CVD Assisted Hydrophobic Graphene Quantum Dots: Fluorescence Sensor for Aromatic Amino Acids

In this paper, an hydrophobic graphene quantum dots(h-GQDs) based PL sensor was demonstrated which can distinguish between aromatic and non-aromatic amino acids. The h-GQDSs prepared using Chemical Vapour Deposition method from acetylene gas and hydrogen gas was used as cocatalyst. The characterization of h-GQDs was carried out by UV-Visible absorption spectrophotometer, Dynamic Light Scattering, Scanning Electron Microscopy, Fourier Transform Infrared Spectrophotometer, Raman spectroscopy. These CVD assisted h-GQDs form stable dispersion in organic solvents and are hydrophobic in nature. It was observed that photoluminescence (PL) intensity of h-GQDs systems in the presence of aromatic amino acids is enhanced due to electron transfer from aromatic amino acids to h-GQDs whereas with non-aromatic amino acids PL intensity is quenched. Hence h-GQDs systems can selectively distinguish between aromatic and non-aromatic amino acid. The mechanistic insight is also discussed in the paper. Besides fluorescence sensors for aromatic amino acids, the h-GQDs system can also be used as a fluorescence hydrophobic coating material as when coated on glass substrate it shows very high contact angle (107 degrees).