A novel cobalt-based metal-organic framework catalyst for enhanced luminol chemiluminescence and choline detection.

A cobalt-based metal-organic framework (Co2DDA, DDA = 1,5-diamino-4,8-dihydroxy-9,10-anthracenedione) was synthesized in this study. Under the catalysis of Co2DDA, the chemiluminescence (CL) intensity of the luminol-H2O2 system increased by approximately 6000-fold. The catalytic mechanism of Co2DDA was elucidated through CL spectrum, UV-vis absorption spectroscopy, radical scavenger experiments, and electron spin resonance (ESR) spectroscopy. The results demonstrated that Co2DDA exhibited excellent catalytic activity, facilitating the decomposition of H2O2 under alkaline conditions and enhancing the production of reactive oxygen species (ROS), including 1O2, •OH, and O2•-. These ROS rapidly react with luminol to produce the excited-state oxidation product 3-aminophthalate anion (3-APA*), which emits strong CL at 440 nm when transitioning to the ground state. Under the cascade catalysis of choline oxidase (ChOx) and Co2DDA, the system exhibited a remarkable response toward choline. Based on this finding, a sensitive CL method for the detection of choline was developed. Under optimized conditions, the proposed CL system showed a good linear relationship in the concentration range of 5-150 μM, with a detection limit as low as 4.21 μM (3σ/K). Significantly, this strategy can be further extended to the detection of other biomolecules that generate H2O2 as a reaction product.