Electrostatic protein immobilization using charged polyacrylamide gels and cationic detergent microfluidic Western...

Area of Science:

• Biotechnology
• Analytical Chemistry
• Biochemistry

Background:

• Microfluidic Western blotting (WB) traditionally relies on sandwich immunoassay formats, limiting analyte capture to known targets.
• Existing methods require significant sample consumption and assay duration compared to potential microfluidic advancements.

Purpose of the Study:

• To develop a novel protein immobilization matrix for fully integrated microfluidic Western blotting.
• To enable "pan-analyte" capture, immobilizing all proteins regardless of prior target knowledge.

Main Methods:

• Development of an electrostatic immobilization gel (EIG) using polyacrylamide grafted with concentrated point charges (zwitterionic macromolecules).
• Utilizing cetyl trimethylammonium bromide polyacrylamide gel electrophoresis (CTAB-PAGE) for protein sizing prior to immobilization.
• Electrophoretic probing with labeled antibodies for detection of immobilized proteins.

Main Results:

• Demonstrated "pan-analyte" immobilization of various model proteins (Protein G, ovalbumin, BSA, β-galactosidase, lactoferrin) with capture efficiencies from 21% to 100%.
• Achieved high signal-to-noise ratios (34-275) for antibody detection of immobilized target proteins (Protein G, lactoferrin).
• Significant improvements over traditional slab-gel WB: 200x reduction in sample consumption, 12x reduction in assay duration, and automated operation.

Conclusions:

• The EIG facilitates a "pan-analyte" capture strategy in microfluidic WB, overcoming limitations of target-specific assays.
• This novel approach significantly enhances protein immunoblotting efficiency and performance.
• The microfluidic WB assay shows potential for nonbiopsy-based diagnosis, exemplified by lactoferrin assessment in tear fluid for Sjögren's Syndrome detection.