinds of materials with chemical methods, there has been little focus on the biosynthesis of gold nanoclusters with green and facile methods. In this study, a facile, scalable, cost-effective and environmentally benign biosynthesis approach was developed to produce fluorescent gold nanoclusters (AuNCs). Biomasses including egg white, egg yolk and serums were used as both capping agents and reductants in the biosynthesis of AuNCs. As a new kind of fluorescent imaging agent, they were used for in vitro and in vivo tumor imaging that can efficiently track cancer cells with excellent biocompatibility. This work provides new insight into green biosynthesis and biomedical applications of fluorescent metallic nanoclusters.