ELECTROBIOFABRICATION: A PLATFORM TECHNOLOGY ESPECIALLY SUITED FOR BIOMIMETIC ADDITIVE MANUFACTURING

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2020

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Abstract

Nature provides an array of examples to inspire the fabrication of functional material systems. Among biology’s enviable capabilities is its ability to induce the emergence of multi-scale morphological patterns – converting homogeneous media into systems with anisotropies and persistent gradients in composition. Interestingly, biology does not invest extensive genetic resources to achieve such morphological complexity, but rather relies on a small set of structural polymers (e.g., collagen, cellulose and chitin). These observations emphasize the importance of excitable media: mesoscale structure emerges within “excitable” media (i.e., stimuli-responsive biopolymers) in response to the set of spatiotemporally varying contextual cues that induce biopolymer interactions.
This dissertation is focused on the development of a platform technology ElectroBioFabrication, where we use convenient electrical signals, exploit a rich array of biological polymers and mechanism to fabricate biomaterials that recapitulate the diverse functionalities of nature’s materials system. Our results illustrate ElectroBioFabrication offers unique features to access the richness of biological assembly mechanism. First, the excitable media we use are biogeneric or biomimetic, and thus possess the intrinsic information for bottom-up assembly. For instance, the natural aminopolysaccharide chitosan and a thiolated polymer mimicking cysteine- rich proteins are used as excitable media. Second, a set of diffusible chemical signals that biology uses can also be generated electrochemically as contextual cues. In particular, we demonstrate that pH, oxidant and phenolic cues can be electro- generated with exquisite quantitative and spatiotemporal controllability. Third, a variety of biological interaction mechanisms can be triggered by these cues to guide hierarchical structure organization. Examples of interactions include non-covalent bio-specific interactions, disulfide linkages and thiol-quinone conjugates. Importantly, enlisting biological mechanisms allows the electrofabricated material systems to dynamically respond to external stimuli (e.g., pH and redox), and enables access to the biotechnology toolbox (e.g., enzymatic assembly and protein engineering) to confer biological functionality. We envision that ElectroBioFabrication will emerge as an important platform technology for organizing soft matter into dynamic material systems that mimic biology’s complexity of structure and versatility of function.

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