Cellulose nanocrystals (CNCs) possess the ability to form helical periodic structures that generate structural colors. Due to the helicity, such self‐assembled cellulose structures preferentially reflect left‐handed circularly polarized light of certain colors, while they remain transparent to right‐handed circularly polarized light. This study shows that combination with a liquid crystal enables modulation of the optical response to obtain light reflection of both handedness but with reversed spectral profiles. As a result, the nanophotonic systems provide vibrant structural colors that are tunable via the incident light polarization. The results are attributed to the liquid crystal aligning on the CNC/glucose film, to form a birefringent layer that twists the incident light polarization before interaction with the chiral cellulose nanocomposite. Using a photoresponsive liquid crystal, this effect can further be turned off by exposure to UV light, which switches the nematic liquid crystal into a nonbirefringent isotropic phase. The study highlights the potential of hybrid cellulose systems to create self‐assembled yet advanced photoresponsive and polarization‐tunable nanophotonics.
Synthesis of superabsorbent particles from nontoxic wheat gluten (WG) protein, as an industrial co‐product, is presented. A natural molecular cross‐linker named genipin (a hydrogenated glycoside) is used together with a dianhydride (ethylenediaminetetraacetic EDTAD), to enable the preparation of a material with a network structure capable of swelling up to ≈4000% in water and ≈600% in saline solution. This represents an increase in swelling by over 10 times compared to the already highly absorbing gluten reference material. The carboxylation (using EDTAD) and the cross‐linking of the protein result in a hydrogel with liquid retention capacity as high as 80% of the absorbed water remaining in the WG network on extensive centrifugation, which is higher than that of commercial fossil‐based superabsorbents. The results also show that more polar forms of the reacted genipin are more effectively grafted onto the protein, contributing to the swelling and liquid retention. Microscopy of the materials reveals extensive nanoporosity (300 nm), contributing to rapid capillarity‐driven absorption. The use of proteins from agricultural industries for the fabrication of sustainable protein superabsorbents is herein described as an emerging avenue for the development of the next generation daily‐care products with a minimal environmental impact.
It is always a challenge to determine the total cellulase activity efficiently without reducing accuracy. The most common total cellulase activity assay is the filter paper assay (FPA) established by the International Union of Pure and Applied Chemistry (IUPAC). A new procedure to measure the FPA with microplate-based assay was studied in this work, which followed the main idea of IUPAC to dilute cellulase preparation to get fixed glucose release. FPAs of six cellulase preparations were determined with the microplate-based assay. It is shown that FPAs of cellulase Youtell, RCconc, R-10, Lerkam, Yishui and Sinopharm were 67.9, 46.0, 46.1, 27.4, 7.6 and 8.0 IU/ml respectively. There was no significant difference at the 95% confidence level between the FPA determined with IUPAC and the microplate-based assay. It could be concluded that the FPA could be determined by the microplate-based assay with the same accuracy and much more efficiency compared with that by IUPAC.
Anisotropic carbon-rich
microcapsule morphologies are of great
value in many applications including catalysis, energy storage, biomedicine,
and osmosis-triggered drug delivery, due to an observed shape effect.
However, high-precision synthesis, to generate large yields of well-defined
anisotropic shapes, is generally challenging. Here, we show for the
first time that a modified carbon-rich waste-material, a fractionated
and acetylated Kraft lignin, enables facile production of large amounts
of well-defined “acorn-like” microcapsules with heterogeneous
shell thicknesses. This is due to the inherent physicochemical properties
of the fractionated lignin at the oil/water (O/W) interface. The acorn-shape
is strongly related to two distinct lignin-molecule populations, that
phase separate during microcapsule formation. Fine-tuning the post-treatment
conditions (pressure or hydrothermal temperature) results in a number
of different microcapsule shapes; hemisphere, bowl, mini-tablets,
or spheres with single holes. Further chemical modification to their
surfaces is also demonstrated. The present study provides a new library
of shape-anisotropic carbon-rich building blocks that open new avenues
for assembling hierarchical material with a high level of complexity.
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