High-throughput and rapid fluorescent visualization sensor of urinary citrate by CdTe quantum dots.

In this paper, we have presented a novel CdTe quantum dots (QDs) based fluorescent sensor for visual and turn-on sensing of citrate in human urine samples. The europium ion (Eu(3+)) can lead to the fluorescence quenching of thioglycollic acid (TGA) modified CdTe QDs due to photoinduced electron transfer accompanied by the change of emission color from yellow to orange. Next, addition of citrate breaks the preformed assembly because citrate can replace the CdTe QDs, based on the fact that the Eu(3+) ion displays higher affinity with citrate than the CdTe QDs. Thus the photoinduced electron transfer is switched off, and the fluorescence emission of CdTe QDs is rapidly (within 5min) recovered, simultaneously, the orange emission color restores to yellow. Such proposed strategy may conveniently discriminate the patient of renal stone from normal person by naked eyes. In addition to visualization detection, the fluorescence responses can be used for well quantifying citrate in the range of 0.67-133μM. So, the present, simple, low-cost and visualized citrate fluorescence sensor has great potential in the applications for earlier screening in clinical detection.