Colorimetric and fluorescence dual-mode pH sensor based on nitrogen-doped carbon dots and its diverse applications

• Published in: Mikrochimica acta (1966) 2023-12, Vol.190 (12), p.478-478, Article 478
• Main Authors: Zhou, Xueying, Pang, Yuanhao, Wang, Yu, Yan, Wenju, Zhang, Yun, Zou, Jianmei, Yuan, Yali
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Carbon dots; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Colorimetry; Dimercaprol; Fluorescence; Hydrogen-ion concentration; Microengineering; Nanochemistry; Nanotechnology; Nitrogen; Original Paper; Phenylenediamine; Sensors; Tryptophan; Water sampling
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-023-06064-8

A dual-mode pH sensor based on nitrogen-doped carbon dots (N-CDs) with the source of o-phenylenediamine and tryptophan has been constructed. Under the stimulation of pH, the N-CDs exhibited prominent both color and fluorescence changes, leading to the rarely discovered colorimetric and fluorescent dual-readouts for the evaluation of pH. The mathematic relationship was established between pH and fluorescence intensity of N-CDs, and between pH and the UV–Vis absorbance ratio at 630 nm and 488 nm of N-CDs, respectively, over a quite broad pH range of 2.2 to 12.0. Multiple techniques are used to explore the dual-mode pH-responsive mechanism, and the preliminary explanation is put forward. The experimental results show that the N-CDs have visualized pH sensing applicability for actual samples, including various water samples and HeLa cell. Furthermore, the N-CD ink is developed for successful information encryption and anti-counterfeiting. This work might provide valuable insights into the sensing mechanism of CDs, and the application potential of CDs in broader fields. Graphical Abstract