Facile Synthesis of Carbon Dots from Amido Black 10b for Sensing in Real Samples

Herein, a one-step hydrothermal synthesis method was adopted to fabricate carbon dots (CDs) from amido black 10b in a sodium hydroxide solution. The morphology and composition of the CDs were investigated by XRD, FTIR TEM, XPS, UV-vis, and fluorescence spectroscopy. The obtained CDs (AB-CDs) with an average diameter of 19.4 nm displayed a well-dispersed characteristic in aqueous solutions. The as-prepared CDs showed bright blue fluorescence and good photostability, with a high quantum yield of 24.1%. AB-CDs displayed a selective and noticeable turn-off response to Fe³⁺. Accordingly, the quantitative detection of Fe³⁺ was achieved in the range of 5-200 μmol L^-1 with a detection limit of 1.84 μmol L^-1. The fluorescence response mechanism of Fe³⁺ to AB-CDs was ascribed to static quenching due to the emergence of the ground-state complex. Moreover, ascorbic acid could restore the fluorescence of AB-CDs quenched by Fe³⁺ by reducing Fe³⁺ to Fe²⁺. The developed nanoprobe was used to detect ascorbic acid with a limit of detection of 7.26 μmol L^-1 in the range of 20-300 μmol L^-1. Furthermore, the developed sensing system was successfully applied for an Fe³⁺ assay in a lake water sample and ascorbic acid detection in a human urine sample. The AB-CD-based analytical system showed its latent practical value in the chemical analysis and bioanalytical fields.