Construction of dual-channel ratio sensing platform and molecular logic gate for visual detection of oxytetracycline based on biomass carbon dots prepared from cherry tomatoes stalk

Abstract

In this work, blue carbon dots (Stalk-Trp CDs) with high fluorescence quantum yield were successfully prepared from biological waste cherry tomato stalk and tryptophan. The morphology, composition, and properties of Stalk-Trp CDs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, infrared spectroscopy, ultraviolet–visible absorption spectroscopy, and fluorescence spectroscopy. On this basis, a dual-channel ratio sensing platform (Stalk-Trp CDs@Eu) was constructed using the interaction of Stalk-Trp CDs with Eu3+, which reduced the detection limit of the antibiotic oxytetracycline from 0.15 µmol/L to 0.018 µmol/L. Channel 1 of the dual-channel ratio sensing platform is a neutral environment (pH = 6.5), and the specific response of the probe to OTC causes its fluorescence to change from blue to purple. Channel 2 is an alkaline environment (pH = 11.5), and the fluorescence of the probe turns green only in the presence of OTC. The interaction mechanism of the dual-channel ratio sensing platform with the antibiotics oxytetracycline (OTC), chlortetracycline (CTC), and tetracycline (TC) was also revealed. The detection results of OTC in honey and milk by using Stalk-Trp CDs@Eu were highly consistent with the HPLC method recommended by the national standard. This shows that the dual-channel ratio sensing platform has great practical application value in the field of antibiotic detection.