A microwave-assisted hydrothermal route was employed to prepare fluorescent tannic acid (TA)-derivatized graphitic carbon nitride quantum dots. The resulting dots display blue fluorescence (best measured at excitation/emission wavelengths of 350/452 nm) with a quantum yield as high as ~44%. The incorporated TA imparts a fluorescence switching behavior in that very low concentrations of Cu(II) can quench the fluorescence, while (AA) can restore it. It is presumed that AA causes Cu(II) to be transformed to Cu(I). Based on these findings, a fluorometric method was designed for AA detection. The probe allows AA to be detected with a 50 pM limit of detection and a linear analytical range that extends from 0.1 to 200 nM of AA. Real and spiked samples were successfully assayed by the probe to demonstrate its analytical applicability. [Figure not available: see fulltext.].
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Acknowledgements The authors wish to acknowledge funding from National Research Foundation (NRF) of South Africa through the South African Research Chair Initiative (SARCHI) in Nanotechnology. OJA thanks the National Research Foundation (NRF) for a postdoctoral fellowship and funding under SA Research Chair for Nanotechnology.
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