A sandwich-type ECL immunosensor for the sensitive determination of CEA content based on red emission carbon quantum dots as luminophores†
Abstract
A sandwich-type electrochemiluminescent (ECL) immunosensor was constructed using red-emitting carbon quantum dots (RCQDs) as luminophores. RCQDs were prepared in a single step by a simple green microwave synthesis method using ethanol extracts from Scindapsus aureus leaves. The prepared RCQDs emitted fluorescence in the near-infrared (NIR) window (680 nm) and presented good ECL properties. The secondary antibody label was fabricated by the synthesis of aminated graphene (NH2-G), which can remarkably quench the ECL intensity of RCQDs modified on electrodes because of the ECL resonance energy transfer (ERET). The immunological recognition that induced ECL quenching made the immunosensor feasible to sensitively detect biomarkers, such as carcinoembryonic antigen (CEA). Under optimal conditions, the ECL intensity and the CEA concentration logarithm showed a good linear relationship in the range of 0.005–300 ng mL−1 with a detection limit of 0.25 pg mL−1. In addition, the ECL immunosensor has also been successfully applied in the determination of human serum samples. The sensor has good stability, specificity and reproducibility, demonstrating that it can be a new type of immunosensor for medical diagnosis.
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