Au NPs enhanced GERS detection of the freshness of fruits and vegetables . It can be used as a probe for surface-enhanced Raman spectroscopy (SERS, Figure ). Au or Ag nanoparticles were synthesized into reduced graphene oxide nanosheets (e.g., Au@G and Ag@G). The materials can be used as a probe for the analysis of the freshness of fruits and vegetables (e.g., Carrot, Wax apple, Lemon, Red pepper, and Tomato) . One-pot synthesis of Au NPs@carbon dots was reported for the cytosensing of metals in cancer cells . Au