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Liquefaction of Biopolymers: Solvent-free Liquids and Liquid Crystals from Nucleic Acids and Proteins
ConspectusBiomacromolecules, such as nucleic acids, proteins, and virus particles, are persistent molecular entities with dimensions that exceed the range of their intermolecular forces hence undergoing degradation by thermally induced bond-scission upon heating. Consequently, for this type of molecule, the absence of a liquid phase can be regarded as a general phenomenon. However, certain advantageous properties usually associated with the liquid state of matter, such as processability, flowability, or molecular mobility, are highly sought-after features for biomacromolecules in a solvent-free environment. Here, we provide an overview over the design principles and synthetic pathways to obtain solvent-free liquids of biomacromolecular architectures approaching the topic from our own perspective of research. We will highlight the milestones in synthesis, including a recently developed general surfactant complexation method applicable to a large variety of biomacromolecules as well as other synthetic principles granting access to electrostatically complexed proteins and DNA.These synthetic pathways retain the function and structure of the biomacromolecules even under extreme, nonphysiological conditions at high temperatures in water-free melts challenging the existing paradigm on the role of hydration in structural biology. Under these conditions, the resulting complexes reveal their true potential for previously unthinkable applications. Moreover, these protocols open a pathway toward the assembly of anisotropic architectures, enabling the formation of solvent-free biomacromolecular thermotropic liquid crystals. These ordered biomaterials exhibit vastly different mechanical properties when compared to the individual building blocks. Beyond the preparative aspects, we will shine light on the unique potential applications and technologies resulting from solvent-free biomacromolecular fluids: From charge transport in dehydrated liquids to DNA electrochromism to biocatalysis in the absence of a protein hydration shell. Moreover, solvent-free biological liquids containing viruses can be used as novel storage and process media serving as a formulation technology for the delivery of highly concentrated bioactive compounds. We are confident that this new class of hybrid biomaterials will fuel further studies and applications of biomacromolecules beyond water and other solvents and in a much broader context than just the traditional physiological conditions. © 2017 American Chemical Society.
A wafer-scale two-dimensional platinum monosulfide ultrathin film via metal sulfurization for high performance photoelectronics
2D nonlayered materials have attracted enormous research interests due to their novel physical and chemical properties with confined dimensions. Platinum monosulfide as one of the most common platinum-group minerals has been less studied due to either the low purity in the natural product or the extremely high-pressure conditions for synthesis. Recently, platinum monosulfide (PtS) 2D membranes have emerged as rising-star materials for fundamental Raman and X-ray photoelectron spectral analysis as well as device exploration. However, a large-area homogeneous synthesis route has not yet been proposed and released. In this communication, we report a facile metal sulfurization strategy for the synthesis of a 4-inch wafer-scale PtS film. Enhanced characterization tools have been employed for thorough analysis of the crystal structure, chemical environment, vibrational modes, and atomic configuration. Furthermore, through theoretical calculations the phase diagram of the Pt–S compound has been plotted for showing the successful formation of PtS in our synthesis conditions. Eventually, a high-quality PtS film has been reflected in device demonstration by a photodetector. Our approach may shed light on the mass production of PtS films with precise control of their thickness and homogeneity as well as van der Waals heterostructures and related electronic devices.
Affinity for the Interface Underpins Potency of Antibodies Operating In Membrane Environments
The contribution of membrane interfacial interactions to recognition of membrane-embedded antigens by antibodies is currently unclear. This report demonstrates the optimization of this type of antibodies via chemical modification of regions near the membrane but not directly involved in the recognition of the epitope. Using the HIV-1 antibody 10E8 as a model, linear and polycyclic synthetic aromatic compounds are introduced at selected sites. Molecular dynamics simulations predict the favorable interactions of these synthetic compounds with the viral lipid membrane, where the epitope of the HIV-1 glycoprotein Env is located. Chemical modification of 10E8 with aromatic acetamides facilitates the productive and specific recognition of the native antigen, partially buried in the crowded environment of the viral membrane, resulting in a dramatic increase of its capacity to block viral infection. These observations support the harnessing of interfacial affinity through site-selective chemical modification to optimize the function of antibodies that target membrane-proximal epitopes. © 2020 The Author(s)Rujas et al. describe the site-selective chemical modification of antibodies to improve the molecular recognition of epitopes at membrane surfaces. The modification using aromatic compounds dramatically enhanced the virus neutralization potency and native antigen binding efficiency of HIV-1 antibodies directed against the membrane-embedded MPER epitope. © 2020 The Author(s)
Antibacterial Ti-Cu alloy with enhanced mechanical properties as implant applications
The service life as hard tissue implantation for clinical application needs compatible mechanical properties, e.g. strength, modulus, etc, and certain self-healing in case of internal infection. Therefore, for sake of improving the properties of Ti-Cu alloy, the microstructure, mechanical properties, corrosion resistance and antibacterial properties of Ti-xCu alloy (x = 2, 5, 7 and 10 wt.%) prepared by Ar-arc melting followed by heat treatment were studied. The results show that the Ti-Cu alloy was mainly composed of α-Ti matrix and precipitated Ti2Cu phase. The Cu element mainly accumulates in the lamellar structure and forms the precipitated Ti2Cu phase. As the increase of Cu content, the lamellar Ti2Cu phase increases, the compressive strength and elastic modulus also were altered. The Ti-7Cu alloy exhibited the higher compressive strength (2169 MPa) and the lower elastic modulus (108 GPa) compared with other Ti-Cu alloys. The corrosion resistance of Ti-xCu alloys increases with the increase of Cu content. When the Cu content was greater than 5 wt.%, the value of corrosion current density for Ti-Cu alloy was less than 1 μAcenterdotcm−2, which is also significantly lower than that of CP-Ti. The antibacterial test revealed that only the Ti-Cu alloy with 5 wt.% or greater Cu content could display a strong antibacterial rate against E. coli and S. aureus. Therefore, the prepared Ti-7Cu alloy via heat treatment showed excellent mechanical properties, corrosion resistance, and antibacterial properties, which would meet the replacement of human hard tissue and clinical applications.
Characterization of Fluorescent Proteins with Intramolecular Photostabilization*
Genetically encodable fluorescent proteins have revolutionized biological imaging in vivo and in vitro. Despite their importance, their photophysical properties, i. e., brightness, count-rate and photostability, are relatively poor compared to synthetic organic fluorophores or quantum dots. Intramolecular photostabilizers were recently rediscovered as an effective approach to improve photophysical properties of organic fluorophores. Here, direct conjugation of triplet-state quenchers or redox-active substances creates high local concentrations of photostabilizer around the fluorophore. In this paper, we screen for effects of covalently linked photostabilizers on fluorescent proteins. We produced a double cysteine mutant (A206C/L221C) of α-GFP for attachment of photostabilizer-maleimides on the β-barrel near the chromophore. Whereas labelling with photostabilizers such as trolox, a nitrophenyl group, and cyclooctatetraene, which are often used for organic fluorophores, had no effect on α-GFP-photostability, a substantial increase of photostability was found upon conjugation to azobenzene. Although the mechanism of the photostabilizing effects remains to be elucidated, we speculate that the higher triplet-energy of azobenzene might be crucial for triplet-quenching of fluorophores in the blue spectral range. Our study paves the way for the development of fluorescent proteins with photostabilizers in the protein barrel by methods such as unnatural amino acid incorporation. © 2021 The Authors. ChemBioChem published by Wiley-VCH GmbH
Ultra-strong bio-glue from genetically engineered polypeptides
The development of biomedical glues is an important, yet challenging task as seemingly mutually exclusive properties need to be combined in one material, i.e. strong adhesion and adaption to remodeling processes in healing tissue. Here, we report a biocompatible and biodegradable protein-based adhesive with high adhesion strengths. The maximum strength reaches 16.5 ± 2.2 MPa on hard substrates, which is comparable to that of commercial cyanoacrylate superglue and higher than other protein-based adhesives by at least one order of magnitude. Moreover, the strong adhesion on soft tissues qualifies the adhesive as biomedical glue outperforming some commercial products. Robust mechanical properties are realized without covalent bond formation during the adhesion process. A complex consisting of cationic supercharged polypeptides and anionic aromatic surfactants with lysine to surfactant molar ratio of 1:0.9 is driven by multiple supramolecular interactions enabling such strong adhesion. We demonstrate the glue’s robust performance in vitro and in vivo for cosmetic and hemostasis applications and accelerated wound healing by comparison to surgical wound closures.