An Active and Soft Hydrogel Actuator to Stimulate Live Cell Clusters by Self-folding

Area of Science:

• Materials Science
• Biomedical Engineering
• Polymer Science

Background:

• Hydrogels are crucial in various applications, with mechanical properties dictating their success.
• Controlling hydrogel mechanical properties is essential for advanced applications like actuators.
• Existing hydrogel actuators often lack sophisticated control over mechanical stimulation for biological applications.

Purpose of the Study:

• To develop an advanced hydrogel actuator capable of self-folding and stimulating live cell clusters.
• To precisely control the mechanical properties of the hydrogel actuator through tunable parameters.
• To investigate the biological response of cell clusters to mechanical stimulation from the hydrogel actuator.

Main Methods:

• Fabrication of a two-layer hydrogel actuator with differential expansion ratios for self-folding and curvature control.
• Tuning hydrogel expansion ratios via polymer molecular weight, concentration, and temperature-sensitive molecules.
• Applying temperature changes to induce repeated compression and tension on live cell clusters.

Main Results:

• The hydrogel actuator demonstrated controlled self-folding, creating various curvatures in response to temperature.
• Mechanical stimulation by the actuator led to repeated compression and tension on cell clusters.
• Significant upregulation of vascular endothelial growth factor (VEGF) and insulin-like growth factor-binding protein-2 (IGFBP-2) was observed in stimulated MCF-7 tumor cells.

Conclusions:

• A novel strategy for creating active, soft hydrogel actuators with tunable mechanical properties was successfully developed.
• The hydrogel actuator effectively stimulates live cell clusters, inducing specific biological responses.
• This technology holds significant potential for applications in tissue engineering, drug delivery, and micro-scale actuators.