A highly-occupied, single-cell trapping microarray for determination of cell membrane permeability.

Area of Science:

• Biophysics
• Cell Biology
• Microfluidics

Background:

• Cell membrane semi- and selective permeability is crucial for cellular function.
• Existing microfluidic devices for permeability studies have limitations, including single-cell observation or complex fabrication.
• A need exists for a simple, parallel single-cell trapping device for permeability measurements at controlled temperatures.

Purpose of the Study:

• To develop a pumpless, single-layer microarray for parallel, single-cell trapping and membrane permeability analysis.
• To assess the device's performance using model particles and to measure membrane permeability of rat hepatocytes and circulating tumor cells at different temperatures.

Main Methods:

• A pumpless, single-layer microarray device was fabricated for single-cell trapping.
• Device performance was benchmarked using 18.8 μm spherical particles, achieving high trap occupancy.
• Membrane permeability of rat hepatocytes and Brx-142 cells was measured at 4, 22, and 37 °C by monitoring volumetric changes in non-isotonic environments.

Main Results:

• The developed microarray demonstrated high trap occupancy (up to 86.8%) for single cells and deterministic lateral displacement for size exclusion.
• Rat hepatocytes exhibited high membrane permeability to water, DMSO, and glycerol via lipid and aquaporin pathways.
• Brx-142 cells showed lower membrane permeability than hepatocytes, with coupled water/DMSO transport but less water/glycerol interaction.

Conclusions:

• The novel microfluidic device enables simple, parallel, and temperature-controlled single-cell membrane permeability studies.
• The findings provide insights into cell membrane biophysics, including aquaporin function and solute transport coupling.
• This technology supports biobanking of rare cells and precious tissues by characterizing their membrane properties.