Algal Cellulose Research Articles

High-aligned oppositely-charged nanocellulose/MXene aerogel membranes through synergy of directional freeze-casting and structural densification for osmotic-energy harvesting

Optimization of ion-transport paths can considerably improve ion-transport capabilities in charged nanochannels. Thus, the assembly of high-charge-density one- and two-dimensional nanomaterials into aligned nanochannels is necessary for high-performance osmotic-energy harvesting. Herein, we prepared cellulose/MXene aerogel membranes with opposite charges and aligned nanochannels via chemical modification on algal cellulose nanofibers and MXene nanosheets, unidirectional freeze casting, and structural densification to considerably enhance the ionic conductivity in low-concentration solutions (maximum conductivity of 2.88 × 10−3 S cm−1). In particular, the aligned membrane had an output power density of 2.97 and 4.89 times higher than membranes used for suction filtration and isotropic nanochannels, respectively, demonstrating the necessity for nanostructure control. In addition, due to the photothermal effect of MXene, the positively–negatively (P–N) charged unit produced a maximum output power density of 8.87 W m−2 under a concentration gradient of artificial seawater and river water and simulated sunlight. Moreover, the unit maintained 90.4% of its original output capacity after 168 h of operation. As a proof of concept, we created nine series of P–N units and successfully powered an electronic calculator with an output voltage of 1.85 V. This study reveals improvements in developing renewable materials with an aligned nanostructure for high-performance osmotic-energy conversion.

Recycled Waste as Polyurethane Additives or Fillers: Mini-Review.

The intensive development of the polyurethanes industry and limited resources (also due to the current geopolitical situation) of the raw materials used so far force the search for new solutions to maintain high economic development. Implementing the principles of a circular economy is an approach aimed at reducing the consumption of natural resources in PU production. This is understood as a method of recovery, including recycling, in which waste is processed into PU, and then re-used and placed on the market in the form of finished sustainable products. The effective use of waste is one of the attributes of the modern economy. Around the world, new ways to process or use recycled materials for polyurethane production are investigated. That is why innovative research is so important, in which development may change the existing thinking about the form of waste recovery. The paper presents the possibilities of recycling waste (such as biochar, bagasse, waste lignin, residual algal cellulose, residual pineapple cellulose, walnut shells, silanized walnut shells, basalt waste, eggshells, chicken feathers, turkey feathers, fiber, fly ash, wood flour, buffing dust, thermoplastic elastomers, thermoplastic polyurethane, ground corncake, Tetra Pak®, coffee grounds, pine seed shells, yerba mate, the bark of Western Red Cedar, coconut husk ash, cuttlebone, glass fibers and mussel shell) as additives or fillers in the formulation of polyurethanes, which can partially or completely replace petrochemical raw materials. Numerous examples of waste applications of one-component polyurethanes have been given. A new unexplored niche for the research on waste recycling for the production of two components has been identified.

Algal cellulose reinforced polyvinyl alcohol composite hydrogel with controlled niacinamide release for cosmeceutical applications

Niacinamide, a multi-functional cosmeceutical ingredient, has been extensively formulated in skincare products. To enhance the efficacy of niacinamide penetration into the skin, numerous hybrid hydrogels and drug delivery systems have been extensively developed as carriers for efficient entrapment and release of niacinamide. However, the mechanical properties and limited capacity of achieving high loading and sustained drug release are predominantly determined by synthetic polymers. Hence, it becomes imperative to develop innovative hybrid materials. Here, we successfully fabricated algal cellulose/Polyvinyl alcohol (PVA) composite hydrogels by employing cellulose extracted from Cladophora spp. and Ulva spp. through alkaline treatment. The physiochemical characteristics and properties of the composite hydrogels including niacinamide entrapment and release efficiency were examined. The results found that reinforcing PVA with algal cellulose resulted in a reduction in pore size with an increase in both number and distribution. The reinforcement also led to enhanced thermal stability and improved swelling properties. The Ulva cellulose/PVA composite hydrogel exhibited a higher swelling ratio and encapsulation efficiency compared to Cladophora cellulose/PVA composite hydrogel. Furthermore, the results of release kinetics confirmed that the Ulva cellulose/PVA composite hydrogel showed the most effective mechanism of niacinamide release from hydrogel, transitioning from non-Fickian to Fickian model. This suggests that it is a suitable material for niacinamide delivery as a cosmeceutical ingredient via the transdermal route. This study implies that the Ulva cellulose/PVA composite hydrogel could serve as a promising vehicle for niacinamide delivery across the skin.

Assessment of the Alga Cladophora glomerata as a Source for Cellulose Nanocrystals.

Nanocellulose is isolated from cellulosic fibers and exhibits many properties that macroscale cellulose lacks. Cellulose nanocrystals (CNCs) are a subcategory of nanocellulose made of stiff, rodlike, and highly crystalline nanoparticles. Algae of the order Cladophorales are the source of the longest cellulosic nanocrystals, but manufacturing these CNCs is not well-studied. So far, most publications have focused on the applications of this material, with the basic manufacturing parameters and material properties receiving little attention. In this article, we investigate the entirety of the current manufacturing process from raw algal biomass (Cladophora glomerata) to the isolation of algal cellulose nanocrystals. Yields and cellulose purities are investigated for algal cellulose and the relevant process intermediates. Furthermore, the effect of sulfuric acid hydrolysis, which is used to convert cellulose into CNCs and ultimately determines the material properties and some of the sustainability aspects, is examined and compared to literature results on wood cellulose nanocrystals. Long (>4 μm) CNCs form a small fraction of the overall number of CNCs but are still present in measurable amounts. The results define essential material properties for algal CNCs, simplifying their future use in functional cellulosic materials.

Extraction and characterization of modified algae derivative cellulose and its mixtures for dye removal

A new bio-sorbent derived from green algae biomass, Arthrospira platensis (Spirulina), was found to be economically practical for water decontamination. This biosorbent comprised of microalgae cellulose, poly(lactic acid) (PLA), Dabai activated carbon (AC), and montmorillonite (MMT), each plays a distinctive role in removing methylene blue (MB) dye. The presence of hydroxyl and carbonyl functional groups in algae cellulose, confirmed by the FTIR analysis, offered binding sites for dye removal. Scanning electron microscopy demonstrated the morphological structure of the biosorbent, highlighting the combined effect of microalgae cellulose, PLA, Dabai AC, and MMT mixtures. The inclusion of Dabai AC and MMT improved micropores and mesopores, enhancing adsorption reactions. The Brunauer-Emmett-Teller (BET) analysis confirmed that the sample containing microalgae cellulose, Dabai AC, and MMT clay in PLA had a specific surface area of 0.784 m2/g, three times higher than the PLA + cellulose sample. Additionally, adding 1% MMT to the sample improved the particle dispersion on the surface of the hydrophobic PLA, thereby improving its thermal properties. Remarkably, the biosorbent effectively eliminated 86.8% of MB dye from an initial concentration of 50 mg/L after 60 min of Vis-light irradiation using Ultraviolet-visible spectroscopy.

Low-cost biosorption of Fe(II) and Fe(III) from single and binary solutions using Ulva lactuca-derived cellulose nanocrystals-graphene oxide composite film

The marine algal biomass of Ulva lactuca was utilized for the extraction of cellulose and the development of cellulose nanocrystals/graphene oxide film. Cellulose nanocrystals with 50–150 nm were produced by H2SO4 hydrolysis of the algal cellulose. The adsorption efficiency of the nanocomposite film for Fe(II) and Fe(III) ions was successfully evaluated using Box-Behnken design. The maximum removal for Fe(II) (64.15%) could be attained at pH 5.13, adsorbent dosage 7.93 g L−1 and Fe(II) concentration 15.39 mg L−1, while the biosorption of Fe(III) was 69.92% at pH 5.0, adsorbent dosage 2 g L−1, and Fe(III) concentration 15.0 mg L−1. However, in the binary system, the removal efficiency of Fe(II) was enhanced to 95.48% at Fe(II):Fe(III) ratio of 1:1, while the Fe(III) removal was increased to 79.17% at ratio 1:2. The pseudo-second-order kinetics exhibited better fitting to the experimental results of Fe(II) and Fe(III) adsorption in both single and binary systems. The intra-particle diffusion was prominent during the biosorption, but the effect of the external mass transfer was significant. The Langmuir, Freundlich, Langmuir–Freundlich, Temkin, and Dubinin-Radushkevich isotherms showed satisfactory fitting to the experimental data, but they differ in priority based on iron state and pH. The adsorption of Fe(II) in the presence of Fe(III) in a mixture was best represented by the extended Langmuir model, while the extended Langmuir–Freundlich model best fitted the adsorption of Fe(III). The FT-IR analysis indicated that physisorption through electrostatic interaction/complexation is the predominant mechanism for the adsorption of iron using the nanocomposite film.

Recent Progress on Tailoring the Biomass-Derived Cellulose Hybrid Composite Photocatalysts.

Biomass-derived cellulose hybrid composite materials are promising for application in the field of photocatalysis due to their excellent properties. The excellent properties between biomass-derived cellulose and photocatalyst materials was induced by biocompatibility and high hydrophilicity of the cellulose components. Biomass-derived cellulose exhibited huge amount of electron-rich hydroxyl group which could promote superior interaction with the photocatalyst. Hence, the original sources and types of cellulose, synthesizing methods, and fabrication cellulose composites together with applications are reviewed in this paper. Different types of biomasses such as biochar, activated carbon (AC), cellulose, chitosan, and chitin were discussed. Cellulose is categorized as plant cellulose, bacterial cellulose, algae cellulose, and tunicate cellulose. The extraction and purification steps of cellulose were explained in detail. Next, the common photocatalyst nanomaterials including titanium dioxide (TiO2), zinc oxide (ZnO), graphitic carbon nitride (g-C3N4), and graphene, were introduced based on their distinct structures, advantages, and limitations in water treatment applications. The synthesizing method of TiO2-based photocatalyst includes hydrothermal synthesis, sol-gel synthesis, and chemical vapor deposition synthesis. Different synthesizing methods contribute toward different TiO2 forms in terms of structural phases and surface morphology. The fabrication and performance of cellulose composite catalysts give readers a better understanding of the incorporation of cellulose in the development of sustainable and robust photocatalysts. The modifications including metal doping, non-metal doping, and metal-organic frameworks (MOFs) showed improvements on the degradation performance of cellulose composite catalysts. The information and evidence on the fabrication techniques of biomass-derived cellulose hybrid photocatalyst and its recent application in the field of water treatment were reviewed thoroughly in this review paper.

Enzyme-assisted extraction of fucoidan from Kjellmaniella crassifolia based on kinetic study of enzymatic hydrolysis of algal cellulose

Fucoidan extraction from Kjellmaniella crassifolia was enhanced through β-glucosidase fortified cellulase treatment. Kinetic study of the hydrolysis of isolated seaweed cellulose by commercial enzymes was carried out, and cellulolytic enzyme cocktail was optimized according to the degradation kinetics using response surface methodology for fucoidan extraction. Cellulose (9.88 wt%, d.b.) found in the seaweed was highly crystalline (CrI: 83.24 %). β-glucosidase apparently improved the affinity of the cellulolytic enzymes for the cellulose by eliminating cellobiose feedback inhibition. Treating the seaweed with 30 FPU cellulase supplemented with 286.64 CBU β-glucosidase per gram cellulose, followed by conventional ethanol precipitation, the fucoidan extraction yield based on seaweed feedstock dry matter reached 4.74 %. The total sugar content and sulfate content of the product reached 76.68 % and 22.83 %, respectively, with fucose accounting for 62.46 % of the total sugar. The product extracted under optimal conditions exhibited apparently concentration-dependent antioxidant activity, with IC50 values for DPPH, Hydroxyl and ABTS radical scavenging reaching 2.43 mg/mL, 1.02 mg/mL and 1.12 mg/mL, respectively. The results showed that the proposed enzymatic treatment based on cellulose hydrolysis kinetics effectively disrupted the cell wall and facilitated the release and extraction of fucoidan from the seaweed.

Deletion of AA9 Lytic Polysaccharide Monooxygenases Impacts A. nidulans Secretome and Growth on Lignocellulose.

ABSTRACTLytic polysaccharide monooxygenases (LPMOs) are oxidative enzymes found in viruses, archaea, and bacteria as well as eukaryotes, such as fungi, algae and insects, actively contributing to the degradation of different polysaccharides. In Aspergillus nidulans, LPMOs from family AA9 (AnLPMO9s), along with an AA3 cellobiose dehydrogenase (AnCDH1), are cosecreted upon growth on crystalline cellulose and lignocellulosic substrates, indicating their role in the degradation of plant cell wall components. Functional analysis revealed that three target LPMO9s (AnLPMO9C, AnLPMO9F and AnLPMO9G) correspond to cellulose-active enzymes with distinct regioselectivity and activity on cellulose with different proportions of crystalline and amorphous regions. AnLPMO9s deletion and overexpression studies corroborate functional data. The abundantly secreted AnLPMO9F is a major component of the extracellular cellulolytic system, while AnLPMO9G was less abundant and constantly secreted, and acts preferentially on crystalline regions of cellulose, uniquely displaying activity on highly crystalline algae cellulose. Single or double deletion of AnLPMO9s resulted in about 25% reduction in fungal growth on sugarcane straw but not on Avicel, demonstrating the contribution of LPMO9s for the saprophytic fungal lifestyle relies on the degradation of complex lignocellulosic substrates. Although the deletion of AnCDH1 slightly reduced the cellulolytic activity, it did not affect fungal growth indicating the existence of alternative electron donors to LPMOs. Additionally, double or triple knockouts of these enzymes had no accumulative deleterious effect on the cellulolytic activity nor on fungal growth, regardless of the deleted gene. Overexpression of AnLPMO9s in a cellulose-induced secretome background confirmed the importance and applicability of AnLPMO9G to improve lignocellulose saccharification.IMPORTANCE Fungal lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that boost plant biomass degradation in combination with glycoside hydrolases. Secretion of LPMO9s arsenal by Aspergillus nidulans is influenced by the substrate and time of induction. These findings along with the biochemical characterization of novel fungal LPMO9s have implications on our understanding of their concerted action, allowing rational engineering of fungal strains for biotechnological applications such as plant biomass degradation. Additionally, the role of oxidative players in fungal growth on plant biomass was evaluated by deletion and overexpression experiments using a model fungal system.

Drying Method Effect on Structural and Surface Properties of Brown Algae Cellulose

Drying Method Effect on Structural and Surface Properties of Brown Algae Cellulose

Microalgal nanocellulose - opportunities for a circular bioeconomy.

Over 3 billion years, photosynthetic algae have evolved complex uses for cellulose, the most abundant polymer worldwide. A major cell-wall component of lignocellulosic plants, seaweeds, microalgae, and bacteria, cellulose can be processed to nanocellulose, a promising nanomaterial with novel properties. The structural diversity of macro- and microalgal nanocelluloses opens opportunities to couple low-impact biomass production with novel, green-chemistry processing to yield valuable, sustainable nanomaterials for a multitude of applications ranging from novel wound dressings to organic solar cells. We review the origins of algal cellulose and the applications and uses of nanocellulose, and highlight the potential for microalgae as a nanocellulose source. Given the limited state of current knowledge, we identify research challenges and strategies to help to realise this potential.

A review on the properties and applications of chitosan, cellulose and deep eutectic solvent in green chemistry

The concept of green chemistry has attracted attention due to the green synthesis and ecofriendly nature of the compounds leading to the green and sustainable chemical industries and processes. Chitosan is an ecofriendly material, which is biodegradable, non-toxic, and biocompatible. It has the potential to be modified into biofilms for various applications such as biomedical, packaging, and pharmaceutical fields. Nevertheless, some poor properties of chitosan restrict its wide applications. The incorporation of nanocellulose fillers into chitosan matrix can enhance the mechanical and thermal properties of chitosan. Cellulose nanomaterials can be achieved through chemical and mechanical modifications. The common type of nanocellulose are cellulose nanofibers (CNFs), cellulose nano-whiskers (CNWs), tunicate CNCs (t-CNCs), algae cellulose particles (AC) and bacterial cellulose particles (BC). Nanocellulose are applied as the reinforcement fillers in various polymer matrices such as polysaccharides, proteins, lipids, polylactic acid etc. Deep eutectic solvents (DES) are relatively novel green solvents, which can be applied in various fields. DES are widely applied in metal processing, polymer processing and synthesis. Even though there are not much studies available on DES for synthesis of nanocomposite films; however they are used as eco-friendly solvents in manufacturing processes. This study reviews the discovery, structure, properties of chitosan and cellulose, their derivatives and applications. In addition, the paper also discusses the properties of DES and their applications.

Characteristics of Cellulose Nanofibrils (CNF) Film from Red Algae Pulp

Red algae cellulose is a promising feedstock for value-added industrial products because it has a faster growth rate, thinner fiber structure, and is easier to extract fiber fromthan wood. To evaluate red algae cellulose as a feed material for its potential applications, CNFs were produced with bleached red algae pulp and then the CNF films were characterized in this study. Both CNFs from the 1-stage and 3-stage bleached red algae pulps were well fibrillated, although the CNF from 1-stage bleached red algae pulp contained short fibrosis and fibrillated fibers due to residual non-cellulosic compounds. The aspect ratio of the CNF from 3-stage bleached red algae pulp was higher than that of the wood-driven CNF. Besides, the film fabricated with the 3-stage bleached red algae CNF produced a tensile index value of 117.1 Nm/g, which was comparable to the strength of the wood CNF film. The 3-stage bleached algae CNF film had higher elongation and water resistance than the wood CNF film. Thus, utilization of red algae as a raw material for CNF production can widen the choice of feedstocks for potential industrial applications.

Cellulose in Nature - Versatile sources for Novel Applications: A Literature Review

Introduction: Cellulose is the most abundant organic compound and the main component of the plant cell wall. However, it can be derived from other sources: tunicates, algae, and bacteria. Different sources of cellulose were shown to produce end-products of different mechanical properties and were considered for producing cellulose in non-industrial conditions. Methods: Procedures for the extraction of cellulose from different sources are described. They are similar for plants and algae, including bleaching and purification processes amongst others, while bacteria found in symbiotic cultures of bacteria and yeasts (SCOBYs) are capable of growing cellulose layers above their cultivation media. After extraction or bacterial cultivation, mechanical treatments are performed in order to modify new cellulose layers for specific applications. Results: Plant sources of cellulose are various and widely available, and often used for the industrial production of cellulose. Algae-derived microcrystalline cellulose (MCC) is similar to that from plant sources, but has higher crystallinity and, often, requires simpler extraction processes. Finally, cellulose grown by bacteria found in SCOBYs is the most optimal for non-industrial conditions, owing to the simplest cultivation and extraction procedures. Discussion: On a large scale, plant sources of cellulose are the optimal ones. The main downside of algal cellulose is that it is season-dependent, and more difficult to acquire than bacterial and plant sources. While having access to laboratory conditions for incubations and using a pure bacterial culture would be preferable, cultivation methods are simple enough to be adapted for home conditions. Also, conditions of incubation can be varied based upon the intended properties of the end-product: the efficiency of cellulose growth and its properties depend on the chosen carbon source. When bacteria produce a cellulose layer or it is extracted from another source, mechanical treatments for tuning porosity and other properties are applied. Conclusion: Sources of cellulose are numerous, and some are more suitable than others for non-industrial production, namely, using easily obtainable SCOBYs. This allows for a wide variety of applications: from artificial skin and face masks, to sustainable batteries and different food products.

Structural features of brown algae cellulose

Currently, cellulose is one of the most requested natural polymers and the material has a wide range of industrial applications. The most studied and extensively used source of cellulose are coniferous and deciduous wood. At the same time, taking into account the structural and chemical properties of the biopolymer, the influence on the formation of nano-, micro- and macro-characteristics, and the conditions of its biosynthesis, the industry increasingly pay attention to its alternative sources, including algae. In this work, a protein-polysaccharide complex, where cellulose is the principal component, was isolated from samples of brown algae samples collected from the White and Yellow Seas. The structural features of the brown algae cellulose complexes were studied using classical physicochemical methods, as well as FTIR spectroscopy, X-ray spectroscopy, and scanning electron microscopy Analyses revealed stable phase Iβ forms of cellulose predominated in arctic brown algal samples, and the degree of crystallinity of the cellulose product was 54–59%. Scanning electron microscopy revealed that the compound has a fibrous structure, which is most pronounced in samples derived from arctic kelp. These results expand our understanding of use of algal cellulose and macrophytes as a valuable raw material for the production of sorption and composite cellulose-based materials.

Algal cellulose as a reinforcement in rigid polyurethane foam

Algae has long been used as a food and a potential source of valuable and bioactive compounds due to residues left after the extraction process. Discovery of an alternative approach to the residues contributes to commercial feasibility in algae biorefinery. This study aimed to examine the cellulose composition in macroalgae. The physiochemical characteristics of cellulose and its potential use as a reinforcement to polyurethane (PU) foam were investigated. A green filamentous freshwater algal biomass composed of Cladophora sp. and Microspora sp. was treated via alkalization. The treated algae was use as a filler agent to synthesize PU-composite foams. Morphological, chemical, mechanical, physiochemical and viscoelastic properties of cellulose and PU-composite foam were investigated through field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) compressive tests, and dynamic mechanical analysis (DMA). A cellulose yield of 37.2% was obtained from Kai algae via alkalization and the crystallinity index was 63.6%. The use of algae and algal cellulose to synthesize PU-composites resulted in foam density increase, while the compressive modulus decreased. The addition of algal cellulose as filler in PU foam significantly reduced the cell size of foam. Using algae at 0.5% (w/v) and algal cellulose at 1.0% (w/v) as filler in PU-composites increased stiffness at 25–50 °C and transition temperature and decreased loss modulus. These results indicated that algae and algal cellulose added during PU-composite foam production may be integrated into the foam structure and result in more open cells and softer foam. The PU-composite showed greater shock absorbent capacity than PU foam. The results provided a new alternative approach in algal cell residue utilization in terms of material, which could be useful for the packaging industry.

High aspect ratio cellulose nanofibrils from macroalgae Laminaria hyperborea cellulose extract via a zero-waste low energy process

Homogeneous high aspect ratio cellulose nanofibrils (CNFs) were prepared from Laminaria hyperborea (LH) seaweed cellulose without any initial mechanical, biological or chemical pre-treatments. Fourier-transform infrared spectrophotometry revealed that LH cellulose was of the cellulose Iα allomorph, typical of algal cellulose. Compared with wood derived CNF, significant enhancements in crystallinity, viscoelastic properties, water retention values (WRV) and morphological characteristics were identified with a single pass at 1 wt. % cellulose content through a high-pressure homogeniser. Further mechanical fibrillation did not lead to appreciable improvements in material properties that would justify the added energy consumption, which at a single pass is at least a factor of 10 lower than with wood cellulose processing. Good quality CNFs with little compromise in material properties were also obtainable at 2–3 wt. % cellulose contents as identified from viscoelastic analysis, WRV and morphological analysis. LHCNFs also showed good thermal stability, which in summary presents a multifunctional high value cellulose nanomaterial that can find application in various fields.Graphic abstract

Interfacial molecular interactions of cellobiohydrolase Cel7A and its variants on cellulose

BackgroundMolecular-scale mechanisms of the enzymatic breakdown of cellulosic biomass into fermentable sugars are still poorly understood, with a need for independent measurements of enzyme kinetic parameters. We measured binding times of cellobiohydrolase Trichoderma reesei Cel7A (Cel7A) on celluloses using wild-type Cel7A (WTintact), the catalytically deficient mutant Cel7A E212Q (E212Qintact) and their proteolytically isolated catalytic domains (CD) (WTcore and E212Qcore, respectively). The binding time distributions were obtained from time-resolved, super-resolution images of fluorescently labeled enzymes on cellulose obtained with total internal reflection fluorescence microscopy.ResultsBinding of WTintact and E212Qintact on the recalcitrant algal cellulose (AC) showed two bound populations: ~ 85% bound with shorter residence times of < 15 s while ~ 15% were effectively immobilized. The similarity between binding times of the WT and E212Q suggests that the single point mutation in the enzyme active site does not affect the thermodynamics of binding of this enzyme. The isolated catalytic domains, WTcore and E212Qcore, exhibited three binding populations on AC: ~ 75% bound with short residence times of ~ 15 s (similar to the intact enzymes), ~ 20% bound for < 100 s and ~ 5% that were effectively immobilized.ConclusionsCel7A binding to cellulose is driven by the interactions between the catalytic domain and cellulose. The cellulose-binding module (CBM) and linker increase the affinity of Cel7A to cellulose likely by facilitating recognition and complexation at the substrate interface. The increased affinity of Cel7A to cellulose by the CBM and linker comes at the cost of increasing the population of immobilized enzyme on cellulose. The residence time (or inversely the dissociation rates) of Cel7A on cellulose is not catalysis limited.

Relationship of Distribution of Carboxy Groups to Molar Mass Distribution of TEMPO-Oxidized Algal, Cotton, and Wood Cellulose Nanofibrils.

Distributions of carboxy groups among the molecules in 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNs) prepared from wood, cotton, and algal celluloses were investigated. Most C6-carboxy groups in TOCNs were esterified with anthracene-methyl (-CH2C14H9) groups, showing an ultraviolet light (UV) absorption peak at 365 nm. The anthracene-methylated TOCNs were dissolved in 8% (w/w) lithium chloride/N,N-dimethylacetamide (LiCl/DMAc). After dilution to 1% LiCl/DMAc, the solutions were subjected to size-exclusion chromatography with multiangle laser-light scattering, refractive index, and UV detection. For algal TOCN, C6-carboxy group-rich molecules were present predominantly in the low-molar-mass region, which was consistent with the core-clad cellulose chain packing structures in individual algal cellulose microfibrils and partial depolymerization of the oxidized cellulose molecules. In contrast, wood and cotton TOCNs had almost homogeneous distributions of C6-carboxy groups in all molar mass regions, which could not be explained in terms of the simple core-clad cellulose chain packing structures.

DNA G-quadruplexes binding and antitumor activity of palladium aryl oxime ligand complexes encapsulated in either albumin or algal cellulose nanoparticles.

The interactions between two Pd complexes, designated as [Pd3(C,N-(C6H4C(Cl) = NO)-4)6] (complex 1) and [Pd3(C12H8C = NO)6] (complex 2), with the human telomeric G-quadruplex DNA, 5'-G3(T2AG3)3-3' (HTG21), were monitored using spectroscopic, biological, and molecular modeling studies. According to the UV-vis results, these complexes can strongly induce and stabilize G-quadruplex DNA structure with Kb1 = 4.5(±0.3) × 106 M-1 and Kb2 = 1.0(±0.2) × 107 M-1via groove mode in comparison with duplex DNA. The release mechanism of the Pd complexes from BSA nanoparticles followed a biphasic pattern unlike that of algal cellulose nanoparticles in vitro. In addition, the cytotoxicity of these complexes on MCF-7 cancer cells and PBMC normal cells was evaluated and compared with cisplatin under similar experimental conditions. Furthermore, to determine and verify the interaction mode of these compounds with G-quadruplex, the molecular docking technique was also performed. Our data clearly demonstrated that complex 2 had higher activity and cytotoxicity than that of complex 1 and could be further investigated in the future as a drug discovery platform.