4 results
Search Results
Now showing 1 - 4 of 4
- ItemLiquefaction of Biopolymers: Solvent-free Liquids and Liquid Crystals from Nucleic Acids and Proteins(Washington, DC : ACS Publications, 2017) Liu, Kai; Ma, Chao; Göstl, Robert; Zhang, Lei; Herrmann, AndreasConspectusBiomacromolecules, 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.
- ItemReversibly Photo-Modulating Mechanical Stiffness and Toughness of Bioengineered Protein Fibers(Weinheim : Wiley-VCH, 2020) Sun, Jing; Ma, Chao; Maity, Sourav; Wang, Fan; Zhou, Yu; Portale, Giuseppe; Göstl, Robert; Roos, Wouter H.; Zhang, Hongjie; Liu, Kai; Herrmann, AndreasLight-responsive materials have been extensively studied due to the attractive possibility of manipulating their properties with high spatiotemporal control in a non-invasive fashion. This stimulated the development of a series of photo-deformable smart devices. However, it remained a challenge to reversibly modulate the stiffness and toughness of bulk materials. Here, we present bioengineered protein fibers and their optomechanical manipulation by employing electrostatic interactions between supercharged polypeptides (SUPs) and an azobenzene (Azo)-based surfactant. Photo-isomerization of the Azo moiety from the E- to Z-form reversibly triggered the modulation of tensile strength, stiffness, and toughness of the bulk protein fiber. Specifically, the photo-induced rearrangement into the Z-form of Azo possibly strengthened cation–π interactions within the fiber material, resulting in an around twofold increase in the fiber's mechanical performance. The outstanding mechanical and responsive properties open a path towards the development of SUP-Azo fibers as smart stimuli-responsive mechano-biomaterials. © 2020 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH
- ItemSignificant Upregulation of Alzheimer's β-Amyloid Levels in a Living System Induced by Extracellular Elastin Polypeptides(Weinheim : Wiley-VCH, 2019) Ma, Chao; Su, Juanjuan; Sun, Yao; Feng, Yang; Shen, Nolan; Li, Bo; Liang, Yingxia; Yang, Xintong; Wu, Hui; Zhang, Hongjie; Herrmann, Andreas; Tanzi, Rudolph E.; Liu, Kai; Zhang, CanAlzheimer's disease (AD) is a neurodegenerative disorder and the primary cause of age-related dementia. The etiology of AD is complex and has not been completely elucidated. Herein, we report that treatment with elastin-like polypeptides (ELPs), a component of the brain extracellular matrix (ECM), significantly increased the levels of AD-related amyloid-β peptides (Aβ) both in vitro and in vivo. Regarding the molecular mechanism(s), the upregulation of Aβ levels was related to increased proteolytic processing of the amyloid precursor protein. Furthermore, nesting tests demonstrated that the ELP-treated animals showed significant neurobehavioral deficits with cognitive impairment. These results suggest that the elastin is associated with AD-related pathological and behavioral changes. This finding presents a new aspect for Alzheimer's amyloidosis event and provides a great promise in developing ELP-based model systems to better understand the pathogenesis of AD. © 2019
- ItemSupercharged Proteins and Polypeptides(Weinheim : Wiley-VCH, 2020) Ma, Chao; Malessa, Anke; Boersma, Arnold J.; Liu, Kai; Herrmann, AndreasElectrostatic interactions play a vital role in nature. Biomacromolecules such as proteins are orchestrated by electrostatics, among other intermolecular forces, to assemble and organize biochemistry. Natural proteins with a high net charge exist in a folded state or are unstructured and can be an inspiration for scientists to artificially supercharge other protein entities. Recent findings show that supercharging proteins allows for control of their properties such as temperature resistance and catalytic activity. One elegant method to transfer the favorable properties of supercharged proteins to other proteins is the fabrication of fusions. Genetically engineered, supercharged unstructured polypeptides (SUPs) are just one promising fusion tool. SUPs can also be complexed with artificial entities to yield thermotropic and lyotropic liquid crystals and liquids. These architectures represent novel bulk materials that are sensitive to external stimuli. Interestingly, SUPs undergo fluid–fluid phase separation to form coacervates. These coacervates can even be directly generated in living cells or can be combined with dissipative fiber assemblies that induce life-like features. Supercharged proteins and SUPs are developed into exciting classes of materials. Their synthesis, structures, and properties are summarized. Moreover, potential applications are highlighted and challenges are discussed. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim