Carbon quantum dots with ultra-high quantum yield for versatile turn-on sensor of gluten and cyanide Ions

In this work, we reported the synthesis of carbon quantum dots (CQDs) with high fluorescent quantum yield (90.7 %). These nanoparticles were applied in a turn-off/turn-on sensor able to detect cyanide ions. In this sensing strategy, Fe3+ ions were added to the aqueous suspension of CQDs to quench the fluorescence of the system, which was recovered from the presence of cyanide ions. Furthermore, a sensor array was developed using the LDA chemometric tool, to classify different species present in cookie formulations, including gluten. The turn-off/turn-on sensor proved to be sensitive and effective for detecting cyanide ions, with a detection limit of 3.77 ppm. This high sensibility and selectivity allowed quantifying the analyte in a real sample of tap water. [Display omitted] •A fluorescent nanoprobe with ultra-high quantum yield (90.7 %) for sensing of allergens and toxic substances was obtained.•Carbon Quantum Dots (CD-90) synthesized by one-step hydrothermal treatment and showed high fluorescence signal at 440 nm.•CD-90 were used as fluorescent nanoprobes in the construction of a sensor array for detection of gluten in cookies samples.•Fe3+ ions quenched the fluorescence of CD-90, which was recovery by adding CN− ions.•CN− ions were identified in tap water sample with recovery of 94.8 % and RSD of 7.34 %.