Optimized Lytic Polysaccharide Monooxygenase Action Increases Fiber Accessibility and Fibrillation by Releasing Tension Stress in Cellulose Cotton Fibers.

Lytic polysaccharide monooxygenase (LPMO) enzymes have recently shaken up our knowledge of the enzymatic degradation of biopolymers and cellulose in particular. This unique class of metalloenzymes cleaves cellulose and other recalcitrant polysaccharides using an oxidative mechanism. Despite their potential in biomass saccharification and cellulose fibrillation, the detailed mode of action of LPMOs at the surface of cellulose fibers still remains poorly understood and highly challenging to investigate.

Asymmetric modification of cellulose nanocrystals with PAMAM dendrimers for the preparation of pH-responsive hairy surfaces.

In this work, we present a straightforward method to attach a globular dendrimer at the reducing end of cellulose nanocrystals obtained from tunicates (t-CNC). We investigated the first four generations of poly(amidoamine) dendrimers (PAMAMs G0 to G3) to obtain hybrid t-CNCs. The aggregation behavior of hybrid t-CNCs was studied by dynamic light scattering (DLS) and scanning transmission electron microscopy (STEM); and interactions of these asymmetric nanoparticles with gold surface were elucidated using quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR).

pH-Responsive Properties of Asymmetric Nanopapers of Nanofibrillated Cellulose.

Inspired by plant movements driven by the arrangement of cellulose, we have fabricated nanopapers of nanofibrillated cellulose (NFC) showing actuation under pH changes. Bending was achieved by a concentration gradient of charged groups along the film thickness. Hence, the resulting nanopapers contained higher concentration of charged groups on one side of the film than on the opposite side, so that pH changes resulted in charge-dependent asymmetric deprotonation of the two layers.

Hybrid Gibbsite Nanoplatelet/Cellulose Nanocrystal Multilayered Coatings for Oxygen Barrier Improvement.

We have investigated the ability of multilayered hybrid thin films of cellulose nanocrystals (CNCs) and gibbsite nanoplatelets (GNPs) to be built by the layer-by-layer (LbL) technique onto substrates selected for packaging applications, and to improve the oxygen barrier properties. Using complementary structural characterization techniques, namely atomic force microscopy, ellipsometry, and spectral reflectance, we show that when deposited onto model silicon substrates these hybrid films were homogenous and of reduced porosity, and were comprised of alternately deposited monolayers of GNPs and CNCs. The successful deposition of such homogeneous and dense hybrid thin films onto various types of flexible substrates showing different chemical compositions, hydrophilicity, and surface morphology, ranging from cardboard to smart paper, polyethylene (PE) films, and PE-coated cardboard was also confirmed by scanning electron microscopy observations.

Synthesis and Self-Assembly of Xylan-Based Amphiphiles: From Bio-Based Vesicles to Antifungal Properties.

This work aims at designing functional biomaterials through selective chemical modification of xylan from beechwood. Acidic hydrolysis of xylan led to well-defined oligomers with an average of six xylose units per chain and with an aldehyde group at the reductive end. Reductive amination was performed on this aldehyde end group to introduce an azide reactive group.

Periodate oxidation of 4-O-methylglucuronoxylans: Influence of the reaction conditions.

This work aims at studying the sodium periodate oxidation of 4-O-methylglucuronoxylans (MGX) in different experimental conditions for a control of the oxidation degree. A series of sodium periodate oxidation reactions were conducted at three NaIO4/xylose molar ratios: 0.05, 0.