Effect of Anisotropy of Cellulose Nanocrystal Suspensions on Stratification, Domain Structure Formation, and Structural Colors

Outstanding optical and mechanical properties can be obtained from hierarchical assemblies of nanoparticles. Herein, the formation of helically ordered, chiral nematic films obtained from aqueous suspensions of cellulose nanocrystals (CNCs) were studied as a function of the initial suspension state. Specifically, nanoparticle organization and the structural colors displayed by the resultant dry films were investigated as a function of the anisotropic volume fraction (AVF), which depended on the initial CNC concentration and equilibration time. The development of structural color and the extent of macroscopic stratification were studied by optical and scanning electron microscopy as well as UV–vis spectroscopy. Overall, suspensions above the critical threshold required for formation of liquid crystals resulted in CNC films assembled with longer ranged order, more homogeneous pitches along the cross sections, and narrower specific absorption bands. This effect was more pronounced for the suspensions that were closer to equilibrium prior to drying. Thus, we show that high AVF and more extensive phase separation in CNC suspensions resulted in large, long-range ordered chiral nematic domains in dried films. Additionally, the average CNC aspect ratio and size distribution in the two separated phases were measured and correlated to the formation of structured domains in the dried assemblies

Lignin-First Integrated Hydrothermal Treatment (HTT) and Synthesis of Low-Cost Biorefinery Particles

Hydrothermal treatments (HTT) are used in the biorefineries to effectively valorize carbohydrate fractions and their products. However, lignin is often marginalized as a secondary component. Herein, we propose a new biorefinery approach focused on lignin valorization. We demonstrate that high-value lignins can be extracted using a simple, green, and affordable process consisting of an optimized HTT followed by lignin extraction with aqueous acetone under ambient conditions. Significantly, the chemical structure and molecular mass of the lignin can be tailored by the selection of the process variables while maintaining a high yield, in the range of ∼60–90%. For example, the average molecular mass (Mw) of the isolated lignins is in the range between 2.5 and 5 kDa, while the amount of β-O-4 linkages is 4–28 per 100 Ar. The extracted lignins are further used to generate micro- and nanoparticles by using an aerosol flow system. The introduced lignin profiling affords control of particle properties, including average size and distribution, surface energy, and wettability. Overall, the suggested approach allows customization of lignin products while achieving a 58% reduction in the lignin particles production costs compared to the lowest prime figures reported so far

Benchmarking the Humidity-Dependent Mechanical Response of (Nano)fibrillated Cellulose and Dissolved Polysaccharides as Sustainable Sand Amendments

Soil quality is one of the main limiting factor in the development of the food sector in arid areas, mainly due to its poor mechanics and lack of water retention. Soil’s organic carbon is nearly absent in arid soils, though it is important for water and nutrient transport, to soil mechanics, to prevent erosion, and as a long-term carbon sink. In this study, we evaluate the potential benefits that are brought to inert sand by the incorporation of a range of, mainly, cellulosic networks in their polymeric or structured (fiber) forms, analogously to those found in healthy soils. We explore the impact of a wide range of nonfood polysaccharide-based amendments, including pulp fibers, nanocellulose, cellulose derivatives, and other readily available polysaccharide structures derived from arthropods (chitosan) or fruit peels (pectin) residues. A practical methodology is presented to form sand–polymer composites, which are evaluated for their soil mechanics as a function of humidity and the dynamics of their response to water. The mechanics are correlated to the network of polymers formed within the pores of the sandy soil, as observed by electron microscopy. The response to water is correlated to both the features of the network and the individual polysaccharides’ physicochemical features. We expect this work to provide a rapid and reproducible methodology to benchmark sustainable organic amendments for arid soils

<i>In Situ</i> Biofabrication of Microbial Cellulose Capsules Carrying Cubosomes: Toward Colon Targeted Multidrug Delivery

The colon is a main absorption site (nutrients and drugs) and a target for oral therapeutic delivery. However, the latter is challenged by the fact that most drugs degrade during transit in the gastrointestinal tract (GIT). Herein, we rationally designed a universal controlled-release system based on cubosomes contained in microbial nanocellulose capsules that enabled oral administration and pH-triggered delivery of bioactives. We show that the bicontinuous cubosome structure allows the simultaneous incorporation of drugs with differing polarity or surface energy. Furthermore, the multidrug cubosomes combined with the cellulose carrier by in situ biofabrication was demonstrated as a route toward multicomponent 3D capsules with added protection in the GIT. The obtained capsules were subsequently coated with sodium alginate to enable responsiveness, achieving dual cargo-controlled release and site-specific administration. In sum, we successfully engineered pH-responsive, nontoxic microcapsules as a versatile platform for colon-targeted multidrug delivery