UBC Theses and Dissertations
Tandem modular protein-based hydrogels as extracellular matrix mimetic biomaterials Lv, Shanshan
New generations of protein-based hydrogels are being developed rapidly over the last several decades for potential applications in biomedicine as well as basic biological studies. Protein-based hydrogels have been explored as synthetic extracellular matrices (ECM) for applications in cell culture and tissue regeneration. A variety of proteins, including silk protein, fibrin, collagen and elastin have been studied. Most of these proteins are non-globular proteins. However, a large number of ECM proteins are tandem modular proteins that consist of many individually folded domains. We hypothesize that tandem modular proteins may also be used in constructing novel hydrogels that can mimic the physical and biochemical characteristics of natural extracellular matrices. In this dissertation, we explored the feasibility of using tandem modular proteins for constructing protein-based biomaterials. First, through self-assembly of two complementary leucine zipper sequences, artificial tandem modular proteins were engineered to form physically cross-linked hydrogels mimicking ECM. Going a step further, a photochemical cross-linking strategy is employed to covalently cross-link engineered artificial elastomeric protein to biomaterials that exhibit mechanical properties mimicking the passive elasticity of muscles. To optimize the biocompatibility of the tandem modular protein-based hydrogels, a protein domain which contains cell-binding sequences is used to construct ECM-mimetic hydrogels. The hydrogels can support cell adhension. Our result also suggests a possible method to design functional hydrogels. To prove the possibility of designing functional hydrogels, an xylanase was used to design enzymatic hydrogels. Our result shows that the enzymes remain active after being cross-linked into hydrogels. The possibility was further proved by fluorescent hydrogels designed from tandem modular protein based on Cyan Fluorescent Protein (CFP) and Yellow Fluorescent Protein (YFP). The fluorescent hydrogels can be applied as force sensors in cells with picoNewton (pN) sensitivity.
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