Electro-assembly of a dynamically adaptive molten fibril state for collagen

Abstract

Collagen is a biological building block that is hierarchically assembled into diverse morphological structures that, in some cases, is dynamically adaptive in response to external cues and in other cases forms static terminal structures. Technically, there is limited capabilities to guide the emergence of collagen’s hierarchical organization to recapitulate the richness of biological structure and function. Here, we report an electro-assembly pathway to create a dynamically adaptive intermediate molten fibril state for collagen. Structurally, this intermediate state is composed of partially aligned and reversibly associating fibrils with limited hierarchical structure. These molten fibrils can be reversibly reconfigured to offer dynamic properties such as stimuli-stiffening, stimuli-contracting, self-healing, and self-shaping. Also, molten fibrils can be guided to further assemble to recapitulate the characteristic hierarchical structural features of native collagen (e.g., aligned fibers with D-banding). We envision that the electro-assembly of collagen fibrils will provide previously unidentified opportunities for tailored collagen-based biomedical materials.

Electrically Controlled Click‐Chemistry for Assembly of Bioactive Hydrogels on Diverse Micro‐ and Flexible Electrodes

“…[12,13] Electrochemical methods where water hydrolysis and the associated localized pH changes are used to form gels on electrodes have also been explored. A number of systems based on chitosan, [14,15] alginic acid, [16] alginate with calcium carbonate, [17] collagen [18,19] and silk [20,21] have been demonstrated. However, these mainly result from precipitation and modifying weak interactions between macromolecules, rather than the formation of covalent bonds.…”

Electro-Biofabrication. Coupling Electrochemical and Biomolecular Methods to Create Functional Bio-Based Hydrogels

“…Importantly, these molten fibrils are reversibly organized (i.e., the molten fibrils can be redissolved in acid) and can respond to external stimuli. For instance, the as-deposited molten fibrils have structural features and optical properties consistent with the collagen found in the cornea, while mechanical stretching aligned and densified the fibrils (Figure b) allowing subsequent treatments to generate higher-ordered structural features characteristic of the collagen found in tendons …”

“…(b) Stretching the molten fibril network aligns and densifies the network. Adapted with permission under a Creative Commons CC BY 4.0 License from ref . Copyright 2022 American Association for the Advancement of Science.…”

“…126−129 Recently, the Qu group reported an electroassembly method in which collagen could be partially assembled from a slightly acidic solution of individual molecules into an intermediate "molten fibril" state. 130 As illustrated in Figure 11a, the pH change is integral to the assembly process, while the electric field is important for inducing the collagen molecules to migrate and partially align within this molten fibril state. Importantly, these molten fibrils are reversibly organized (i.e., the molten fibrils can be redissolved in acid) and can respond to external stimuli.…”

“…For instance, the as-deposited molten fibrils have structural features and optical properties consistent with the collagen found in the cornea, 131 while mechanical stretching aligned and densified the fibrils (Figure 11b) allowing subsequent treatments to generate higher-ordered structural features characteristic of the collagen found in tendons. 130 4.2. Characterizing the Flow of Electrons through Hydrogels.…”