A simple fluorescent "Turn off-on" sensor based on P, N-doped graphene quantum dots for Hg2+and Cysteine determination

A new dual-doped, Phosphorus(P) and Nitrogen(N), fluorescent graphene quantum dots (P, N-GQDs) have been synthesized and used to detect "Mercury(II)-Cysteine (Hg2+-Cys)" as a "Turn off-on" fluorescent sensor. First, blue-green emitting P, N-GQDs with high quantum efficiency were successfully prepared for the first time from lemon salt by thermal pyrolysis method, which is simple and fast. The structure of P, N-GQDs was analyzed by the spectroscopic techniques. Next, P, N-GQDs were examined as a "Turn-off" fluorescent sensor to detect various metal ions. It was determined that the fluorescence intensity of P, N-GQDs was selectivity quenched only with Hg2+ ions. Afterwards, Hg2+ loaded P, N-GQDs (P, N-GQDs@Hg) were studied as a "Turn-on" fluorescent sensor to detect various amino acids/biomolecules. The fluorescence intensity of P, N-GQDs@Hg was determined to be almost completely (about 95%) and selectively recovered with cysteine. Thus, it was determined that P, N-GQDs could be used selectively and sensitively as "Turn off-on" fluorescence sensors for "Hg2+-Cys". Furthermore, the limit of detection (LOD) was determined as 0.13 & mu;M for Hg2+ and 0.65 & mu;M for Cys and the interference experiments were carried out for each ion and molecule. In addition, the designed method was successfully applied to the real samples. Consequently, the P, N-GQDs could be applied as a very precise and selective "Turn-off-on" fluorescence sensor for Hg2+ and Cys.

Journal

SENSORS AND ACTUATORS A-PHYSICAL

Year

2023

Volume

356

ISSN

0924-4247

eISSN

1873-3069

DOI

10.1016/j.sna.2023.114362

WoS UID

WOS:001040059900001