Distance-based quantitation of urinary ammonia using a low-cost cellulose-based thread sensor impregnated with...

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Point-of-Care Diagnostics

Background:

• Metabolic disorders like hyperammonemia require effective point-of-care (POC) detection methods.
• Urinary ammonia is a relevant, yet underexplored, non-invasive biomarker for metabolic conditions.
• Conventional ammonia detection methods are often time-consuming and expensive.

Purpose of the Study:

• To develop a green, low-cost microfluidic distance-based thread analytical device (dTAD) for quantifying urinary ammonia.
• To utilize curcumin as a colorimetric indicator for ammonia detection on a cellulose-based thread platform.
• To establish a user-friendly, naked-eye detectable assay for ammonia in urine samples.

Main Methods:

• Curcumin was immobilized onto cellulose threads via a simple immersion technique.
• The dTAD device utilizes a distance-based colorimetric readout correlating ammonia concentration to color change.
• Ammonia quantification was validated using theoretical prediction (mass balance volatilization and Darcy's law) and experimental measurements.

Main Results:

• The curcumin-based thread sensor demonstrated strong selectivity against common urine interferants.
• A linear detection range of 20.0–80.0 mmol L^-1 with an R² value of 0.994 was achieved.
• A limit of detection (LOD) of 5.0 mmol L^-1 was determined, with 91%-102% recovery in human urine samples.

Conclusions:

• The developed dTAD is a simple, affordable, and versatile POC diagnostic tool for urinary ammonia.
• The device offers rapid analysis (3.0 min) at a low cost (<$0.20 per sensor), meeting REASSURED criteria.
• This represents the first application of a distance-based thread device for ammonia quantification in biofluid samples.