A signal-off photoelectrochemical aptasensor for highly sensitive detection of T-2 toxin using 3D CdS/CdIn2S4 heterostructured nanostars by in-situ generated electron donor strategy

T-2 toxin, as one of the most toxic food contamination sources in nature, threatens the body's hematopoietic tissue and immune organs. Therefore, it is very important to achieve sensitive detection of T-2 toxin for human health. In this work, three-dimensional (3D) CdS/CdIn2S4 heterostructured nanostars (HNSs) were prepared by a one-pot hydrothermal approach. The resultant CdS/CdIn2S4 HNSs exhibited excellent photoelectrochemical (PEC) properties, which served as highly photoactive substrate for constructing a signal-off PEC sensor to detect T-2 toxin, coupling with enzyme-mediated signal amplification strategy. Plainly, alkaline phosphatase (ALP) can catalyze L-ascorbic acid 2-phosphate (AAP) to in-situ generate ascorbic acid (AA) in the blank PEC system, which heightened the photocurrent. With the introduction of the target, ALP-revised aptamer (ALP-aptamer) was liberated from the photoelectrode via the specific recognition between the aptamer and T-2 toxin, and thereby reduced the AA concentration, making the PEC signals negatively correlated with the T-2 toxin concentrations. The constructed aptasensor has a broad linear range from 0.1 pg mL-1 to 100 ng mL-1 (R2 = 0.9976) and a low detection limit down to 0.077 pg mL-1 for analysis of T-2 toxin. This method shows great potential in food safety and environmental analysis.