Functional Cellulose Beads: Preparation, Characterization, and Applications

Tentacle-type poly(hydroxamic acid)-modified macroporous cellulose beads: Synthesis, characterization, and application for heavy metal ions adsorption

Herein, a facile yet efficient template method to fabricate macroporous cellulose beads (MCBs) is reported. In this method, micro-size CaCO₃ is utilized to create macroporous structure for fast mass transfer, and tentacle-type poly(hydroxamic acid) as adsorption ligand is immobilized on the MCBs to improve adsorption capacity. The obtained tentacle-type poly(hydroxamic acid)-modified MCMs (TP-CMCBs) show uniform spherical shape (about 80 μm), bimodal pore system (macropores≈3.0 μm; diffusional pores≈14.5 nm), and high specific surface area (52.7 m²/g). The adsorption performance of TP-CMCBs is evaluated by heavy metal ions adsorption. TP-CMCBs exhibit not only high adsorption capacities (342.5, 261.5 and 243.2 mg/g for Cu²⁺, Mn²⁺ and Ni²⁺, respectively.), but also fast adsorption rate (>70% of its equilibrium uptake within 30 min). Additionally, TP-CMCBs have excellent reusability, as evidenced by that the adsorption capacities have no obvious change even after five-time consecutive adsorption-desorption cycles. All results demonstrate that the proposed TP-CMCBs have great potential in removal of heavy metal ions.

Performance and multi-scale investigation on the phase miscibility of poly(lactic acid)/amided silica nanocomposites

In this work, amino-functionalized nano-SiO₂ (m@g-SiO₂) was synthesized through coupling reaction on the surface of nano-SiO₂. Moreover, the optimum preparation conditions of m@g-SiO₂ were selected via orthogonal experiments as follows: reaction temperature of 80 °C, reaction time of 8 h, the mass ratio of stearic acid, N,N'‑carbonyldiimidazole, imidazole hydrochloride and g-SiO₂ of 0.5:0.7:0.7:1. Fourier transform infrared spectroscopy, static angle measurement and X-ray photoelectron spectroscopy unanimously confirmed the formation of m@g-SiO₂. Furthermore, poly(lactic acid)(PLA)/m@g-SiO₂ nanocomposites was prepared with m@g-SiO₂ as fillers to improve the comprehensive performance of PLA. Then, the mechanical properties and crystallization behavior of PLA/m@g-SiO₂ nanocomposites were studied, which showed that the impact strength and elongation-at-break of PLA/m@g-SiO₂ (0.3 wt%) nanocomposites were increased by 78.05% and 1148%, respectively, and its crystallinity was increased by 26.46%. Simultaneously, thermal gravimetric analysis indicated that the thermal stability of PLA/m@g-SiO₂ nanocomposites was improved. Eventually, the multi-scale investigation on the phase miscibility of PLA/m@g-SiO₂ nanocomposites was probed by rheological behaviors analysis and the molecular dynamics simulations, which confirmed that surface modification of SiO₂ greatly enhanced the interaction energy and miscibility between the filler and PLA bulk.

Hydrophobic functionalization reactions of structured cellulose nanomaterials: Mechanisms, kinetics and in silico multi-scale models

Nanoscale-interfaced cellulose nanomaterials are extracted from polysaccharides, which are widely available in nature, biocompatible and biodegradable. Moreover, the latter have a potential to be recycled, upcycled, and formulate therefore a great theoretical predisposition to be used in a number of applications. Nanocrystals, nano-fibrils and nanofibers possess reactive functional groups that enable hydrophobic surface modifications. Analysed literature data, concerning mechanisms, pathways and kinetics, was screened, compared and assessed with regard to the demand of a catalyst, different measurement conditions and added molecule reactions. There is presently only a scarce technique description for carbonOH bond functionalization, considering the elementary chemical steps, sequences and intermediates of these (non)catalytic transformations. The overview of the prevailing basic research together with in silico modelling approach methodology gives us a deeper physical understanding of processes. Finally, to further highlight the applicability of such raw materials, the review of the development in several multidisciplinary fields was presented.

Functionalization of Porous Cellulose with Glyoxyl Groups as a Carrier for Enzyme Immobilization and Stabilization

The functionalization of the internal surface of macroporous carriers with glyoxyl groups has proven to highly stabilize a large variety of enzymes through multipoint covalent immobilization. In this work, we have translated the surface chemistry developed for the fabrication of glyoxyl-agarose carriers to macroporous cellulose (CEL). To that aim, CEL-based microbeads were functionalized with glyoxyl groups through a stepwise alkoxylation (or alkylation)/oxidation synthetic scheme. This functionalization sequence was analyzed by solid-state NMR, while the scanning electron miscroscopy of CEL microbeads reveals that the mild oxidation conditions negligibly affect the morphological properties of the material. Through the optimal functionalization protocol using rac-glycidol, we introduce up to 200 μmols of aldehyde groups per gram of wet CEL, a similar density to the one obtained for the benchmarked agarose-glyoxyl carrier. This novel CEL-based carrier succeeds to immobilize and stabilize industrially relevant enzymes such as d-amino acid oxidase from Trigonopsis variabilis and xylanases from Trichoderma reseei. Remarkably, the xylanases immobilized on the optimal CEL-based materials present a half-life time of 51 h at 60 °C and convert up to 90% of the xylan after four operation cycles for the synthesis of xylooligosaccharides.

Preparation of aerogel beads and microspheres based on chitosan and cellulose for drug delivery: A review

Spherical aerogels are not easily broken during use and are easier to transport and store which can be used as templates for drug delivery. This review summarizes the possible approaches for the preparation of aerogel beads and microspheres based on chitosan and cellulose, an overview to the methods of manufacturing droplets is presented, afterwards, the transition mechanisms from sol to a spherical gel are reviewed in detail followed by different drying processes to obtain spherical aerogels with porous structures. Additionally, a specific focus is given to aerogel beads and microspheres to be regarded as drug delivery carriers. Furthermore, a core/shell architecture of aerogel beads and microspheres for controlled drug release is described and subjected to inspire readers to create novel drug release system. Finally, the conclusions and outlooks of aerogel beads and microspheres for drug delivery are summarized.

Amidoxime-functionalized bead cellulose for the decomposition of highly toxic organophosphates

Regenerated bead cellulose is a promising material with excellent mechanical and rheological properties, ideally suited for advanced environmental applications. By introducing the amidoxime functional group into the glucose unit at the C-6 position, highly effective reactive sorbent was prepared and used to destroy priority hazardous substances such as organophosphate pesticides or nerve-paralytic chemical warfare agents (CWAs). Quantum mechanical (QM) calculations were performed to study the interactions of organophosphates with amidoxime functional groups at the molecular level. It was found that the energetic reaction barrier of the rate-limiting step is markedly reduced (from 31.40 to 11.37 kcal mol⁻¹) in the case of the amidoxime-catalysed degradation of parathion methyl, which resulted in a dramatic increase in the degradation rate; this was fully confirmed by experiments, in which the pesticide degradation proceeded at the time scale of several hours (t_1/2 = 20–30 hours at pH 7.22).

Amidoxime-functionalized bead cellulose accelerates the cleavage of phosphoester bonds in toxic organophosphates.

Topochemical Engineering of Cellulose-Carboxymethyl Cellulose Beads: A Low-Field NMR Relaxometry Study

The demand for more ecological, highly engineered hydrogel beads is driven by a multitude of applications such as enzyme immobilization, tissue engineering and superabsorbent materials. Despite great interest in hydrogel fabrication and utilization, the interaction of hydrogels with water is not fully understood. In this work, NMR relaxometry experiments were performed to study bead-water interactions, by probing the changes in bead morphology and surface energy resulting from the incorporation of carboxymethyl cellulose (CMC) into a cellulose matrix. The results show that CMC improves the swelling capacity of the beads, from 1.99 to 17.49, for pure cellulose beads and beads prepared with 30% CMC, respectively. Changes in water mobility and interaction energy were evaluated by NMR relaxometry. Our findings indicate a 2-fold effect arising from the CMC incorporation: bead/water interactions were enhanced by the addition of CMC, with minor additions having a greater effect on the surface energy parameter. At the same time, bead swelling was recorded, leading to a reduction in surface-bound water, enhancing water mobility inside the hydrogels. These findings suggest that topochemical engineering by adjusting the carboxymethyl cellulose content allows the tuning of water mobility and porosity in hybrid beads and potentially opens up new areas of application for this biomaterial.

Chemical functionalization of nano fibrillated cellulose by glycidyl silane coupling agents: A grafted silane network characterization study

Nano fibrillated cellulose (NFC) has turned into a material widely studied due to its desirable performance for numerous organic systems. Nevertheless, its surface is not very compatible with most organic systems; hence, chemical functionalization methods offer a path to solve this problem. In this study, NFC is successfully functionalized with two silane coupling agents: 3-glycidyloxypropyl trimethoxysilane (GPS) and 3-glycidyloxypropyl dimethylethoxysilane (GPMES) by a simple, direct, and environmentally friendly method. Different analyses have been carried out in order to confirm the chemical modification of NFC. ATR-IR, XPS, and ²⁹Si NMR spectroscopies confirmed the chemical modification that allowed the understanding of the structure and the conformation onto the modified NFC surface. SEM and AFM microscopies were performed to study possible alterations in morphology; a slight change was observed. Thermal properties were also analyzed by TGA analysis. It remains stable after chemical functionalization. Grafted NFC showed good performance compared to the pristine one. It allows a better dispersion into organic systems improving their properties.

Preparation of Cellulose Particles with a Hollow Structure

In this study, we report the preparation of hollow cellulose particles via a solvent-releasing method with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([Emim]Ac). A dispersion comprising [Emim]Ac droplets with dissolved cellulose and a hexane medium containing a stabilizer was poured into a large amount of acetone (precipitant), resulting in the precipitation of cellulose and the formation of solid cellulose particles with a hollow structure. We found that the formation of the hollow structure resulted from the equilibrium phase separation. Porous structures were also obtained using ethanol or t-butanol as a precipitant, where cellulose immediately precipitated (i.e., exhibited non-equilibrium phase separation). In the case where acetone was used as the precipitant, the diffusion rate of [Emim]Ac from the droplets into the precipitant was relatively low; that is, the precipitation of cellulose was delayed, which allowed the cellulose to be phase-separated into a thermodynamically stable structure (equilibrium phase separation), resulting in the formation of the hollow structure.

An ultrafast and highly efficient enrichment method for both N-Glycopeptides and N-Glycans by bacterial cellulose

A powerful and fast glycopeptide/glycan enrichment method is critical for the efficiency and throughput of mass spectrometry (MS)-based glycoproteomic and glycomic analyses, especially for large-scale sample analysis. Here, we report an ultrafast and effective method for both intact N-glycopeptide and N-glycan enrichment and apply it to human serum samples. In this method, a natural hydrophilic material, bacterial cellulose (BC), was adopted and fully optimized for enrichment. This method offers the following advantages: (i) The enrichment material has natural hydrophilicity and is low-cost, biocompatible, biodegradable and easily accessible; (ii) the whole enrichment procedure is remarkably simple and fast. It takes only 10 min for intact glycopeptides/glycans to be easily purified from mixtures; (iii) the specificity of this method is over 94% for both glycan and glycopeptide enrichment; and (iv) the outstanding specificity of this technique enables high isolation efficiency for the enrichment of both intact glycopeptides and glycans. A total of 36 N-glycans and 31 N-glycopeptides were identified from human immunoglobulin G (IgG). The glycan and glycopeptide absorption capacity of BC was as high as 333 μg/mg and 250 μg/mg (IgG/BC) respectively. The selectivity for glycan and glycopeptide enrichment reached 1:100 (IgG/bovine serum albumin (BSA), molar ratio) and 1:200 (maltoheptaose (DP7)/BSA, molar ratio), respectively. Furthermore, a total of 159 N-glycans and 523 N-glycopeptides were identified in human serum by using this method. Overall, the BC-based enrichment method we present here provides an ultrafast and highly efficient method for the enrichment of both N-glycopeptides and N-glycans in complex samples and shows great potential in large-scale glycoproteomic and glycomic analyses.

Cellulose-based Biosensor for Bio-molecules Detection in Medical Diagnosis: A Mini-Review

Background::

Biosensors are widely applied for the detection of bio-molecules in blood glucose , cholesterol, and gene. Cellulose as the most dominating natural polymer has attracted more and more interest, especially in the field of medicine such as advanced medical diagnosis. Cellulose could endow biosensors with improved biocompatibility, biodegradability and nontoxicity, which could help in medical diagnosis. This mini-review summarizes the current development of cellulose-based biosensors as well as their applications in medical diagnosis in recent years.

Methods:

After reviewing recent years’ publications we can say that, there are several kinds of cellulose used in biosensors including different cellulose derivatives, bacterial cellulose and nanocellulose. Different types of cellulose-based biosensors, such as membrane, nano-cellulose and others were briefly described in addition to the detection principle. Cellulose-based biosensors were summarized as in the previous papers. The description of various methods used for preparing cellulose-based biosensors was also provided.

Results:

Cellulose and its derivatives with their unique chemical structure proved to be versatile materials providing a good platform for achieving immobilizing bioactive molecules in biosensors. These cellulose-based biosensors possess various desirable properties such as accuracy, sensitivity, convenience, low cost and fast response. Among them, cellulose paper-based biosensors have the advantages of low cost and easy operation. Nano-cellulose has unique properties such as a large aspect ratio, good dispersing ability and high absorption capacity.

Conclusion:

Cellulose displays a promising application in biosensors which could be used to detect different bio-molecules such as glucose, lactate, urea, gene, cell, amino acid, cholesterol, protein and hydroquinone. In future, the attention will be focused on designing miniaturized, multifunctional, intelligent and integrated biosensors. Creation of low cost and environmentally friendly biosensors is also very important.

Development of mechanical properties of regenerated cellulose beads during drying as investigated by atomic force microscopy

The mechanical properties as well as the size changes of swollen cellulose beads were measured in situ during solvent evaporation by atomic force microscopy (AFM) indentation measurement combined with optical microscopy. Three factors are proposed to govern the mechanical properties of the cellulose beads in the swollen state and during drying: (i) the cellulose concentration, (ii) the interaction between the cellulose entities, (iii) the heterogeneity of the network structure within the cellulose beads.

Cellulose Beads Derived from Waste Textiles for Drug Delivery

Cellulose beads were successfully prepared from waste denim using a dissolution-regeneration approach with ionic liquids as the dissolving solvent. Cellulose beads with different morphologies were achieved by altering the dissolving and coagulating solvents. The morphological differences were quantified by N₂ physisorption. The impact of morphology on the cellulose beads’ potential application was investigated in the context of drug loading and release. The results show that the fibrous morphology showed a better loading capacity than the globular analogue due to its higher surface area and pore volume.

Macro- and Microstructural Evolution during Drying of Regenerated Cellulose Beads

The macro- and microstructural evolution of water swollen and ethanol swollen regenerated cellulose gel beads have been determined during drying by optical microscopy combined with analytical balance measurements, small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS). Two characteristic length scales, which are related to the molecular dimension of cellulose monomer and elongated aggregates of these monomers, could be identified for both types of beads by SAXS. For ethanol swollen beads, only small changes to the structures were detected in both the SAXS and WAXS measurements during the entire drying process. However, the drying of cellulose from water follows a more complex process when compared to drying from ethanol. As water swollen beads dried, they went through a structural transition where elongated structures changed to spherical structures and their dimensions increased from 3.6 to 13.5 nm. After complete drying from water, the nanostructures were characterized as a combination of rodlike structures with an approximate size of cellulose monomers (0.5 nm), and spherical aggregates (13.5 nm) without any indication of heterogeneous meso- or microporosity. In addition, WAXS shows that cellulose II hydrate structure appears and transforms to cellulose II during water evaporation, however it is not possible to determine the degree of crystallinity of the beads from the present measurements. This work sheds lights on the structural changes that occur within regenerated cellulose materials during drying and can aid in the design and application of cellulosic materials as fibers, adhesives, and membranes.

Bottom-up assembly of nanocellulose structures

Nanocelluloses, both cellulose nanofibrils and cellulose nanocrystals, are gaining research traction due to their viability as key components in commercial applications and industrial processes. Significant efforts have been made to understand both the potential of assembling nanocelluloses, and the limits and prospectives of the resulting structures. This Review focuses on bottom-up techniques used to prepare nanocellulose-only structures, and details the intermolecular and surface forces driving their assembly. Additionally, the interactions that contribute to their structural integrity are discussed along with alternate pathways and suggestions for improved properties. Six categories of nanocellulose structures are presented: (1) powders, beads, and droplets; (2) capsules; (3) continuous fibres; (4) films; (5) hydrogels; and (6) aerogels and dried foams. Although research on nanocellulose assembly often focuses on fundamental science, this Review also provides insight on the potential utilization of such structures in a wide array of applications.

Cellulose Aerogel Microparticles via Emulsion-Coagulation Technique

Cellulose aerogel microparticles were made via emulsification/nonsolvent induced phase separation/drying with supercritical CO₂. Cellulose was dissolved in NaOH-based solvent with and without additives in order to control solution gelation. Two emulsions, cellulose solution/oil and cellulose nonsolvent/oil, were mixed to start nonsolvent induced phase separation (or coagulation) of cellulose inside each cellulose droplet leading to the formation of so-called microgels. Different options of triggering coagulation were tested, by coalescence of droplets of cellulose solution and cellulose nonsolvent and by diffusion of nonsolvent partly soluble in the oil, accompanied by coalescence. The second option was found to be the most efficient for stabilization of the shape of coagulated cellulose microgels. The influence of gelation on particle formation and aerogel properties was investigated. The aerogel particles' diameter was around a few tens of microns, and the specific surface area was 250-350 m²/g.

Preparation of Cellulose/Silver Composite Particles Having a Recyclable Catalytic Property

We reported the preparation of porous cellulose particles by the solvent-releasing method, in which a solution of cellulose, dissolved in 1-butyl-3-methylimidazolium chloride and N,N'-dimethylformamide, was dropped into a large amount of 1-butanol using a syringe. The obtained particles had a high specific area because of their porous structure. Herein, to functionalize the cellulose particles, carboxylate groups are introduced into their porous structure by 2,2,6,6-tetramethylpiperidine-1-oxyl-mediated oxidation and ion exchange of carboxylate groups to Ag cations is conducted. Composite cellulose/Ag particles were synthesized by the reduction reaction using the carboxylate groups as a scaffold without free silver nanoparticles in the medium. The obtained composite particles exhibited a high catalytic ability, which was evaluated by examining the reduction of 4-nitrophenol. Moreover, we determined that the catalytic efficiency was maintained for at least three cycles by immobilizing Ag on cellulose particles.

Polysaccharide-based chromatographic adsorbents for virus purification and viral clearance

Viruses still pose a significant threat to human and animal health worldwide. In the fight against viral infections, high-purity viral stocks are needed for manufacture of safer vaccines. It is also a priority to ensure the viral safety of biopharmaceuticals such as blood products. Chromatography techniques are widely implemented at both academic and industrial levels in the purification of viral particles, whole viruses and virus-like particles to remove viral contaminants from biopharmaceutical products. This paper focuses on polysaccharide adsorbents, particulate resins and membrane adsorbers, used in virus purification/removal chromatography processes. Different chromatographic modes are surveyed, with particular attention to ion exchange and affinity/pseudo-affinity adsorbents among which commercially available agarose-based resins (Sepharose®) and cellulose-based membrane adsorbers (Sartobind®) occupy a dominant position. Mainly built on the development of new ligands coupled to conventional agarose/cellulose matrices, the development perspectives of polysaccharide-based chromatography media in this antiviral area are stressed in the conclusive part.

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Chromatography has been and is still extensively implemented in virus purification/removal downstream processes.

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Typical application fields are the manufacturing of purified viral vaccines and virus-free biopharmaceuticals.

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Agarose and cellulose remain the primary polysaccharide bases for chromatography adsorbents in such virus-related applications.

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Present R&D studies mainly focus on multimodal chromatography and affinity ligands.

Implementation of Combinatorial Genetic and Microenvironmental Engineering to Microbial-Based Field-Deployable Microbead Biosensors for Highly Sensitive and Remote Chemical Detection

Bioreporters, microbial species genetically engineered to provide measurable signals in response to specific chemicals, have been widely investigated as sensors for biomedical and environmental monitoring. More specifically, the bioreporter encapsulated within a biocompatible material, such as a hydrogel that can provide a suitable microenvironment for its prolonged activity as well as efficient scalable production, has been viewed as a more broadly applicable mode of biosensors. In this study, alginate-based microbeads encapsulated with the bacterial bioreporter capable of expressing green fluorescence protein in response to nitro compounds (e.g., trinitrotoluene and dinitrotoluene) are developed as biosensors. To significantly enhance the sensitivity of the microbial-based microbead biosensors, "multifaceted" modification strategies are simultaneously employed: (1) multiple genetic modifications of the bioreporter, (2) tuning the physicomechanical properties of the encapsulating microbeads, (3) controlling the initial cell density within the microbeads, and (4) enrichment of nitro compounds inside microbeads via functional nanomaterials. These microbial and microenvironmental engineering approaches combine to significantly enhance the sensing capability, even allowing highly sensitive remote detection under a low-vapor phase. Thus, the strategy developed herein is expected to contribute to various cell-based biosensors.

Recent Advances on Cellulose-Based Nano-Drug Delivery Systems: Design of Prodrugs and Nanoparticles

BACKGROUND

Cellulose being the first abundant biopolymers in nature has many fascinating properties, including low-cost, good biodegradability, and excellent biocompatibility, which made cellulose a real potential material to create nano-drug delivery systems (nano-DDS). This review aims to present and discuss some remarkable recent advances on the drug delivery applications of cellulosebased prodrugs and nanoparticles.

METHODS

By searching the research literatures over last decade, a variety featured studies on cellulosebased nano-DDS were summarized and divided into prodrugs, prodrug nanoparticles, solid or derivative nanopartilces, amphiphilic copolymer nanoparticles, and polyelectrolyte complex nanoparticles. Various methods employed for the functionalization, pharmacodynamic actions and applications were described and discussed.

RESULTS

Many types of cellulose-based nano-DDS can ensure efficient encapsulation of various drugs and then overcome the free drug molecule shortcomings. Among all the method described, cellulosebased amphiphilic nanoparticles are most frequently used. These formulations have the higher drug loading capability, a simple and flexible way to achieve multi-functional. Apart from hydrophilic or hydrophobic modification, cellulose or its derivatives can form nanoparticles with different small molecules and macromolecules, leading to a large spectrum of cellulose-based nano-DDS and providing some unexpected advantages.

CONCLUSION

Thorough physicochemical characterization and profound understanding of interactions of the cellulose-based nano-DDS with cells and tissues is indispensable. Moreover, studies toward technics parameter optimization and scale up from the laboratory to production level should be undertaken. The development of intravenous and orally applicable cellulose-based nano-DDS will be an important research area, and these systems will have more commercial status in the market.

Fabrication and evaluation of carboxymethylated diethylaminoethyl cellulose microcarriers as support for cellular applications

Cellulose based microcarriers can be used in biomedical science as supports for cell adhesion and proliferation. However, to facilitate cell attachment to their surface, they require appropriate functional surface charge. Cell function such as adhesion and growth is increased on the modified surfaces with cationic and anionic groups. In this research, diethylaminoethyl cellulose was carboxymethylated to produce soluble multifunctional cellulose with simultaneous presence of cationic and anionic functional groups. Then, carboxymethylated diethylaminoethyl cellulose (CM-DEAEC) were produced by ionic crosslinking. Various instrumental techniques were applied to characterize the microcarriers. Biological tests were also performed to determine cell seeding efficiency, proliferation and attachment on microcarriers. Fabricated CM-DEAEC microcarriers had 1500-1800 μm diameter, +26.0 surface potential, 376% swelling behavior and 233 °C glass transition temperature respectively. The findings showed that CM-DEAEC microcarriers support cellular attachment and proliferation very well and hence are promising materials for cell therapy and tissue engineering applications.

Analysis of the Effect of Processing Conditions on Physical Properties of Thermally Set Cellulose Hydrogels

Cellulose-based hydrogels were prepared by dissolving cellulose in aqueous sodium hydroxide (NaOH)/urea solutions and casting it into complex shapes by the use of sacrificial templates followed by thermal gelation of the solution. Both the gelling temperatures used (40–80 °C), as well as the method of heating by either induction in the form of a water bath and hot press or radiation by microwaves could be shown to have a significant effect on the compressive strength and modulus of the prepared hydrogels. Lower gelling temperatures and shorter heating times were found to result in stronger and stiffer gels. Both the effect of physical cross-linking via the introduction of additional non-dissolving cellulosic material, as well as chemical cross-linking by the introduction of epichlorohydrin (ECH), and a combination of both applied during the gelation process could be shown to affect both the mechanical properties and microstructure of the hydrogels. The added cellulose acts as a physical-cross-linking agent strengthening the hydrogen-bond network as well as a reinforcing phase improving the mechanical properties. However, chemical cross-linking of an unreinforced gel leads to unfavourable bonding and cellulose network formation, resulting in drastically increased pore sizes and reduced mechanical properties. In both cases, chemical cross-linking leads to larger internal pores.

Binary mixtures of ionic liquids-DMSO as solvents for the dissolution and derivatization of cellulose: Effects of alkyl and alkoxy side chains

The efficiency of mixtures of ionic liquids (ILs) and molecular solvents in cellulose dissolution and derivatization depends on the structures of both components. We investigated the ILs 1-(1-butyl)-3-methylimidazolium acetate (C₄MeImAc) and 1-(2-methoxyethyl)-3-methylimidazolium acetate (C₃OMeImAc) and their solutions in dimethyl sulfoxide, DMSO, to assess the effect of presence of an ether linkage in the IL side-chain. Surprisingly, C₄MeImAc-DMSO was more efficient than C₃OMeImAc-DMSO for the dissolution and acylation of cellulose. We investigated both solvents using rheology, NMR spectroscopy, and solvatochromism. Mixtures of C₃OMeImAc-DMSO are more viscous, less basic, and form weaker hydrogen bonds with cellobiose than C₄MeImAc-DMSO. We attribute the lower efficiency of C₃OMeImAc to "deactivation" of the ether oxygen and C2H of the imidazolium ring due to intramolecular hydrogen bonding. Using the corresponding ILs with C2CH₃ instead of C2H, namely, 1-butyl-2,3-dimethylimidazolium acetate (C₄Me₂ImAc) and 1-(2-methoxyethyl)-2,3-dimethylimidazolium acetate (C₃OMe₂ImAc) increased the concentration of dissolved cellulose; without noticeable effect on biopolymer reactivity.

Layered Double Hydroxide-Cellulose Hybrid Beads: A Novel Catalyst for Topochemical Grafting of Pulp Fibers

Cellulose-based materials are very attractive for emerging bioeconomy as they are renewable, inexpensive, and environmentally friendly. Cellulose beads are spherical and porous and can be highly engineered to be used as catalyst support material. This type of inorganic catalysts is cost-effective and suitable for multiple re-usage and has been rarely explored in cellulose reaction research. In this work, NiFe-layered double hydroxide (LDH) was tailor-made in situ on anionic cellulose beads to form a hybrid, supported photocatalyst for the first time. The hybrid beads were prepared in a size larger than the pulp fibers in order to make the catalysis reaction heterogeneous in nature. Hydrophilic pulp fibers were converted into hydrophobic pulp by photocatalytic topochemical grafting of ethyl acrylate using the LDH-cellulose bead catalyst. The approach identified for the modification of the pulp fibers is the "hydrogen abstraction-UV photografting" because the low-energy, UV radiation-induced grafting offers advantages, such as a reduced degradation of the backbone polymer and a control over the grafting reaction. After grafting, the pulp fibers showed increased water repellency and unaltered thermal stability, indicating the hydrophobic, plasticizing nature of the pulp, which in turn accounts for its thermoformable behavior. These acrylated pulp fibers can be further designed/customized for waterproof or oil absorption applications.

Morphology Control of Porous Cellulose Particles by Tuning the Surface Tension of Media during Drying

We previously reported the preparation of cellulose particles by the solvent releasing method (SRM). The obtained cellulose particles had a porous structure filled with a surrounding medium. However, the structure was fragile and easily collapsed because of the capillary pressure as the medium evaporated, resulting in dense cellulose particles. To control the morphology of the cellulose particles in a dry state, we focused our study on the influence of the surface tension of the surrounding medium on the structure of cellulose particles because the capillary pressure is proportional to the surface tension. Different media such as toluene, acetone, and pentane were investigated. The morphologies of the resulting cellulose particles were estimated by volume changes, specific surface areas, and compressive strengths. From these results, as the surface tension of the media filling the particles was lowered, the particle's specific surface area increased, resulting in the formation of softer particles.

Fabrication and Evaluation of Cellulose-Alginate-Hydroxyapatite Beads for the Removal of Heavy Metal Ions from Aqueous Solutions

In the present study, the potential of synthesized mixed cellulose, alginate and hydroxyapatite beads for the efficient removal of Ni (II) and Cu (II) ions from aqueous solutions was investigated. Cellulose, alginate and hydroxyapatite are known for their individual adsorption capacity. Beads were prepared in different ratios of these materials. The prepared beads were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). FTIR and XRD analysis showed characteristic peaks assigned to cellulose, alginate and hydroxyapatite. Thermal stability was observed to increase with increase of hydroxyapatite percentage in beads. SEM images showed increased surface porosity and roughness with the increase of cellulose percentage. The prepared beads were used for the removal of Ni (II) and Cu (II) ions from aqueous solutions and the process was optimized with respect to pH, contact time, adsorbent dose and initial concentration of metal ions. The values of the coefficient of determination (R2) of the Langmuir and Freundlich adsorption model indicated that the adsorbed Cu (II) and Ni (II) ions form monolayer coverage on the adsorbent surface. In kinetic analysis, Pseudo-second-order model fitted the kinetic experimental data well, as it showed high R2 value; above 0.9990.

Topochemical Engineering of Cellulose-Based Functional Materials

Topochemical engineering is a method of designing the fractionation (disassembly) and fabrication (assembly) of highly engineered functional materials using a combination of molecular and supramolecular techniques. Cellulose is one of the naturally occurring biopolymers, currently considered to be an important raw material for the design and development of sustainable products and processes. This feature article deals with new insights into how cellulose can be processed and functionalized using topochemical engineering in order to create functional fibers, enhance biopolymer dissolution in water-based solvents, and control the shaping of porous materials. Subsequently, topochemical engineering of cellulose offers a variety of morphological structures such as highly engineered fibers, functional cellulose beads, and reactive powders that find relevant applications in pulp bleaching, enzyme and antimicrobial drug carriers, ion exchange resins, photoluminescent materials, waterproof materials, fluorescent materials, flame retardants, and template materials for inorganic synthesis. The topochemical engineering of biopolymers and biohybrids is an exciting and emerging area of research that can boost the design of new bioproducts with novel functionalities and technological advancements for biobased industries.

An ideal enzyme immobilization carrier: a hierarchically porous cellulose monolith fabricated by phase separation method

Cellulose monolith with a hierarchically porous morphology was utilized as a novel solid support for enzyme immobilization. After a series of modifications, succinimidyl carbonate (SC)-activated cellulose monolith (SCCL monolith) was obtained and it was employed to immobilize a model enzyme (horseradish peroxidase, HRP) through covalent bonding. The HRP immobilization capacity on SCCL monolith was calculated as 21.0 mg/g. The thermal stability measurement illustrated that the immobilized HRP exhibited a largely improved thermal resistance compared to its free counterpart. The reusability of the immobilized HRP was investigated, and it could be reused at least 10 cycles without significant activity loss. Therefore, cellulose monolith is found to be an ideal solid support for enzyme immobilization.

Chitosan-Cellulose Multifunctional Hydrogel Beads: Design, Characterization and Evaluation of Cytocompatibility with Breast Adenocarcinoma and Osteoblast Cells

Cytocompatible polysaccharide-based functional scaffolds are potential extracellular matrix candidates for soft and hard tissue engineering. This paper describes a facile approach to design cytocompatible, non-toxic, and multifunctional chitosan-cellulose based hydrogel beads utilising polysaccharide dissolution in sodium hydroxide-urea-water solvent system and coagulation under three different acidic conditions, namely 2 M acetic acid, 2 M hydrochloric acid, and 2 M sulfuric acid. The effect of coagulating medium on the final chemical composition of the hydrogel beads is investigated by spectroscopic techniques (ATR–FTIR, Raman, NMR), and elemental analysis. The beads coagulated in 2 M acetic acid displayed an unchanged chitosan composition with free amino groups, while the beads coagulated in 2 M hydrochloric and sulfuric acid showed protonation of amino groups and ionic interaction with the counterions. The ultrastructural morphological study of lyophilized beads showed that increased chitosan content enhanced the porosity of the hydrogel beads. Furthermore, cytocompatibility evaluation of the hydrogel beads with human breast adenocarcinoma cells (soft tissue) showed that the beads coagulated in 2 M acetic acid are the most suitable for this type of cells in comparison to other coagulating systems. The acetic acid fabricated hydrogel beads also support osteoblast growth and adhesion over 192 h. Thus, in future, these hydrogel beads can be tested in the in vitro studies related to breast cancer and for bone regeneration.

Chiral catalysts immobilized on achiral polymers: effect of the polymer support on the performance of the catalyst

Achiral polymeric supports can have important positive effects on the activity, stability and selectivity of supported chiral catalysts.

Cellulose modification and shaping – a review

This review aims to present cellulose as a versatile resource for the production of a variety of materials, other than pulp and paper. These products include fibers, nonwovens, films, composites, and novel derivatized materials. This article will briefly introduce the structure of cellulose and some common cellulose derivatives, as well as the formation of cellulosic materials in the micro- and nanoscale range. The challenge with dissolution of cellulose will be discussed and both derivatizing and nonderivatizing solvents for cellulose will be described. The focus of the article is the critical discussion of different shaping processes to obtain a variety of cellulose products, from commercially available viscose fibers to advanced and functionalized materials still at the research level.