Copper nanoclusters capped with tannic acid as a fluorescent probe for real-time determination of the activity of pyrophosphatase

The authors show that copper nanoclusters capped with tannic acid (TA-CuNCs) are viable fluorescent probes for the determination of the activity of pyrophosphatase (PPase). The fluorescence of the TA-CuNCs is quenched by Fe(III) but restored on subsequant addition of pyrophosphate (PPi). If, however, PPi is split by PPase into two phosphate ions, the fluorescence of the TA-CuNCs is quenched again. Under optimized conditions, fluorescence intensity linearly correlates with the activity of PPase in the range from 0.50 to 18.0 U L−1 with a detection limit of 0.19 U L−1. The method was employed to the determination of PPase in spiked human serum samples and gave satisfactory results.