Room-temperature phosphorescence sensor based on manganese doped zinc sulfide quantum dots for detection of urea

In this work, a simple scheme was proposed to prepare a urea-sensing system, which was composed of water-soluble Mn-doped ZnS phosphorescent QDs and urease. It allows for effective and quantitative detection of urea. The phosphorescence properties of MPA-capped Mn-doped ZnS QDs were explored to develop an RTP method for facile, rapid, cost-effective and selective detection of urea. This method does not need any deoxidant or other inducers and detects urea in biological fluids without being interfered from autofluorescence or the scattering light of the matrix. The new RTP sensor for urea detection has a detection limit of 0.014 mM and two linear ranges from 0 to 10 mM and from 10 to 60 mM. The precision for 11 replicate detections of 0.1 mM urea was 4.7%. The recoveries on spiked urine samples are 95-103%. It was successfully applied to the determination of urine without any complicated sample pretreatment.