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A MnO2 nanosheet-based ratiometric fluorescent nanosensor with single excitation for rapid and specific detection of ascorbic acid

Lyu, Yanlong, Tao, Zhanhui, Lin, Xiaodong, Qian, Pengcheng, Li, Yunfei, Wang, Shuo, Liu, Yaqing
Analytical and bioanalytical chemistry 2019 v.411 no.18 pp. 4093-4101
ascorbic acid, beverages, blood serum, cost effectiveness, dehydroascorbic acid, detection limit, false positive results, fluorescence, human health, manganese, manganese dioxide, nanosheets, oxidation, sensors (equipment), wavelengths
Ascorbic acid (AA) detection in biological sample and food sample is critical for human health. Herein, a MnO₂ nanosheet (MnO₂-NS)-based ratiometric fluorescent nanosensor has been developed for high sensitive and specific detection of AA. The MnO₂-NS presents peroxidase-like activity and can oxidize non-fluorescent substrate of o-phenylenediamine (OPDA) into fluorescent substrate, presenting maximum fluorescence at 568 nm (F₅₆₈). If MnO₂-NS is premixed with AA, the MnO₂-NS is then decomposed as Mn²⁺ by AA, decreasing the fluorescent intensity of F₅₆₈. Meantime, AA is oxidized as dehydroascorbic acid (DHAA), which can react with OPDA to generate fluorescent substrate. A new fluorescence response is found at 425 nm (F₄₂₅). The dual fluorescent responses can be excited with a universal excitation wavelength, simplifying the detection procedure. With F₄₂₅/F₅₆₈ as readout, limit of detection for AA reaches as low as 10.0 nM. Satisfactory recoveries are found for AA detection in serum and diverse beverages. The ratiometric strategy significantly eliminates false-negative and false-positive results, providing a cost-effective, rapid, and reliable way for AA detection in real sample.