Measurements of interfacial curvatures and evidence for morphological transition in semifluorinated non-isometric microemulsions

Choi, Sung-Min; Nostro, Pierandrea Lo; Chen, S. H.

doi:10.1007/3-540-48953-3_22

Cited by 3 publications

(2 citation statements)

References 18 publications

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“…For unextended ELP gels from ([I 0.6 V 0.4 ]PAVG) 50 at 37 °C, the data were fit to the clipped random wave (CRW) model, − which offers a simplified description of random inhomogeneous two-phase media. This model has been successfully applied to investigate the arrested phase separation of these ELPs, in addition to bicontinuous microemulsions and phase separating polymer blends (Figure a−c, Table ).…”

Section: Resultsmentioning

confidence: 99%

Toughening of Thermoresponsive Arrested Networks of Elastin-Like Polypeptides To Engineer Cytocompatible Tissue Scaffolds

et al. 2016

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Formulation of tissue engineering or regenerative scaffolds from simple bioactive polymers with tunable structure and mechanics is crucial for the regeneration of complex tissues, and hydrogels from recombinant proteins, such as elastin-like polypeptides (ELPs), are promising platforms to support these applications. The arrested phase separation of ELPs has been shown to yield remarkably stiff, biocontinuous, nanostructured networks, but these gels are limited in applications by their relatively brittle nature. Here, a gel-forming ELP is chain-extended by telechelic oxidative coupling, forming extensible, tough hydrogels. Small angle scattering indicates that the chain-extended polypeptides form a fractal network of nanoscale aggregates over a broad concentration range, accessing moduli ranging from 5 kPa to over 1 MPa over a concentration range of 5–30 wt %. These networks exhibited excellent erosion resistance and allowed for the diffusion and release of encapsulated particles consistent with a bicontinuous, porous structure with a broad distribution of pore sizes. Biofunctionalized, toughened networks were found to maintain the viability of human mesenchymal stem cells (hMSCs) in 2D, demonstrating signs of osteogenesis even in cell media without osteogenic molecules. Furthermore, chondrocytes could be readily mixed into these gels via thermoresponsive assembly and remained viable in extended culture. These studies demonstrate the ability to engineer ELP-based arrested physical networks on the molecular level to form reinforced, cytocompatible hydrogel matrices, supporting the promise of these new materials as candidates for the engineering and regeneration of stiff tissues.

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Section: Resultsmentioning

confidence: 99%

Toughening of Thermoresponsive Arrested Networks of Elastin-Like Polypeptides To Engineer Cytocompatible Tissue Scaffolds

et al. 2016

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“…The Gaussian random process at the core of the CRW model allows for real-space simulations of the density distribution in these arrested ELP networks, providing a 3D picture that summarizes the interpretations of the gel nanostructure. This visualization method was initially described in the context of bicontinuous microemulsions by Chen and co-workers and utilized to describe anisometric systems with various spectral distribution functions , The order parameter field of the random process is given by where N = 10 000 is the number of cosine waves in the simulation, r is the real space vector, and k n and ϕ n describe the random wavevector, which is sampled according to the spectral distribution function. Based on the assumption of an isotropic system, each wavevector is assigned a random phase and random orientation, and the wavevector magnitude is described by a function, f ( k ), which for the CRW model is given by ,− where k is the wavevector magnitude and a , b , and c are model parameters.…”

Section: Resultsmentioning

confidence: 99%

Arrested Phase Separation of Elastin-like Polypeptide Solutions Yields Stiff, Thermoresponsive Gels

Glassman

Olsen

2015

Biomacromolecules

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The preparation of new responsive hydrogels is crucial for the development of soft materials for various applications, including additive manufacturing and biomedical implants. Here, we report the discovery of a new mechanism for forming physical hydrogels by the arrested phase separation of a subclass of responsively hydrophobic elastin-like polypeptides (ELPs). When moderately concentrated solutions of ELPs with the pentapeptide repeat (XPAVG)n (where X is either 20% or 60% valine with the remainder isoleucine) are warmed above their inverse transition temperature, phase separation becomes arrested, and hydrogels can be formed with shear moduli on the order of 0.1-1 MPa at 20 wt % in water. The longest stress relaxation times are well beyond 10(3) s. This result is surprising because ELPs are classically known for thermoresponsive coacervation that leads to macrophase separation, and solids are typically formed in the bulk or by supplemental cross-linking strategies. This new mechanism can form gels with remarkable mechanical behavior based on simple macromolecules that can be easily engineered. Small angle scattering experiments indicate that phase separation arrests to form a network of nanoscale domains, exhibiting rheological and structural features consistent with an arrested spinodal decomposition mechanism. Gel nanostructure can be modeled as a disordered bicontinuous network with interdomain, intradomain, and curvature length scales that can be controlled by sequence design and assembly conditions. These studies introduce a new class of reversible, responsive materials based on a classic artificial biopolymer that is a versatile platform to address critical challenges in industrial and medical applications.

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Clipped random wave analysis of anisometric lamellar microemulsions

Choy

Chen

2001

Phys. Rev. E

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Small-angle neutron scattering experiments were performed on C10E4-D2O-octane (where C10E4 is tetraethylene glycol monodecyl ether) anisometric microemulsions in the lamellar phase at a constant surfactant volume fraction of 20% and at the hydrophile-lipophile balance temperature of 22.5 degrees C. The results were analyzed using a clipped random wave model with a specific spectral distribution function developed by us previously. This enabled us to generate three-dimensional morphologies of the microemulsions, which showed clearly that in sufficiently anisometric microemulsions the oil-water interface was no longer connected. At large anisometry isolated regions of oil or water were found, and the transition from a bicontinuous structure at isometry to these isolated micelles far from isometry goes through an intermediate cylindrical morphology when the oil-to-water or water-to-oil ratio is around 4 to 1. We further computed the joint distribution function of the mean curvature H and Gaussian curvature K of the entire oil-water interface for each anisometric microemulsion. In particular, we show the distribution of , , and

-(2) for different isolated regions within an oil-rich microemulsion at an oil-to-water ratio of 85% to 15%. These distributions allowed us to prove that the isolated regions formed in highly anisometric microemulsions were small and had spherical topology.

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Measurements of interfacial curvatures and evidence for morphological transition in semifluorinated non-isometric microemulsions

Cited by 3 publications

References 18 publications

Toughening of Thermoresponsive Arrested Networks of Elastin-Like Polypeptides To Engineer Cytocompatible Tissue Scaffolds

Toughening of Thermoresponsive Arrested Networks of Elastin-Like Polypeptides To Engineer Cytocompatible Tissue Scaffolds

Arrested Phase Separation of Elastin-like Polypeptide Solutions Yields Stiff, Thermoresponsive Gels

Clipped random wave analysis of anisometric lamellar microemulsions

-(2) for different isolated regions within an oil-rich microemulsion at an oil-to-water ratio of 85% to 15%. These distributions allowed us to prove that the isolated regions formed in highly anisometric microemulsions were small and had spherical topology.

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