Nanoscale luminescence sensing platform: highly stable carbon dots for reliable and cost-effective quercetin quantification

초록

A naturally occurring bioflavonoid, quercetin (QC), is well known for its potent antioxidant properties and significant applications in medicine and nutrition. Therefore, its rapid, sensitive, and accurate quantification is vital for evaluating food quality and monitoring health. In this study, greenish blue-emissive nitrogen and sulfur co-doped carbon dots (NS-CDs) were synthesized and successfully used as highly efficient luminescent probes for detecting QC. The NS-CDs were prepared via a simple one-step hydrothermal process, using histidine as the carbon source and cysteamine as the nitrogen and sulfur sources, thus eliminating the need for toxic reagents or additional surface modifications. The optical features of the as-prepared NS-CDs were characterized through emission and absorption techniques, and high-resolution transmission electron microscopy (HRTEM) images confirmed their morphology. The NS-CDs exhibited a strong greenish-blue emission maximum at 476 nm with a notable quantum yield of 18.36%, along with high photostability and colloidal stability. When QC was introduced, the fluorescence intensity of the NS-CDs was progressively diminished via non-radiative complex formation and the inner filter effect (IFE) process. Fluorescence lifetime measurements, spectral overlaps, and absorbance spectral findings verified the static quenching mechanism and IFE phenomena. This strong interaction enabled sensitive and quantitative detection of QC over a linear range of 3-51 mu M, with a notably low detection limit of 4.33 nM. The developed fluorescence sensing platform demonstrates high selectivity even against structurally related interferents, along with advantages such as a broad detection range, rapid response time (<2 min), ease of operation, and cost-effectiveness. Consequently, NS-CDs offer a robust and versatile method for accurately quantifying QC in wine and onion samples, highlighting their potential applications in food quality control and safety monitoring in the food industry.

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