Stable and Monochromatic All-Inorganic Halide Perovskite Assisted by Hollow Carbon Nitride Nanosphere for Ratiometric Electrochemiluminescence Bioanalysis

Lead halide perovskites have been promising electrochemiluminescence (ECL) candidates because of their excellent photophysical attributes, but their poor stability has severely restricted ECL applications. Herein, the in situ assembly of all-inorganic perovskite CsPbBr3 nanocrystals (CPB) into hollow graphitic carbon nitride nanospheres (HCNS) were described as a novel ECL emitter. The architecture guaranteed not only improved stability because of the peripheral HCNS protecting shell but also high-performance ECL of CPB because of a matching band-edge arrangement. Dual-ECL readouts were obtained from the nanocomposite including an anodic ECL from CPB and a cathodic ECL from HCNS. The former displayed prominent color purity to construct an efficient ECL resonance energy transfer system, and the latter served as an internal standard for a ratiometric analysis. A well-designed DNA probe was further utilized for the targeting of CD44 receptors on the MCF-7 cell surface and the double signal amplification. The sensing strategy exhibited good analytical performance for MCF-7 cells, ranging from 1.0 X 10(5) to 3.2 x 10(5) cells mL(-1) with a detection limit of 320 cells mL(-1). Sensitive and accurate evaluation of CD44 expression was finally achieved at 0.22 pM. This work is the first attempt to use halide perovskite for reliable ECL bioanalysis and provides a perspective to design a perovskite-based nanocomposite as a high-performance ECL emitter for its exclusive ECL system.