Creation of regenerated cellulose microspheres with diameter ranging from micron to millimeter for chromatography 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.

Synthesis of Cellulose Acetate Butyrate Microspheres as Precursor for Hard Carbon-Based Electrodes in Symmetric Supercapacitors

Cellulose microspheres have a wide range of applications due to their unique properties and versatility. Various preparation methods have been explored to tailor these microspheres for specific applications. Among these methods, the acetate method using cellulose acetate is well known. However, replacement of the acetate group through the butyrate group significantly extends the variety of morphological properties. In the present work, microspheres based on cellulose acetate butyrate are being developed with modified characteristics in terms of particle size, porosity, surface morphology and the inner structure of the microspheres. While the inner structure of cellulose acetate microspheres is predominantly porous, microspheres prepared from cellulose acetate butyrate are mainly filled or contain several smaller microspheres. Carbon materials from cellulose acetate butyrate microspheres exhibit a high specific surface area of 567 m2 g-1, even without further activation. Activation processes can further increase the specific surface area, accompanied by an adaptation of the pore structure. The prepared carbons show promising results in symmetrical supercapacitors with aqueous 6 M KOH electrolytes. Activated carbons derived from cellulose acetate butyrate microspheres demonstrate an energy density of 12 Wh kg-1 at a power density of 0.9 kW kg-1.

A Cost-Effective and Chemical-Recycling Approach for Facile Preparation of Regenerated Cellulose Materials

Cellulose is difficult to melt or dissolve. The dissolution and regeneration process paves the way to convert cellulose into diverse forms but still suffers from high costs and environmental pollution. Here, we developed a method that uses aqueous alkali to efficiently dissolve cellulose at a temperature above 0 °C in minutes for fabricating regenerated cellulose. Cellulose was modified with minimal carboxymethyl groups to weaken the intermolecular interaction and improve its dissolution. The modified cellulose can be commercially obtained from carboxymethyl cellulose manufacturing with low cost and high quality. The use of only aqueous alkali reduces pollution and facilitates chemical recycling, and the moderate dissolving temperature reduces energy consumption. The regenerated cellulose materials display excellent mechanical properties and can be recycled or biodegraded after use. The method allows the use of diverse raw materials and modifications to broaden its applicability. The study develops a low-cost and eco-friendly method to fabricate regenerated cellulose.

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.

Adjustable strength and toughness of dual cross-linked nanocellulose films via spherical cellulose as soft-phase

Nanocellulose films possess numerous merits ascribing to their inherent biocompatibility, non-toxic and biodegradability properties. The potential for practical applications would be improved if their mechanical strength and toughness requirements could be met simultaneously. Herein, dual cross-linked nanocellulose (DC) film was fabricated by the treatments of chemical and physical cross-linking, which was mechanically superior to pure nanocellulose (CNF) films. To further increase the toughness of DC films, spherical cellulose (Sph) was incorporated into DC film (DC-Sph film), and analyzed under different humidity conditions (RH) (from 10 % to 90 %). The changes of functional groups of CNF, DC and DC-Sph films were detected by FTIR and XPS spectrum. The epichlorohydrin and Sph content were optimized, followed by the investigation of RH on the toughness of films. The highest tensile strength (146.6 ± 4.6 MPa) was obtained in DC film at 50 % RH, while the DC-Sph film showed the largest toughness (40.3 ± 3.7 kJ/m2) at 70 % RH. Furthermore, the possible toughening mechanism of DC-Sph film was also discussed.

Emerging horizons and prospects of polysaccharide-constructed gels in the realm of wound healing

Polysaccharides, with the abundant availability, biodegradability, and inherent safety, offer a vast array of promising applications. Leveraging the remarkable attributes of polysaccharides, biomimetic and multifunctional hydrogels have emerged as a compelling avenue for efficacious wound dressing. The gels emulate the innate extracellular biomatrix as well as foster cellular proliferation. The distinctive structural compositions and profusion of functional groups within polysaccharides confer excellent physical/chemical traits as well as distinct restorative involvements. Gels crafted from polysaccharide matrixes serve as a robust defense against bacterial threats, effectively shielding wounds from harm. This comprehensive review delves into wound physiology, accentuating the significance of numerous polysaccharide-based gels in the wound healing context. The discourse encompasses an exploration of polysaccharide hydrogels tailored for diverse wound types, along with an examination of various therapeutic agents encapsulated within hydrogels to facilitate wound repair, incorporating recent patent developments. Within the scope of this manuscript, the perspective of these captivating gels for promoting optimal healing of wounds is vividly depicted. Nevertheless, the pursuit of knowledge remains ongoing, as further research is warranted to bioengineer progressive polysaccharide gels imbued with adaptable features. Such endeavors hold the promise of unlocking substantial potential within the realm of wound healing, propelling us toward multifaceted and sophisticated solutions.

Novel cationic cellulose beads for oral delivery of poorly water-soluble drugs

Cellulose beads emerge as carriers for poorly water-soluble drugs due to their eco-friendly raw materials and favorable porous structure. However, drug dissolution may be limited by their poor swelling ability and the presence of closed pores caused by shrinkage of the pristine cellulose beads. In this study, novel cellulose beads that can swell in acidic environment were prepared by introducing ethylenediamine (EDA) on dialdehyde cellulose (DAC), thereby addressing the shrinkage and closed pore problem of cellulose beads. The effect of the ratio of EDA on the swelling behavior and amine content of beads was studied. Three model drugs with different physicochemical properties were selected to study the physical state of loaded drugs and their release behavior. According to the results of XRPD and DSC, indomethacin and itraconazole loaded in the beads were amorphous at a drug loading of 20%, but fenofibrate was partially crystalline. Both bead size and the ratio of amine groups influenced the release behavior of the model drugs. The in vitro dissolution results showed that the cationic beads greatly improved the solubility and dissolution rate of the drug compared with the crystalline drug. Beads with a small size and high ratio of EDA tend to achieve a better drug dissolution rate and cumulative release percentage. Physical stability studies of the itraconazole-loaded beads were also implemented under four different temperature/humidity conditions for up to two months. The results showed that crystallization only appeared after two months of storage at 40°/75% RH, and the drug maintained a non-crystalline state in the other three storage conditions (0 °C/0 %RH, 0 °C/32 %RH, 25 °C/32 %RH). In conclusion, the novel pH-responsive cationic cellulose beads show great potential as a carrier for improving the rate and extent of dissolution of poorly soluble drugs and maintaining supersaturation.

MIL-88B(Fe)/cellulose microspheres as sorbent for the fully automated dispersive pipette extraction towards trace sulfonamides in milk samples prior to UPLC-MS/MS analysis

MIL-88B(Fe)/cellulose microspheres (MIL-88B(Fe)/CMs) were characterized by the means of SEM, XRD, TGA and N₂ adsorption-desorption test. The composite was used as the sorbent for fully automated dispersive pipette extraction (DPX), after introducing CMs as the support, the loss of MIL-88B(Fe) in DPX was avoided. Coupled to UPLC-MS/MS, the proposed method was employed for the analysis of trace sulfonamides (SAs) in milk samples. The parameters affecting the extraction efficiency, including pH of sample solution, the rate of aspiration and dispense, amount of the adsorbent, type and volume of elution solvent were optimized. Under the optimal conditions, good linearity (r ≥ 0.9978 for five analytes), high sensitivity (limit of detection: 0.00660-0.0136 μg kg^-1) and satisfactory recovery (69.8%-100.9%) were achieved. Furthermore, the sorbent showed desirable reusability over eight extraction cycles. Compared with other methods for the pretreatment of SAs, the proposed method showed advantages of high sensitivity, less sorbent consumption, environmental friendliness and automation, providing a promising protocol for sample preparation.

Solvent-free preparation of uniform styrene/maleimide copolymer microspheres from solid poly(styrene-alt-maleic anhydride) microspheres

A solvent-free strategy to prepare poly(styrene-alt-maleimide) (SMI) provides a facile and environmentally friendly pathway to a large-scale low cost production of monodisperse SMI microspheres.

Fiber-Based Biopolymer Processing as a Route toward Sustainability

Some of the most abundant biomass on earth is sequestered in fibrous biopolymers like cellulose, chitin, and silk. These types of natural materials offer unique and striking mechanical and functional features that have driven strong interest in their utility for a range of applications, while also matching environmental sustainability needs. However, these material systems are challenging to process in cost-competitive ways to compete with synthetic plastics due to the limited options for thermal processing. This results in the dominance of solution-based processing for fibrous biopolymers, which presents challenges for scaling, cost, and consistency in outcomes. However, new opportunities to utilize thermal processing with these types of biopolymers, as well as fibrillation approaches, can drive renewed opportunities to bridge this gap between synthetic plastic processing and fibrous biopolymers, while also holding sustainability goals as critical to long-term successful outcomes.

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.

Selective capture of toxic anionic dyes of a novel prepared DMDAAC-grafted chitosan/genipin/cellulose hydrogel beads with antibacterial activity

Novel eco-friendly and green dimethyldiallylammonium chloride (DMDAAC) grafted chitosan/genipin/cellulose hydrogel beads (CCBG-g-PDMDAAC), were fabricated as selective adsorbents for anionic dyes. The physical and chemical structural changes of the prepared hydrogels were evaluated by FTIR, XRD, SEM and TG-DSC analysis. Results showed CCBG-g-PDMDAAC efficiently and selectively adsorb anionic dyes (Reactive Red 195-RR195 and Methyl orange-MO) from mixture of dye solutions. Endowed chitosan-based hydrogels the advantage of acid insolubility and good adsorption. RR195 and MO adsorption process were described better with pseudo-second-order kinetic model and Langmuir isotherm model with a maximum adsorption capacity of 1333.52 and 190.48 mg/g, respectively, indicating that monolayer chemisorption controlled the sorption process. Moreover, the hydrogels exhibited nice reusability and against S. aureus and E. coli. The hydrogels are promising for the potential application in wastewater treatment and antibacterial simultaneously.

Recent Progress in High-Strength and Robust Regenerated Cellulose Materials

High-strength petroleum-based materials like plastics have been widely used in various fields, but their nonbiodegradability has caused serious pollution problems. Cellulose, as the most abundant sustainable polymer, has a great chance to act as the ideal substitute for plastics due to its low cost, wide availability, biodegradability, etc. Herein, the recent achievements for developing cellulose "green" solvents and regenerated cellulose materials with high strength via the "bottom-up" route are presented. Cellulose can be regenerated to produce films/membranes, hydrogels/aerogels, filaments/fibers, microspheres/beads, bioplastics, etc., which show potential applications in textiles, biomedicine, energy storage, packaging, etc. Importantly, these cellulose-based materials can be biodegraded in soil and oceans, reducing environmental pollution. The cellulose solvents, dissolving mechanism, and strategies for constructing the regenerated cellulose functional materials with high strength and performances, together with the current achievements and urgent challenges are summarized, and some perspectives are also proposed. The near future will be an exciting era for high-strength biodegradable and renewable materials. The hope is that many environmentally friendly materials with good properties and low cost will be produced for commercial use, which will be beneficial for sustainable development in the world.

Synergistic stabilization of oil in water emulsion with chitin particles and tannic acid

The aim of the present study was to explore the effect of CP and TA on stability of oil in water emulsion stabilized by the two components, so as to fabricate the most efficient chitin based emulsifying agents. It was found that there was synergistic effect for CP and TA in stabilizing emulsion, specifically, the complex of chitin particles (CP) (3 g/L) with tannic acid (TA) (2 g/L) produced the most physically and oxidatively stable oil-in-water emulsion compared with other groups in this study. This is because CP-TA (3/5) complex had the lowest zeta potential, the lowest the oil water interfacial tension, the highest viscosity and the highest content of TA with excellent antioxidant activity. Furthermore, this is because there was intense interaction between CP and TA in CP-TA complex from results of FTIR, XRD and ITC, which then result in the formation of large CP-TA particles.

Ethanol-induced coacervation in aqueous gelatin solution for constructing nanospheres and networks: Morphology, dynamics and thermal sensitivity

Ethanol was used to induce coacervation in aqueous solutions of gelatin. Coacervation resulted from phase separation driven by ethanol as a poor solvent for gelatin, impacting aggregation of gelatin chains. Static coacervation was performed to investigate coacervate morphology, and gelatin concentration and ethanol temperature influenced the morphologies of the gelatin coacervates. High-concentration gelatin solutions (>4.8 wt%) treated with lower temperature ethanol (<25 °C) formed network morphologies, while low-concentration gelatin solution (<4.8 wt%) treated with ethanol near room temperature formed nanosphere assemblies. Dispersive nanospheres were obtained after treatment with higher temperature ethanol (~45 °C). Stirring the mixture of gelatin solution and ethanol resulted in dispersed nanospheres where the size was adjusted by changing the volume ratio of aqueous gelatin solution and ethanol (V_Gel:V_EtOH) and the gelatin concentration. Turbidity and absorbance measurements were carried out to further investigate coacervation dynamics. The cocervation system reached dynamic equilibrium according to the V_Gel:V_EtOH, suggesting phase separation and molecular arrangements were key. DLS results showed that reversible changes in coacervate radius could be attained by periodic heating and cooling cycles (25-60 °C). This work provides useful information for constructing gelatin-based materials using a facile coacervation method.

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.

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.

Effect of Cellulose Solvents on the Characteristics of Cellulose/Fe2O3 Hydrogel Microspheres as Enzyme Supports

Cellulose hydrogels are considered useful biocompatible and biodegradable materials. However, as few cellulose-dissolving solvents can be used to prepare cellulose hydrogel microspheres, the use of unmodified cellulose-based hydrogel microspheres for enzyme immobilization remains limited. Here, we prepared cellulose/Fe2O3 hydrogel microspheres as enzyme supports through sol-gel transition using a solvent-in-oil emulsion. Cellulose-dissolving solvents including 1-ethyl-3-methylimidazolium ([Emim][Ac]), an aqueous mixture of NaOH and thiourea, tetrabutylammonium hydroxide, and tetrabutylphosphonium hydroxide were used to prepare regular shaped cellulose/Fe2O3 microspheres. The solvent affected microsphere characteristics like crystallinity, hydrophobicity, surface morphology, size distribution, and swelling properties. The immobilization efficiency of the microspheres for lipase was also significantly influenced by the type of cellulose solvent used. In particular, the lipase immobilized on cellulose/Fe2O3 microspheres prepared using [Emim][Ac] showed the highest protein loading, and its specific activity was 3.1-fold higher than that of free lipase. The immobilized lipase could be simply recovered by a magnet and continuously reused.

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.

Technologies and Formulation Design of Polysaccharide-Based Hydrogels for Drug Delivery

Polysaccharide-based hydrogel particles (PbHPs) are very promising carriers aiming to control and target the release of drugs with different physico-chemical properties. Such delivery systems can offer benefits through the proper encapsulation of many drugs (non-steroidal and steroidal anti-inflammatory drugs, antibiotics, etc) ensuring their proper release and targeting. This review discusses the different phases involved in the production of PbHPs in pharmaceutical technology, such as droplet formation (SOL phase), sol-gel transition of the droplets (GEL phase) and drying, as well as the different methods available for droplet production with a special focus on prilling technique. In addition, an overview of the various droplet gelation methods with particular emphasis on ionic cross-linking of several polysaccharides enabling the formation of particles with inner highly porous network or nanofibrillar structure is given. Moreover, a detailed survey of the different inner texture, in xerogels, cryogels or aerogels, each with specific arrangement and properties, which can be obtained with different drying methods, is presented. Various case studies are reported to highlight the most appropriate application of such systems in pharmaceutical field. We also describe the challenges to be faced for the breakthrough towards clinic studies and, finally, the market, focusing on the useful approach of safety-by-design (SbD).

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.

Progress in Preparation of Silk Fibroin Microspheres for Biomedical Applications

As a natural biomaterial, silk fibroin (SF) holds great potential in biomedical applications with its broad availability, good biocompatibility, high mechanical strength, ease of fabrication, and controlled degradation. With emerging fabrication methods, nanoand microspheres made from SF have brought about unique opportunities in drug delivery, cell culture, and tissue engineering. For these applications, the size and distribution of silk fibroin particles (SFPs) are critical and require precise control during fabrication. Herein, we review common and emerging SFPs fabrication methods and their biomedical applications, and also the challenges and opportunities for SFPs in the near future. Lay Summary: The application of silk in textile has an extraordinarily long history and new biomedical applications emerged owing to the good biocompatibility and versatile fabrication options of its major protein component, silk fibroin. With the development of nanotechnology and microfabrication, silk fibroin has been fabricated into nano- or microspheres with precisely controlled shape and distribution. In this review, we summarize common and emerging silk fibroin particle fabrication methods and their biomedical applications, and also discuss their challenges and opportunities in the nearest future.

Review on the Production of Polysaccharide Aerogel Particles

A detailed study of the production of polysaccharide aerogel (bio-aerogel) particles from lab to pilot scale is surveyed in this article. An introduction to various droplets techniques available in the market is given and compared with the lab scale production of droplets using pipettes and syringes. An overview of the mechanisms of gelation of polysaccharide solutions together with non-solvent induced phase separation option is then discussed in the view of making wet particles. The main steps of particle recovery and solvent exchange are briefly described in order to pass through the final drying process. Various drying processes are overviewed and the importance of supercritical drying is highlighted. In addition, we present the characterization techniques to analyse the morphology and properties of the aerogels. The case studies of bio-aerogel (agar, alginate, cellulose, chitin, κ-carrageenan, pectin and starch) particles are reviewed. Potential applications of polysaccharide aerogel particles are briefly given. Finally, the conclusions summarize the prospects of the potential scale-up methods for producing bio-aerogel particles.

Radiation synthesis and performance of novel cellulose-based microsphere adsorbents for efficient removal of boron (III)

A novel cellulose-based microsphere containing glucamine groups, referred as CVN, was successfully synthesized by radiation-induced graft polymerization of 4-vinylbenzyl chloride onto cellulose microspheres and subsequent functionalization with N-methyl-d-glucamine. The adsorption by CVN for boron (III) from aqueous solutions was evaluated systematically by batch adsorption technique. Langmuir models could fit well with the adsorption behavior of CVN. The CVN adsorbents exhibited a high adsorption capacity up to 12.4mgg^-1 towards boron (III) over the wide pH range of 5-8. After the addition of chloride salts, the boron uptake of CVN was enhanced that was attributed to the compensation of the surface charge generated by boron (III) adsorption leading to favor the adsorption. At high concentrations of salts, the ionic strength and different salts have no effect on the adsorption of boron(III). This work provides a new sustainable, cost effective material as a promising specific adsorbent for the removal of boron (III) from saline solutions.

Microscale magnetic microparticle-based immunopurification of cytokinins from Arabidopsis root apex

Cytokinins (CKs) are pivotal plant hormones that have crucial roles in plant growth and development. However, their isolation and quantification are usually challenging because of their extremely low levels in plant tissues (pmol g^-1 fresh weight). We have developed a simple microscale magnetic immunoaffinity-based method for selective one-step isolation of CKs from very small amounts of plant tissue (less than 0.1 mg fresh weight). The capacity of the immunosorbent and the effect of the complex plant matrix on the yield of the rapid one-step purification were tested using a wide range of CK concentrations. The total recovery range of the new microscale isolation procedure was found to be 30-80% depending on individual CKs. Immunoaffinity extraction using group-specific monoclonal CK antibodies immobilized onto magnetic microparticles was combined with a highly sensitive ultrafast mass spectrometry-based method with a detection limit close to one attomole. This combined approach allowed metabolic profiling of a wide range of naturally occurring CKs (bases, ribosides and N⁹ -glucosides) in 1.0-mm sections of the Arabidopsis thaliana root meristematic zone. The magnetic immunoaffinity separation method was shown to be a simple and extremely fast procedure requiring minimal amounts of plant tissue.

Porous Cellulose Beads Fabricated from Regenerated Cellulose as Potential Drug Delivery Carriers

Highly porous cellulose beads (CBs) of various mean sizes were successfully prepared from regenerated cellulose of paper wastes. The drug delivery characteristics of CBs with different mean sizes were investigated using curcumin as the model drug under controlled conditions. The loading capacity and efficiency of curcumin onto CBs were substantially influenced by factors such as their morphological characteristics, curcumin concentration, and duration of loading. The release kinetic profiles of curcumin from CBs of different mean sizes were investigated in media of pH values resembling digestive juices and intestinal fluids. Release kinetic models were used to simulate and elucidate release kinetics and mechanisms of curcumin from CBs under specific conditions. The loading capacity and efficiency of curcumin onto CBs could be enhanced via the optimization of curcumin solution concentration and the morphological characteristics of CBs, whereas the release kinetic profiles of curcumin from CBs could be modulated by varying the mean diameter of CBs. Optimized CBs derived from regenerated cellulose of paper wastes are potentially useful as cost-effective drug delivery carriers.

Highly sensitive analysis of polycyclic aromatic hydrocarbons in environmental water with porous cellulose/zeolitic imidazolate framework-8 composite microspheres as a novel adsorbent coupled with high-performance liquid chromatography

In this work, novel cellulose/zeolitic imidazolate frameworks-8 composite microspheres have been successfully fabricated and utilized as sorbent for environmental polycyclic aromatic hydrocarbons efficient extraction and sensitive analysis. The composite microspheres were synthesized through the in situ hydrothermal growth of zeolitic imidazolate frameworks-8 on cellulose matrix, and exhibited favorable hierarchical structure with chemical composition as assumed through scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction patterns, and Brunauer-Emmett-Teller surface areas characterization. A robust and highly efficient method was then successfully developed with as-prepared composite microspheres as novel solid-phase extraction sorbent with optimum extraction conditions, such as sorbent amount, sample volume, extraction time, desorption conditions, volume of organic modifier, and ionic strength. The method exhibited high sensitivity with low limit of detection down to 0.1-1.0 ng/L and satisfactory linearity with correlation coefficients ranging from 0.9988 to 0.9999, as well as good recoveries of 66.7-121.2% with relative standard deviations less than 10% for environmental polycyclic aromatic hydrocarbons analysis. Thus, our method was convenient and efficient for polycyclic aromatic hydrocarbons extraction and detection, potential for future environmental water samples analysis.

Construction of biocompatible regenerated cellulose/SPI composite beads using high-voltage electrostatic technique

Regenerated cellulose/SPI composite beads fabricated by a high-voltage electrostatic technique exhibited good cytocompatibility.

The effect of zinc oxide (ZnO) addition on the physical and morphological properties of cellulose aerogel beads

Microsized open porous cellulose aerogel beads were made using mixtures of NaOH and urea and its properties tuned by varying ZnO.

Tailored beads made of dissolved cellulose--investigation of their drug release properties

In the frame of this work, we have investigated drug entrapping and release abilities of new type of porous cellulose beads (CBs) as a spherical matrix system for drug delivery. For that purpose, CBs prepared with three different methods were used as drug carriers and three compounds, anhydrous theophylline (Thp), riboflavin 5'-phosphate sodium (RSP) and lidocaine hydrochloride monohydrate (LiHCl) were used as model drug substances. The loading procedure was carried out by immersing swollen empty beads into the solutions of different concentrations of model drugs. The morphology of empty and loaded beads was examined using a field emission scanning electron microscopy (FE-SEM). Near-infrared (NIR) imaging was performed to identify the drug distributions on and within the loaded CBs. The drug amount incorporated into CBs was examined spectrophotometrically and in vitro drug release studies were performed to determine the drug release rates. The results of FE-SEM and chemical NIR imaging analyses revealed that incorporated drug were distributed on the surface and but also within the internal structure of the CBs. Physical properties of CBs and solubility of model drugs had effect on loading efficacy. Also, the drug release rates were controlled by solubility of model drugs (diffusion controlled release). In conclusion, CBs from dissolved cellulose show promise in achieving controlled drug delivery.