An "off-on" electrochemiluminescence aptasensor for determination of lincomycin based on CdS QDs/carboxylated g-C₃N₄

A novel electrochemiluminescence (ECL) aptasensor for the determination of lincomycin (LIN) was developed based on CdS QDs/carboxylated g-C₃N₄ (CdS QDs/C-g-C₃N₄). CdS QDs/C-g-C₃N₄ served as the substrate of the aptasensor, and then CdS QDs/C-g-C₃N₄-modified electrode was incubated with aptamer DNA (Apt-DNA). When the non-specific sites of the electrode surface was blocked by 6-mercaptohexanol, the ferrocene-labeled probe (Fer-DNA) was assembled onto the electrode surface through base complementation with Apt-DNA. In the absence of LIN, the ECL signal was quenched effectively by Fer-DNA and a decreased ECL emission (off state) was acquired. On the contrary, LIN was specifically bond with Apt-DNA, and Fer-DNA was detached from the aptasensor surface because of the deformation of Apt-DNA, resulting in an effectively enhanced ECL signal (on state). The constructed ECL aptasensor exhibited a wide detection range for LIN determination (0.05 ng mL^-1-100 μg mL^-1) with a low detection limit (0.02 ng mL^-1). Importantly, the proposed ECL aptasensor showed outstanding accuracy and specificity for LIN determination, and also provided a potential strategy for other antibiotic determinations.