Facile preparation of red emission Hg-doped ZnSe QDs and ratiometric determination of alkaline phosphatase based on in situ generation of dual fluorescent reporter

Abstract

Abstract In this study, highly red emissive mercury-doped zinc selenide quantum dots (Hg-doped ZnSe QDs) were prepared by facile mixing of Hg2+ and ZnSe QDs. Further, a ratio fluorometric technique was designed for ultrasensitive detection of alkaline phosphatase (ALP) based on in situ generation of Hg-doped ZnSe QDs and quinoxaline derivative (QXD). Under the catalysis of ALP, ascorbic acid (AA) was generated from ascorbic acid 2-phosphate, and the as-generated AA underwent a redox reaction with Hg2+ to produce dehydroascorbic acid (DHA) and Hg, which resulted in significant suppression of red fluorescence at 635 nm because the lack of Hg2+ blocked the formation of Hg-doped ZnSe QDs. Furthermore, the occurrence of reaction between DHA and o-phenylenediamine produced fluorescent QXD, which caused the significant enhancement of blue fluorescence at 436 nm. Thus, a novel ratio nanoprobe utilizing Hg-doped ZnSe QDs and QXD as dual fluorescent reporter was fabricated for measuring ALP activity. The linear ranges were 0.001–0.02 U L−1 and 0.02–1.4 U L−1 with the detection limit of 0.001 U L−1. Furthermore, the nanoprobe enabled visual detection of ALP activity when exposed to ultraviolet light, and it exhibited satisfactory results for measuring ALP activity in human serum. This study provides a valuable method for ALP-related disease diagnosis and drug screening.