Multicolor and Attenuated Light Intensity Responses in Protein Hydrogels Arising from Photoregulated Crosslink...

Area of Science:

• Biomaterials Science
• Protein Engineering
• Photochemistry

Background:

• Light-responsive hydrogels offer remote control over material properties but struggle with multicolor addressability and dynamic mechanical regulation.
• Current systems often use single photoswitches and primarily alter stiffness via crosslinking density.

Purpose of the Study:

• To develop a fully protein-based hydrogel with multicolor light responsiveness and optical control over crosslink dynamics.
• To introduce orthogonal control over reversible and irreversible crosslinks for advanced biomaterial design.

Main Methods:

• Incorporation of two visible light-responsive photoceptors: cyanobacterial phytochrome Cph1 (reversible red/far-red light control) and CarH (irreversible green light-induced gel-sol transitions).
• Investigation of light intensity-dependent mechanical responses and dark-adaptation effects in Cph1-based hydrogels.

Main Results:

• The hydrogel achieved multicolor addressability using distinct light wavelengths for reversible and irreversible crosslinking.
• Cph1-based hydrogels showed an unexpected inverse relationship between red light intensity and stiffness, stiffening in the dark.
• Light-driven bidirectional photoisomerization was identified as the mechanism modulating crosslink lifetimes.

Conclusions:

• Established orthogonal control of reversible and irreversible crosslinks in a single biomaterial system.
• Demonstrated photoregulated crosslink dynamics for tunable mechanical properties.
• Presented new design principles for multicolor light-responsive biomaterials with dynamic mechanical control.