Three-fluorescence sensor for minute-time scale low-cost analysis of urinary oxalate in urolithiasis metabolic assessment.

Since oxalate plays an important role in the metabolic assessment of urolithiasis, there is need for convenient and efficient methods for oxalate detection. Herein, we report a three-signal fluorescence strategy for oxalate analysis based on the ability of oxalate to reduce Cu2+ to Cu+, and the ability of pyrophosphate-cerium coordination polymeric networks (PPi-Ce CPNs), cadmium telluride quantum dots (CdTe QDs), and N-Methyl Mesoporphyrin (NMM) to selectively detect Cu2+ and Cu+. The detection range was 100 nM to 1 mM, the turnaround time was 6 min, while the limits of detections for PPi-Ce CPNs, QDs and NMM as reporters were 25 nM, 10 nM and 40 nM, respectively. Visual detection of oxalate relied on color change in the solution, which could be observed using the naked eye. The fluorescent system was used for oxalate analysis in 44 urine samples (32 calcium oxalate stone patients, 12 controls without urolithiasis), and the results were consistent with clinical diagnosis and imaging data. Moreover, the visual system was used to analyze 8 urine samples (4 patients and 4 controls), and showed good consistency with clinical diagnosis and computed tomography imaging results. These findings suggest that the method has potential application for the metabolic assessment of urolithiasis.

Rapid and highly sensitive visual detection of oxalate for metabolic assessment of urolithiasis via selective recognition reaction of CdTe quantum dots.

Urolithiasis is a common disease that affects 5% to 8.8% of the world population with high recurring frequency. Therefore, there is an urgent need for the rapid and efficient diagnostics of urolithiasis. In this study, we developed a quantum dots (QDs)-based sensor for detecting urolithiasis oxalate. Urolithiasis oxalate was quantified by reducing Cu2+ to Cu+, which can be selectively recognized by CdTe QDs. The homogeneous sensing system shows high sensitivity for oxalate detection in the range of 0.1 µM to 10 mM within 6 min; moreover, the visual detection of 10 µM oxalate could be achieved by the naked eye. Our method was tested on 53 clinical samples; it showed 100% specificity and sensitivity for calcium oxalate urolithiasis compared with clinical diagnosis, even for hematuria samples. Furthermore, this method can be expanded to other wide range of biochemistry applications for medical diagnosis and point-of-care testing.