A Simple Paper-based Colorimetric Device for Rapid and Sensitive Urinary Oxalate Determinations.

Area of Science:

• Analytical Chemistry
• Biomedical Diagnostics
• Materials Science

Background:

• Oxalate measurement is crucial for diagnosing urinary conditions like kidney stones.
• Current methods for oxalate detection can be complex, expensive, and time-consuming.
• There is a need for rapid, sensitive, and cost-effective point-of-care diagnostic tools.

Purpose of the Study:

• To develop a simple and inexpensive paper-based colorimetric device (cPAD) for quantifying oxalate.
• To evaluate the performance of the cPAD for oxalate detection in artificial urine samples.

Main Methods:

• A colorimetric assay utilizing oxalate decarboxylase and formate dehydrogenase on a paper device.
• Detection based on the color change of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) from yellow to purple.
• Quantification of oxalate by correlating purple color intensity with concentration.

Main Results:

• The cPAD achieved quantitative oxalate detection in the range of 10 - 1000 μM.
• A high linear correlation (R² = 0.9994) was observed between color intensity and oxalate concentration.
• A detection limit of 10 μM was achieved with the naked eye, with 81-92% recovery in artificial urine.

Conclusions:

• The developed cPAD provides a simple, rapid, and sensitive method for oxalate determination.
• This device is suitable for point-of-care diagnostic urinary oxalate measurements.
• The inexpensive nature of the cPAD makes it a promising tool for widespread clinical application.