Solvent-dependent carbon dots for multifunctional sensing of temperature, pH, and proton pump inhibitors

Multifunctional sensing, a strategy to improve the efficiency of analysis and detection, has attracted much attention. In this study, a multifunction sensing platform was developed for temperature, pH, and proton pump inhibitors (PPI) with fluorescence carbon dots. Solvent-dependent carbon dots (PG-CDs) were synthesized through a one-step solvothermal method from phloroglucinol with the assistance of HCl. Base on the effect of functional groups on the surface, solvent-dependent behavior, temperature and pH responsive fluorescence can be observed. The PG-CDs display a reversible temperature-sensitive fluorescent behavior within 15-65 °C in N, N-dimethylacetamide. The fluorescence intensity of PG-CDs also responded to pH in a range of 3.0-7.0 with good reversibility and anti-interference. Therefore, the platform for temperature and pH sensing was proposed. In addition, since the synergistic effect of dynamic and static quenching, proton pump inhibitors (PPI) can be detected sensitively, including esomeprazole (EPZ), omeprazole (OPZ), and rabeprazole (RPZ). The linear range of detection for EPZ, OPZ, and RPZ is 2.0-80.0, 2.0-75.0, and 10.0-200.0 μM and the limits of detection is 0.29, 0.55, and 2.99 μM, separately. The recoveries for real samples were between 91.83 and 102.3%, which indicated that the platform for PPI sensing had good accuracy.