Paper-based microfluidic device for serum zinc assay by colorimetry

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Public Health

Background:

• Zinc is vital for human health, and deficiency causes malnutrition.
• Accurate, accessible methods for measuring serum zinc are needed for community healthcare.
• Current diagnostic methods can be expensive and inaccessible in resource-limited settings.

Purpose of the Study:

• To design and fabricate a low-cost, paper-based microfluidic device (μPAD) for quantifying serum zinc concentration.
• To develop a colorimetric detection method using dithizone and smartphone-based image analysis.
• To validate the device's accuracy against gold-standard methods for real-world application.

Main Methods:

• Fabrication of a μPAD with dithizone-doped spotting zones for zinc detection.
• Colorimetric analysis of zinc-chelates using smartphone photography and image processing.
• Optimization of the μPAD design and doping protocol for linear correlation with zinc concentration.
• Validation using artificial plasma and real human blood serum samples.

Main Results:

• The μPAD demonstrated a monotonic color change with zinc concentration across the physiological range (5-25 μM).
• Optimized protocols yielded high linearity in water (R² = 0.94) and artificial plasma (R² = 0.98).
• The device accurately measured zinc levels in real serum samples, showing high parity with gold-standard methods.

Conclusions:

• The developed μPAD offers a rapid, inexpensive, and accurate method for serum zinc measurement.
• This technology has significant potential for diagnosing micronutrient malnutrition in community healthcare settings.
• The device is suitable for resource-limited environments, improving accessibility to essential diagnostics.