An Optogenetic Platform to Dynamically Control the Stiffness of Collagen Hydrogels

Abstract

The extracellular matrix (ECM) is comprised of a meshwork of biomacromolecules whose composition, architecture, and macroscopic properties, such as mechanics, instruct cell fate decisions during development and disease progression. Current methods implemented in mechanotransduction studies either fail to capture real-time mechanical dynamics or utilize synthetic polymers that lack the fibrillar nature of their natural counterparts. Here we present an optogenetic-inspired tool to construct light-responsive ECM mimetic hydrogels comprised exclusively of natural ECM proteins. Optogenetic tools offer seconds temporal resolution and submicron spatial resolution, permitting researchers to probe cell signaling dynamics with unprecedented precision. Here we demonstrated our approach of using SNAP-tag and its thiol targeted substrate, benzylguanine-maleimide, to covalently attach blue-light responsive proteins to collagen hydrogels. The resulting material (OptoGel) -in addition to encompassing the native biological activity of collagen-stiffens upon exposure to blue light and softens in the dark. Optogels have immediate use in dissecting the cellular response to acute mechanical inputs and may also have applications in next-generation bio-interfacing prosthetics.

Synthetic biology as driver for the biologization of materials sciences

“…At least 2× reversible. [ 173 ] Dronpa145 N Dronpa145 N was covalently coupled via SpyCatcher/SpyTag interaction to a protein polymer ((GB1-SpyCatcher) 3 ). Reversible gel–sol phase transition by light-controlled Dronpa145 N tetramer–monomer transformation.…”

“…The authors apply this principle for the synthetic reconstitution of intracellular stress granules [ 172 ]. A similar design concept was followed by the Wilson group, conjugating the blue-light photoreceptors EL222 to collagen hydrogels [ 173 ]. To this aim, cysteine residues in collagen hydrogels were covalently functionalized with maleimide-benzylguanine (the SNAP-tag ligand) while EL222 was fused to SNAP-tag.…”

“…In this configuration, illumination with blue light resulted in EL222 dimerization and an increase in the hydrogel crosslink density leading to a higher stiffness. However, in the dark, EL222 spontaneously dissociated and the hydrogel returned to the initial soft state [ 173 ].…”

Advanced Optogenetic-Based Biosensing and Related Biomaterials

“…Hopkins et al [ 39 ] used a SNAP-tag® (New England Biolabs Inc, Ipswich, MA, USA) and its thiol-targeted substrate, benzylguanine-maleimide, to covalently attach blue-light-responsive proteins to collagen hydrogels. The resulting material (OptoGel) encompasses the native biological activity of collagen, stiffens upon exposure to blue light and softens in the dark.…”

“… Optical manipulation of protein subcellular localization in cells [ 35 ] to be implemented as a way to calibrate new multimodal microscopy [ 29 ] tools. Optogenetic-inspired tools (optogels) to construct light-responsive extracellular matrix (ECM) mimetic hydrogels better mimicking natural ECM [ 39 ] and having light adjustable mechanical properties [ 38 ]. Optogels have immediate use in dissecting the cellular response to acute mechanical inputs and are suitable extensions towards 3D cellular biosensing platforms.…”