Saccharide-sensitive phase transition of a lectin-loaded gel

Kokufata, Etsuo; Yong-qing, Zhang; Tanaka, Toyoichi

doi:10.1038/351302a0

Cited by 217 publications

(108 citation statements)

References 12 publications

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“…Natural proteins such as collagen [1] and elastin [2] have been used to develop materials with tailored structural and mechanical properties, while catalysis by enzymes (e.g., glucose oxidase [3] ) has been used to build smart, environmentally-responsive hydrogel networks. The ability of proteins to selectively bind ligands has been used to develop materials that change their degree of physical or chemical crosslinking in the presence of biological antigens, [4,5] small molecule drugs, [6] and carbohydrates, [7][8][9] resulting in environmentallyresponsive biomaterials. In each of these previous studies a nanometer-scale function associated with a specific protein was exploited to build a material that performed an intriguing macroscopic function.…”

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confidence: 99%

Dynamic Materials Based on a Protein Conformational Change

2007

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Natural proteins perform a variety of functions in biological systems, including actuation, catalysis, structural support, and molecular sequestering. The variety of natural protein functions suggest that they could serve as valuable and versatile building blocks for synthesis of functional materials. Based on this premise, several investigators have developed schemes to include functional proteins into hydrogel networks to take advantage of their structural, catalytic, and ligand binding properties. Natural proteins such as collagen [1] and elastin [2] have been used to develop materials with tailored structural and mechanical properties, while catalysis by enzymes (e.g., glucose oxidase [3] ) has been used to build smart, environmentally-responsive hydrogel networks. The ability of proteins to selectively bind ligands has been used to develop materials that change their degree of physical or chemical crosslinking in the presence of biological antigens, [4,5] small molecule drugs, [6] and carbohydrates, [7][8][9] resulting in environmentallyresponsive biomaterials. In each of these previous studies a nanometer-scale function associated with a specific protein was exploited to build a material that performed an intriguing macroscopic function. A function that has not been explored as extensively in materials science is the ability of proteins to undergo complex conformational changes. Proteins change conformations in response to a broad range of stimuli, including light, pH, and the binding of biological molecules. Over 200 conformational changes are well-characterized, [10] representing a vast unexplored databank of molecular building blocks for design of dynamic materials. Recent studies have demonstrated the utility of protein conformational changes in nano-scale engineered systems, including cooperative nanometer-scale motors [11] and molecular shuttles, [12] suggesting that dynamic protein molecules could also be a useful component of 3-dimensional materials. To that end, we recently reported an approach that used a dynamic protein as a partial cross-linker in a chemically cross-linked hydrogel network, and these hydrogels changed their volume in the presence of a specific protein-binding molecule.[13] Here we describe assembly of protein-based, dynamic materials using a novel photochemical approach. This approach allows for high concentrations of protein to be functionally included into a network in response to light, and the resulting materials undergo striking volume changes upon protein-ligand binding. Photochemical assembly also enables spatial control over the location of dynamic proteins in a hydrogel network, which is likely to be important in potential materials science and engineering applications.

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confidence: 99%

Dynamic Materials Based on a Protein Conformational Change

2007

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“…Depending on the specific behavior and application, polymers can be designed to sense and respond to changes in the environmental conditions such as temperature, [1][2][3][4] pH, [5][6][7][8] magnetic or electric fields, [9][10][11] ionic strength, 12,13 added saccharides, 14,15 antigen binding, 16 or light. 17,18 Even multiple functionalities can be combined in order to respond, e.g., to both pH and temperature due to incorporation of two stimuliresponsive polymers.…”

Section: Introductionmentioning

confidence: 99%

Phase Behavior and Temperature-Responsive Molecular Filters Based on Self-Assembly of Polystyrene-block-poly(N-isopropylacrylamide)-block-polystyrene

et al. 2007

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This work describes the synthesis of temperature-responsive polystyrene-block-poly(N-isopropylacrylamide)-block-polystyrene triblock copolymers, i.e., PS-b-PNIPAM-b-PS, their self-assembly and phase behavior in bulk, and demonstration of aqueous thermoresponsive membranes. A series of PS-b-PNIPAM-b-PS triblock copolymers were synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. The hydrophobic PS end blocks were selected to form the minority component, whereas the temperatureresponsive PNIPAM midblock accounted for the majority component. The self-assembly and phase behavior in bulk of PS-b-PNIPAM-b-PS as well as selected blends with low molecular weight PNIPAM homopolymers were studied using transmission electron microscopy (TEM). Classical lamellar, cylindrical, spherical, and bicontinuous double gyroid morphologies were observed in the dried state. In aqueous solutions, the glassy PS domains act as physical cross-links, and hydrogels were therefore formed. The bulk block copolymer morphology had a strong effect on the degree of swelling in aqueous solutions upon cooling below the coil-globule transition temperature of the PNIPAM midblock. Bulk compositions with spherical PS domains and PNIPAM continuous phase swelled in water up to 58 times by weight, whereas composition having cylindrical PS domains or bicontinous gyroid structure in bulk swelled 20 or 10 times by weight, respectively. Finally, lamellar compositions did not show any swelling. Composite membranes for separation studies were prepared by spin-coating thin films of PS-b-PNIPAM-b-PS on top of meso/macroporous polyacrylonitrile (PAN) support membrane. The permeability was measured as a function of temperature using aqueous mixture of poly(ethylene glycol) (PEG) with several well-defined molecular weights. The permeability showed a temperature switchable on/off behavior, where higher permeability is obtained below transition temperature of PNIPAM, and the molecular cutoff limits for the PEG molecules are surprisingly lowsbetween 108 and 660 g/mol. The results encourage to further develop and optimize these materials for responsive nanofiltration applications.

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“…Polymer gels are a promising system for such smart functions because of their collapse phase transition, predicted theoretically by Dušek and Patterson in 1968 [1] and then observed experimentally by T. Tanaka in 1978 [2]. Since then, manifestations of this transition have been shown in a variety of circumstances [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Gel collapse can be driven by any one of the four basic types of intermolecular interactions operational in water solutions and in molecular biological systems [10], namely, by Van der Waals interactions, hydrogen bonds, hydrophobic interactions, and by Coulomb interactions between ionized (dissociated) groups.…”

Section: Introductionmentioning

confidence: 99%

“…Gel collapse can be triggered by a variety of external 'stimuli,' including change of temperature (either heating or cooling) [22][23][24][25][26][27], solvent composition [28][29][30][31][32], pH [33][34][35][36], ionic strength [37,38], and also kinetic influences, such as external electric or magnetic fields [7,[39][40][41][42], currents and light [12,43]. This wealth of properties guarantees rich applications, including super-absorbing materials exemplified by disposable diapers and sanitary napkins [17], materials releasing drugs in a controlled manner [14,27,34,44], catalysis [45], and mimetics of various organic systems [46][47][48][49][50][51][52][53][54][55][56], to name but a few.…”

Section: Introductionmentioning

confidence: 99%

Multiple point adsorption in a heteropolymer gel and the Tanaka approach to imprinting: experiment and theory

Ito

Chuang

Alvarez‐Lorenzo

et al. 2003

Progress in Polymer Science

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Heteropolymer gels can be engineered to release specific molecules into or absorb molecules from a surrounding solution. This remarkable ability is the basis for developing gel applications in extensive areas such as drug delivery, waste cleanup, and catalysis. Furthermore, gels are a model system for proteins, many of whose properties they can be created to mimic. A key aspect of gels is their volume phase transition, which provides a macroscopic mechanism for effecting microscopic changes. The phase transition allows one to control the gel's affinity for target molecules through tiny changes in the solution temperature, salt concentration, pH, or the like. We summarize recent experiments that systematically characterize the gel affinity as a function of adsorbing monomer concentration, solution salt concentration, and cross-linker concentration, on both sides of the phase transition. We provide a physical theory that explains the results and discuss enhancements via imprinting.

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Saccharide-sensitive phase transition of a lectin-loaded gel

Cited by 217 publications

References 12 publications

Dynamic Materials Based on a Protein Conformational Change

Dynamic Materials Based on a Protein Conformational Change

Phase Behavior and Temperature-Responsive Molecular Filters Based on Self-Assembly of Polystyrene-block-poly(N-isopropylacrylamide)-block-polystyrene

Multiple point adsorption in a heteropolymer gel and the Tanaka approach to imprinting: experiment and theory

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