Implementation and application of a novel 2D magnetic twisting cytometry based on multi-pole electromagnet

Area of Science:

• Biophysics
• Cell Mechanics
• Biomaterials

Background:

• Characterizing cell mechanical properties is crucial for understanding cellular functions and disease.
• Existing techniques like magnetic tweezers (MT) offer valuable insights but can be limited in certain applications.
• Developing novel instrumentation can expand the scope of mechanical cell characterization.

Purpose of the Study:

• To implement and validate a novel 2D magnetic twisting cytometry (MTC) system.
• To characterize the mechanical properties of HL-1 cardiomyocytes using the developed MTC instrument.
• To compare MTC findings with previous magnetic tweezers (MT) measurements.

Main Methods:

• A novel 2D magnetic twisting cytometry (MTC) setup was engineered using a multi-pole high permeability electromagnet for controlled field strength and direction.
• High-frequency measurements up to 1 kHz were achieved through a high-performance twisting electromagnet and heterodyning technology.
• A separate feedback-controlled electromagnet was used for high magnetic field polarization to ensure high remanence of ferromagnetic beads.

Main Results:

• The instrument successfully operated in both MTC and magnetic tweezers (MT) modes, marking a first in combined functionality.
• Anisotropy and log-normal distribution of cell stiffness in HL-1 cardiomyocytes were observed.
• The frequency-dependent cellular response was accurately modeled using the soft glassy rheology model.

Conclusions:

• The novel 2D MTC system provides a versatile platform for probing cell mechanics at high frequencies.
• The observed mechanical properties of cardiomyocytes, including anisotropy and stiffness distribution, are consistent across different magnetic techniques.
• The soft glassy rheology model effectively describes the viscoelastic behavior of living cells over a range of frequencies.