High-throughput viscoelastic characterization of cells in hyperbolic microchannels

Area of Science:

• Biophysics
• Cell Mechanics
• Microfluidics

Background:

• Cell viscoelastic properties are crucial indicators of cell state and disease.
• Existing microfluidic techniques for measuring cell viscoelasticity suffer from complex stress distributions, leading to inaccuracies.
• High-throughput measurement of cell mechanical properties is essential for biological and medical research.

Purpose of the Study:

• To develop a novel microfluidic approach for accurate and high-throughput measurement of cell viscoelastic properties.
• To overcome the limitations of complex stress distributions in current microchannel designs.
• To establish a straightforward stress-strain relationship for precise determination of viscoelastic properties.

Main Methods:

• Utilized novel hyperbolic microchannels for measurements under constant extensional stress.
• Employed mechanical calibration particles (polyacrylamide) to quantify stresses within the channels.
• Measured oil droplets and microgel beads to validate the system's accuracy in determining rheological properties.
• Applied the methodology to HL60 human leukemia cells treated with drugs affecting cell stiffness.

Main Results:

• Hyperbolic microchannels enable precise measurements at rates up to 100 cells per second.
• The measurement buffer exhibits strain-thickening behavior up to 200 s^-1.
• Successfully detected changes in relaxation times for oil droplets and accurately recovered Young's moduli for microgel beads.
• Demonstrated clear changes in cell stiffness in treated leukemia cells, with minimal impact on relaxation times.

Conclusions:

• The hyperbolic microchannel approach provides a streamlined and time-efficient solution for assessing viscoelastic properties.
• This method allows for accurate characterization of large cell populations and other microscale soft particles.
• The findings offer a valuable tool for understanding cell mechanics in health and disease.