Fabrication of L-Cysteine functionalized Graphene quantum dots as a fluorescent nanosensing probe for determination of mercury

Abstract

A highly sensitive and selective nanosensing probe for mercury ion is reported. Herein highly luminescent cysteine(cys) functionalized Graphene quantum dots(GQDs) were fabricated through facile one-step pyrolysis method by using ethylene glycol and cysteine. The coating of cysteine not only increases quantum yield to 41% but also enhances selective detection of ppb level of mercury ion in the waste water. The fluorescence intensity of Cys-GQDs was sequentially quenched by different concentrations of mercury ion via forming non-luminescent complexes of Cys-GQDs-Hg(II). HR-TEM study clearly shows a monodisperse Cys-GQDs of sizes 2-5 nm with a spherical shape. Raman spectra of Cys-GQDs display the D and G bands at 1350 cm−1 and 1580 cm−1 respectively. Optimum pH is 8 for mercury detection. The minimum limit for accurate detection of mercury is 0.64 ppb

Metal ion sensing with graphene quantum dots: detection of harmful contaminants and biorelevant species

“…41 Greater attention has been paid to the influence of pH and working pH range on selectivity and PL properties of GQDs since this mechanism was first suggested, as highlighted by the examples in the Tables presented in this review. 81,89,90 Surface modification of GQDs has also been employed as an adjuvant to heteroatom doping to improve Fe 3+ selectivity. 44 GQDs were furnished with dopamine units (Fig.…”

“…41 Greater attention has been paid to the influence of pH and working pH range on selectivity and PL properties of GQDs since this mechanism was first suggested, as highlighted by the examples in the Tables presented in this review. 81,89,90…”

One-step synthesis of fluorescent graphene quantum dots as an effective fluorescence probe for vanillin detection

“…[4][5][6] Owing to these properties, GQDs have immense potential applications in photovoltaic devices, 7 bioimaging instruments, 8 sensors and biosensors, 9,10 etc. Until now, GQDs have been used as a uorescent probe for the detection of a broad range of analytes such as metal ions, [11][12][13][14][15] organic matter, 16,17 proteins, 18 and other biomolecules. 19,20 Vanillin (Fig.…”