Tuning the erosion rate of artificial protein hydrogels through control of network topology

Shen, Wei; Zhang, Kechun; Kornfield, Julia A.; Tirrell, David A.

doi:10.1038/nmat1573

Cited by 278 publications

(328 citation statements)

References 25 publications

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“…It has been shown that the predominate mechanism of erosion of HSH hydrogels is diffusion of small-number closed-loop complexes formed via strand exchanged between coiled coils (28). When a closed-loop forms at the surface of the hydrogel it can diffuse into open buffer solution on a timescale faster than reattachment to the greater network via a subsequent strand exchange.…”

Section: Resultsmentioning

confidence: 99%

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Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks

Wheeldon

Gallaway

Barton

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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Here, we present two bifunctional protein building blocks that coassemble to form a bioelectrocatalytic hydrogel that catalyzes the reduction of dioxygen to water. One building block, a metallopolypeptide based on a previously designed triblock polypeptide, is electron-conducting. A second building block is a chimera of artificial ␣-helical leucine zipper and random coil domains fused to a polyphenol oxidase, small laccase (SLAC). The metallopolypeptide has a helix-random-helix secondary structure and forms a hydrogel via tetrameric coiled coils. The helical and random domains are identical to those fused to the polyphenol oxidase. Electron-conducting functionality is derived from the divalent attachment of an osmium bis-bipyrdine complex to histidine residues within the peptide. Attachment of the osmium moiety is demonstrated by mass spectroscopy (MS-MALDI-TOF) and cyclic voltammetry. The structure and function of the ␣-helical domains are confirmed by circular dichroism spectroscopy and by rheological measurements. The metallopolypeptide shows the ability to make electrical contact to a solid-state electrode and to the redox centers of modified SLAC. Neat samples of the modified SLAC form hydrogels, indicating that the fused ␣-helical domain functions as a physical cross-linker. The fusion does not disrupt dimer formation, a necessity for catalytic activity. Mixtures of the two building blocks coassemble to form a continuous supramolecular hydrogel that, when polarized, generates a catalytic current in the presence of oxygen. The specific application of the system is a biofuel cell cathode, but this protein-engineering approach to advanced functional hydrogel design is general and broadly applicable to biocatalytic, biosensing, and tissue-engineering applications.biocatalysis ͉ biofuel cell ͉ biomaterial ͉ laccase ͉ protein P rotein engineering provides the tool set to design and produce peptides and proteins that form the building blocks of new bio-inspired materials. The tool set allows for the manipulation of natural and artificial DNA sequences encoding the peptides or proteins of interest, and the subsequent biological production of the translated products. The methodology is powerful in that it allows for exact control over the identity and sequence of each residue and, consequently, the structural folding patterns of the resultant peptides or proteins (1). And, just as function stems from structure, it is also controlled within the protein-engineering scheme of materials design. There are a number of successful examples of hydrogels designed for tissueengineering and drug-delivery applications that use functional protein domains to obtain structural responsiveness to environmental cues (2-4). These examples include responsiveness to pH (5), temperature (6), shear stress (7), and ligand binding (8, 9) among others (refs. 2 and 10; ref. 3 and references therein). A wider range of applications, such as bioelectrocatalysis and biosensing, will benefit from the advantages of protein-based materials design pr...

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Section: Resultsmentioning

confidence: 99%

“…Other strategies for controlling the erosion rate of coiled-coil cross-links have been studied elsewhere (26,28).…”

Section: Resultsmentioning

confidence: 99%

Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks

Wheeldon

Gallaway

Barton

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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“…Tirrell et al have demonstrated that genetically synthesized triblock copolymers consisting of leucine zipper helix endblocks and a water-soluble polyelectrolyte midblock will self-assemble into pH-and temperature-sensitive hydrogels upon dimerization of the leucine zipper coils [181,[209][210][211]. The leucine zipper domains are composed of a repeating heptad motif designated abcdefg, where a and d are hydrophobic amino acids (leucine is preferred at position d), and e and g are charged amino acids (glutamic acid is common).…”

Section: Leucine Zipper Based Triblock Proteinsmentioning

confidence: 99%

“…In order to control the erosion rate of the gels and thus the rate of drug release, Tirrell et al investigated two approaches: (1) introduction of cysteine residues into each coil end block of the triblock proteins in an asymmetric way, resulting in favorable intermolecular disulfide bond formation in addition to the coiled-coil dimers, and (2) introduction of dissimilar coil domains in each triblock protein, resulting in the preferential formation of intermolecular coiled-coil dimers while discouraging the formation of intramolecular loops ( Figure 17) [209][210][211]. They observed that the erosion rate of mixed-endblock hydrogels is reduced by two to three orders of magnitude relative to the symmetric-endblock hydrogels.…”

Section: Leucine Zipper Based Triblock Proteinsmentioning

confidence: 99%

Peptide-based biopolymers in biomedicine and biotechnology

Chow

Nunalee

Lim

et al. 2008

Materials Science and Engineering: R: Reports

273

227

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Peptides are emerging as a new class of biomaterials due to their unique chemical, physical, and biological properties. The development of peptide-based biomaterials is driven by the convergence of protein engineering and macromolecular self-assembly. This review covers the basic principles, applications, and prospects of peptide-based biomaterials. We focus on both chemically synthesized and genetically encoded peptides, including poly-amino acids, elastin-like polypeptides, silk-like polymers and other biopolymers based on repetitive peptide motifs. Applications of these engineered biomolecules in protein purification, controlled drug delivery, tissue engineering, and biosurface engineering are discussed.

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“…A critical requirement for materials designed to interact with cell receptors is the organization of multiple ligands on the surface of a scaffold in order to engage the receptors more effectively. Kaufmann et al have demonstrated a new approach for the preparation of bioactive elastin-mimetic hydrogels (27) (29)(30)(31). Hydrophobic forces drive the assembly of the coiled-coil bundles as the hydrophobic planes along the length of the -helices are buried.…”

Section: Genetically Engineered Polypeptides In Hard Tissue Engineeringmentioning

confidence: 99%

Bioinspired Strategies for Hard Tissue Regeneration

George¹,

Huang²

2011

Advances in Biomimetics

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Tuning the erosion rate of artificial protein hydrogels through control of network topology

Cited by 278 publications

References 25 publications

Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks

Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks

Peptide-based biopolymers in biomedicine and biotechnology

Bioinspired Strategies for Hard Tissue Regeneration

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