Inner filter effect mediated fluorescent sensing of rutin based on amino acid-derived novel nitrogen and sulfur co-doped carbon dots

Abstract

Nitrogen and sulfur co-doped carbon dots (N,S-CDs) were constructed through a hydrothermal synthesis employing l-cysteine and d-aspartic acid as precursors in this study. A novel scheme has been proposed for synthesizing N,S-CDs utilizing two amino acids, aiming to detect rutin. The N,S-CDs exhibit excellent luminescence performance as fluorescent sensors with a dimension of 2.5 ± 0.14 nm and excitation/emission wavelengths of 350/429 nm. The rutin quenching mechanisms in N,S-CDs was verified as the inner filter effect (IFE) by spectral analysis, fluorescence lifetime detection, and Parker equation calculation. The system features with N,S-CDs and rutin as the IFE fluorophore and IFE absorber. The fluorescence quenching efficiency of N,S-CDs presented a good linear correlation with rutin concentration in the 20–500 μmol·L^-1 range based on (F₀–F)/F₀ = 0.0014C + 0.0152 (R² = 0.9941) with the detection limit of 8.05 μmol·L^-1. This method accurately detects the rutin concentration in samples of human urine and serum. The technique developed in this research boasts a wide linear range, fast response time, a wide pH range, excellent stability, and simplicity. It holds a promising potential for the application in the medicine and pharmacy fields.