Abstract We report (1) successful extraction and characterization of cellulose from northern hemisphere green macroalgae Ulva lactuca ( Ulva fenestrata ) collected along the Swedish west coast and cultivated indoors under controlled conditions, followed by (2) its utilization in the production of lignin-free cellulose nanofibrils (CNF). Cellulose was extracted by sequential treatment with ethanol, hydrogen peroxide, sodium hydroxide, and hydrochloric acid, yielding a cellulose-rich insoluble fraction. The extracted cellulose was disintegrated into CNF using a mechanical homogenization process without any further enzymatic pre-treatments. In addition, regenerated cellulose was prepared. XRD characterization of the CNF showed characteristic peaks for the cellulose I allomorph and confirmed that the nanofibrils were semicrystalline with a crystallinity index of 48%. Regenerated cellulose was mostly amorphous with an XRD pattern indicating the presence of the cellulose II allomorph. The cellulose fractions were essentially free from inorganic substances and thermally stable up to around 260 °C. Structural mapping with CP-MAS 13 C-NMR sustains the cellulose content of CNF and regenerated cellulose, respectively, yet ion chromatography identified the presence of 10–15% xylose in the fractions. Optotracing was used as a novel and non-disruptive tool to selectively assess the polysaccharide composition of the cellulose fractions and produced CNF aiming to shed light on this hitherto non-resolved origin of xylose in Ulva cell wall matter. Fluorescence excitation and emission spectra of a panel of 4 oligothiophenes identified and verified the presence of cellulose and sustain the conclusion that the isolated fractions consist of cellulose intertwined with a small amount of a xylose-containing glucan copolymer. Graphic abstract
Hydrogels based on the polysaccharide ulvan from the green macroalgae Ulva fenestrata were synthesized and evaluated as an adsorbent for heavy metals ions and methylene blue. Ulvan was extracted from Ulva fenestrata using diluted hydrochloric acid and recovered by precipitation with EtOH. The extracted ulvan was converted into ulvan dialdehyde via periodate-oxidation and subsequently combined with gelatin yielding hydrogels. The hydrogels showed good water-uptake capacity with a maximum swelling degree of 2400 % in water and 900 % in PBS buffer. Adsorption tests of methylene blue showed a maximum adsorption capacity of 465 mg/g. The adsorption data of methylene blue followed the pseudo-second order kinetics and agreed with the Langmuir adsorption isotherm. The maximum adsorption capacity of heavy metal ions was 14 mg/g for Cu2+, 7 mg/g for Co2+and 6 mg/g for Ni2+and Zn2+ indicating that the hydrogels have a stronger affinity for Cu2+ than for Co2+, Ni2+, and Zn2+.
Side streams from wheat processing constitute a widely available renewable resource from biomass rich in carbohydrate polymers and proteins, with great potential as biopolymeric matrices for the production of biobased films for food packaging applications. In this study, arabinoxylan (AX) was extracted with high purity from wheat bran via alkaline extraction and was combined with wheat gluten for the preparation of AX-gluten glycoprotein films using citric acid (CA) as a crosslinker and glycerol as plasticizer. Self-standing and flexible films were prepared via solvent casting and further cured at 150 °C to initiate crosslinking. FTIR analysis and solubility tests revealed that chemical crosslinking had occurred to some extent involving both the AX and gluten components, suggesting the formation of glycoprotein structures. However, the evaluation of the mechanical and barrier properties of the films showed that CA mainly works as a plasticizing agent rather than a crosslinking agent at the conditions used in the study. UV–Vis spectroscopy measurements showed that the films had an excellent ability to block UV-light. This study demonstrates the successful preparation of AX-gluten glycoprotein films with excellent mechanical and barrier properties, which can be tuned by the protein content and CA addition balancing both plasticizing and crosslinking effects.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Cultivation of seaweed has been conducted for centuries in Asia, but is largely undeveloped in Sweden even though there is potential for this industry. Seaweed offers benefits compared with land-ba ...
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
