A ratiometric fluorescence and light scattering sensing platform based on Cu-doped carbon dots for tryptophan and Fe(III)

A new Cu-doped carbon dots (Cu-CDs) were synthesized rapidly and simply via one-step thermolysis of Na-2[Cu(EDTA)] and ascorbic add (AA) at 250 degrees C for 2 h with a high quantum yield of 9.8%. The Cu-CDs exhibits two signals of fluorescence at 396 nm and second-order scattering (SOS) at 617 nm under a single excitation wavelength of 308 nm, and can be obviously enhanced by tryptophan (Trp) or Fe(III) leading to the ratiometric fluorescence and SOS response with a good linear wider range of 0.5-250 mu M and 0.1-50 mu M, respectively. This sensing system exhibits good selectivity and sensitivity toward Trp and Fe(III) over other analytes with a low detection limit of 275 nM and 46 nM, respectively. Furthermore, the proposed sensing system displays a prospective application for quantitative assay of Trp and Fe(III) in practical sample. (C) 2019 Elsevier B.V. All rights reserved.