CE09 - Nanomatériaux et nanotechnologies pour les produits du futur

Spherical cholesteric liquid crystal template for enzyme activity model on polysaccharides – CLICTEAM

Submission summary

Lignocellulosic materials, generated in large amounts from agricultural practices, are one the most promising renewable feedstocks available for human exploitation. Lignocellulose mainly contains polysaccharides such as cellulose and hemicelluloses. Its biological conversion with enzymes is very attractive since it offers the possibility of producing a range of saccharide compounds in an ecofriendly way (low energy and water consumption). Such compounds could be further processed, offering great potential as materials, or in pharmaceutical, cosmetic or food industries. Enzymatic hydrolysis at high solid loadings (=15% w/w) would render the conversion process more economically feasible. However, this remains a real challenge given the poor understanding we have of enzyme activity in a dense medium, which can limit the diffusion of the enzyme and alter its mode of action.
The aim of the CLICTEAM project is to create an experimental platform to mimic enzymatic activity in plant cell walls. To simulate the complex organization of polysaccharides in the cell wall, the major challenge is to align cellulose and associated macromolecules into dense structures in a controlled manner. Acidic hydrolysis of cellulose fibers produces rod-like nano-sized monocrystals (200 nm long x 10 nm section). It has been shown that highly concentrated suspensions of cellulose nanocrystals (CNCs) self-assemble to form stable cholesteric liquid crystalline phases. Recent developments in microfluidics have enabled the fabrication of spherical shells of conventional liquid crystals. In the CLICTEAM project, we will adapt this technique to fabricate cellulose-based spherical walls, to which hemicelluloses (xyloglucan) will be added. This system will allow to mimic the densely organized cellulosic architectures found in cell wall and to follow in situ enzymatic degradation in this highly constrained and organized environment.
The first objective of the CLICTEAM project will be to produce and characterize CNC-xyloglucan shells with tailorable structure. This innovative device will provide an experimental platform to study enzymatic activity. Second, we will investigate the structural changes induced by the enzymes into the CNC cholesteric structure by using multiphoton imaging, and follow the enzyme dynamics in the dense cellulosic cholesteric phase by taking advantage of the autofluorescence of proteins after deep UV excitation. Analyzing the products resulting from enzymatic hydrolysis will indicate if the enzyme mode of action is altered by the low hydrated medium.
The challenging objective of mimicking enzymatic activity in plant cells by using a synthetic experimental platform requires a multidisciplinary approach, bringing together expertise in areas as diverse as bio-chemistry, physics and topology. It also requires the use of diverse cutting-edge experimental techniques: from microfluidics to deep UV auto-fluorescence microscopy. The CLICTEAM project brings together both the expertise and the infrastructures required for its success. INRA-BIA is expert on: i) the structure of polysaccharides, in particular native and modified cellulose nanocrystals, with the focus on understanding the cell wall structure, and ii) enzyme activity in plant cell walls. The GULLIVER team (CNRS-ESPCI) is specialist in confined liquid crystals, with expertise in both microfluidic methods and 3D organization of the cholesteric phase. The synchrotron SOLEIL (CEA/SACLAY-CNRS) provides expertise in top-level experimental techniques such as deep UV excitation and multiphoton imaging, which are key techniques for tracking the enzyme in situ.
The CLICTEAM project would provide fundamental information on the enzyme activity in plant cell walls, facing a central societal challenge: the use of plant biomass and the development of biorefinery where enzymes are implemented in low hydrated medium, for the production of bioethanol and platform molecules, and animal feeding.

Project coordination

Isabelle CAPRON (Biopolymères, Interactions Assemblages)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

GULLIVER GULLIVER
SOLEIL Synchrotron SOLEIL
BIA Biopolymères, Interactions Assemblages

Help of the ANR 313,952 euros
Beginning and duration of the scientific project: January 2019 - 48 Months

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