Time resolved fluorescence sensor array for discrimination of phosphate anions by using transition metal dichalcogenide quantum dots and Tb (III).

Phosphate detection has garnered widespread attention due to their biological and environmental impact. Among several optical techniques, time resolved fluorescence (TRF) provides a sensitive way for discrimination of analytes in a complex mixture as it suffers less interference from the background, thus providing a high signal to noise ratio. The sensitization of rare earth metal (REM) ions by semiconducting quantum dots (QDs) can help the former overcome the drawback of low absorption coefficient, thus allowing one to exploit the additional advantage of the REM, viz, the long-excited state lifetime. Herein, we have developed a TRF based sensor array consisting of three QDs, i.e., MoS 2 , WS 2 and MoSe 2 as energy sensitizers to Tb 3+ ion. Different QDs possess variable energy transfer ability to Tb 3+ ion. Hence, they can be used for discrimination of phosphates. It was also observed that CrO 4 2- can competitively bind to Tb 3+ and further, enhance the efficiency of the sensor array which could discriminate six different phosphates at 200 μM concentration in aqueous as well as serum media with a detection limit of 10 μM in aqueous media. Thus, the sensitivity of the TRF based sensor array is rarely compromised in a complex mixture, which is advantageous over a fluorescence-based sensor array.