Advances, Challenges, and Opportunities in Electrochemiluminescence Bioimaging

As an imaging technique triggered by redox reactions at the electrode, electrochemiluminescence (ECL), requiring no external light excitation, is becoming a widely used tool in bioimaging. Taking advantage of its near-zero background and high signal-to-noise ratio (SNR), ECL is increasingly demonstrating its potential as a uniquely quantitative tool for biological analysis. The rapid development of luminophores, electrodes, and optical imaging systems has significantly improved ECL performance, enabling high-spatiotemporal-resolution ECL imaging. Currently, progress in ECL bioimaging has involved in vitro immunoassays, in vivo cell imaging, and heterogeneous tissue imaging. In this review, we highlight the core mechanisms and constructions of ECL bioimaging. Building upon this foundation, its applications in multiscale biology are discussed, from immunoassays to tissue imaging. Despite these advances, ECL bioimaging faces challenges arising from low photon flux and penetration depth. We then highlight the intrinsic challenges and opportunities of ECL bioimaging in terms of spatiotemporal resolution, three-dimensional (3D) excitation, biocompatibility, and multiplex imaging. This review aims to outline a roadmap for the future of ECL bioimaging, which is expected to become a central bioanalytical tool with widespread applications, ranging from basic biological research to clinical diagnostics.