A novel dual-model photoelectrochemical/electrochemical sensor for kanamycin detection based on Z-scheme TiO2 disk/methylene blue

Herein, a new dual-model photoelectrochemical (PEC)/electrochemical (EC) sensor for the detection of kanamycin (Kana) was developed based on Z-scheme titanium dioxide (TiO2) disk/methylene blue (MB) sensibilization. Metal-organic frameworks-derived porous TiO2 disk were synthesized, and exhibited excellent anodic photocurrent under visible light excitation. Then, amino-labeled double-stranded DNA (dsDNA) was introduced onto the modified electrode. The photocurrent was enhanced with MB embedded in dsDNA to form a Z-scheme TiO2/MB sensibilization. When the target Kana was present, it specifically bound to the aptamer in the dsDNA, leading to the disruption of dsDNA structure and the release of MB. This release of MB and the increase of target spatial resistance, resulted in a significant weakening of the PEC signal and a decreased oxidation peak current of MB. The PEC sensor successfully detected Kana in the range of 2~1000 pM with a LOD of 0.17 pM. Meanwhile, The EC sensor for Kana detection showed a linear range of 5 pM∼500 pM with a LOD of 1.8 pM. Additionally, the sensor exhibited excellent selectivity, reproducibility, stability, and good recoveries when applied to milk and honey samples. As a result, this method has the potential to be applied in ensuring food safety through the rapid determination of antibiotics in food.