Smartphone-assisted sensing platform based on S, Fe-doped carbon dots as efficient nano-enzyme for colorimetric detection of tetracycline in solution

Understanding the real-time concentration levels of tetracycline (TC) in water environment was of great significance, which could avoid threats to ecological balance and human health. In this study, a colorimetric sensor based on S, Fe-doped carbon dot (S, Fe-doped CDs) was constructed for detection of TC. The S, Fe-doped CDs with excellent peroxidase-like activity were prepared via hydrothermal method, and they could catalyze H₂O₂ to generate hydroxyl radical (•OH) and superoxide radical (•O₂⁻). The presence of S and Fe elements in CDs provided multiple active sites for chromogenic substrates. The colorimetric sensor for TC detection demonstrated good linear relationship ranged from 6 to 100 μg/mL, limit detection of 36 ng/mL, and it possessed excellent selectivity in presence of metal ions and organics. Furthermore, the visual detection platform coupled smartphone were established, which enabled rapid and accurate detection of TC in various environmental conditions. This study demonstrated great potential in the rapid monitoring of environmental pollutants, and combining functional nanomaterials with mobile technology had opened up new avenues for real-time detection in resource-limited environments.