Controlled Strain of 3D Hydrogels under Live Microscopy Imaging

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Biophysics

Background:

• External forces significantly influence tissue development and maintenance.
• Existing in vitro methods often rely on 2D substrates, limiting 3D hydrogel stretching.
• 3D techniques for straining soft hydrogels remain less accessible.

Purpose of the Study:

• To present a novel, accessible method for externally stretching soft hydrogels in three dimensions.
• To enable in situ microscopy and quantitative analysis of hydrogel deformation under mechanical stress.
• To facilitate biomimetic studies of cellular responses to mechanical forces in 3D environments.

Main Methods:

• A 3D-printed stretching device with low-cost electronics was developed.
• Soft fibrin hydrogels (>100 μm thick, ~100 Pa modulus) were polymerized onto silicone strips.
• Hydrogels were stretched circumferentially using the device, with real-time confocal microscopy and image processing for deformation analysis.

Main Results:

• The method successfully strained extremely soft hydrogels in a 3D configuration.
• Homogenous strains and fiber alignment were observed throughout the gel's 3D thickness.
• The system demonstrated flexibility in sample geometry and size manipulation.

Conclusions:

• This adaptable method provides a simple and replicable approach for 3D hydrogel stretching.
• It allows for in situ microscopy and analysis of cellular responses under biomimetic 3D mechanical loading.
• The technique can be extended to various hydrogel types (collagen, polyacrylamide, PEG) for broader applications in mechanobiology.