Low-concentration antibiotic detection in water based on enhanced photothermal effect

Streptomycin sulfate (STS) is a broad-spectrum antibiotic widely present in water as a source of pollution. STS produces ototoxicity and nephrotoxicity if ingested in excess. Here, we propose a photothermal sensor to detect contaminated water based on a Nb2CTx MXene integrated few-mode fiber coupler (FMFC) and the photothermal effect of STS. Nb2CTx MXene exhibits strong absorption ability for biomolecules, which can enhance the interaction between STS and light by depositing it on the surface of the FMFC, thereby improving the detection performance of the proposed sensor. Under irradiation of a 405 nm laser, the photon energy is absorbed by STS and converted into heat energy, changing the transmission characteristics of the few-mode fiber. The results show that the sensitivity reaches 210.66 nm/(mg/ml) in the linear range of 0.02–0.1 mg/ml, with a detection limit of 94.93 ng/ml. In practical applications, the photothermal effect is stimulated by natural light to improve the suitability of the device application. Furthermore, this photothermal sensor eliminates complicated sample processing, making it potentially applicable for real-time food safety, environmental pollutant detection, and disease diagnosis.