Dual-quenching sensing system from Cu-MOFs/SOx to near-infrared electrochemiluminescence silver nanosheets for sensitive analysis of CEA.

In this study, a highly sensitive biosensor for the detection of carcinoembryonic antigen (CEA) was developed by integrating the excellent properties of a near-infrared electrochemiluminescence (NIR ECL) substance and a double ECL signal quencher. Silver nanosheets (Ag-Cys) exhibiting NIR electrochemiluminescence were synthesized via a simple chemical reaction using AgNO and l-cysteine (L-Cys) as precursors. The incorporation of L-Cys not only reduces photochemical damage but also preserved the antigen-binding activity, facilitating the construction of a high-performance immunosensor. In addition, copper-based metal-organic frameworks coated with sarcosine oxidase (Cu-MOFs/SOx) was synthesized and employed as a double quencher toward Ag-Cys based on electron transfer and resonance energy transfer mechanisms. The resulting sensor exhibited high sensitivity and selectivity, with a wide linear range of 0.00005-100 ng mL and a low detection limit of 43.65 fg mL.