Spatiotemporal mapping of microscale stiffness during collagen polymerization and crosslinking by optical...

Area of Science:

• Biophysics
• Materials Science
• Biotechnology

Background:

• Extracellular matrix (ECM) mechanical properties are crucial for cellular functions.
• Characterizing ECM biomechanics at the microscale is challenging.
• Collagen networks undergo significant changes during polymerization and crosslinking.

Purpose of the Study:

• To evaluate Optical multifrequency time-harmonic elastography (OMTHE) for rapid mechanical characterization of collagen networks.
• To compare OMTHE with tabletop magnetic resonance elastography (ttMRE) and optical intensity changes.
• To track dynamic stiffening during collagen polymerization and chemical crosslinking.

Main Methods:

• OMTHE was optimized for point-wise shear wave excitation in small sample volumes.
• Shear wave speed (SWS) was measured at vibration frequencies of 3–10 kHz and frame rates up to 4 kHz.
• Collagen polymerization and glutaraldehyde crosslinking were monitored using OMTHE.

Main Results:

• OMTHE detected SWS increases during collagen polymerization 6 ± 3 min earlier than optical density.
• Chemical crosslinking showed a lag-free SWS increase from 1.7 ± 0.4 m/s to 2.5 ± 0.5 m/s.
• OMTHE results closely matched relative SWS changes observed with ttMRE.

Conclusions:

• OMTHE enables rapid mechanical characterization of ECM-derived collagen networks.
• The technique offers micrometer spatial and second temporal resolution.
• OMTHE is a valuable tool for studying biomechanical property changes in small biological samples.