Silane-dextran chemistry on lateral flow polymer chips for immunoassays

Area of Science:

• Biomedical Engineering
• Materials Science
• Analytical Chemistry

Background:

• Early disease diagnosis significantly improves patient prognosis for various conditions, including cardiovascular diseases.
• Disposable microfluidic chips offer a promising platform for high-performance diagnostic testing.
• Precise control over surface chemistry is essential for reliable liquid distribution in microfluidic devices.

Purpose of the Study:

• To develop and validate a novel surface hydrophilization and antibody immobilization protocol for cycloolefin-copolymer (COC) microfluidic test chips.
• To enable the use of disposable microfluidic chips for sensitive and reliable sandwich immunoassays.
• To demonstrate the stability and utility of the developed surface chemistry in a clinically relevant assay.

Main Methods:

• Fabrication of microfluidic chips via injection molding of Zeonor (COC).
• Development of a surface modification protocol involving direct silanisation of the COC substrate.
• Covalent coupling of dextran to amino groups for stable, hydrophilic surface coating and subsequent antibody immobilization.

Main Results:

• A stable, low-contact-angle surface coating was achieved using dextran, with stability lasting over two months.
• The developed surface chemistry enabled effective antibody immobilization for sandwich immunoassays.
• A C-reactive protein (CRP) assay demonstrated a low detection limit (2.6 ng/mL), a dynamic range of 10^2, and a coefficient of variance of 15%.

Conclusions:

• The novel surface hydrophilization and antibody immobilization protocol is effective for COC-based microfluidic diagnostic chips.
• The developed platform and surface chemistry support the creation of stable, reliable, and sensitive disposable diagnostic devices.
• This approach has the potential to advance early disease diagnosis through high-performance point-of-care testing.