Identifying the coiled-coil triple helix structure of ß-peptide nanofibers at atomic resolution

Peptide self-assembly represents a powerful bottom-up approach to the fabrication of new nanomaterials. ß3-peptides are non-natural peptides composed entirely of ß-amino acids, which have an extra methylene in the backbone and we reported the first fibers derived from the self-assembly of ß3-peptides that adopt unique 14-helical structures. ß3-peptide assemblies represent a class of stable nanomaterials that can be used to generate bio- and magneto-responsive materials with proteolytic stability. However, the three-dimensional structure of many of these materials remains unknown. In order to develop structure-based criteria for the design of new ß3-peptide-based biomaterials with tailored function, we investigated the structure of a tri-ß3-peptide nanoassembly by molecular dynamics simulations and X-ray fiber diffraction analysis. Diffraction data was collected from aligned fibrils formed by Ac-ß3[LIA] in water and used to inform and validate the model structure. Models with threefold radial symmetry resulted in stable fibers with a triple-helical coiled-coil motif and measurable helical pitch and periodicity. The fiber models revealed a hydrophobic core and twist along the fiber axis arising from a maximization of contacts between hydrophobic groups of adjacent tripeptides on the solvent-exposed fiber surface. These atomic structures of macro-scale fibers derived from ß3-peptide-based materials provide valuable insight into the effects of the geometric placement of the side-chains and the influence of solvent on the core fiber structure which is perpetuated in the superstructure morphology

Identifying the coiled-coil triple helix structure of ß-peptide nanofibers at atomic resolution

Peptide self-assembly represents a powerful bottom-up approach to the fabrication of new nanomaterials. ß3-peptides are non-natural peptides composed entirely of ß-amino acids, which have an extra methylene in the backbone and we reported the first fibers derived from the self-assembly of ß3-peptides that adopt unique 14-helical structures. ß3-peptide assemblies represent a class of stable nanomaterials that can be used to generate bio- and magneto-responsive materials with proteolytic stability. However, the three-dimensional structure of many of these materials remains unknown. In order to develop structure-based criteria for the design of new ß3-peptide-based biomaterials with tailored function, we investigated the structure of a tri-ß3-peptide nanoassembly by molecular dynamics simulations and X-ray fiber diffraction analysis. Diffraction data was collected from aligned fibrils formed by Ac-ß3[LIA] in water and used to inform and validate the model structure. Models with threefold radial symmetry resulted in stable fibers with a triple-helical coiled-coil motif and measurable helical pitch and periodicity. The fiber models revealed a hydrophobic core and twist along the fiber axis arising from a maximization of contacts between hydrophobic groups of adjacent tripeptides on the solvent-exposed fiber surface. These atomic structures of macro-scale fibers derived from ß3-peptide-based materials provide valuable insight into the effects of the geometric placement of the side-chains and the influence of solvent on the core fiber structure which is perpetuated in the superstructure morphology

Machine learning-assisted exploration of a versatile polymer platform with charge transfer-dependent full-color emission

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Systematic Comparison of the Structural and Dynamic Properties of Commonly Used Water Models for Molecular Dynamics Simulations

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Interactions between Liquid Metal Droplets and Bacterial, Fungal, and Mammalian Cells

Liquid metals (LMs) have emerged as novel materials for biomedical applications. Here, the interactions taking place between cells and LMs are reported, presenting a unique opportunity to explore and understand the LM-biological interface. Several high-resolution imaging techniques are used to characterize the interaction between droplets of gallium LM and bacterial, fungal, and mammalian cells. Adhesive interactions between cells and LM droplets are observed, causing deformation of the LM droplet surface, resulting in surface wrinkling and in some cases, breakage of the native oxide layer present on the LM droplet surface. In many instances, the cell wall deforms to intimately contact the LM droplets. Single-cell force spectroscopy is performed to quantify the adhesion forces between cells and LM and characterize the nature of the adhesion. It is proposed that the flexible nature of the cell enables multiple adhesion sites with the LM droplets, imparting tensile forces on the LM droplet surface, which results in surface wrinkling on the LM droplets due to their liquid nature. Molecular dynamics simulations also suggest that flexible biomolecules on the cell surface can disrupt the Ga2O3 layer formed at the LM droplet surface. This study reveals a unique biointerfacial interaction and provides insights into the mechanisms involved