A Fluorescence Resonance Energy Transfer Biosensor Based on Graphene Quantum Dots and Protoporphyrin IX for the Detection of Melamine.

Graphene quantum dots (GQDs), which have high photostability, anti-photobleaching and scintillation, good biocompatibility and low toxicity, are important member of the fluorescent material family, and have attracted extensive research interest. In this paper, a fluorescence resonance energy transfer (FRET) biosensor based on protoporphyrin IX (PpIX) and GQDs was developed for melamine detection. PpIX was bound to the surface of GQDs to produce self-assembled nanosensors, and a FRET process occurred between GQDs and PpIX. However, due to the combination of melamine and PpIX, the FRET process was shut down in the presence of melamine. The FRET system could quickly and accurately detect melamine with a detection range of 1.0 × 10-8 to 2.0 × 10-6 mol/L based on the fluorescence intensity ratio of PpIX and GQDs, and the detection limit was 3.6 × 10-9 mol/L. This method obtained satisfactory results when it was employed to the determination of melamine in milk samples.