Mercaptopropionic acid capped cadmium selenide quantum dots based urea Biosensor

Here a simple fluorescence "Turn-On" based strategy is used for the determination of urea using water soluble mercaptopropionic acid capped cadmium selenide quantum dots (MPA-CdSe QDs). These MPA-CdSe QDs were pH sensitive and this property is used for urea detection after the immobilization of urease. The principle of detection is to measure and correlate the enhancement of fluorescence intensity of MPA-CdSe QDs caused by the enzymatic reaction between urease with urea and release of ammonia. Ammonia release leads to raise in the pH value which turns on the fluorescence intensity of MPA-CdSe QDs in the presence of increasing concentration of urea varying from 1 to 120 mM with a lower detection limit of 1 mM.