Target-triggered ‘colorimetric-fluorescence’ dual-signal sensing system based on the versatility of MnO2 nanosheets for rapid detection of uric acid

Abstract

A simple dual-signal assay that combined colorimetric and fluorometric strategy for uric acid (UA) rapid detection was designed based on the versatility of facile synthesized MnO₂ nanosheet. The oxidization of 3,3′,5,5′-tetramethylbenzidine (TMB) and the fluorescence quenching of quantum dots (QDs) occurred simultaneously in the presence of MnO₂ nanosheet. UA could decompose MnO₂ nanosheet into Mn²⁺, resulting in the fluorescence recovery of QDs, along with the fading of the blue color of ox TMB. Based on the principles above, the detection of UA could be realized by the change of the dual signals (colorimetric and fluorometric). The linear range of the colorimetric mode was 5–60 μmol L⁻¹, and the limit of detection (LOD) was 2.65 μmol L⁻¹; the linear range of the fluorescence mode was wide at 5–120 μmol L⁻¹, and the LOD could be as low as 1.33 μmol L⁻¹. The method was successfully used for analyzing UA levels in human serum samples, indicating that this new dual-signal method could be applied in clinical diagnosis.