Controlling the self-assembly behavior of aqueous chitin nanocrystal suspensions

As with many other bio-sourced colloids, chitin nanocrystals (ChNCs) can form liquid crystalline phases with chiral nematic ordering. In this work, we demonstrate that it is possible to finely tune the liquid crystalline behavior of aqueous ChNC suspensions. Such control was made possible by carefully studying how the hydrolysis conditions and suspension treatments affect the colloidal and self-assembly properties of ChNCs. Specifically, we systematically investigate the effects of duration and acidity of chitin hydrolysis required to extract ChNCs, as well as the effects of the tip sonication energy input, degree of acetylation, pH and ionic strength. Finally, we show that by controlled water evaporation, it is possible to retain and control the helicoidal ordering in dry films, leading to hierarchical architecture analogous to that found in nature, e.g. in crab shells. We believe that this work serves as a comprehensive insight into ChNC preparation and handling which is required to unlock the full potential of this material in both a scientific and industrial context.This work was supported by the European Research Council [ERC-2014-STG H2020 639088], the BBSRC David Phillips Fellowship [BB/K014617/1], the EPSRC [EP/N509620/1], and Lord Lewis Research Studentship in Chemistry

Cucurbit[8]uril-derived graphene hydrogels

The scalable production of uniformly distributed graphene (GR)-based composite materials remains a sizable challenge. While GR-polymer nanocomposites can be manufactured at large scale, processing limitations result in poor control over the homogeneity of hydrophobic GR sheets in the matrices. Such processes often result in difficulties controlling stability and avoiding aggregation, therefore eliminating benefits that might have otherwise arisen from the nanoscopic dimensions of GR. Here, we report an exfoliated and stabilized GR dispersion in water. Cucurbit[8]uril (CB[8])-mediated host guest chemistry was used to obtain supramolecular hydrogels consisting of uniformly distributed GR and guest-functionalized macromolecules. The obtained GR-hydrogels show superior bioelectrical properties over identical systems produced without CB[8]. Utilizing such supramolecular interactions with biologically-derived macromolecules is a promising approach to stabilize graphene in water and avoid oxidative chemistry.Marie Sklodowska-Curie individual research grant (H2020-MSCAIF- 2017, P.ID: 797106) The Winston Churchill Foundation of the United States EPSRC Doctoral Training Grant EP/N509620/1 EPSRC Programme Grant NOtCH (EP/L027151/1

The Self-Assembly of Cellulose Nanocrystals: Hierarchical Design of Visual Appearance.

By controlling the interaction of biological building blocks at the nanoscale, natural photonic nanostructures have been optimized to produce intense coloration. Inspired by such biological nanostructures, the possibility to design the visual appearance of a material by guiding the hierarchical self-assembly of its constituent components, ideally using natural materials, is an attractive route for rationally designed, sustainable manufacturing. Within the large variety of biological building blocks, cellulose nanocrystals are one of the most promising biosourced materials, primarily for their abundance, biocompatibility, and ability to readily organize into photonic structures. Here, the mechanisms underlying the formation of iridescent, vividly colored materials from colloidal liquid crystal suspensions of cellulose nanocrystals are reviewed and recent advances in structural control over the hierarchical assembly process are reported as a toolbox for the design of sophisticated optical materials

The self-assembly of chitin nanocrystals into hierarchically structured functional materials

To drive more sustainable technological innovations, highly abundant natural resources such as a biopolymer chitin need to be better exploited. In this work, chitin was used to produce rod-shaped nanoparticles, known as chitin nanocrystals (ChNCs) via acid hydrolysis. Firstly, hydrolysis in hydrochloric acid with varied acidity (3.0 and 5.0 M) and duration (90 to 540 min) was investigated to correlate hydrolysis conditions to colloidal and self- assembly properties of the resulting ChNCs. The post processing using tip sonication was investigated, showing that while it reduced the nanoparticle size, the self-assembly properties were not strongly affected, which contrasts with the previously reported findings for cellulose nanocrystals. Using ChNCs allowed to increase the surface charge by means of deacetylation while maintaining the nanoparticle dimensions unaffected, providing evidence that too high surface charge hinders the self-assembly. On the other hand, the process of deacetylation if applied on chitin before the acidic hydrolysis, allows to reduce the nanocrystal thickness without changing the surface charge strongly. As such, nanoparticles of higher aspect ratio can be produced. The importance of the chitin source was evaluated, revealing that ChNCs prepared from mushroom Agaricus bisporus were longer, higher aspect ratio, and less crystalline, when compared to shrimp derived ChNCs. Furthermore, fungal ChNCs exhibited self-assembly at lower nanoparticle concentrations and had smaller chiral nematic pitch in comparison to shrimp ChNC studied at comparable conditions. This broad investigation into the preparation conditions of ChNCs is the first of its kind; the field of cellulose nanocrystals is flourishing owing to comparable studies on cellulose nanocrystals. The effect of ionic strength and pH was revisited to demonstrate that these two parameters can be used to effectively tune the self-assembly of ChNCs, and in turn tune the helicoidal nanoarchitecture preserved in the solid state. While the shrimp ChNC system was found to be limited to pitch values ranging from 650 to 4,000 nm in solid state, fungal ChNC suspension could be evaporated to reach helicoidal pitch values small enough to manifest structural colouration. Optical properties of such ChNC films, reported for the first time, were studied in relation to previously published works and theory to understand their low reflectance, which could be increased by an in-situ post-treatment using a concentrated alkali. The resulting chitin conversion into chitosan retained the nanoarchitecture and increased the birefringence from 0.001-0.003 (chitin) to approximately 0.015 (chitosan). Overall, this work provides the basis for designing ChNC preparation conditions to obtain desired colloidal and liquid crystalline properties, outlines the differences between ChNCs and a much more studied system of cellulose nanocrystals, and shows that ChNCs can be successfully used to be used as a functional material.EPSRC 1800758, Lord Lewis Research Studentship in Chemistry (Robinson College, University of Cambridge

Controlling the Self-Assembly Behavior of Aqueous Chitin Nanocrystal Suspensions

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Research data supporting "Controlling the self-assembly behavior of aqueous chitin nanocrystal suspensions"

Supporting data for the article titled "Controlling the self-assembly behavior of aqueous chitin nanocrystal suspensions". The article was accepted for publication in 2019 in the journal "Biomacromolecules". Electronic supporting information is available from the publisher (ACS Publications). The data is provided with a structured set of folders compressed in zip, each related to different characterisation methods used. The individual tick of the scale bar images corresponds to a spacing of 10 µm. See the Readme file for more information.This work was supported by the European Research Council [ERC-2014-STG H2020 639088, ERC-2017-POC 790518], the BBSRC David Phillips Fellowship [BB/K014617/1], the EPSRC [EP/R511675/1, EP/N509620/1], and Lord Lewis Research Studentship in Chemistry.

Research data supporting "Chiral Self-Assembly of Cellulose Nanocrystals is Driven by Crystallite Bundles"

A detailed summary is provided in the file "DataSummary.pdf" that accompanies the dataset. Note that the total dataset size is approximately 3.7 GB.This work was supported by the following funds: BBSRC [BB/V00364X/1] (S.V., R.M.P.); EPSRC [EP/K503757/1, EP/P030467/1, EP/N509620/1, EP/L015978/1]; Philip Leverhulme Prize [PLP-2019-271]; ERC Horizon 2020 Framework Programme [Marie Curie Individual Fellowship 893136-MFCPF, ERC SeSaME ERC‐2014‐STG H2020 639088, ERC 2017 POC 790518, ERC BiTe ERC‐2020‐CoS-101001637, ITN-H2020 Plamatsu 722842]; Emil Aaltonen Foundation; Lord Lewis Research Studentship in Chemistry

Research data supporting "Revealing the Structural Coloration of Self-Assembled Chitin Nanocrystal Films"

Supporting data for the article titled "Revealing the Structural Coloration of Self-Assembled Chitin Nanocrystal Films", as published in Advanced Materials (2022). The data is provided within a structured set of folders compressed in zip, each correlating to a specific data type reported in the article and supplementary information. Please see .txt document: Data for "Revealing the Structural Coloration of Self-Assembled Chitin Nanocrystal Films" for further detailsThis work was supported by: the European Research Council [ERC-2017-POC 790518], the BBSRC [BB/K014617/1, BB/V00364X/1], the EPSRC [EP/N509620/1, EP/L015978/1], Marie Skłodowska-Curie grant agreement [No. 722842], and Lord Lewis Research Studentship in Chemistry, Erasmus + traineeship (NLMAASTRI01)

Research Data Supporting "Solid state NMR of isotope labelled murine fur: A powerful tool to study atomic level keratin structure and treatment effects"

NMR spectroscopy data in Bruker file format. See file included in the uploaded zipped folder for correspondence between the raw data and the experiments discussed in the paper.This research data supports "Solid state NMR of isotope labelled murine fur: A powerful tool to study atomic level keratin structure and treatment effects" which was published in "Journal of Biomolecular NMR".EPSRC (PhD studentships) MRC (RG75828) NIH

Chiral self-assembly of cellulose nanocrystals is driven by crystallite bundles.

The transfer of chirality across length-scales is an intriguing and universal natural phenomenon. However, connecting the properties of individual building blocks to the emergent features of their resulting large-scale structure remains a challenge. In this work, we investigate the origins of mesophase chirality in cellulose nanocrystal suspensions, whose self-assembly into chiral photonic films has attracted significant interest. By correlating the ensemble behaviour in suspensions and films with a quantitative morphological analysis of the individual nanoparticles, we reveal an inverse relationship between the cholesteric pitch and the abundance of laterally-bound composite particles. These 'bundles' thus act as colloidal chiral dopants, analogous to those used in molecular liquid crystals, providing the missing link in the hierarchical transfer of chirality from the molecular to the colloidal scale