Highly efficient ratiometric electrochemiluminescence biosensor with amyloid aggregation as antifouling coating and g-C3N4 as internal standard for carcinoembryonic antigen immunoassay

The electrochemical antifouling sensing interface can effectively resist the adsorption of non-specific biomolecules, which provides a powerful means for the sensitive determination of various biomarkers in complex media. Therefore, the development of simple and efficient antifouling coatings is particularly important. Herein, we utilized tris (2-carboxyethyl) phosphine to rapidly reduce disulfide bonds in bovine serum albumin (BSA) to generate amyloid aggregation (PTB), thus forming a macroscopic two-dimensional film through one-step self-assembly. Compared to other antifouling interfaces, PTB has the advantages of simple preparation means, high stability and reproducibility, as well as good antifouling properties. At the same time, a layer of polyaniline (PANI) was electrodeposited on the modified electrode to improve the electron transmission rate, which improves the detection efficiency of the sensor. Furthermore, g-C3N4 was introduced as an internal standard substance to eliminate instrument errors. According to the ratio of electrochemiluminescence (ECL) signals of [Ru(bpy)3]2+ and g-C3N4, a ratiometric sensing strategy was designed to improve detection accuracy and sensitivity. Based on this, the proposed biosensor can achieve sensitive detection of CEA with a detection limit as low as 0.43 fg/mL (S/N = 3), which has important significance for early clinical diagnosis.