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

Area of Science:

• Materials Science
• Analytical Chemistry
• Biomedical Engineering

Background:

• Citrate levels in urine are indicative of kidney health.
• Accurate and accessible methods for citrate detection are needed for early disease screening.
• Existing methods may lack the sensitivity or ease of use for widespread clinical application.

Purpose of the Study:

• To develop a novel fluorescent sensor for the visual and quantitative detection of citrate in human urine.
• To utilize cadmium telluride (CdTe) quantum dots (QDs) for a turn-on fluorescence sensing mechanism.
• To establish a low-cost, rapid, and visually discernible method for potential kidney stone patient screening.

Main Methods:

• Modification of CdTe QDs with thioglycolic acid (TGA).
• Utilizing europium ion (Eu(3+)) for fluorescence quenching of TGA-modified CdTe QDs via photoinduced electron transfer.
• Exploiting the higher affinity of Eu(3+) for citrate to displace CdTe QDs, thereby recovering fluorescence.
• Visual detection based on color change (yellow to orange and back to yellow) and quantitative analysis via fluorescence intensity.

Main Results:

• A novel CdTe QDs-based fluorescent sensor was successfully developed.
• The sensor demonstrated a visual, turn-on fluorescence response within 5 minutes upon citrate addition.
• Eu(3+) induced fluorescence quenching of CdTe QDs, which was reversed by citrate.
• The sensor accurately quantified citrate in urine samples within a concentration range of 0.67–133 μM.
• The system showed potential for discriminating between patients with renal stones and healthy individuals via naked-eye observation.

Conclusions:

• The developed sensor offers a simple, low-cost, and visualized method for citrate detection in human urine.
• The rapid and visual nature of the sensor is suitable for preliminary screening of conditions like kidney stones.
• This approach holds significant potential for early clinical detection and monitoring of urinary citrate levels.