Cellulose-based Hydrogel Research Articles

A Simple Regeneration Process Using a CO2-Switchable-Polarity Solvent for Cellulose Hydrogels.

Cellulose is one of the main components of plant cell walls, abundant on earth, and can be acquired at a low cost. Furthermore, there has been increasing interest in its use in environmentally friendly, carbon-neutral, sustainable materials. It is expected that the applications of cellulose will expand with the development of a simple processing method. In this study, we dissolved cellulose in aqueous N-butyl-N-methylpyrrolidinium hydroxide solution ([C4mpyr][OH]/H2O) and investigated the cellulose regeneration process based on changes in solubility upon application of CO2 gas. We investigated the effect of transformation of the anion chemical structure on cellulose solubility by flowing CO2 gas into [C4mpyr][OH]/H2O and conducted pH, FT-IR, and 13C NMR measurements. We observed that the changes in anion structure allowed for the modulation of cellulose solubility in [C4mpyr][OH]/H2O, thus establishing a simple and safe cellulose regeneration process. This regeneration process was also applied to enable the production of cellulose hydrogels. The hydrogel formed using this method was revealed to have higher mechanical strength than an analogous hydrogel produced using the same dissolution solvent with the addition of a cross-linker. The ability to produce cellulose-based hydrogels of different mechanical properties is expected to expand the possible applications.

Novel carboxymethyl cellulose-based hydrogel embedded with metal organic framework for efficient cationic dye removal from water

The rGO/CMC/β-CD (RCβ) hydrogel was synthesized from reduced graphene oxide (rGO), β-cyclodextrin (β-CD) and sodium carboxymethyl cellulose (CMC) by radical polymerization. A novel hydrogel adsorbent was created by growing the metal-organic framework (Cu-BTC) in-situ on RCβ hydrogel, which has excellent adsorption capacities for cationic dyes in wastewater. The adsorption parameters such as the amount of adsorbent, pH of solution and adsorption time were optimized through batch adsorption experiments. Under the optimal conditions of pH 6.0, adsorbent dosage of 0.01 g and experimental temperature of 25 °C, Langmuir isothermal model was used to fit the maximum adsorption capacities of methylene blue (MB), crystal violet (CV) and malachite green (MG), which were 892.66, 842.75 and 633.77 mg g−1, respectively. The fitting results of adsorption kinetics revealed that the pseudo-second-order model can describe the adsorption process better. Based on proposed studies, the dye molecules were adsorbed onto RCβ@Cu-BTC hydrogel mainly through electrostatic interaction, hydrogen bonding and π–π interactions. After five cycles, the adsorption efficiency of the RCβ@Cu-BTC hydrogel for MB, CV and MG can still reach 80 %, 77 % and 72 %, which shows that the adsorbent has good adsorption performance. Various adsorption experiments shows that RCβ@Cu-BTC hydrogel has great potential in treating dye wastewater.

Stretchable, self-healing, adhesive and anti-freezing ionic conductive cellulose-based hydrogels for flexible supercapacitors and sensors

Stretchable, self-healing, adhesive and anti-freezing ionic conductive cellulose-based hydrogels for flexible supercapacitors and sensors

Studies of the Sorption-Desorption of Pesticides from Cellulose-Based Derivative Nanocomposite Hydrogels

This study analyzed the effect of cellulose derivatives, namely methylcellulose (MC) and carboxymethylcellulose (CMC), on the stability of zeolite in a polymeric solution that would synthesize a three-dimensional network of poly(methacrylic acid)-co-polyacrylamide (PMAA-co-PAAm). Additionally, it investigated the effect of pH on the release of paraquat (PQ) and difenzoquat (DFZ) herbicides. Similar to previous studies with hydrogels containing CMC, the presence of bi and trivalent salts, such as Ca+2 and Al+3, also drastically reduced their swelling degree from 6.7 g/g in NaCl (0.15 mol·L−1) to 2.1 g/g in an AlCl3 solution (0.15 mol·L−1) for the MC nanocomposite. The viscosity results may suggest that the formation of a polysaccharide-zeolite complex contributed to the zeolite stabilization. As for the adsorption results, all samples adsorbed practically the entire concentration of both herbicides in an aqueous solution. Finally, it was also observed that the valence of the salts and molecular weight of the herbicide affect the release process, where DFZ was the herbicide with the highest concentration released. Both nanostructured hydrogels with CMC and MC exhibited lower release at pH = 7.0. These results demonstrated that a more in-depth evaluation of the phenomena involved in the application of these materials in controlled-release systems could help mitigate the impact caused by pesticides.

Biomimetic multiscale structure with hierarchically entangled topologies of cellulose-based hydrogel sensors for human-computer interaction

The development of high-performance cellulose-based sensors with superior interfacial compatibility, flexibility, and strength has always been challenging. Drawing inspiration from the intricate multiscale hierarchy found in resilient natural materials, the incorporation of this structure into cellulose-based hydrogels using biomimetic strategies is anticipated to enhance their properties. Therefore, the cellulose/polyacrylamide (PAM) hybrid hydrogels are fabricated using the aqueous AlCl3/ZnCl2 system through an all-green one-pot method at room temperature, achieving efficient dissolution of cellulose at multiple scales and in-situ polymerization of polyacrylamide. The multiscale cellulose/PAM hydrogels achieve good interfacial compatibility, with the reinforcing mechanism being confirmed through a combination of experimental validation and atomic simulations. The findings underscore the key elements that drive the multiscale behavior of hydrogels, encompassing a range of factors such as multiple interfacial interactions, hierarchical molecular entanglements, and microskeleton reinforcement. The hydrogels exhibit satisfactory stretchability (412 %), compressive strength (1.2 MPa), conductivity (1.65 S m−1), and ultralong circulability (> 12,000 cycles), rendering them suitable for various scenarios of human-computer interaction. This work establishes a comprehensive interpretation of the strengthening mechanism in cellulose-based multiscale hierarchical structures, thereby providing novel insights for the advanced design strategies of other promising hierarchical materials.

Evaluation of a Kenaf Nanocrystalline Cellulose-based Hydrogel Containing Platelet Lysate for Full-thickness Wound Healing

Introduction: Healing full-thickness wounds is often challenging and time-consuming, with complications such as scarring and infections. The standard treatment, split skin grafting, has limitations due to the availability of healthy donors and suitability for immunocompromised patients. Method: Autologous platelet lysate (PL) has been popular for tissue regenerative potential because it contains growth factors (GF) and is a safer option for bedridden patients with weak immune systems. However, PL has inconsistent clinical efficacy, high costs, and a short half-life. To address these issues, this study explores a novel delivery system by fabricating a chitosan/nanocrystalline cellulose (CS/NCC) hydrogel to sustainably deliver autologous PL to the wound site. Notably, NCC was prepared from kenaf bast fibers using acid hydrolysis and integrated into the CS matrix through physical entrapment without any chemical crosslinkers. The composite hydrogel was then enriched with autologous PL and further characterized for its physicochemical properties, in vitro GF release, and compatibility with skin cells. At the molecular level, gene expression of wound healing genes was facilitated using qPCR, revealing that the PL-supplemented hydrogel upregulated the expression of extracellular matrix genes. An in vivo study using a full-thickness wound model demonstrated that the CS-NCC-PL hydrogel dressing achieved 81.8% wound closure within 14 days, compared to the control groups. Result: Histological analysis indicated enhanced re-epithelialization, angiogenesis, and collagen deposition. Particularly, the CS-NCC-PL hydrogel group showed a significantly higher hydroxyproline content (60.62 ± 11.46 μg/100 mg) by day 14. Immunohistochemistry results revealed elevated levels of α-SMA and CD31, markers of myofibroblast presence and angiogenesis, peaking at day 7. Conclusion: These findings suggest that the CS-NCC-PL hydrogel is a promising personalized wound dressing for bedridden patients, offering improved healing outcomes in hospital settings.

Targeted recognition and enhanced biotransformation of phytochemicals by a dual-functional cellulose-based hydrogel bioreactor

The combined technology of molecular imprinting and immobilization is a promising strategy for improving biocatalytic performance. In this work, a dual-functional cellulose-based hydrogel bioreactor with targeted recognition and transformation functions was innovatively designed by cellulose-based molecularly imprinted polymers (CM-MIPs) hydrogel coupled with layered double hydroxide immobilized enzyme (LDH-E). Firstly, CM-MIPs hydrogel was prepared by using phlorizin, 4-pinylpyridine, and cellulose microspheres as template molecule, functional monomer, and support material, respectively. Meanwhile, layered double hydroxide (LDH) taken as a carrier to immobilize β-glucosidase. The prepared LDH was layered sheet-like structure with ultra-thin thickness of approximately only 1.5 nm, and β-glucosidase was immobilized on both sides of the LDH. Further, the dual-functional bioreactor was constructed by the anion exchange, which possessed maximum targeted adsorption capacity to phlorizin of 15.25 mg/g, exhibited 1.2 folds higher transformation efficiency than LDH-E, and the phloretin content increased 26 folds to that in Lithocarpus litseifolius (Hance) Chu leaves extracts. Moreover, the transformation efficiency remained above 70 % even after five consecutive transformations. Overall, the dual-functional bioreactor has broad prospects for the application in targeted recognition and transformation of phytochemicals, and provides a new insight on multifunctional bio-based reactors in natural production field.

Reversible fluorescence/photochromic switching of repeated-response cellulose-based hydrogels for information encryption

The rapid development of anti-counterfeiting technology has brought new challenges to the repeatability and stability of reversible fluorescence/photochromic switching hydrogels. To address this issue, a series of chemical cross-linked cellulose-based intelligent responsive hydrogels were synthesized by free-radical graft copolymerization in a hydrothermal process. This strategy allows for the creation of a chemical cross-linked three-dimensional structure that anchors photochromic ammonium molybdate and fluorescent carbon dots together, resulting in enhanced stability and mechanical properties. Especially, the tensile and compressive strength of hydrogel reached a maximum value of 280 kPa and 560 kPa, respectively, which far exceeds that of some reported hydrogels. The resultant hydrogels exhibited desired reversible fluorescence/photochromic switching, reversible printing and erasing of patterns, and information encryption/decryption. Notably, the change of photochromism from yellow to green can be realized, and the self-fading process can be shortened to 25 min at 60 °C instead of 6 h at room temperature. More importantly, the fluorescence quenching phenomenon of the hydrogel occurs gradually after 2 min of continuous irradiation, and it can be recovered by selective treatment with ethanol. Overall, this study provides a simple strategy for the preparation of environmentally friendly reversible fluorescence/photochromic switching cellulose-based hydrogels for information encryption.

Development of cellulose-based self-healing hydrogel smart packaging for fish preservation and freshness indication

Biomass-based composite packaging materials loaded with functional fillers have good application prospects in food preservation and freshness detection. Self-healing hydrogel packaging films based on nanocellulose (CNF), polyvinyl alcohol (PVA), and ZIF-8 embedded with curcumin (Cur@ZIF-8) were developed in this study. The synthesis of Cur@ZIF-8 was demonstrated by characterization experiments. The addition of Cur@ZIF-8 enhanced the water vapor barrier property, tensile strength, and elongation at break of hydrogel films by 49.2 %, 193.5 %, and 172.9 %, respectively, and endowed them with excellent antimicrobial, antioxidant, and ammonia sensitivity. In packaging tests with fish, hydrogel films loaded with Cur@ZIF-8 inhibited spoilage and microbial growth to extend the shelf life of fish to 9 days, and the color change of hydrogel films allowed for real-time monitoring of fish freshness. This study provided a new solution for smart packaging materials with dual functions of preservation and freshness indication.

Cellulose-based dual-crosslinked hydrogels with strong wet adhesion and benign on-demand detachment

Cellulose-based dual-crosslinked hydrogels with strong wet adhesion and benign on-demand detachment

Enhancing frost-resistant and electrically conductive properties of bacterial cellulose-based IPN hydrogel wound dressings via photopolymerization: Towards epidermal sensor applications

Conventional wound dressings are limited in their application due to the difficulty of maintaining normal use in cold conditions and a lack of functionality. In this study, photopolymerization was employed to fabricate a wound dressing with the capacity to monitor vital signs in cold environments. Utilizing bacterial cellulose (BC) to form an Interpenetrating Network (IPN) structure, the dressing exhibits enhanced water retention and mechanical properties, with a notable increase in mechanical strength to 540.37 KPa. Moreover, it maintains excellent mechanical resilience and electrical conductivity (9.01 × 10−3 S/cm) even at temperatures as low as −20 ℃. Incorporation of positively charged quaternary ammonium salts imparts potent antibacterial properties to the hydrogel against Staphylococcus aureus and Escherichia coli by electrostatically adsorbing to and disrupting negatively charged bacterial cell membranes, resulting in the leakage of internal fluids. The efficacy of the hydrogel in promoting wound healing was validated through rat-infected wound models. Hematoxylin and eosin (H&E) staining confirmed a reduction in inflammation at the wound site, improved wound healing, and a marked increase in the wound healing rate. Moreover, the hydrogel has remarkable electrical conductivity (1.25 × 10−2 S/cm), enabling the detection of subtle signals (e.g., strain 0.25 %) crucial for emergency wound management to prevent infections. Of significant importance, these hydrogels can function as electrodes for monitoring electrocardiogram (ECG) signals and respiratory status, facilitating timely assessment of vital signs in casualties. This innovative hydrogel wound dressing holds promise for simultaneously monitoring human vital signs and treating wounds in cold outdoor settings, thus offering broad applications in the realms of wound management and dressing for cold outdoor sports.

Single-Component Cellulose Acetate Sulfate Hydrogels for Direct Ink Writing 3D Printing.

Hydrogels, typically favored for 3D printing due to their viscoelasticity, are now trending toward ecofriendly alternatives amid growing environmental concerns. In this study, we crafted cellulose-based hydrogels, specifically employing cellulose acetate sulfate (CAS). By keeping the acetyl group substitution degree (DSacetyl = 1.8) and CAS molecular weight constant, we varied rheological properties by adjusting sulfate group substitution (DSsulfate = 0.4, 0.7, and 1.0) and CAS concentration (2-5 wt %). Rheological characterizations, including shear-thinning, yield stress, and thixotropy, were performed to identify optimal conditions for formulating CAS hydrogel ink in direct ink writing for 3D printing under selected experimental conditions. Based on rheological findings, CAS hydrogels with DSsulfate 0.7 and concentration of 4 wt % was used for 3D printing, with subsequent evaluation of printing metrics. Additionally, the effect of ionic cross-linking using Ca2+ ions on the structural integrity of 3D-printed structures was evaluated, demonstrating effective preservation through reinforced polymer networks. The shrinking and swelling behaviors of the 3D-printed structures were also significantly affected by this ionic cross-linking. Building on these findings, this work could broaden the range of cellulose derivatives available for the preparation of cellulose-based hydrogels for 3D printing.

A Novel Cellulose-Based Composite Hydrogel Microsphere Material: for Efficient Adsorption of Co(II) and Ni(II) Ions in Water

A Novel Cellulose-Based Composite Hydrogel Microsphere Material: for Efficient Adsorption of Co(II) and Ni(II) Ions in Water

Tailoring the Structure and Physico-Chemical Features of Cellulose-Based Hydrogels Using Multi-Epoxy Crosslinking Agents.

Hydrogel features can be designed and optimized using different crosslinking agents to meet specific requirements. In this regard, the present work investigates the physico-chemical features of cellulose-based hydrogels, designed by using different epoxy crosslinkers from the same glycidyl family, namely epichlorohydrin (ECH), 1,4-butanediol diglycidyl ether (BDDE), and trimethylolpropane triglycidyl ether (TMPTGE). The effect of the crosslinker's structure (from simple to branched) and functionality (mono-, bi- and tri-epoxy groups) on the hydrogels' features was studied. The performances of the hydrogels were investigated through the gel fraction, as well as by ATR-FTIR, DVS, SEM, DSC, and TG analyses. Also, the swelling and rheological behaviors of the hydrogels were examined. The advantages and limitations of each approach were discussed and a strong correlation between the crosslinker structure and the hydrogel properties was established. The formation of new ether bonds was evidenced by ATR-FTIR spectroscopy. It was emphasized that the pore size is directly influenced by the crosslinker type, namely, it decreases with the increasing number of epoxy groups from the crosslinker molecule, i.e., from 46 ± 11.1 µm (hydrogel CE, with ECH) to 12.3 ± 2.5 µm (hydrogel CB, with BDDE) and 6.7 ± 1.5 µm (hydrogel CT, with TMPTGE). The rheological behavior is consistent with the swelling data and hydrogel morphology, such as CE with the highest Qmax and the largest pore size being relatively more elastic than CB and CT. Instead, the denser matrices obtained by using crosslinkers with more complex structures have better thermal stability. The experimental results highlight the possibility of using a specific crosslinking agent, with a defined structure and functionality, in order to establish the main characteristics of hydrogels and, implicitly, to design them for a certain field of application.

Synthesis of Cellulose-Based Hydrogel-Nanocomposites for Medical Applications.

This study focused on synthesizing a cellulose-based hydrogel nanocomposite as a green hydrogel by adding a microcrystalline cellulose (MC) solution to carboxymethyl cellulose sodium (CMC-Na) with citric acid as a cross-linker. Y2O3 nanoparticles were incorporated during hydrogel preparation in different ratios (0.00% (0 mmol), 0.03% (0.017 mmol), 0.07% (0.04 mmol) and 0.10% (0.44 mmol)). FTIR analysis confirmed the cross-linking reaction, while XRD analysis revealed the hydrogels' amorphous nature and identified sodium citrate crystals formed from the reaction between citric acid and CMC-Na. The swelling test in deionized water (pH 6.5) at 25 °C showed a maximum swelling percentage of 150% after 24 h in the highest nanoparticle ratio. The resulting cellulose hydrogels were flexible and exhibited significant antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The synthesized cellulose-based hydrogel nanocomposites are eco-friendly and suitable for medical applications.

Tailoring cellulose-based hydrogels by phosphorylation of unbleached kraft pulps for adsorption applications

Tailoring cellulose-based hydrogels by phosphorylation of unbleached kraft pulps for adsorption applications

Ion confinement effect enabled by carboxymethyl cellulose/tannic acid hybrid hydrogel electrolyte toward stable zinc anode

Zinc metal batteries have garnered considerable attention ascribing to its cost effectiveness, intrinsic safety, and eco-friendliness. Nevertheless, zinc metal batteries yet are confronted with service life issue arising from dendrite and side reactions. Here, a highly ionic confined and hydrogen bond-enhanced tannic acid-modified carboxymethyl cellulose-based hybrid hydrogel electrolyte is designed for regulating structure of Zn2+ solvent and inhibiting dendrites growth, and simultaneously remaining operational under severe condition like low temperature. The phenolic hydroxyl group in tannic acid and the carboxyl group in carboxymethyl cellulose can respectively engage in chelation and coordination with Zn2+ to regulate Zn2+ transportation channel for guiding uniform zinc plating/stripping. Simultaneously, the enhanced ion confinement effect changes the solvation structure of Zn2+ to reduce H2O activity, effectively alleviating corrosion and hydrogen evolution reaction induced by H2O. Based on the principles of thermodynamics and reaction kinetics combined with theoretical calculations and experimental findings, the mechanism underlying its pivotal role in attenuating hydrogen evolution and fostering zinc deposition is elucidated systematically. The carboxymethyl cellulose/tannic acid hydrogel electrolyte endows exceptional cycling longevity (2, 100 h at 0.5 mA cm−2/0.25 mAh cm−2) for Zn||Zn battery, as well as high Coulombic efficiency for Zn||Cu battery (averagely 98.31 % within 500 cycles at 1 mA cm−2/mAh cm−2. Moreover, the assembled Zn||Zn battery, Zn||NH4V4O10 battery and Zn||NH4V4O10 pouch battery utilizing carboxymethyl cellulose/tannic acid hydrogel electrolyte can even function normally under severe conditions like low temperature and bending. This study provides valuable reference to develop hydrogel electrolytes with the ability to withstand low temperature and stabilize zinc anode.

Review Article About Gel Polymers and Their Applications

One of the important applications of hydrogels is agricultural applications, as there is a controlled release of nutrients from the hydrogel into the soil, which are fertilizers loaded on the hydrogel. A large part of the fertilizer added to the soil is lost through leaching, especially in highly porous soils, in chemical processes, heavy rains, etc. A number of different polysaccharides, such as chitosan, pectin and carboxymethyl cellulose have been used to prepare hydrogels as a fertilizer release system for soil revitalization. Many studies have been conducted in this field. For example, Agaba et.al indicated that moisture retention in a particular soil due to the hydrogel is necessary to create a forest. Planted Water affects soil properties such as aeration, temperature, nutrient transfer, water absorption and conversion, which affects plant growth. Dimitri et al investigated the applicability of cellulose-based hydrogels in three different formulations, i.e. crosslinked by carbodiimide, as a carrier for sustained and controlled release of water and as nutrients in arid and desert regions.

Synthesis and characterization of biocompatible hydrogel from textile–garment waste for personal hygiene products

The objective of the present study is to synthesise cellulose-based hydrogel from cellulosic waste that is produced in the garment and textile industries. Carboxymethyl cellulose was synthesized via carboxymethylation subsequent to the separation of cellulose. The progress of reaction was monitored by measuring the degree of carboxymethyl cellulose substitution. Carboxymethyl cellulose was graft co-polymerized with acrylic acid and acrylamide in the presence of N,N-methylene-bis-acrylamide to develop a superabsorbent hydrogel. The generated hydrogel was put through several mechanical and physical tests, as well as FTIR, XRD, TGA and SEM investigations, to evaluate its real formation and characteristics. The prepared hydrogel demonstrated favorable swelling properties, as well as excellent adsorption of ions and dyestuffs. The maximum water absorption capability of the superabsorbent material obtained from textile and garment waste was 182 g/g. Furthermore, the prepared hydrogel exhibits exceptional biocompatibility, biodegradability, environmental friendliness, and non-toxicity. These qualities make it an exceptional material for use in personal care items and protective gear.

Wide-humidity, anti-freezing and stretchable multifunctional conductive carboxymethyl cellulose-based hydrogels for flexible wearable strain sensors and arrays

Hydrogels play an important role in the design and fabrication of wearable sensors with outstanding flexibility, high sensitivity and versatility. Since hydrogels lose and absorb water during changes in humidity and temperature, it is critical and challenging to obtain hydrogels that function properly under different environmental conditions. Herein, a dual network hydrogel based on tannic acid (TA) reinforced polyacrylamide (PAM) and sodium carboxymethylcellulose (CMC) was constructed, while the introduction of the green solvents Solketal and LiCl endowed the hydrogel with greater possibilities for further modification to improve the water content and consistency of the mechanical properties over 30–90 % RH. This composite hydrogel (PTSL) has long-term stability, excellent mechanical strength, and freezing resistance. As strain sensors, they are linear over the entire strain range (R2 = 0.994) and have a high sensitivity (GF = 2.52 over 0–680 % strain range). Furthermore, the hydrogel's exceptional electrical conductivity and freezing resistance are a result of the synergistic effect of Solketal and LiCl, which intensifies the contact between the water molecules and the colloidal phase. This research could address the suitability of hydrogels over a wide range of humidity and temperature, suggesting great applications for smart flexible wearable electronics in harsh environmental conditions.