A displacement assay for the sensing of carbohydrate using zinc oxide biotracers

Due to the high isoelectric point of the ZnO quantum dots (QDs), ZnO QDs were employed as biolabels for carbohydrates to construct a biosensor for determination of the carcinoembryonic antigen (CEA), which act as the carbohydrate. The assay was based on the competition between a quantum dots labeled CEA and analyte CEA using concanavalin A (Con A) as the recognition element. The extent of completion was monitored by the square wave stripping voltammetry. The displacement assay results showed that there are two changes model of the current response to the analyte CEA concentration (0–30 ng/mL and 30–80 ng/mL). The most likely reason for this was also discussed in the paper.