Rosenvalentin4571

A series of lanthanide-based nanopaper (Nd-nanopaper) was synthesized via a neodymium organic framework (Nd-MOFs)-grafted TEMPO-oxidized cellulose nanofibrils (tCNF) using a solvothermal reaction. Not using the traditional down-conversion visible emissions of anti-counterfeiting techniques, this Nd-nanopaper achieved down-conversion near-infrared (NIR) and up-conversion visible emissions. The down-conversion luminescent property of these Nd-nanopapers exhibited characteristic NIR luminescence (λEm = 1080 nm) of Nd3+ ions with 311 nm excitation, undergoing an "antenna" effect. In contrast, the up-conversion visible light emission (λEm =450 nm) of Nd-nanopaper was detected under 580 nm excitation. #link# The mechanism of up-conversion fluorescence was ascribed to excited-state absorption and energy transfer up-conversion. Interestingly, Nd-nanopaper induced both up and down-conversions for visible and NIR emissions that were completely devoid of the interference from fluorescent brighteners and background fluorescence. These switchable up and down-conversion fluorescent Nd-nanopapers with visible and NIR dual emissions or dual channels could be applied in high level anti-counterfeiting applications.Cellulose-lignin composite fibres were spun from ionic liquid (IL) solutions by dry-jet wet spinning. Birch pre-hydrolysed Kraft (PHK) pulp and organosolv beech (BL) or spruce lignin (SL) were dissolved in the IL 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) to prepare spinning dopes. Fibres with lignin concentrations of up to 50 % were spun successfully. The fibres were analysed focusing on important properties for the production of carbon fibres (CF). Due to the higher molar mass of the SL compared to the BL, SL showed higher stability in the spinning process, giving higher lignin content in the final fibres. link2 The CF yield after carbonization increased with increasing lignin content. The higher carbon content of SL compared to BL, resulted in moderately higher CF yield of the SL fibres, compared to fibres with BL. Overall, the produced cellulose-lignin composite fibres show great potential as precursors for CF production.Transdermal immunomodulation is of increasing interest as an efficient drug delivery method. It non-invasively delivers drugs directly to skin-resident immune cells, thereby avoiding the first-pass metabolism. Herein, we prepared ovalbumin-conjugated hyaluronic acid-methacrylate (HAMA-OVA) and schizophyllan-methacrylate (SPGMA) hybrid nanogels and investigated their suitability for topical delivery. The particle size was controlled to between 100 and 300 nm using ultrasonication and filtering processes. The nanogels penetrated the porcine stratum corneum layer and were deposited in the dermis via hybridization with HAMA. In addition, the hybridized SPGMA promoted the internalization of the nanogels into dendritic cells (DCs; JAWSII), which resulted in an improvement in the ovalbumin delivery efficiency. In molecular biological assessments, the hybrid nanogels upregulated the DC activation marker interleukin-6 and induced DC maturation, indicating antigen-presenting behavior. These results suggest that HAMA/SPGMA hybrid nanogels are a promising topical delivery carrier for immunomodulation and vaccinations.Alginate is an abundant natural polysaccharide widely utilized in various biomedical applications. Alginate also possesses numerous hydroxyl and carboxylate functional groups that allow chemical modifications to introduce different functionalities. However, it is difficult to apply various chemical reactions to alginate due to limited solubility in organic solvents. Herein, functional moieties for radical polymerization and cell adhesion were separately conjugated to hydroxyl and carboxylate groups of alginate, respectively, in order to independently control the crosslinking density and cell adhesive properties of hydrogels. Sodium counterions of alginate are first substituted with tetrabutylammonium ions to facilitate the dissolution in an organic solvent, followed by in situ conjugations of (1) cell adhesion molecules (CAM) via carbodiimide-mediated amide formation and (2) methacrylate via ring-opening nucleophilic reaction. Enpp-1-IN-1 resulting CAM-linked methacrylic alginate was able to not only crosslink different monomers to form hydrogels with varying mechanical properties, but also induce stable cell adhesion to the hydrogels.Bacterial cellulose (BC) is a good material candidate for wound dressing because of its fine 3-D network structure, high mechanical strength and water holding capability, and good biocompatibility. In this study, a composite hydrogel was prepared by using 1,4-butanediol diglycidyl ether (BDDE) to cross-link BC and hyaluronic acid (HA). Cross-linked BC/HA composites exhibited a denser and smoother surface. This dense morphology improved water retention capability and dimensional stability. BDDE cross-linked BC/HA composite with 2% HA and 1% BDDE showed better overall properties, including water stability (12.7 % water solubility), mechanical properties (tensile strength ∼ 0.61 MPa and Young's modulus ∼1.62 MPa) and thermal stability (maximum degradation temperature 360 °C), as compared to BC/HA without crosslinking. In addition, cell toxicity assays and morphology indicated the BDDE cross-linked BC/HA composite significantly promoted cell proliferation and adhesion. This chemically cross-linked BC/HA composite may have many new biomedical applications in wound care.Cellulose can be dissolved in concentrated acidic aqueous solvents forming extremely viscous solutions, and, in some cases, liquid crystalline phases. In this work, the concentrated phosphoric acid aqueous solvent is revisited implementing a set of advanced techniques, such as cryo-transmission electronic microscopy (cryo-TEM), polarization transfer solid-state nuclear magnetic resonance (PTssNMR), and diffusing wave spectroscopy (DWS). Cryo-TEM images confirm that this solvent system is capable to efficiently dissolve cellulose. No cellulose particles, fibrils, or aggregates are visible. Conversely, PTssNMR revealed a dominant CP signal at 25 °C, characteristic of C-H bond reorientation with correlation time longer than 100 ns and/or order parameter above 0.5, which was ascribed to a transient gel-like network or an anisotropic liquid crystalline phase. Increasing the temperature leads to a gradual transition from CP to INEPT-dominant signal and a loss of birefringence in optical microscopy, suggesting an anisotropic-to-isotropic phase transition. Finally, an excellent agreement between optical microrheology and conventional mechanical rheometry was also obtained.Depolymerization of chitin results in chitooligosaccharides (COS) that induce immunostimulatory effects and disease protective responses and have many potential applications in agriculture and medicine. Isolation of bioactive COS with degree of polymerization (DP) larger than six from chitin hydrolyzates is hampered by their water insolubility. Enzymatic synthesis by exploiting the transglycosylation activity of GH18 chitinases offers a potential strategy to access oligomers in the range of bioactive DPs. We engineered SpChiD chitinase as a glycosynthase by mutation of the assisting residue of the catalytic triad in the substrate-assisted mechanism for polymerization of an oxazoline substrate (DP5ox). The insoluble polymer containing DP10 was partially hydrolyzed due to the significant residual hydrolase activity of the mutant enzyme. Combined mutations that strongly reduce the hydrolytic activity, in which the original catalytic triad only retains the essential acid/base residue, together with neighboring mutations in the -1/+1 subsites region, render glycosynthase-like chitinases able to produce chitin oligomers with DP10 as major product in good yields.This work demonstrates a unique approach of utilizing alkali lignin (AL), as smart additive to in situ BC fermentation in which it concurrently acts as promoter to microbial growth as well as reinforcing filler for fabrication of multifunctional composites. Traditionally, BC fermentation is accompanied by inhibitor formation with sudden drop in pH leading to low yield and biomass growth. AL due to its antioxidant nature prevents formation of gluconic acid as byproduct, at ∼0.25 wt.% AL based on inhibitory byproduct kinetics. Interestingly, AL self-assembles to form primary and secondary structures in BC pores, resulting in simultaneous improvement in thermal stability as well as toughness. The BC/AL films show strong UV-blocking capacity with prolonged radical scavenging activity and preventing browning of freshly cut apples making it suitable as food packaging. Therefore, present work opens up new avenues for fabrication of high-performance BC-based composites through selection of smart materials which can simultaneously improve BC bioprocessing.Artemisia sphaerocephala Krasch (ASK) is an important member of Compositae (Asteraceae) family. link3 Its seeds have been widely used as traditional medicine and to improve the quality of food. Water soluble and water insoluble polysaccharides are found in the seeds of this plant. Research has been conducted on the extraction of polysaccharides, their modification and determination of their structure. To date different techniques for extraction purposes have been applied which are reviewed here. Antioxidant, antidiabetic, anti-obesogenic, antitumor, and immunomodulatory activities have been explored using in vivo and in vitro methods. Moreover, these polysaccharides have been used as packaging material and as a sensing component for monitoring the freshness of packaged food. Some experimental results have shown that the quality of foods is also improved by using them as a food additive. We have also indicated some of the potential areas that are needed to be explored.Periodate oxidation of polysaccharides has transitioned from structural analysis into a modification method for engineered materials. This review summarizes the research on this topic. Fibers, fibrils, crystals, and molecules originating from forests that have been subjected to periodate oxidation can be crosslinked with other entities via the generated aldehyde functionality, that can also be oxidized or reduced to carboxyl or alcohol functionality or used as a starting point for further modification. Periodate-oxidized materials can be subjected to thermal transitions that differ from the native cellulose. Oxidation of polysaccharides originating from forests often features oxidation of structures rather than liberated molecules. This leads to changes in macro, micro, and supramolecular assemblies and consequently to alterations in physical properties. This review focuses on these aspects of the modulation of structural hierarchies due to periodate oxidation.Cellulose-based oil-in-water (O/W) emulsions were studied by diffusing wave spectroscopy (DWS) regarding the effect of the cellulose concentration and mixing rate on the average droplet size, microrheological features and stability. Furthermore, the microstructure of these emulsions was imaged by cryo-scanning electron microscopy (cryo-SEM). The micrographs showed that cellulose was effectively adsorbed at the oil-water interface, resembling a film-like shell that protected the oil droplets from coalescing. The non-adsorbed cellulose that was observed in the continuous aqueous medium, contributed to the enhancement of the viscosity of the medium, leading to an improvement in the stability of the overall system. Generally, the higher the cellulose concentration and mixing rate, the smaller the emulsion droplets formed, and the higher was their stability. The combination of both techniques, DWS and cryo-SEM, revealed a very appealing and robust methodology for the characterization and design of novel emulsion-based formulations.