Eduardo Da Concepción

Thioflavin T dramatically enhances the structural and mechanical properties of the Fmoc-FF hydrogel and drives the self-assembly by interfering the metastable phase of the two-step nucleation process.

Abstract

The self-assembly of peptides is a key direction for fabrication of advanced materials. Novel approaches for fine tuning of macroscopic and microscopic properties of peptide self-assemblies are of a high demand for constructing biomaterials with desired properties. In this work, while studying the kinetics of the Fmoc-Diphenylalanine (Fmoc-FF) dipeptide self-assembly using the Thioflavin T (ThT) dye, we observed that the presence of ThT strongly modifies structural and mechanical properties of the Fmoc-FF hydrogel. Notably, the presence of ThT resulted in a tenfold increase of the gelation time and in the formation of short and dense fibers in the hydrogel. As a result of these morphological alteration higher thermal stability, and most important, tenfold increase of the hydrogel rigidity was achieved. Hence, ThT not only slowed the kinetics of the Fmoc-FF hydrogel formation, but also strongly enhanced its mechanical properties. In this study, we provide a detailed description of the ThT effect on the hydrogel properties and suggest the mechanisms for this phenomenon, paving the way for the novel approach to the control of the peptide hydrogels’ micro- and macroscale properties.

Structurally characterizing new materials is tremendously challenging, especially when single crystal structures are hardly available which is often the case for covalent organic frameworks. Yet, knowledge of the atomic structure is key to establish structure‐function relations and enable functional material design. Herein a new protocol is proposed to unambiguously predict the structure of poorly crystalline materials through a likelihood ordering based on the X‐ray diffraction (XRD) pattern. Key of the procedure is the broad set of structures generated from a limited number of building blocks and topologies, which is submitted to operando structural characterization. The dynamic averaging in the latter accounts for the operando conditions and inherent temporal character of experimental measurements, yielding unparalleled agreement with experimental powder XRD patterns. The proposed concept can hence unquestionably identify the structure of experimentally synthesized materials, a crucial step to design next generation functional materials.

All‐nitrogenated sugars (ANSs), in which all hydroxy groups in a carbohydrate are replaced with amino groups, are anticipated to be privileged structures with useful biological activities. In their Communication (DOI: 10.1002/anie.202015141), Takaaki Sato, Noritaka Chida et al. report synthesis, transformation, and biological tests of ANS derivatives. The key to success is a seven‐step synthesis of ANSs by the sequential Overman rearrangement enabling formal simultaneous substitution of four or five hydroxy groups in monosaccharides with amino groups.

Nature Chemistry, Published online: 13 July 2020; doi:10.1038/s41557-020-0504-6

Multivalent binding is a common strategy to enhance the interactions between weak binding partners. Now, following this principle, DNA origami scaffolds have been used to arrange DNA aptamers into specific geometries and to optimize linker spacings and flexibilities, which results in artificial binding sites with very high affinities for their corresponding ligands.

Abstract

An efficient protocol for the preparation of indolo[1,2‐a]quinazolines via palladium‐catalyzed decarboxylative annulation of indols with α‐oxocarboxylic acids has been realized by using primary amine as a directing group (DG). This transformation proceeds smoothly with exclusive regioselectivity and represents an one‐pot Domino synthesis of indo‐lo[1,2‐a]quinazolines from α‐oxocarboxylic acids.