Antibiotic residue detection by novel photoelectrochemical extended-gate field-effect transistor sensor

Residual antibiotics in the environment may pose threats to both ecological system and public health, necessitating the development of efficient analytical strategy for monitoring and control. This study proposes a photoelectrochemical extended-gate field-effect transistor (PEGFET) sensor for specific and sensitive detection of kanamycin. The sensor utilizes ITO glass as the extended gate electrode (photoelectrode) and titanium dioxide as the photosensitive material. It leverages the interaction between kanamycin and its corresponding aptamer to influence the ability of gold nanocluster to catalyze the oxidation of 3,3'-diaminobenzidine (DAB). This interaction results in different amounts of DAB precipitate on the photoelectrode surface, leading to gate voltage shift and source-drain current response. This sensing platform achieves trace detection of kanamycin with a limit of detection (LOD) at nM level and a wide linear detection range from 10 nM to 100 μM. The results demonstrate that the PEGFET with incorporated photoelectrochemical process can significantly enhance the sensitivity of traditional EGFET sensor, and the photoelectric signal originates from the change in electron transfer ability of the photoelectrode. The reported PEGFET with photo-responsive extended gate presents a new and promising structure in FET sensor design for enhanced detection performances in chemical and biological sensing.