Optimization of binding B-lymphocytes in a microfluidic channel: surface modification, stasis time and shear response

Area of Science:

• Biomedical Engineering
• Microfluidics
• Cell Biology

Background:

• Cell immobilization in microfluidic channels is challenging due to shear stress.
• Maintaining cell integrity and function under flow is critical for microfluidic assays.

Purpose of the Study:

• To optimize the binding of human B-lymphocyte cells (HR1K) within microfluidic channels.
• To quantify cell binding strength under varying shear stress conditions.
• To establish parameters for live/dead cell testing in microfluidic devices.

Main Methods:

• Utilized glass-polydimethylsiloxane hybrid chips with a 3-(glycidyloxypropyl)trimethoxysilane (GPTMS) linker.
• Covalently immobilized anti-CD20 antibody for cell capture.
• Investigated different bonding methods (plasma bonding with/without masking, clamping) and stasis times.
• Assessed cell detachment under flow rates up to 200 μl min⁻¹.
• Measured membrane integrity and calcium spiking to evaluate cell viability and function.

Main Results:

• GPTMS linker significantly improved cell retention compared to no linker (15% vs. 90% detachment at 200 μl min⁻¹).
• Masked plasma bonding and clamping methods showed comparable, effective cell immobilization (15-20% detachment).
• Live HR1K cells maintained functionality under flow, while non-viable cells detached more readily (>80% detachment).

Conclusions:

• Optimized surface chemistry and bonding protocols enable robust cell immobilization in microfluidics.
• The developed method preserves cell viability and function during microfluidic experiments.
• This approach is suitable for developing microfluidic-based live/dead cell assays.