Simultaneous enrichment and separation based on ion concentration polarization effect on a paper based analytical...

Area of Science:

• Analytical Chemistry
• Biotechnology
• Materials Science

Background:

• Concentration polarization is a key phenomenon in microfluidic devices.
• Separating and enriching amphoteric molecules like proteins remains challenging.
• Paper-based analytical devices (PADs) offer potential for portable diagnostics.

Purpose of the Study:

• To develop a paper-based analytical device (PAD) for simultaneous enrichment and separation of ions and amphoteric components.
• To demonstrate the application of this PAD for rapid colorimetric detection of human serum albumin (HSA).
• To evaluate the PAD's performance for point-of-care testing of microalbuminuria.

Main Methods:

• Utilized electric field (E) and pH gradient (double gradient) in an ion depletion zone.
• Established anion concentration polarization interface on a paper fluid channel.
• Visualized separation using colored ions and protein probes; optimized for protein separation and enrichment.

Main Results:

• Achieved 10-fold enrichment and separation of colored proteins (phycocyanin, bovine hemoglobin) in 900 seconds.
• Developed a rapid colorimetric detection of HSA using smartphone camera with a limit of detection (LOD) of 5.2 mg·L⁻¹.
• Demonstrated good agreement with clinical immunoturbidimetry method for HSA detection in human urine samples.

Conclusions:

• The PAD effectively performs simultaneous separation and enrichment of target components from complex samples.
• Enhanced specificity and sensitivity of detection, paving the way for point-of-care microalbuminuria testing.
• The developed PAD shows significant potential for sample pretreatment and detection in physiological samples.