Journal Article•
Phase Transitions in Concentrated Solution Self-Assembly of Globular Protein-Polymer Block Copolymers
TL;DR: The phase behavior of mCherry-b-PNIPAM (mChP) block copolymers with four different PNIPAM coil fractions was investigated in concentrated aqueous solution as a function of both concentration and temperature.
Abstract: The phase behaviour of mCherry-b-PNIPAM (mChP) block copolymers with four different PNIPAM coil fractions is investigated in concentrated aqueous solution as a function of both concentration and temperature, demonstrating both order–order transitions (OOTs) and order–disorder transitions (ODTs) in globular protein–polymer block copolymers. Independent of coil volume fraction from 0.25 to 0.70, the temperature–concentration phase diagrams share several common features. At low concentrations, mCherry-b-PNIPAM forms a homogeneous disordered phase, and macrophase separation into an ordered conjugate-rich phase and a solvent-rich phase is observed at temperatures above the PNIPAM thermoresponsive transition temperature. mChP solutions are also observed to undergo a low-temperature ODT driven by increasing concentration. The order–disorder transition concentration (ODTC) behaviour of mChP is minimized for symmetric conjugates, suggesting that repulsive solvent-mediated protein–polymer interactions provide a driving force for self-assembly. Both coil fraction and solvent selectivity have large effects on the morphologies formed—disordered micelles, hexagonally packed cylinders, lamellae, and perforated lamellae are identified with the combination of small-angle X-ray scattering (SAXS), depolarized light scattering (DPLS), turbidimetry, and differential scanning calorimetry (DSC). An OOT is observed upon increasing temperature for three of the studied coil fractions at concentrations of 40–50 wt% due to changing solvent selectivity. SANS contrast-matching experiments show that water is weakly selective for PNIPAM at low temperatures and strongly selective for mCherry at high temperatures.
Citations
More filters
TL;DR: This review summarizes recent approaches aimed at producing multicomponent hydrogels, with descriptions of contemporary chemical and physical approaches for forming networks, and of the use of both synthetic and biologically derived molecules to impart desired properties.
148 citations
TL;DR: Giant surfactants as discussed by the authors are polymer-tethered molecular nanoparticles (MNPs) and can be considered as a subclass of giant molecules and serve as functionalized heads with persistent shape and volume, which may vary in size, symmetry, and surface chemistry.
Abstract: Giant surfactants are polymer-tethered molecular nanoparticles (MNPs) and can be considered as a subclass of giant molecules. The MNPs serve as functionalized heads with persistent shape and volume, which may vary in size, symmetry, and surface chemistry. The covalent conjugation of MNPs and polymer tails affords giant surfactants with diverse composition and architecture. Synthetic strategies such as “grafting-from” and “grafting-onto” have been successfully applied to the precise synthesis of giant surfactants, which is further facilitated by the emergence of “click” chemistry reactions. In many aspects, giant surfactants capture the essential features of small-molecule surfactants, yet they have much larger sizes. They bridge the gap between small-molecule surfactants and traditional amphiphilic macromolecules. Their self-assembly behaviors in solution are summarized in this Review. Micelle formation is affected not only by their primary chemical structures, but also by the experimental conditions. This new class of materials is expected to deliver general implications on the design of novel functional materials based on MNP building blocks in the bottom-up fabrication of well-defined nanostructures. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1309–1325
67 citations
11 Jun 2019
TL;DR: Elastin-like polypeptides (ELPs) are exquisite building motifs in designing self-assembling protein polymers with dynamic functions.
Abstract: Taking inspiration from naturally-occurring proteins, scientists have created protein polymers consisting of functional amino acid sequences that have evolved in nature. The functions of protein polymers can be custom-designed through the modular assembly of protein domains or minimized functional motifs. Elastin-like polypeptides (ELPs) are one of the exquisite building motifs in designing protein polymers. They exhibit stimuli-responsive self-assembling properties, remarkable elasticity, and favorable biological characteristics such as low platelet adhesion and low immunogenicity. With these characteristics, ELP-based materials have been demonstrated to be promising candidates for nanobiomaterial applications such as tissue engineering, drug delivery, and nanobiodevices. This review describes the recent developments in designing modular protein polymers containing ELPs as the building units.
55 citations
TL;DR: In this paper, the phase behaviours of mCherry-b-poly(hydroxypropyl acrylate) (PHPA) and m-Cherry b-poly (oligoethylene glycol acrylated) (POEGA) in concentrated aqueous solution were investigated.
47 citations
TL;DR: A brief review of the recent advances in assembly and reconfigurability of polymer-based nanostructures can be found in this article, where the authors highlight the role of computer simulation in discovering the fundamental principles of assembly science and providing critical design tools for assembly engineering of complex polymeric materials.
Abstract: Polymer-based nanomaterials have captured increasing interest over the past decades for their promising use in a wide variety of applications including photovoltaics, catalysis, optics, and energy storage. Bottom-up assembly engineering based on the self- and directed-assembly of polymer-based building blocks has been considered a powerful means to robustly fabricate and efficiently manipulate target nanostructures. Here, we give a brief review of the recent advances in assembly and reconfigurability of polymer-based nanostructures. We also highlight the role of computer simulation in discovering the fundamental principles of assembly science and providing critical design tools for assembly engineering of complex nanostructured materials.
47 citations
References
More filters
TL;DR: The latest red version matures more completely, is more tolerant of N-terminal fusions and is over tenfold more photostable than mRFP1, and three monomers with distinguishable hues from yellow-orange to red-orange have higher quantum efficiencies.
Abstract: Fluorescent proteins are genetically encoded, easily imaged reporters crucial in biology and biotechnology. When a protein is tagged by fusion to a fluorescent protein, interactions between fluorescent proteins can undesirably disturb targeting or function. Unfortunately, all wild-type yellow-to-red fluorescent proteins reported so far are obligately tetrameric and often toxic or disruptive. The first true monomer was mRFP1, derived from the Discosoma sp. fluorescent protein "DsRed" by directed evolution first to increase the speed of maturation, then to break each subunit interface while restoring fluorescence, which cumulatively required 33 substitutions. Although mRFP1 has already proven widely useful, several properties could bear improvement and more colors would be welcome. We report the next generation of monomers. The latest red version matures more completely, is more tolerant of N-terminal fusions and is over tenfold more photostable than mRFP1. Three monomers with distinguishable hues from yellow-orange to red-orange have higher quantum efficiencies.
4,607 citations
TL;DR: There is growing optimism that ever more sophisticated polymer-based vectors will be a signficant addition to the armoury currently used for cancer therapy.
Abstract: Polymers can be conjugated to anticancer drugs and proteins to improve their therapeutic index. Some such conjugates are in routine clinical use and there are exciting advances in development, such as polymer-based combination therapies.
1,880 citations
TL;DR: A general purification method for recombinant proteins based upon the selective interaction between a poly-histidine peptide, which is fused to the protein of interest, and a novel metal chelate adsorbent is described.
Abstract: We describe a general purification method for recombinant proteins based upon the selective interaction between a poly-histidine peptide, which is fused to the protein of interest, and a novel metal chelate adsorbent. The principle of the technique is illustrated with mouse dihydrofolate reductase. DNA elements coding for adjacent histidines were fused to the mouse dihydrofolate reductase gene. Subsequent expression in E. coli resulted in the production of hybrid proteins that could be purified by immobilized metal ion affinity chromatography, followed by removal of the histidine affinity peptide with carboxypeptidase A.
1,112 citations
TL;DR: The biological functions of encapsulated drugs and cells can be dramatically enhanced by designing biomaterials with controlled organizations at the nanometer scale.
Abstract: Research in the areas of drug delivery and tissue engineering has witnessed tremendous progress in recent years due to their unlimited potential to improve human health. Meanwhile, the development of nanotechnology provides opportunities to characterize, manipulate and organize matter systematically at the nanometer scale. Biomaterials with nano-scale organizations have been used as controlled release reservoirs for drug delivery and artificial matrices for tissue engineering. Drug-delivery systems can be synthesized with controlled composition, shape, size and morphology. Their surface properties can be manipulated to increase solubility, immunocompatibility and cellular uptake. The limitations of current drug delivery systems include suboptimal bioavailability, limited effective targeting and potential cytotoxicity. Promising and versatile nano-scale drug-delivery systems include nanoparticles, nanocapsules, nanotubes, nanogels and dendrimers. They can be used to deliver both small-molecule drugs and various classes of biomacromolecules, such as peptides, proteins, plasmid DNA and synthetic oligodeoxynucleotides. Whereas traditional tissue-engineering scaffolds were based on hydrolytically degradable macroporous materials, current approaches emphasize the control over cell behaviors and tissue formation by nano-scale topography that closely mimics the natural extracellular matrix (ECM). The understanding that the natural ECM is a multifunctional nanocomposite motivated researchers to develop nanofibrous scaffolds through electrospinning or self-assembly. Nanocomposites containing nanocrystals have been shown to elicit active bone growth. Drug delivery and tissue engineering are closely related fields. In fact, tissue engineering can be viewed as a special case of drug delivery where the goal is to accomplish controlled delivery of mammalian cells. Controlled release of therapeutic factors in turn will enhance the efficacy of tissue engineering. From a materials point of view, both the drug-delivery vehicles and tissue-engineering scaffolds need to be biocompatible and biodegradable. The biological functions of encapsulated drugs and cells can be dramatically enhanced by designing biomaterials with controlled organizations at the nanometer scale. This review summarizes the most recent development in utilizing nanostructured materials for applications in drug delivery and tissue engineering.
959 citations
TL;DR: The recent advances and the scientific progress in electrically contacted, layered enzyme electrodes are addressed, and the future applications of the systems in various bioelectronic devices, for example, amperometric biosensors, sensoric arrays, logic gates, and optical memories are discussed.
Abstract: Integration of redox enzymes with an electrode support and formation of an electrical contact between the biocatalysts and the electrode is the fundamental subject of bioelectronics and optobioelectronics. This review addresses the recent advances and the scientific progress in electrically contacted, layered enzyme electrodes, and discusses the future applications of the systems in various bioelectronic devices, for example, amperometric biosensors, sensoric arrays, logic gates, and optical memories. This review presents the methods for the immobilization of redox enzymes on electrodes and discusses the covalent linkage of proteins, the use of supramolecular affinity complexes, and the reconstitution of apo-redox enzymes for the nanoengineering of electrodes with protein monolayers of electrodes with protein monolayers and multilayers. Electrical contact in the layered enzyme electrode is achieved by the application of diffusional electron mediators, such as ferrocene derivatives, ferricyanide, quinones, and bipyridinium salts. Covalent tethering of electron relay units to layered enzyme electrodes, the cross-linking of affinity complexes formed between redox proteins and electrodes functionalized with relay-cofactor units, or surface reconstitution of apo-enzymes on relay-cofactor-functionalized electrodes yield bioelectrocatalytic electrodes. The application of the functionalized electrodes as biosensor devices is addressed and further application of electrically "wired" enzymes as catalytic interfaces in biofuel cells is discussed. The organization of sensor arrays, self-calibrated biosensors, or gated bioelectronic devices requires the microstructuring of biomaterials on solid supports in the form of ordered micro-patterns. For example, light-sensitive layers composed of azides, benzophenone, or diazine derivatives associated with solid supports can be irradiated through masks to enable the patterned covalent linkage of biomaterials to surfaces. Alternatively, patterning of biomaterials can be accomplished by noncovalent interactions (such as in affinity complexes between avidin and a photolabeled biotin, or between an antibody and a photoisomerizable antigen layer) to provide a means of organizing protein microstructures on surfaces. The organization of patterned hydrophilic/hydrophobic domains on surfaces, by using photolithography, stamping, or micromachining methods, allows the selective patterning of surfaces by hydrophobic, noncovalent interactions. Photoactivated layered enzyme electrodes act as light-switchable optobioelectronic systems for the amperometric transduction of recorded photonic information. These systems can act as optical memories, biomolecular amplifiers, or logic gates. The photoswitchable enzyme electrodes are generated by the tethering of photoisomerizable groups to the protein, the reconstitution of apo-enzymes with semisynthetic photoisomerizable cofactor units, or the coupling of photoisomerizable electron relay units.
860 citations