So much more than paper

As the most abundant biopolymer on Earth since it can be found in every plant cell wall, cellulose has emerged as an ideal candidate for the development of renewable and biodegradable photonic materials, substituting conventional pigments.We would like to acknowledge invaluable discussions with group members as well as funding from the BBSRC David Phillips Fellowship (BB/K014617/1) and the European Research Council (ERC-2014-STG H2020 639088 and ERC-PoC-2017_790518 PixCell)

Small-Angle Neutron Scattering Reveals the Structural Details of Thermosensitive Polymer-Grafted Cellulose Nanocrystal Suspensions.

Thanks to the use of small-angle neutron scattering (SANS), a detailed structural description of thermosensitive polymer-grafted cellulose nanocrystals (CNCs) was obtained and the behavior of aqueous suspensions of these derivatized biosourced particles upon temperature increase was revealed. Although literature data show that the surface grafting of thermosensitive polymers drastically enhances the colloidal properties of CNCs, direct space microscopic investigation techniques fail in providing sufficient structural information on these objects. In the case of CNCs decorated with temperature-sensitive polyetheramines following a peptide coupling reaction, a qualitative and quantitative analysis of SANS spectra shows that CNCs are homogeneously covered by a shell comprising polymer chains in a Gaussian conformation with a thickness equal to their radius of gyration in solution, thus revealing a mushroom regime. An increase of the temperature above the lower critical solution temperature (LCST) of the polyetheramine results in the formation of finite size bundles whose aggregation number depends on the particle concentration and suspension temperature deviation from the LCST. SANS analysis further reveals local changes at the CNC surface corresponding to a release of water molecules and a related denser polymer shell conformation. Noticeably, data show a full reversibility at all length scales when a sample was cooled down to below the LCST after being heated above it. Overall, the results obtained by SANS allow an in-depth structural investigation of derivatized CNCs, which is of high interest for the design of functional materials comprising these biosourced colloids.Institut Carnot PolyNat (ANR N° 16-CARN-025-01), France

Research data supporting Co-assembly of Cellulose Nanocrystals and Silk Fibroin into Photonic Cholesteric Films

The dataset is compressed into “.zip” files grouped in folders corresponding to the figures in which they were reported. All spectra were exported in format that are accessible with free software, and sometimes in additional format that require a license (Matlab, Origin, MS Excel).EPSRC (1525292), MSCA Individual fellowship (BINGO 743543), the Office of Naval research, USA (N000141812258), National Science Foundation, USA (award CMMI-1752172)

Research Data supporting "Modeling the Cholesteric Pitch of Apolar Cellulose Nanocrystal Suspensions Using a Chiral Hard-Bundle Model"

The data is grouped in folders as separated .zip files ordered by their apparition in the different figures. An attached summary (pdf) is provided listing all the files, their extensions and the required software to access them.European Union’s Horizon 2020 Research and Innovation Programme [676045], BBSRC David Phillips fellowship [BB/K014617/1], EPSRC [EP/K503757/1, EP/R511675/1], European Research Council [ERC-2014-STG H2020 639088

Research Data supporting "Angular optical response of cellulose nanocrystal films explained by the distortion of the arrested suspension upon drying"

The data are organized and grouped in dedicated .zip files for each Figure they contribute to. All figures (1-21) are present in high resolution in each sub-folder. Software for file extensions: .tif, .png (image format), .m and .fig (MATLAB), text files (.txt). For further details, see the file "Open data summary"

Elaboration of superparamagnetic nanorods using iron oxide nanoparticles and polymers.

International audienceIn this presentation, we give an account of the formation of colloidal and supracolloidal aggregates obtained by controlled co-assembly of 7 nm particles with copolymers

The angular optical response of cellulose nanocrystal films explained by the distortion of the arrested suspension upon drying.

Cellulose nanocrystals (CNCs) are bio-sourced chiral nanorods that can form stable colloidal suspensions able to spontaneously assemble above a critical concentration into a cholesteric liquid crystal, with a cholesteric pitch usually in the micron range. When these suspensions are dried on a substrate, solid films with a pitch of the order of few hundreds of nanometers can be produced, leading to intense reflection in the visible range. However, the resulting cholesteric nanostructure is usually not homogeneous within a sample and comports important variations of the cholesteric domain orientation and pitch, which affect the photonic properties. In this work, we first propose a model accounting for the formation of the photonic structure from the vertical compression of the cholesteric suspension upon solvent evaporation, starting at the onset of the kinetic arrest of the drying suspension and ending when solvent evaporation is complete. From that assumption, various structural features of the films can be derived, such as the variation of the cholesteric pitch with the domain tilt, the orientation distribution density of the final cholesteric domains and the distortion of the helix from the unperturbed cholesteric case. The angular-resolved optical response of such films is then derived, including the iridescence and the generation of higher order reflection bands, and a simulation of the angular optical response is provided, including its tailoring under external magnetic fields. Second, we conducted an experimental investigation of CNC films covering a structural and optical analysis of the films. The macroscopic appearance of the films is discussed and complemented with angular-resolved optical spectroscopy, optical and electron microscopy, and our quantitative analysis shows an excellent agreement with the proposed model. This allows us to access the precise composition and the pitch of the suspension when it transited into a kinetically arrested phase directly from the optical analysis of the film. This work highlights the key role that the anisotropic compression of the kinetically arrested state plays in the formation of CNC films and is relevant to the broader case of structure formation in cast dispersions and colloidal self-assembly upon solvent evaporation.This work was supported by a BBSRC David Phillips fellowship [BB/K014617/1], the EPSRC grants [1525292], [EP/R511675/1], [EP/N016920/1] and [EP/K503757/1], The Isaac Newton Trust Cambridge [1423(g) 76933] and the European Research Council grants [ERC-2014-STG H2020 639088] and [ERC-PoC-2017 790518]

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

Aggregation of antibody drug conjugates at room temperature: SAXS and light scattering evidence for colloidal instability of a specific subpopulation

Coupling an hydrophobic drug onto monoclonal antibodies via Lysine residues is a common route to prepare antibody-drug conjugates (ADC), a promising class of biotherapeutics. But a few chemical modifications on protein surface often increases aggregation propensity, without clear understanding of the aggregation mechanisms at stake (loss of colloidal stability, self- assemblies, denaturation...), and the statistical nature of conjugation introduces polydispersity in the ADC population, which raises questions on whether the whole ADC population becomes unstable. To characterize the average interactions between ADC, we monitored small angle X-ray scattering in solutions of monoclonal IgG1 human antibody drug conjugate, with average degree of conjugation of 0, 2, or 3 drug molecules per protein. To characterize stability, we studied kinetics of aggregation at room temperature. Intrinsic Fuchs stability ratio of the ADC was estimated from the variation over time of scattered light intensity and hydrodynamic radius, in buffers of varying pH, and at diverse sucrose (0% or 10%) and NaCl (0 or 100 mM) concentrations. We show that stable ADC stock solutions became unstable upon pH shift, well below the pH of maximum average attraction between IgGs. Data indicates that aggregation can be ascribed to a fraction of ADC population usually representing less than 30 mol% of the sample. In contrast to the case of (monodisperse) monoclonal antibodies, our results suggest that a poor correlation between stability and average interaction parameters should be expected as a corollary of dispersity of ADC conjugation. In practice, the most unstable fraction of the ADC population can be removed by filtrations, which affects remarkably the apparent stability of the samples. Finally, the lack of correlation between the kinetic stability and variations of the average inter-ADC interactions is tentatively attributed to the uneven nature of charge distributions and the presence of patches on the drug-modified antibodies.This work was supported by the French National Research Agency (program Blanc International, grant ANR 2010-INT 1501, and program Investissement d’Avenir ANR-11- LABX-0011-01, and by SANOFI research grant to BFP. Authors are grateful to Javier Perez and Aurélien Thureau for their help and advice in SAXS measurements at SOLEIL. We thank Sophie Norvez from MMC laboratory in ESPCI for her help with circular dichroism.This is the author accepted manuscript. The final version is available from the American Chemical Society via http://dx.doi.org/10.1021/acs.langmuir.6b0065

Printing of Responsive Photonic Cellulose Nanocrystal Micro-Film Arrays

Interactive materials capable of changing appearance upon exposure to external stimuli, such as photonic inks, are generally difficult to achieve on a large scale as they often require self-assembly processes that are difficult to control macroscopically. Here we overcome this problem by preparing arrays of cellulose nanocrystal (CNC) micro-films from discrete nanoliter sessile droplets. The obtained micro-films show extremely uniform and intense color, enabling exceptional consistency in optical appearance across the entire array. The color can be controlled through the initial ink formulation, enabling the printing of polychromatic dot-matrix images. Moreover, the high surface-to-volume ratio of the micro-films and the intrinsic hydrophilicity of the natural building block allow for a dramatic real-time colorimetric response to changes in relative humidity. The printed CNC micro-film arrays overcome the existing issues of scalability, optical uniformity and material efficiency, which have held back the adoption of CNC-based photonic materials in cosmetics, interactive-pigments or anti-counterfeit applications.The European Research Council [ERC-2014-STG H2020 639088], the BBSRC David Phillips Fellowship [BB/K014617/1], the EPSRC [EP/L016087/1, EP/L015978/1, EP/N016920/1], and the Winton Programme for the Physics of Sustainability