Quenching of graphene quantum dots fluorescence by alkaline phosphatase activity in the presence of hydroquinone diphosphate

Abstract

In this work, a turn-off photoluminescent sensing proof-of-concept based on blue luminescent graphene quantum dots (GQDs) as the fluorescent probe was developed. For that purpose, GQDs optical response was related with the catalytic enzymatic activity of alkaline phosphatase (ALP), in the presence of hydroquinone diphosphate (HQDP). The hydrolysis of HQDP by ALP generated hydroquinone (HQ). The oxidation of HQ, enzymatically produced, to p-benzoquinone (BQ) resulted in the quenching of GQDs fluorescence (FL). Therefore, the developed luminescent sensing mechanism allowed the FL quenching with ALP activity to be related and thus quantified the concentration of ALP down to 0.5 nM of enzyme. This innovative design principle appears as a promising tool for the development of enzymatic sensors based on ALP labeling with fluorescent detection or even for direct ALP luminescent quantification in an easy, fast and sensitive manner.

Applications of fluorescent materials in the detection of alkaline phosphatase activity

“…This technique is simple and rapid, with LODs as low as 0.008 U L −1. 81,82 FRET was also used to quench the fluorescence of CQDs in the presence of MnO 2 nanosheets. Similarly, the ALP‐catalyzed hydrolysis of acid 2‐phosphate into ascorbic acid destroyed MnO 2 nanosheets via the reduction of MnO 2 to Mn 2+ by ascorbic acid.…”

“…ALP can also hydrolyze hydroquinone diphosphate into hydroquinone. The oxidation of hydroquinone generates p ‐benzoquinone, which quenches the fluorescence of GQDs 82 …”