Single-strand DNA-scaffolded copper nanoclusters for the determination of inorganic pyrophosphatase activity and screening of its inhibitor

A fluorescence method for the determination of inorganic pyrophosphatase (PPase) activity has been established based on copper nanoclusters (CuNCs). The polythymine of 40 mer (T40) acts as a template for the reduction reaction from Cu 2+ to Cu 0 by ascorbic acid (AA). This reaction leads to the formation of fluorescent CuNCs with excitation/emission peaks at 340/640 nm. However, the higher binding affinity between inorganic pyrophosphate (PPi) and Cu 2+ hinders the effective formation of CuNCs. This shows low fluorescence intensity. PPase catalyzes the hydrolysis of PPi into Pi during which free Cu 2+ ions are produced. This facilitates the formation of fluorescent CuNCs. Thus, the fluorescence intensity was restored. The fluorescence enhancement of the system has a linear relationship with PPase activity in the range 0.3 to 20 mU·mL −1 , and the detection limit is0.2 mU·mL −1 . The relative intensity (I/I 0 ) at 640 nm for the analytical solution versus system is also employed to screen the inhibitor for PPase with high efficiency. Schematic representation of a fluorescent assay for the determination of inorganic pyrophosphatase activity and screening its inhibitor based on single-strand polythymine-scaffolded copper nanoclusters.