Novel turn-on fluorescent detection of alkaline phosphatase based on green synthesized carbon dots and MnO2 nanosheets

Abstract

Using sterculia lychnophora seeds as precursors for the first time, fluorescent carbon dots (CDs) were synthesized by simple hydrothermal treatment. The quantum yield of as-synthesized CDs was 6.9% by using quinine sulfate as the reference. The fluorescence of CDs could be effectively quenched by a MnO₂ nanosheet based on fluorescence resonance energy transfer (FRET). Ascorbic acid (AA) could reduce MnO₂ to Mn²⁺ and result in the destruction of the MnO₂ nanosheets, which could induce the fluorescence recovery of the CDs. In particular, alkaline phosphatase (ALP) could bio-catalyze acid 2-phosphate (AAP) hydrolysis to AA. Here, an efficient fluorescence probe based on a CDs-MnO₂ nanosheet for rapid and selective detection of ALP was reported for the first time. Excellent performance for the detection of ALP was observed with high sensitivity and a detection limit of 0.4U/L owing to the low background. The detection of ALP in human serum was conducted with satisfactory results, demonstrating its potential applications in clinical diagnosis.

Keywords: Alkaline phosphatase; Carbon dots; Fluorescence; MnO(2) nanosheet.