Graphene Quantum Dots Assembled with Metalloporphyrins for "Turn on" Sensing of Hydrogen Peroxide and Glucose

Noncovalent and multifunctional hybrids have been generated via π-π stacking and electrostatic interactions by combining the nanometer-scale graphene structure of graphene quantum dots (GQDs) with Fe(III) 5,10,15,20-tetrakis(1-methyl-4-pyridyl)porphine (FeTMPyP). The inner filter effect (IFE) of FeTMPyP on the GQDs results in substantial PL quenching of the GQDs. The quenched PL of GQDs by the FeTMPyP can be switched back "on" in response to the reaction between FeTMPyP and H2 O2 , which causes rupture of the cyclic tetrapyrrolic nucleus with consequential loss of iron from FeTMPyP, and then proceeds further to produce colorless dipyrroles and monopyrroles. This "turn on" system can be applied for simple and convenient H2 O2 sensing and can be further extended to the detection of glucose in combination with the specific catalytic effect of glucose oxidase (GOx) through the oxidation of glucose and formation of H2 O2 . Because of the inherent synthetic control available for the design of metalloporphyrins, the GQDs-based optical sensing approach described here has the potential to be highly versatile for other target analytes.