Encapsulating copper nanoclusters in 3D metal-organic frameworks to boost fluorescence for bio-enzyme sensing, inhibitor screening, and light-emitting diode fabrication

Herein, copper nanoclusters (CuNCs) were encapsulated with metal-organic framework based on the confinement effect to fabricate a sensitive fluorescence probe for xanthine oxidase activity monitoring and inhibitor screening. Compared with CuNCs, the yielded fluorescent composite exhibits long fluorescence lifetime, high quantum yield, and strong stability. The fluorescence intensity of the sensor is efficiently quenched by H2O2 (λem = 566 nm), which is a product of the oxidation of xanthine by dissolved oxygen in the presence of xanthine oxidase. On this basis, a fluorescent sensor was reported for xanthine oxidase detection with a detection limit of 0.034 U/L, and a good linear range from 0.4 to 28 U/L. This method is capable of screening xanthine oxidase inhibitors as potential drugs for the treatment of diseases such as hyperuricemia. Moreover, the composite was used to manufacture orange and white light-emitting diodes. Taken together, the present work provides a new heuristic strategy for the monitoring of xanthine oxidase and the screening of its inhibitors, and exhibits some insights into the construction of multicolor light-emitting diodes.