Streamlined integrated protein isoelectric focusing using microfluidic paper-based device

Area of Science:

• Biomaterials Science
• Analytical Chemistry
• Microfluidics

Background:

• Protein separation is crucial for proteomics.
• Existing methods can be complex and costly.
• Paper-based microfluidic devices offer potential for low-cost, portable analysis.

Purpose of the Study:

• To develop an integrated, robust paper-based microdevice for protein separation via isoelectric focusing (IEF).
• To optimize the device design and IEF parameters for efficient protein separation.
• To demonstrate the platform's applicability for real-world samples.

Main Methods:

• Development of a 3D-printed holder integrating a separation channel, reservoirs, and electrodes.
• Optimization of paper substrate, reservoir design, and water/glycerol separation medium.
• Characterization of pH gradient stability, separation efficiency, and resolution.
• Application of the device to analyze spiked saliva samples.

Main Results:

• A stable pH gradient was achieved on a glass-fiber paper substrate.
• The water/glycerol medium reduced evaporation and supported protein separation.
• Efficient protein separation was accomplished within 25 minutes.
• The device showed minimal matrix effects when applied to saliva samples.

Conclusions:

• The developed paper-based IEF microdevice is robust, low-cost, and versatile.
• It offers efficient protein separation suitable for proteomics.
• The platform has potential for sample pre-treatment and integration into lab-on-a-chip systems.