Functional Cellulose Beads: Preparation, Characterization, and Applications

Porous cationic cellulose beads prepared by homogeneous in-situ quaternization and acid induced regeneration for water/moisture absorption

Chemical modification is a reliable and efficient strategy for designing cellulose-based functional materials. Herein, porous quaternized cellulose beads (QCBs) as cationic superabsorbent were fabricated by homogeneous in-situ chemical grafting cellulose molecular chains with glycidyl trimethylammonium chloride (GTAC) in tetraethylammonium hydroxide (TEAOH)/urea aqueous solution followed by acetic acid induced regeneration. The influence of GTAC dosage on the physicochemical-structural properties of cationic QCBs was deeply investigated. Results revealed that cotton liner could well-dissolved in TEAOH/urea aqueous solution, leading to a homogeneous and efficient quaternization medium for cellulose, thereby giving the high DS and positive charge density for quaternized cellulose. NMR results demonstrated the main substitution of GTAC groups at 2-OH and 6-OH positions of the cellulose chains during quaternization reaction. With increasing GTAC dosage, the network skeleton of QCBs gradually transformed from thick fibrils to thin aggregates, as well as enhanced pore volumes and hydrophilicity. Accordingly, QCBs-1.5 with high pore volume (99.70 cm3/g) exhibited excellent absorption capacity and efficiency, absorbing 122.32 g of water and 0.45 g of moisture per gram of the beads in 20 min. This work not only offers a simple strategy for the homogeneous quaternization modification of cellulose, but also provides a porous cellulose-based cationic superabsorbent material.

Fusion of cellulose microspheres with pulp fibers: Creating an unconventional type of paper

Cellulose microspheres (CMS) are a type of spherical regenerated cellulose particles with versatile properties which have been used as carrier materials in medical and technical applications. The integration of CMS into paper products opens up novel application scenarios for paper products in a wide range of fields. However, the incorporation of CMS carriers into paper products is challenging and hitherto no reports do exist in literature. Here, we present a feasibility study to incorporate up to 50 w.% CMS in paper hand sheets using retention aids. Our primary observations highlight the successful formation of uniform paper hand sheets retaining its tensile strengths at elevated CMS concentrations. Sheets with high CMS contents exhibit an increase in density and display enhanced surface smoothness - an outcome of a CMS layer forming atop the fiber base - which effectively bridges voids and rectifies surface irregularities as supported by Gurley testing, infinite focus microscopy and scanning electron microscopy. While our primary objective centered on the general feasibility to manufacture CMS-containing papers, the resulting composite scaffold carries significant potential as a platform for innovative, functional paper-based materials.

Multiporous ZIF-8 carbon/cellulose composite beads: Highly efficient and scalable adsorbents for water treatment

Metal-organic framework (MOF) particles are one of the most promising adsorbents for removing organic contaminants from wastewater. However, powder-type MOF particles face challenges in terms of utilization and recovery. In this study, a novel bead-type adsorbent was prepared using activated carbon based on the zeolitic imidazolate framework-8 (AC-ZIF-8) and a regenerated cellulose hydrogel for dye removal. AC-ZIF-8 particles with a large surface area were obtained by carbonization and chemical activation with KOH. The AC-ZIF-8 powders were efficiently immobilized in hydrophilic cellulose hydrogel beads via cellulose dissolution/regeneration. The prepared AC-ZIF-8/cellulose hydrogel (AC-ZIF-8/CH) composite beads exhibit a large specific surface area of 1412.8 m2/g and an excellent maximum adsorption capacity of 565.13 mg/g for Rhodamine B (RhB). Moreover, the AC-ZIF-8/CH beads were effective over a wide range of pH, temperatures and for different types of dyes. These composite beads also offer economic benefits through desorption of dyes for recycling. The AC-ZIF-8/CH beads can be produced in substantial amounts and used as fillers in a fixed-bed column system, which can purify the continuous inflow of dye solutions. These findings suggest that our simple approach for preparing high-performance adsorbent beads will broaden the application of dye adsorbents, oil-water separation, and catalysts.

Research progress on polybenzoxazine aerogels: Preparation, properties, composites and hybrids fabrication, applications

The unremitting pursuit of high-performance and multifunctional materials has consistently propelled modern industries forward, stimulating research and motivating progress in related fields. In such materials, polybenzoxazine (PBz) aerogel, which combines the virtues of PBz and aerogel, has attracted salient attention recently, emerging as a novel research focus in the realm of advanced materials. In this review, the preparation scheme, microscopic morphology, and fundamental characteristics of PBz aerogels are comprehensively summarized and discussed in anticipation of providing a clear understanding of the correlation between preparation process, structure, and properties. The effective strategies for enhancing the performance of PBz aerogels including composite fabrication and hybridization are highlighted. Moreover, the applications of PBz-based aerogels in various domains such as adsorption (including wastewater treatment, CO2 capture, and microwave adsorption), thermal insulation, energy storage as well as sensors are covered in detail. Furthermore, several obstacles and potential directions for subsequent research are delineated with a view to surmounting the prevailing constraints and achieving a realization of the shift from experimental exploration to practical applications.

Reevaluation of the adhesion between cellulose materials using macro spherical beads and flat model surfaces

Interactions between dry cellulose were studied using model systems, cellulose beads, and cellulose films, using custom-built contact adhesion testing equipment. Depending on the configuration of the substrates in contact, Polydimethylsiloxane (PDMS) film, cellulose films spin-coated either on PDMS or glass, the interaction shows three distinct processes. Firstly, molecular interlocking is formed between cellulose and cellulose when there is a soft PDMS thin film backing the cellulose film. Secondly, without backing, no initial attraction force between the surfaces is observed. Thirdly, a significant force increase, ∆F, is observed during the retraction process for cellulose on glass, and there is a maximum in ∆F when the retraction rate is increased. This is due to the kinetics of a contacting process occurring in the interaction zone between the surfaces caused by an interdigitation of a fine fibrillar structure at the nano-scale, whereas, for the spin-coated cellulose surfaces on the PDMS backing, there is a more direct adhesive failure. The results have generated understanding of the interaction between cellulose-rich materials, which helps design new, advanced cellulose-based materials. The results also show the complexity of the interaction between these surfaces and that earlier mechanisms, based on macroscopic material testing, are simply not adequate for molecular tailoring.

Phosphate-rich cellulose beads for efficient cesium extraction from aqueous solutions: a novel approach for cellulose utilization

In this work, phosphate-rich cellulose beads (CBPs) were first used for cesium extraction from aqueous solutions. These green, abundant, cheap, and renewable CBPs demonstrated a high adsorption capacity and fast absorption rate. Besides, the CBPs also exhibited excellent stability and recycling performance, as well as good selectivity. This study presents the promising application potential of cellulose for efficient cesium extraction from aqueous media.

Cellulose, cellulose derivatives and cellulose composites in sustainable corrosion protection: challenges and opportunities

The use of cellulose-based compounds in coating and aqueous phase corrosion prevention is becoming more popular because they provide excellent protection and satisfy the requirements of green chemistry and sustainable development. Cellulose derivatives, primarily carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC), are widely employed in corrosion prevention. They function as efficient inhibitors by adhering to the metal's surface and creating a corrosion-inhibitive barrier by binding using their -OH groups. Their inhibition efficiency (%IE) depends upon various factors, including their concentration, temperature, chemical composition, the nature of the metal/electrolyte and availability of synergists (X-, Zn2+, surfactants and polymers). Cellulose derivatives also possess potential applications in anticorrosive coatings as they prevent corrosive species from penetrating and encourage adhesion and cohesion, guaranteeing the metal substrate underneath long-term protection. The current review article outlines the developments made in the past and present to prevent corrosion in both the coating phase and solution by using cellulose derivatives. Together with examining the difficulties of the present and the prospects for the future, the corrosion inhibition mechanism of cellulose derivatives in the solution and coating phases has also been investigated.

Carbons Derived from Regenerated Spherical Cellulose as Anodes for Li-Ion Batteries at Elevated Temperatures

Biomass-based materials have emerged as a promising alternative to the conventional graphite anode in Li-ion batteries due to their renewability, low cost, and environmental friendliness. Therefore, a facile synthesis method for porous hard carbons based on cellulose acetate microspheres and bead cellulose is used, and their application as anode materials in Li-ion batteries is discussed. The resulting porous carbons exhibit promising electrochemical characteristics, including a reversible capacity of about 300 mAh g-1 at 0.1 C (37 mA g-1) after 50 cycles, and stable capacities up to 210 mAh g-1 over 1000 cycles at 1 C (372 mA g-1) in half-cells for cellulose acetate microspheres carbonised at 1200 °C. Moreover, at 60 °C cellulose-derived carbons show higher specific capacities than graphite (300 mAh g-1 vs 240 mAh g-1 at 1 C after 500 cycles), indicating their potential for use in high-temperature applications. The different charge storage mechanisms of the prepared hard carbon materials and graphite are observed. While capacity of graphite is mainly controlled by the Faradaic redox process, the cellulose-derived carbons combine Faradaic intercalation and capacitive charge adsorption.

Catalytic activity of Cu2O nanoparticles supported on cellulose beads prepared by emulsion-gelation using cellulose/LiBr solution and vegetable oil

Nanocatalysts tend to aggregate and are difficult to recycle, limiting their practical applications. In this study, an environmentally friendly method was developed to produce cellulose beads for use as supporting materials for Cu-based nanocatalysts. Cellulose beads were synthesized from a water-in-oil emulsion using cellulose dissolved in an LiBr solution as the water phase and vegetable oil as the oil phase. Upon cooling, the gelation of the cellulose solution produced spherical cellulose beads, which were then oxidized to introduce surface carboxyl groups. These beads (diameter: 95-105 μm; specific surface area: 165-225 m2 g-1) have a three-dimensional network of nanofibers (width: 20-30 nm). Furthermore, the Cu2O nanoparticles were loaded onto oxidized cellulose beads before testing their catalytic activity in the reduction of 4-nitrophenol using NaBH4. The apparent reaction rate constant increased with increasing loading of Cu2O nanoparticles and the conversion efficiency was >90 %. The turnover frequency was 376.2 h-1 for the oxidized cellulose beads with the lowest Cu2O loading, indicating a higher catalytic activity compared to those of other Cu-based nanoparticle-loaded materials. In addition to their high catalytic activity, the cellulose beads are reusable and exhibit excellent stability.

pH-Responsive Cellulose/Silk/Fe3O4 Hydrogel Microbeads Designed for Biomedical Applications

In this study, cellulose/Fe3O4 hydrogel microbeads were prepared through the sol-gel transition of a solvent-in-oil emulsion using various cellulose-dissolving solvents and soybean oil without surfactants. Particularly, 40% tetrabutylammonium hydroxide (TBAH) and 40% tetrabutylphosphonium hydroxide (TBPH) dissolved cellulose at room temperature and effectively dispersed Fe3O4, forming cellulose/Fe3O4 microbeads with an average diameter of ~15 µm. Additionally, these solvents co-dissolved cellulose and silk, allowing for the manufacture of cellulose/silk/Fe3O4 hydrogel microbeads with altered surface characteristics. Owing to the negatively charged surface characteristics, the adsorption capacity of the cellulose/silk/Fe3O4 microbeads for the cationic dye crystal violet was >10 times higher than that of the cellulose/Fe3O4 microbeads. When prepared with TBAH, the initial adsorption rate of bovine serum albumin (BSA) on the cellulose/silk/Fe3O4 microbeads was 18.1 times higher than that on the cellulose/Fe3O4 microbeads. When preparing TBPH, the equilibrium adsorption capacity of the cellulose/silk/Fe3O4 microbeads for BSA (1.6 g/g) was 8.5 times higher than that of the cellulose/Fe3O4 microbeads. The pH-dependent BSA release from the cellulose/silk/Fe3O4 microbeads prepared with TBPH revealed 6.1-fold slower initial desorption rates and 5.2-fold lower desorption amounts at pH 2.2 than those at pH 7.4. Cytotoxicity tests on the cellulose and cellulose/silk composites regenerated with TBAH and TBPH yielded nontoxic results. Therefore, cellulose/silk/Fe3O4 microbeads are considered suitable pH-responsive supports for orally administered protein pharmaceuticals.

"Green" electrostatic droplet-assisted forming cellulose microspheres with excellent structural controllability and stability for efficient Cr(VI) removal

This study presents a novel and environmentally friendly method for producing cellulose microspheres (CM) with controllable morphology and size using electrostatic droplets. The traditional droplet method for CM production requires complex equipment and harmful reagents. In contrast, the proposed method offers a simple electrostatic droplet approach to fabricate CM10 at 10 kV, which exhibited a smaller volume, linear microscopic morphology, and a larger specific surface area, with a 36.60 % improvement compared to CM0 (prepared at 0 kV). CM10 also demonstrated excellent underwater structural stability, recovering in just 0.5 s, and exhibited the highest adsorption capacity for Cr(VI) at 190.16 mg/g, a 72.15 % improvement over CM0. This enhanced adsorption capacity can be attributed to the unique structure of CM10 and the introduction of more amino groups. Moreover, CM10 displayed good cyclic adsorption capacity and high dynamic adsorption efficiency, making it highly suitable for practical applications. CM10 exhibited remarkable adsorption capacity, stability, and practical value in treating Cr(VI) wastewater. This work proposes a simple and eco-friendly method for producing CM with excellent structural controllability and stability, providing an effective route for wastewater treatment.

o-Semiquinone Radical and o-Benzoquinone Selectively Degrade Aniline Contaminants in the Periodate-Mediated Advanced Oxidation Process

Advanced oxidation processes (AOPs) often employ strong oxidizing inorganic radicals (e.g., hydroxyl and sulfate radicals) to oxidize contaminants in water treatment. However, the water matrix could scavenge the strong oxidizing radicals, significantly deteriorating the treatment efficiency. Here, we report a periodate/catechol process in which reactive quinone species (RQS) including the o-semiquinone radical (o-SQ•-) and o-benzoquinone (o-Q) were dominant to effectively degrade anilines within 60 s. The second-order reaction rate constants of o-SQ•- and o-Q with aniline were determined to be 1.0 × 108 and 4.0 × 103 M-1 s-1, respectively, at pH 7.0, which accounted for 21% and 79% of the degradation of aniline with a periodate-to-catechol molar ratio of 1:1. The major byproducts were generated via addition or polymerization. The RQS-based process exhibited excellent anti-interference performance in the degradation of aniline-containing contaminants in real water samples in the presence of diverse inorganic ions and organics. Subsequently, we extended the RQS-based process by employing tea extract and dissolved organic matter as catechol replacements as well as metal ions [e.g., Fe(III) or Cu(II)] as periodate replacements, which also exhibited good performance in aniline degradation. This study provides a novel strategy to develop RQS-based AOPs for the highly selective degradation of aniline-containing emerging contaminants.

Upcycling Food By-products: Characteristics and Applications of Nanocellulose

Rising global food prices and the increasing prevalence of food insecurity highlight the imprudence of food waste and the inefficiencies of the current food system. Upcycling food by-products holds significant potential for mitigating food loss and waste within the food supply chain. Food by-products can be utilized to extract nanocellulose, a material that has obtained substantial attention recently due to its renewability, biocompatibility, bioavailability, and a multitude of remarkable properties. Cellulose nanomaterials have been the subject of extensive research and have shown promise across a wide array of applications, including the food industry. Notably, nanocellulose possesses unique attributes such as a surface area, aspect ratio, rheological behavior, water absorption capabilities, crystallinity, surface modification, as well as low possibilities of cytotoxicity and genotoxicity. These qualities make nanocellulose suitable for diverse applications spanning the realms of food production, biomedicine, packaging, and beyond. This review aims to provide an overview of the outcomes and potential applications of cellulose nanomaterials derived from food by-products. Nanocellulose can be produced through both top-down and bottom-up approaches, yielding various types of nanocellulose. Each of these variants possesses distinctive characteristics that have the potential to significantly enhance multiple sectors within the commercial market.

Cross-linked cellulose beads as an eco-friendly support for ZnO/SnO2/carbon xerogel hybrid photocatalyst: Exploring the synergy between adsorption and photocatalysis under simulated sunlight

This paper explores the application of cross-linked cellulose beads as a sustainable and cost-effective support for the ZnO/SnO2/carbon xerogel hybrid photocatalyst. The application of the developed photocatalytic beads, named CB-Cat, was directed at a simultaneous adsorption/photocatalysis process, which was carried out under simulated sunlight. The characterization of the CB-Cat indicated a good dispersion of the photocatalyst of choice throughout the cellulose matrix, confirming its incorporation into the cellulose beads. Furthermore, it is possible to observe the presence of the photocatalyst on the surface of the CB-Cat, confirming its availability for the photonic activation process. The results showed that the simultaneous adsorption/photocatalysis process was optimal for enhancing the efficiency of methylene blue (MB) removal, especially when compared to the isolated adsorption process. Additionally, the regeneration of the CB-Cat between cycles was favorable toward the maintenance of the MB removal efficiency, as the process carried out without regeneration displayed significant efficiency drops between cycles. Finally, the mechanism evaluation evidenced that hydroxyl and superoxide radicals were the main responsible for the MB photocatalytic degradation during illumination with simulated sunlight.

Porous polyvinyl fluoride coated cellulose beads for efficient removal of Cd(II) from phosphoric acid

In order to enhance the removal of cadmium from phosphoric acid, it is imperative to explore novel resources that may be utilized for the development of highly effective and environmentally sustainable adsorbents. Cellulose beads are composed of naturally occurring polysaccharide fibers and find extensive utilization across several industrial sectors and applications. Within this framework, this research paper presents a green and simple method for producing porous cellulose beads using date palm fibers as the preferred raw material. The innovation lies in immersing the obtained cellulose beads in a Polyvinyl fluoride (PVDF)/N,N-dimethylformamide (DMF) suspension as a coating polymer with different concentrations (2.5, 5, 10 %) to maintain their stability in an acidic environment. The surface of cellulose/PVDF beads were subjected to multiple characterizations like Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), size distribution then pH stability confirming that the coating has been perfectly achieved and conserved well the shape of the beads. The coated cellulose/PVDF-2.5 % underwent evaluation by the process of batch adsorption experiments while different parameters were varied including contact time (5, 10, 20, 30, 60, 90 min), temperature (25, 35, 45 and 55 °C), and adsorbent mass (20, 40, 60, 80 and 100 mg). The obtained ICP data showed that the adsorption rate of Cd (II) from phosphoric acid medium decreased while increasing both temperature from 25 to 55 °C and contact time from 5 to 90 min while adding more adsorbent dosage from 20 to 100 mg enhanced the removal percentage. The cellulose/PVDF-2.5 % was more effective with an adsorption capacity equal to 3.4998 mg/g at optimal conditions including 25 °C as the temperature after 5 min as contact time and by adding a mass 100 mg of the biosorbent while the pH = 2 of the solution is maintained the same. The examined material's adsorption processes proved to be exothermic and non-spontaneous, and it proved that the pseudo-second-order model provided the best match for the cellulose/PVDF-2.5 % beads kinetics data. Furthermore, the cellulose beads exhibited exceptional reusability for up to four repeated cycles without undergoing desorption. The present study offers a viable approach for producing environmentally sustainable biomass-derived adsorbents. Additionally, the study validates the potential of cellulose/PVDF beads as an intriguing material for phosphoric acid decadmiation.

Fe(III) cross-linked cellulose-agar hydrogel beads for efficient phosphate removal from aqueous solutions

Fe(III) cross-linked cellulose agar beads (Fe-CLCAB) were synthesized by sol-gel method and employed as adsorbents for the removal of phosphate ions from aqueous medium. The synthesized Fe-CLCAB was characterized by its swelling property, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and UV-Vis absorption spectroscopic analysis. Batch adsorption studies were carried out to find out the optimum conditions of phosphate uptake. The adsorption process was found to fit both Langmuir and Freundlich adsorption isotherm model, pseudo-second-order kinetic model, and Elovich kinetic model. Ninety-four percent phosphate adsorption was achieved with 500 beads at pH 5. Maximum monolayer adsorption capacity was 73.13 mg/g. A two-step elution process using sodium chloride solution was suitable for complete desorption of phosphate from Fe-CLCAB. Six cyclic adsorption-desorption tests were conducted using a 0.1 M NaCl solution as desorbing agent. The removal efficiency of regenerated Fe-CLCAB was 42% of its original value after six cycles, which validates good stability and effectiveness of the prepared hydrogel beads. Ion exchange plays a vital role during adsorption/desorption of phosphate.

A post-sulfonated one-pot synthesized magnetic cellulose nanocomposite for Knoevenagel and Thorpe-Ziegler reactions

The development of biodegradable and active cellulosic-based heterogeneous catalysts for the synthesis of different organic compounds would be attractive in pharmaceutical and petrochemical-related industries. Herein, a post-sulfonated composite of one-pot synthesized magnetite (Fe3O4) and cellulose nanocrystals (CNCs) was used as an effective and easily separable heterogeneous catalyst for activating the Knoevenagel and Thorpe-Ziegler reactions. The composite was developed hydrothermally from microcrystalline cellulose (MCC), iron chlorides, urea, and hydrochloric acid at 180 °C for 20 h in a one-pot reaction. After collecting the magnetic CNCs (MCNCs), post-sulfonation was performed using chlorosulfonic acid (ClSO3H) in DMF at room temperature producing sulfonated MCNCs (SMCNCs). The results confirmed the presence of sulfonated Fe3O4 and CNCs with a hydrodynamic size of 391 nm (±25). The presence of cellulose was beneficial for preventing Fe3O4 oxidation or the formation of agglomerations without requiring the presence of capping agents, organic solvents, or an inert environment. The SMCNC catalyst was applied to activate the Knoevenagel condensation and the Thorpe-Ziegler reaction with determining the optimal reaction conditions. The presence of the SMCNC catalyst facilitated these transformations under green procedures, which enabled us to synthesize a new series of olefins and thienopyridines, and the yields of some isolated olefins and thienopyridines were up to 99% and 95%, respectively. Besides, the catalyst was stable for five cycles without a significant decrease in its reactivity, and the mechanistic routes of both reactions on the SMCNCs were postulated.

Application of Starch, Cellulose, and Their Derivatives in the Development of Microparticle Drug-Delivery Systems

Micro- and nanotechnologies have been intensively studied in recent years as novel platforms for targeting and controlling the delivery of various pharmaceutical substances. Microparticulate drug delivery systems for oral, parenteral, or topical administration are multiple unit formulations, considered as powerful therapeutic tools for the treatment of various diseases, providing sustained drug release, enhanced drug stability, and precise dosing and directing the active substance to specific sites in the organism. The properties of these pharmaceutical formulations are highly dependent on the characteristics of the polymers used as drug carriers for their preparation. Starch and cellulose are among the most preferred biomaterials for biomedical applications due to their biocompatibility, biodegradability, and lack of toxicity. These polysaccharides and their derivatives, like dextrins (maltodextrin, cyclodextrins), ethylcellulose, methylcellulose, hydroxypropyl methylcellulose, carboxy methylcellulose, etc., have been widely used in pharmaceutical technology as excipients for the preparation of solid, semi-solid, and liquid dosage forms. Due to their accessibility and relatively easy particle-forming properties, starch and cellulose are promising materials for designing drug-loaded microparticles for various therapeutic applications. This study aims to summarize some of the basic characteristics of starch and cellulose derivatives related to their potential utilization as microparticulate drug carriers in the pharmaceutical field.

One-pot synthesis of magnetic cellulose nanocrystal and its post-functionalization for doxycycline adsorption

The composite of magnetite (Fe₃O₄) and cellulose nanocrystal (CNC) is considered a potential adsorbent for water treatment and environmental remediation. In the current study, a one-pot hydrothermal procedure was utilized for magnetic cellulose nanocrystal (MCNC) development from microcrystalline cellulose (MCC) in the presence of ferric chloride, ferrous chloride, urea, and hydrochloric acid. The x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), and Fourier-transform infrared spectroscopy analysis confirmed the presence of CNC and Fe₃O₄, while transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis verified their respective sizes (< 400 nm and ≤ 20 nm) in the generated composite. To have an efficient adsorption activity for doxycycline hyclate (DOX), the produced MCNC was post-treated using chloroacetic acid (CAA), chlorosulfonic acid (CSA), or iodobenzene (IB). The introduction of carboxylate, sulfonate, and phenyl groups in the post-treatment was confirmed by FTIR and XPS analysis. Such post treatments decreased the crystallinity index and thermal stability of the samples but improved their DOX adsorption capacity. The adsorption analysis at different pHs revealed the increase in the adsorption capacity by reducing the basicity of the medium due to decreasing electrostatic repulsions and inducing strong attractions.

Bifunctional Cellulose Interlayer Enabled Efficient Perovskite Solar Cells with Simultaneously Enhanced Efficiency and Stability

Interfacial engineering is a vital strategy to enable high-performance perovskite solar cells (PSCs). To develop efficient, low-cost, and green biomass interfacial materials, here, a bifunctional cellulose derivative is presented, 6-O-[4-(9H-carbazol-9-yl)butyl]-2,3-di-O-methyl cellulose (C-Cz), with numerous methoxy groups on the backbone and redox-active carbazole units as side chains. The bifunctional C-Cz shows excellent energy level alignment, good thermal stability and strong interactions with the perovskite surface, all of which are critical for not only carrier transportation but also potential defects passivation. Consequently, with C-Cz as the interfacial modifier, the PSCs achieve a remarkably enhanced power conversion efficiency (PCE) of 23.02%, along with significantly enhanced long-term stability. These results underscore the advantages of bifunctional cellulose materials as interfacial layers with effective charge transport properties and strong passivation capability for efficient and stable PSCs.

Synthesis of Cellulose Nanoparticles from Ionic Liquid Solutions for Biomedical Applications

A method for the synthesis of cellulose nanoparticles using the ionic liquid 1-ethyl-3-methylimidazolium acetate has been optimised. The use of a highly biocompatible biopolymer such as cellulose, together with the use of an ionic liquid, makes this method a promising way to obtain nanoparticles with good capability for drug carrying. The operating conditions of the synthesis have been optimised based on the average hydrodynamic diameter, the polydispersity index, determined by Dynamic Light Scattering (DLS) and the Z-potential, obtained by phase analysis light scattering (PALS), to obtain cellulose nanoparticles suitable for use in biomedicine. The obtained cellulose nanoparticles have been characterised by Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance (ATR), field emission scanning electron microscopy (FESEM) and thermogravimetric analysis (TGA/DTA). Finally, cell viability studies have been performed with a cancer cell line (HeLa) and with a healthy cell line (EA.hy926). These have shown that the cellulose nanoparticles obtained are not cytotoxic in the concentration range of the studied nanoparticles. The results obtained in this work constitute a starting point for future studies on the use of cellulose nanoparticles, synthesised from ionic liquids, for biomedical applications such as targeted drug release or controlled drug release.

Topochemical Design of Cellulose-Based Carriers for Immobilization of Endoxylanase

Xylooligosaccharides (XOSs) gained much attention for their use in food and animal feed, attributed to their prebiotic function. These short-chained carbohydrates can be enzymatically produced from xylan, one of the most prevalent forms of hemicellulose. In this work, endo-1,4-β-xylanase from Thermotoga maritima was immobilized on cellulose-based beads with the goal of producing xylooligosaccharides with degrees of polymerization (DPs) in the range of 4-6 monomeric units. More specifically, the impact of different spacer arms, tethers connecting the enzyme with the particle, on the expressed enzymatic activity and oligosaccharide yield was investigated. After surface functionalization of the cellulose beads, the presence of amines was confirmed with time of flight secondary ion mass spectrometry (TOF-SIMS), and the influence of different spacer arms on xylanase activity was established. Furthermore, XOSs (DPs 2-6) with up to 58.27 mg/g xylan were obtained, which were greatly enriched in longer oligosaccharides. Approximately 80% of these XOSs displayed DPs between 4 and 6. These findings highlight the importance of topochemical engineering of carriers to influence enzyme activity, and the work puts forward an enzymatic system focusing on the production of longer xylooligosaccharides.

Semi-conducting microspheres formed from glucose for semi-active electric field-responsive electrorheological systems

In this study glucose particles were successfully transformed to conducting carbonaceous microspheres through sequential hydrothermal and thermal carbonization. The prepared carbonaceous particles were thereafter used as a dispersed phase in a novel electrorheological fluid. Due to significant enhancements of the conductivity and dielectric properties when compared with the glucose precursor, the prepared electrorheological fluid based on carbonaceous microspheres exhibited a yield stress of over 200 Pa at a particle concentration of 5 wt% at an electric field intensity of 3 kV mm^-1, and overcomes recently published novel electrorheological fluids and others based on carbonized particles. In order to estimate the exact rheological parameters, the measured data were treated using a mathematical model Cho-Choi-Jhon, and the reproducibility and reversible possibility to control the viscosity of the novel prepared electrorheological fluid were confirmed through time dependence tests at various electric field intensities. Not only did this approach lead to carbonaceous conducting particles with high performance in electrorheology, but the yield after carbonization at 500 °C was also 60%. It was thus confirmed that unique carbonaceous conducting particles were prepared using a sustainable method giving high yields, and can be potentially used in many other applications where such carbonaceous particles are required.

Nanocellulose-based drug carriers: Functional design, controllable synthesis, and therapeutic applications

With rising living standards and environmental awareness, materials-oriented chemical engineering has increasingly transitioned from traditional rough models to more resource-saving and eco-friendly models, providing an avenue for bio-based materials in the drug carrier field. Because of its excellent physical and chemical properties, including high specific surface area, abundant accessible hydroxyl groups, biocompatibility, and degradability, nanocellulose (NC) is an emerging bio-based material that has been widely exploited as biomedical materials. The modification techniques of NC, as well as advancements in the design and applications of drug carriers, were primarily discussed in this study. First, the NC modification methods are described; second, the applications of NC and its derivatives as drug carriers are summarized, focusing on NC-based carrier models, types of loaded therapeutic agents, and controlled release stimulators; and finally, the current challenges of NC in the drug carrier field and the directions of future research are also discussed.

Nano-fibrillated cellulose-based scaffolds for enzyme (co)-immobilization: Application to natural product glycosylation by Leloir glycosyltransferases

Polysaccharide-based scaffolds are promising carriers for enzyme immobilization. Here, we demonstrate a porous scaffold prepared by direct-ink-writing 3D printing of an ink consisting of nanofibrillated cellulose, carboxymethyl cellulose and citric acid for immobilization application. Negative surface charge introduced by the components made the scaffold amenable for an affinity-like immobilization via the cationic protein module Z_basic2. Z_basic2 fusions of two sugar nucleotide-dependent glycosyltransferases (C-glycosyltransferase, Z-CGT; sucrose synthase, Z-SuSy) were immobilized individually, or co-immobilized, and applied to synthesize the natural C-glycoside nothofagin. The cascade reaction involved β-C-glycosylation of phloretin (10 mM, ~90 % conversion) from UDP-glucose, provided from sucrose and catalytic amounts of UDP (1.0 mM). Enzymes were co-immobilized at ~65 mg protein/g carrier to receive activities of 9.5 U/g (Z-CGT) and 4.5 U/g (Z-SuSy) in 22-33 % yield (protein) and an effectiveness of 23 % (Z-CGT) and 13 % (Z-SuSy). The scaffold-bound enzymes were recyclable for 5 consecutive reactions.

Continuous production of cellulose microbeads by rotary jet atomization

The replacement of plastic microbeads with biodegradable alternatives is essential due to the environmental persistence of plastics and their accumulation within the human food chain.

HYPOTHESIS

Cellulose microbeads could be such alternative, but their production is hindered by the high viscosity of cellulose solutions. It is expected that this viscosity can be harnessed to induce filament thinning of jets of cellulose solutions to create droplets with diameters within the micrometre range, which can then be converted to solid cellulose microbeads via phase inversion.

EXPERIMENTS

A 3D printed rotating multi-nozzle system was used to generate jets of cellulose dissolved in solutions of [EMIm][OAc] and DMSO. The jets were subject to Rayleigh breakup to generate droplets which were captured in an ethanol anti-solvent bath, initiating phase-inversion, and resulting in regeneration of the cellulose into beads.

FINDINGS

Control of both process (e.g. nozzle dimensions) and operational (e.g. rotational speed and pressure) parameters has allowed suppression of both satellite droplets generation and secondary droplet break-up, and tuning of the filament thinning process. This resulted in the continuous fabrication of cellulose microbeads in the size range 40-500 μm with narrow size distributions. This method can produce beads in size ranges not attainable by existing technologies.

Magnetic porous cellulose surface-imprinted polymers synthetized with assistance of deep eutectic solvent for specific recognition and purification of bisphenols

Magnetic porous cellulose molecularly imprinted polymers-based bisphenols have been developed using Fe₃O₄ as the magnetic material, a deep eutectic solvent as the assisted solvent, and N-isopropylacrylamide as the functional monomer. The resulting magnetic porous cellulose molecularly imprinted polymers were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, vibrating sample magnetometry, thermal gravimetric analysis, and Brunauer-Emmett-Teller analysis. Moreover, the adsorption properties of the magnetic porous cellulose molecularly imprinted polymers toward bisphenol A, bisphenol F, and bisphenol AF were investigated using static, dynamic, and selective adsorption experiments. The introduction of porous cellulose materials significantly improves the capabilities of the material. The adsorption capacity, mass transfer efficiency, and selectivity of the magnetic porous cellulose molecularly imprinted polymers toward bisphenol A were 5.9, 4.0, and 4.4 times those of traditional molecularly imprinted polymers. Moreover, the adsorption stability of the magnetic porous cellulose molecularly imprinted polymers was investigated under different temperature and pH conditions. The adsorption characteristics of the magnetic porous cellulose molecularly imprinted polymers toward the target molecules were investigated using adsorption isotherm, kinetic, and thermodynamic models. Hydrogen bonding is the main interaction formed between the magnetic porous cellulose molecularly imprinted polymers and the target molecules. Magnetic porous cellulose molecularly imprinted polymers have great application value with excellent stability and reusability. Finally, the combination of the magnetic porous cellulose molecularly imprinted polymers and high-performance liquid chromatography or ultra-performance liquid chromatography-mass spectrometry was successfully used for the purification and detection of bisphenols in milk (1.349 ng/mL bisphenol F and 3.014 ng/mL bisphenol AF), canned fruits (1129 ng/mL bisphenol A, 10.11 ng/mL bisphenol F, and 91.87 ng/mL bisphenol AF), and fish (11.91 ng/mL bisphenol AF) samples. Furthermore, the magnetic porous cellulose molecularly imprinted polymer method is more selective, sensitive, and accurate than the traditional precipitation method.

Transformation of Cellulose via Two-Step Carbonization to Conducting Carbonaceous Particles and Their Outstanding Electrorheological Performance

In this study, cellulose was carbonized in two-steps using hydrothermal and thermal carbonization in sequence, leading to a novel carbonaceous material prepared from a renewable source using a sustainable method without any chemicals and, moreover, giving high yields after a treatment at 600 °C in an inert atmosphere. During this treatment, cellulose was transformed to uniform microspheres with increased specific surface area and, more importantly, conductivity increased by about 7 orders of magnitude. The successful transition of cellulose to conducting carbonaceous microspheres was confirmed through SEM, FTIR, X-ray diffraction and Raman spectroscopy. Prepared samples were further used as a dispersed phase in electrorheological fluids, exhibiting outstanding electrorheological effects with yield stress over 100 Pa at an electric field strength 1.5 kV mm⁻¹ and a particle concentration of only 5 wt%, significantly overcoming recent state-of-the-art findings. Impedance spectroscopy analysis showed clear interfacial polarization of this ER fluid with high dielectric relaxation strength and short relaxation time, which corresponded to increased conductivity of the particles when compared to pure cellulose. These novel carbonaceous particles prepared from renewable cellulose have further potential to be utilized in many other applications that demand conducting carbonaceous structures with high specific surface area (adsorption, catalyst, filtration, energy storage).

Design, Synthesis and Adsorption Evaluation of Bio-Based Lignin/Chitosan Beads for Congo Red Removal

The morphology and intermolecular interaction are two of the most important factors in the design of highly efficient dye adsorbent in the industry. Millimeter-sized, bead-type, bio-based lignin/chitosan (Lig/CS) adsorbent was designed for the removal of Congo red (CR), based on the electrostatic attraction, π-π stacking, and hydrogen bonding, which were synthesized through the emulsification of the chitosan/lignin mixture followed by chemical cross-linking. The effects of the lignin/chitosan mass ratio, initial pH, temperature, concentration, and contact time on the adsorption were thoroughly investigated. The highest adsorption capacity (173 mg/g) was obtained for the 20 wt% Lig/CS beads, with a removal rate of 86.5%. To investigate the adsorption mechanism and recyclability, an evaluation of the kinetic model and an adsorption/desorption experiment were conducted. The adsorption of CR on Lig/CS beads followed the type 1 pseudo-second-order model, and the removal rate for CR was still above 90% at five cycles.

A Green Catechol-Containing Cellulose Nanofibrils-Cross-Linked Adhesive

Traditional adhesives with strong adhesion are widely applied in the fields of wood, building, and electronics. However, the synthesis and usage of commercial adhesives are not eco-friendly, which are harmful to human health and to the environment. In this study, a green cellulose nanofibrils/poly(hydroxyethyl methacrylate-co-dopamine methacrylamide) (CNFs/P(HEMA-co-DMA)) adhesive with excellent biocompatibility and strong bonding strength has been fabricated. P(HEMA-co-DMA) with a catechol content of 7.1 mol % was synthesized using dopamine methacrylamide and hydroxyethyl methacrylate. The CNFs/P(HEMA-co-DMA) adhesive was generated by cross-linking P(HEMA-co-DMA) solution using cellulose nanofibrils (CNFs). Strong adhesion was realized on various substrates, with a maximum lap shear strength of 5.50 MPa on steel. The NIH 3T3 cells test demonstrated that the adhesive possessed excellent biocompatibility. The green catechol-containing CNFs-cross-linked adhesive has promising potential for applications in medicine, electronic, food packaging, and engineering.

Facile fabrication of semi-IPN hydrogel adsorbent based on quaternary cellulose via amino-anhydride click reaction in water

Clean and safe water resources play a key role in environmental safety and human health. Recently, hydrogels have attracted extensive attention due to their non-toxicity, controllable performance, and high adsorption. Herein, a semi- interpenetrating network hydrogel (semi-IPN-Gel) adsorbent based on quaternary cellulose (QC) was prepared by the amino-anhydride click reaction between maleic anhydride copolymer and polyacrylamine hydrochloride (PAH), and its adsorption properties for Eosin Y were studied. First, a binary copolymer (PAM) of acrylamide and maleic anhydride was synthesized by free radical polymerization. Then, the PAM, QC and PAH were dissolved in water, and the pH of the solution was adjusted to alkaline. Semi-IPN-Gel was successfully prepared by fast anhydride-amino click reaction. The preparation conditions of hydrogels were optimized by single-factor experiments. Finally, taking Eosin Y as a model pollutant, the adsorption performance of Eosin Y was studied. The factors influencing the adsorption capacity of the absorbents such as initial concentration of the Eosin Y, temperature, the amount of absorbent, ionic strength and pH of the Eosin Y solutions were investigated. And adsorption data were analyzed via the kinetic model and the isothermal model, indicating that the adsorption process of the hydrogel is a single layer chemisorption process.

Understanding the Drying Behavior of Regenerated Cellulose Gel Beads: The Effects of Concentration and Nonsolvents

The drying behavior of regenerated cellulose gel beads swollen with different nonsolvents (e.g., water, ethanol, water/ethanol mixtures) is studied in situ on the macroscopic scale with an optical microscope as well as on nanoscale using small-angle/wide-angle X-ray scattering (SAXS/WAXS) techniques. Depending on the cellulose concentration, the structural evolution of beads during drying follows one of three distinct regimes. First, when the cellulose concentration is lower than 0.5 wt %, the drying process comprises three steps and, regardless of the water/ethanol mixture composition, a sharp structural transition corresponding to the formation of a cellulose II crystalline structure is observed. Second, when the cellulose concentration is higher than 5.0 wt %, a two-step drying process is observed and no structural transition occurs for any of the beads studied. Third, when the cellulose concentration is between 0.5 and 5.0 wt %, the drying process is dependent on the nonsolvent composition. A three-step drying process takes place for beads swollen with water/ethanol mixtures with a water content higher than 20%, while a two-step drying process is observed when the water content is lower than 20%. To describe the drying behavior governed by the cellulose concentration and nonsolvent composition, a simplified phase diagram is proposed.

Synthesis of Polyanionic Cellulose Carbamates by Homogeneous Aminolysis in an Ionic Liquid/DMF Medium

Polyanionic cellulose carbamates were synthesized by rapid and efficient homogeneous aminolysis of cellulose carbonate half-esters in an ionic liquid/DMF medium. Cellulose bis-2,3-O-(3,5-dimethylphenyl carbamate), as a model compound, reacted with different chloroformates to cellulose carbonates. These intermediates were subjected to aminolysis, for which both the reactivity of different chloroformates towards C6-OH and the reactivity/suitability of the respective carbonate half-ester in the aminolysis were comprehensively studied. Phenyl chloroformate and 4-chlorophenyl chloroformate readily reacted with C6-OH of the model cellulose derivative, while 4-nitrophenyl chloroformate did not. The intermediate 4-chlorophenyl carbonate derivative with the highest DS (1.05) was then used to evaluate different aminolysis pathways, applying three different amines (propargyl amine, β-alanine, and taurine) as reactants. The latter two zwitterionic compounds are only sparingly soluble in pure DMF as the typical reaction medium for aminolysis; therefore, several alternative procedures were suggested, carefully evaluated, and critically compared. Solubility problems with β-alanine and taurine were overcome by the binary solvent system DMF/[EMIM]OAc (1:1, v/v), which was shown to be a promising medium for rapid and efficient homogeneous aminolysis and for the preparation of the corresponding cellulose carbamate derivatives or other compounds that are not accessible by conventional isocyanate chemistry. The zwitterionic cellulose carbamate derivatives presented in this work could be promising chiral cation exchangers for HPLC enantiomer separations.

One-Step Fabrication of Hollow Spherical Cellulose Beads: Application in pH-Responsive Therapeutic Delivery

The path to greater sustainability and the development of polymeric drug delivery systems requires innovative approaches. The adaptation and use of biobased materials for applications such as targeted therapeutic delivery is, therefore, in high demand. A crucial part of this relates to the development of porous and hollow structures that are biocompatible, pH-responsive, deliver active substances, and contribute to pain relief, wound healing, tissue regeneration, and so forth. In this study, we developed a facile single-step and water-based method for the fabrication of hollow spherical cellulose beads for targeted drug release in response to external pH stimuli. Through base-catalyzed deprotection, hydrophobic solid and spherical cellulose acetate beads are transformed into hydrophilic cellulose structures with a hollow interior (wall thickness: 150 μm and inner diameter: 650 μm) by a stepwise increment of temperature and treatment time. Besides the pH-responsive fluid uptake properties, the hollow cellulose structures exhibit a maximum encapsulation efficiency of 20-85% diclofenac (DCF), a nonsteroidal anti-inflammatory drug, used commonly to treat pain and inflammatory diseases. The maximum amount of DCF released in vitro increased from 20 to 100% when the pH of the release medium increased from pH 1.2 to 7.4. As for the DCF release patterns and kinetic models at specific pH values, the release showed a diffusion- and swelling-controlled profile, effortlessly fine-tuned by external environmental pH stimuli. Overall, we show that the modified beads exhibit excellent characteristics for transport across the gastrointestinal tract and enhance the bioavailability of the drug. Their therapeutic efficacy and biocompatibility are also evident from the studies on human fibroblast cells. We anticipate that this platform could support and inspire the development of novel sustainable and effective polysaccharide-based delivery systems.

Porous soluble dialdehyde cellulose beads: A new carrier for the formulation of poorly water-soluble drugs

Cellulose beads are porous spherical particles with promising futures for drug delivery applications. In this study, novel dialdehyde cellulose (DAC) beads are developed by periodate oxidation of pristine cellulose for oral delivery of weakly basic poorly water-soluble drugs. Diazepam and itraconazole were studied as model drugs. Drug loadings in DAC beads up to 40% were obtained. Depending on the drug loading, complete or partial amorphization of drugs in DAC beads was observed. Drugs in the amorphous state not only presented a higher extent of dissolution from the DAC beads compared to the crystalline model drug, but the obtained concentration was also supersaturated. This supersaturation is attributed to the amorphization of the drugs in the beads in conjunction with the dissolution of the DAC beads at a neutral pH of the dissolution medium. Further, the effects of two different solvent systems used in the lyophilization step during the preparation of the DAC beads (100% water and 90/10% tert-butanol/water mixture) on their structure were investigated. Interestingly, the selection of the solvent system greatly impacted the bead structure, resulting in radically different drug loading capacity, physical properties, and release behavior of the model drugs. In summary, this is the first study that reports on exploiting soluble, porous, dialdehyde cellulose beads, showing great potential as a carrier for improving the rate and extent of dissolution of poorly soluble drugs and maintaining supersaturation.

New Phenol Esters for Efficient pH-Controlled Amine Acylation of Peptides, Proteins, and Sepharose Beads in Aqueous Media

This paper describes the discovery, synthesis, and use of novel water-soluble acylation reagents for efficient and selective modification, cross-linking, and labeling of proteins and peptides, as well as for their use in the effective modification of sepharose beads under pH control in aqueous media. The reagents are based on a 2,4-dichloro-6-sulfonic acid phenol ester core combined with a variety of linker structures. The combination of these motifs leads to an ideal balance between hydrolytic stability and reactivity. At high pH, good to excellent conversions (up to 95%) and regioselectivity (up to 99:1 N^ε/N^α amine ratio) in the acylation were realized, exemplified by the chemical modification of incretin peptides and insulin. At neutral pH, an unusually high preference toward the N-terminal phenylalanine in an insulin derivative was observed (>99:1 N^α/N^ε), which is up until now unprecedented in the literature for more elaborate reagents. In addition, the unusually high hydrolytic stability of these reagents and their ability to efficiently react at low concentrations (28 μM or 0.1 mg/mL) are exemplified with a hydroxy linker-based reagent and are a unique feature of this work.

Fabrication of highly porous, functional cellulose-based microspheres for potential enzyme carriers

Here, we present highly porous, cellulose-based microspheres using (2,2,6,6-tetramethylpiperidine-1-oxyl) TEMPO-oxidized cellulose fibers (TOCFs) as starting materials. The TOCFs were first dissolved in NaOH/urea solvent and transformed into microspheres via an emulsification method. The carboxyl groups on the surface of TOCFs were successfully carried on the cellulose-based microspheres, which provides them numerous reacting or binding sites, allowing them to be easily functionalized or immobilized with biomolecules for multi-functional applications. Furthermore, the introduction of magnetic nanoparticles awards these microspheres magnetic properties, allowing them to be attracted by a magnetic field. As a proof of concept, we demonstrate the application of using these carboxylate cellulose-based microspheres for enzyme immobilization. The cellulose-based microspheres can successfully create stable covalent bonds with enzymes after the activation of carboxyl groups. The enhanced pH tolerance, thermal stability, convenient recovery, and reusability position the emulsified microspheres as promising carriers for enzyme immobilization.

Deconstruction and Reassembly of Renewable Polymers and Biocolloids into Next Generation Structured Materials

This review considers the most recent developments in supramolecular and supraparticle structures obtained from natural, renewable biopolymers as well as their disassembly and reassembly into engineered materials. We introduce the main interactions that control bottom-up synthesis and top-down design at different length scales, highlighting the promise of natural biopolymers and associated building blocks. The latter have become main actors in the recent surge of the scientific and patent literature related to the subject. Such developments make prominent use of multicomponent and hierarchical polymeric assemblies and structures that contain polysaccharides (cellulose, chitin, and others), polyphenols (lignins, tannins), and proteins (soy, whey, silk, and other proteins). We offer a comprehensive discussion about the interactions that exist in their native architectures (including multicomponent and composite forms), the chemical modification of polysaccharides and their deconstruction into high axial aspect nanofibers and nanorods. We reflect on the availability and suitability of the latter types of building blocks to enable superstructures and colloidal associations. As far as processing, we describe the most relevant transitions, from the solution to the gel state and the routes that can be used to arrive to consolidated materials with prescribed properties. We highlight the implementation of supramolecular and superstructures in different technological fields that exploit the synergies exhibited by renewable polymers and biocolloids integrated in structured materials.

Inactivation of an Enveloped Virus by Immobilized Antimicrobial Peptides

Infections caused by viruses are difficult to treat due to their life cycle, which depends on the replication machinery of the respective host cells. Commonly used antiviral strategies are based upon the application of, e.g., entry inhibitors and other compounds that interfere with virus replication. Besides possible side effects, the rapid occurrence of viral resistance poses a great challenge. Antimicrobial peptides (AMPs), as a component of the innate immunity, are able to kill bacteria and fungi and, in addition, may inactivate enveloped viruses. Many AMPs exert their biological function by impairing microbial and viral membranes. As a result, membrane integrity is lost, leading to bacterial killing and virus inactivation. Covalently immobilized AMPs have been shown to be biocidal too, which is of special interest when the presence of a soluble agent is to be avoided. Here, we demonstrate the conjugation of the human AMP LL37 to a solid support consisting of cellulose beads and its capability to inactivate murine cytomegalovirus as an example. Virus inactivation was highly reduced by several orders of magnitude when an appropriate coupling strategy was chosen. Coupling the AMP via a long and hydrophilic polyethylene glycol spacer proved to perform less effective compared to LL37 immobilization using a short cross-linker. In addition, it was found that LL37-conjugated beads did not induce hemolysis, a prerequisite for the development of blood contacting applications. Our findings may serve as a basis for the development of an implementable device that is able to reduce the viral load under real-life conditions.

Spherical Cellulose Micro and Nanoparticles: A Review of Recent Developments and Applications

Cellulose, the most abundant natural polymer, is a versatile polysaccharide that is being exploited to manufacture innovative blends, composites, and hybrid materials in the form of membranes, films, coatings, hydrogels, and foams, as well as particles at the micro and nano scales. The application fields of cellulose micro and nanoparticles run the gamut from medicine, biology, and environment to electronics and energy. In fact, the number of studies dealing with sphere-shaped micro and nanoparticles based exclusively on cellulose (or its derivatives) or cellulose in combination with other molecules and macromolecules has been steadily increasing in the last five years. Hence, there is a clear need for an up-to-date narrative that gathers the latest advances on this research topic. So, the aim of this review is to portray some of the most recent and relevant developments on the use of cellulose to produce spherical micro- and nano-sized particles. An attempt was made to illustrate the present state of affairs in terms of the go-to strategies (e.g., emulsification processes, nanoprecipitation, microfluidics, and other assembly approaches) for the generation of sphere-shaped particles of cellulose and derivatives thereof. A concise description of the application fields of these cellulose-based spherical micro and nanoparticles is also presented.

Structure Development of the Interphase between Drying Cellulose Materials Revealed by In Situ Grazing-Incidence Small-Angle X-ray Scattering

The nano- to microscale structures at the interface between materials can define the macroscopic material properties. These structures are extremely difficult to investigate for complex material systems, such as cellulose-rich materials. The development of new model cellulose materials and measuring techniques has opened new possibilities to resolve this problem. We present a straightforward approach combining micro-focusing grazing-incidence small-angle X-ray scattering and atomic force microscopy (AFM) to investigate the structural rearrangements of cellulose/cellulose interfaces in situ during drying. Based on the results, we propose that molecular interdiffusion and structural rearrangement play a major role in the development of the properties of the cellulose/cellulose interphase; this model is representative of the development of the properties of joint/contact points between macroscopic cellulose fibers.

Production and Surface Modification of Cellulose Bioproducts

Petroleum-based synthetic plastics play an important role in our life. As the detrimental health and environmental effects of synthetic plastics continue to increase, the renewable, degradable and recyclable properties of cellulose make subsequent products the "preferred environmentally friendly" alternatives, with a small carbon footprint. Despite the fact that the bioplastic industry is growing rapidly with many innovative discoveries, cellulose-based bioproducts in their natural state face challenges in replacing synthetic plastics. These challenges include scalability issues, high cost of production, and most importantly, limited functionality of cellulosic materials. However, in order for cellulosic materials to be able to compete with synthetic plastics, they must possess properties adequate for the end use and meet performance expectations. In this regard, surface modification of pre-made cellulosic materials preserves the chemical profile of cellulose, its mechanical properties, and biodegradability, while diversifying its possible applications. The review covers numerous techniques for surface functionalization of materials prepared from cellulose such as plasma treatment, surface grafting (including RDRP methods), and chemical vapor and atomic layer deposition techniques. The review also highlights purposeful development of new cellulosic architectures and their utilization, with a specific focus on cellulosic hydrogels, aerogels, beads, membranes, and nanomaterials. The judicious choice of material architecture combined with a specific surface functionalization method will allow us to take full advantage of the polymer's biocompatibility and biodegradability and improve existing and target novel applications of cellulose, such as proteins and antibodies immobilization, enantiomers separation, and composites preparation.