Thermoreversible lysozyme hydrogels: properties and an insight into the gelation pathway

Yan, Hui; Frielinghaus, Henrich; Nykänen, Antti; Ruokolainen, Janne; Saiani, Alberto; Miller, Aline F.

doi:10.1039/b716966c

Cited by 53 publications

(73 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Exponents for the 2 phase transitions at the edges of this window have been observed (3), but this connection to power laws is too abstract to be of practical value for proteins. More recently, an elegant example of an aggregated (large-scale) protein stress-phase transition has been obtained by studying hydrogel lysozyme solutions, where long-range hydrophobic forces apparently modulate the formation of ␤-sheet fibrils (29). A break in slope of an elastic plateau modulus as a function of lysozyme concentration is seen on a log-log plot, suggestive either of a connectivity transition or an ␣/␤ order-disorder transition.…”

Section: Discussionmentioning

confidence: 99%

Scaling and self-organized criticality in proteins I

Phillips

2009

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

100

View full text Add to dashboard Cite

The complexity of proteins is substantially simplified by regarding them as archetypical examples of self-organized criticality (SOC). To test this idea and elaborate on it, this article applies the Moret-Zebende SOC hydrophobicity scale to the large-scale scaffold repeat protein of the HEAT superfamily, PR65/A. Hydrophobic plasticity is defined and used to identify docking platforms and hinges from repeat sequences alone. The difference between the MZ scale and conventional hydrophobicity scales reflects longrange conformational forces that are central to protein functionality.hydrophobicity ͉ repeat ͉ scaling T here are many scales (hydrophobicity, charge, helix-forming propensity, etc.) that bioinformatically describe various aspects of amino acid interactions in proteins and their relations to sequence, structure, stability, and functionality, all justified by combining plausible constructs with parameters adjusted through statistical searches. Are all such scales equally useful, and are the substantial differences among them attributable to their inevitably heuristic character? Here, I discuss differences in methodology, with special emphasis on holistic vs. reductionist approaches. I suggest that a better understanding of the limitations and potential of scaling analysis of proteins will result from systematic studies of simple cases first, such as repeat proteins and their associates. Scaling analysis may prove to be a valuable tool in designing proteins with desired functions.Many physical systems exhibit power-law distributions over limited ranges (hence the popularity of log-log graph paper), and power-law distributions are the characteristic feature of the modern theory of phase transitions near a critical point. Self-organized criticality (SOC) is a methodology that attempts to explain why so many complex systems exhibit power-law distributions and appear to be ''accidentally'' located near critical points. It is argued that the critical points are dynamical fixed points (''tipping points'') toward which the system evolves without tuning external parameters (1). The critical points are extrema in some property (or properties) with respect to which the system has been optimized, especially with respect to long-range, highly-cooperative interactions, such as conformational changes.Given the widespread occurrence of power laws, SOC has great intuitive appeal: it has achieved an enduring popularity among theorists (Ͼ2,500 papers discussing SOC, Ͼ25 current books from a single publisher), notably in modeling the critical stability of sand piles against avalanches, but its concrete applications have been limited largely to seismic phenomena. A cautionary remark: power laws, especially in the context of dissipative reactions, have often been interpreted in terms of SOC, but a simpler interpretation involves only slow sweeping of a control parameter toward a global extremal, as could occur in the context of commercial product optimization (2). However, more recently Boolchand and coworkers (3) discovered a r...

show abstract

Section: Discussionmentioning

confidence: 99%

Scaling and self-organized criticality in proteins I

Phillips

2009

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

100

View full text Add to dashboard Cite

show abstract

“…The uniqueness of this protein is that lysozyme-based hydrogels are cytocompatible to living fibroblast cells, suggesting that globular protein-based hydrogels may be useful as scaffolds for tissue engineering. 74,75 Miller and colleagues primarily focused on thermoreversible lysozyme-based gels formed in mixtures of water and dithiothreitol. They reported that gelation of lysozyme was achieved by heating the protein solution up to 85 °C and then slowly cooling back to room temperature, during which lysozyme proteins were denatured and formed β-sheet-rich fibrils that further entangled into a gel network.…”

Section: Gel Systems Based On Natural Polypeptidesmentioning

confidence: 99%

Rheological properties of peptide-based hydrogels for biomedical and other applications

2010

View full text Add to dashboard Cite

Peptide-based hydrogels are an important class of biomaterials finding use in food industry and potential use in tissue engineering, drug delivery and microfluidics. A primary experimental method to explore the physical properties of these hydrogels is rheology. A fundamental understanding of peptide hydrogel mechanical properties and underlying molecular mechanisms is crucial for determining whether these biomaterials are potentially suitable for biotechnological uses. In this critical review, we cover the literature containing rheological characterization of the physical properties of peptide and polypeptide-based hydrogels including hydrogel bulk mechanical properties, gelation mechanisms, and the behavior of hydrogels during and after flow.

show abstract

“…Transparent hydrogels are obtained at 1.5 mM HEWL with 10 mM NaCl. This is in contrast to the freely flowing viscous liquid obtained with no NaCl [10]. When the NaCl concentration is increased to 50 mM, turbid gels form, and when the NaCl concentration is increased further to 100 mM, turbid solutions form where the protein precipitates.…”

mentioning

confidence: 52%

“…HEWL was selected as it is a small globular protein and contains both α-helix and β-sheet in its secondary structure and has high solubility in water. We went on to show that the mesh size of the hydrogel and its mechanical properties could be controlled by varying concentration and our two-dimensional cell culture work demonstrated that these hydrogels are cytocompatable [9,10]. However, before these materials can find any tissue engineering application, cells need to be incorporated throughout the hydrogel and their viability explored.…”

mentioning

confidence: 99%

Protein Fibrillar Hydrogels for three-Dimensional Tissue Engineering

Yan

Nykänen

Ruokolainen

et al. 2009

Research Letters in Nanotechnology

View full text Add to dashboard Cite

Protein self-assembly into highly ordered fibrillar aggregates has attracted increasing attention over recent years, due primarily to its association with disease states such as Alzheimer's. More recently, however, research has focused on understanding the generic behavior of protein self-assembly where fibrillation is typically induced under harsh conditions of low pH and/or high temperature. Moreover the inherent properties of these fibrils, including their nanoscale dimension, environmental responsiveness, and biological compatibility, are attracting substantial interest for exploiting these fibrils for the creation of new materials. Here we will show how protein fibrils can be formed under physiological conditions and their subsequent gelation driven using the ionic strength of cell culture media while simultaneously incorporating cells homogeneously throughout the gel network. The fibrillar and elastic nature of the gel have been confirmed using cryo-transmission electron microscopy and oscillatory rheology, respectively; while cell culture work shows that our hydrogels promote cell spreading, attachment, and proliferation in three dimensions. Copyright © 2009 Hui Yan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Hydrogels have recently attracted increasing attention as tissue engineering scaffolds for repairing and regenerating tissues [1][2][3][4]. There is a wide variety of natural and synthetic materials currently being employed to create such materials but recent research effort has focused on using natural materials as they are cheap, abundant, and require limited functionalization [5][6][7]. With this in mind we have previously demonstrated that hen egg white lysozyme (HEWL) protein can form hydrogels at physiological pH simply by adding a small quantity of the reductant dithiothreitol (DTT) which encourages the protein to gel under mild conditions [8,9]. HEWL was selected as it is a small globular protein and contains both α-helix and β-sheet in its secondary structure and has high solubility in water. We went on to show that the mesh size of the hydrogel and its mechanical properties could be controlled by varying concentration and our two-dimensional cell culture work demonstrated that these hydrogels are cytocompatable [9,10]. However, before these materials can find any tissue engineering application, cells need to be incorporated throughout the hydrogel and their viability explored.In this letter we will outline a novel method for the incorporation of cells in 3-dimensions directly in a HEWL hydrogel by using the ionic strength of cell culture media to drive gel formation while simultaneously incorporating cells homogeneously within the hydrogel. A schematic for this process is given in Figure 1. The resulting gel morphology and mechanical behavior have been explored using cryotransmission electron microscopy and oscillat...

show abstract

Thermoreversible lysozyme hydrogels: properties and an insight into the gelation pathway

Cited by 53 publications

References 49 publications

Scaling and self-organized criticality in proteins I

Scaling and self-organized criticality in proteins I

Rheological properties of peptide-based hydrogels for biomedical and other applications

Protein Fibrillar Hydrogels for three-Dimensional Tissue Engineering

Contact Info

Product

Resources

About