Salty Biofluidic Sample Clean-Up and Preconcentration with a Paper-Based Ion Concentration Polarization Interface

Area of Science:

• Analytical Chemistry
• Biotechnology
• Materials Science

Background:

• Ion concentration polarization (ICP) enables separation and enrichment of charged species from complex media.
• ICP enhances sample purification and improves detection sensitivity.
• Paper-based analytical devices (PADs) offer a low-cost, portable platform for diagnostics.

Purpose of the Study:

• To develop a novel ICP interface on a PAD for direct analysis of complex, high-conductivity samples.
• To demonstrate electrokinetic stacking and enrichment of analytes from salty matrices.
• To validate the PAD for sensitive detection of biomolecules in physiological fluids.

Main Methods:

• Fabrication of a PAD with an integrated ion exchange membrane for ICP.
• Utilized a fluorescent probe to confirm steady ICP effect in solutions up to 400 mM NaCl.
• Applied the PAD for online stacking of total protein from urine followed by colorimetric detection.
• Investigated offline pretreatment of serum samples for amino acid analysis via tandem mass spectrometry.

Main Results:

• Demonstrated successful ICP and analyte stacking from samples with high salt concentrations (up to 400 mM NaCl).
• Achieved a linear response for total protein detection in urine (50-350 mg/L, R² = 0.99) with high recovery (94.8-107.6%) and precision (RSD < 7.1%).
• Results for protein detection correlated well with clinical methods; promising outcomes for serum amino acid analysis.

Conclusions:

• The developed PAD with ICP is a reliable, cost-effective, and user-friendly tool for sample purification and concentration.
• This technology enables direct analysis of complex physiological samples (blood, urine) for point-of-care testing.
• The disposable PAD facilitates sensitive detection and accurate analysis with advanced instrumentation.