Fluorescence turn-on sensing of ascorbic acid and alkaline phosphatase activity based on graphene quantum dots.

A facile fluorescence turn-on approach for the detection of l -ascorbic acid (AA) and alkaline phosphatase (ALP) activity was designed based on graphene quantum dots (GQDs). It is found that the fluorescence intensity of GQDs can be efficiently quenched by para-benzoquinone (BQ). And a turn-on fluorescence signal can be observed if BQ is reduced by AA. In addition, ALP can hydrolyze l -ascorbic acid-2-phosphate (AAP) to produce AA, which also results in the recovery of the GQDs fluorescence. The recovered fluorescence intensity of GQDs was proportional to the concentration of AA or ALP in the concentration ranges of 5.0 × 10 −7 to 2.0 × 10 −5 mol/L and 1.0–90 U/L, respectively. The detection limit for AA and ALP were 2.0 × 10 −7 mol/L and 0.45 U/L. The established method showed a high selectivity for ALP activity compared with other interference components. Furthermore, the detection system as a fluorescence probe has great potential in the development of sensors for widely detecting various analytes with AA producing process. [ABSTRACT FROM AUTHOR]