A TURN-ON DUAL FLUORESCENT SENSOR FOR CYSTEINE AND THIOUREA USING ACRIFLAVINE LOADED GRAPHENEOXIDE
The existence of a dual sensor for the combination of cysteine and thiourea is very rare, despite the presenceof numerous fluorescence sensors for cysteine in the literature. On the other hand, thiourea has been involvedinfluorescence sensors for many metal ion sensors. Here, we have developed an inexpensive and rapid fluorescent sensor for this dual pair using acriflavine-loaded graphene oxide (GO–ACY) in water. Interestingly, GO–ACYdisplayed a good fluorescence for both cysteine and thiourea. Indeed, GO-ACY did not respond to other amino acids, excluding cysteine. Calculated LOD for thiourea was found to be 7.1 × 10 -7 M, and for cysteine, it was found tobe8.4 nM. The presence of thiourea in pharmaceutical drugs also displayed a good fluorescence, indicating that thesensor could be useful for the estimation of drugs that have the thiourea moiety.
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