Highly fluorescent fish scale-derived carbon dots for quercetin sensing

Abstract

A significant focus of carbon dot research is on enhancing the fluorescence emission performance of biomimetic carbon dots to improve their application value in practical analysis. In this study, fish scales were used as a precursor, and citric acid was introduced to improve the quantum yield of carbon dots. The results showed that under 350 nm excitation, citric acid-modified carbon dots (CDs-FS/CA) exhibited a maximum fluorescence emission of 411 nm, and the emission behavior was independent of the excitation wavelength, with a quantum yield of 35.5%. This high quantum yield could be attributed to the presence of citric acid and the participation of hydroxyapatite in fish scales. The CDs-FS/CA had a moderate degree of graphitization, smaller and more concentrated particle size distribution, and a high proportion of pyrrole N. They showed good fluorescence performance through the synergistic effect of surface state sp² C and different N-doped surface states. A good linear relationship in the range of 0–50 μmol L⁻¹ was obtained using CDs-FS/CA for trace detection of quercetin, with a limit of detection of 3.8 nmol L⁻¹, and good recovery in actual sample detection. These results offer a reference for enhancing the quantum yield of CDs obtained from alternative biomass sources and indicate the encouraging commercial feasibility of CDs derived from waste biomass for detecting trace amounts of quercetin.