Development of quantum dot complex for selective detection of pyrophosphate anion with fluorescence quenching

A fluorescent probe termed as quantum dot complex (QDC) was synthesized by surface functionalizing Pd(II) complex to ZnS Qdot surface mediated through dangling S2− ions. The optical and morphological properties of QDC have been studied extensively through various characterization techniques. Steady state fluorescence study revealed the ultrasensitive capacity of QDC to selectively detect pyrophosphate (PPi) anion within few seconds of analyte addition. The limit of detection was found to be 39.4 µM. The sensing phenomenon is based on a unique partial quenching behaviour exhibited by QDC emission on analyte addition. The partial quenching effect is governed by the combined effect of photo-induced electron transfer and reabsorption in the complex system comprising of Qdot, Pd(II) complex and PPi anions. The selectivity results were compared with a statistical analysis by performing paired t-test. Significant difference in quenching efficiency of PPi with other ions, on the emission intensity of QDC was observed (95% confidence interval). Thus the sensor can be said to be demonstrating selectivity.