Smart activatable fluorescent probe provides high-quality signal-to-noise ratio and detection limits for electrochemiluminescence

Y The combination of highly sensitive techniques such as electrochemiluminescence (ECL) with nanotechnology has triggered new analytical applications, especially in immunoassay-based detection systems. In this context, electrochemiluminescent resonance energy transfer (ECL-RET) is of high interest, but longer transferred paths may lead to energy loss and low luminescence efficiency. In this paper, we present an ECL-RET system with nitrogen vacancy-accelerated carbon nitride (CN) as an electrochemiluminescence donor and polyaniline (PANI) as an electrochemiluminescence acceptor. By coating PANI on the CN surface, the distance between the donor and the acceptor was largely reduced, and the efficiency of ECL-RET was greatly improved. Furthermore, protonic acid-doped PANI, as a unique hydrogen sulfide (H2S)-responsive bleaching substance, can be used to establish H2S-activatable fluorescent probes for carcinoembryonic antigen (CEA) detection. PANI has strong absorption (450-800 nm), which can effectively burst the fluorescence of CN (475 nm center). And the fluorescence was significantly restored by H2S-mediated selective conversion of two electrons to colorless reduced PANI. Under optimized conditions, the system has good stability and reproducibility in the range of 0.005 pg/ mL-80 ng/mL. This work demonstrates the potential to open up a promising avenue for improving ECL performance, which has great promise for biosensor applications.