Photoelectrochemical Aptasensors Constructed with Photosensitive PbS Quantum Dots/TiO Nanoparticles for Detection of Kanamycin.

Kanamycin (Kana) is widely used as a veterinary medicine and its abuse causes a serious threat to human health, raising the urgent demand for detection of residual Kana in animal-derived food with high specificity and sensitivity. Here, we developed a photoelectrochemical (PEC) biosensor for rapid quantification of Kana, with lead sulfide quantum dots/titanium dioxide nanoparticles (PbS QDs/TiO NPs) as a photosensitive composite, a Kana-specific DNA aptamer as a functional sensor, and ruthenium(III) hexaammine (Ru(NH)) as a signal booster. To prepare the PEC aptasensor, TiO NPs, PbS QDs, and polyethyleneimine (PEI) were respectively used to modify the indium tin oxide electrode, and then the amine-terminated aptamer probe was connected to the PEI via glutaraldehyde. Finally, Ru(NH) was attached on the surface of the aptamer to increase the photocurrent intensity. When Kana binds competitively with Ru(NH) to the aptamer immobilized on the surface of the aptasensor, Ru(NH) will be released from the aptamer, resulting in a decrease of the photocurrent signal. This PEC aptasensor exhibits a good linear relationship between the photocurrent shift and the logarithm of Kana concentration within the range of 1.0-300.0 nmol L, and the detection limit is 0.161 nmol L. Importantly, the PEC aptasensor presented good detection selectivity owing to specific interaction with Kana and was successfully implemented to quantify Kana in honey and milk, suggesting that the PEC aptasensor has the potential of rapid detection of residual Kana in animal-derived foods.