Cellulose Hydrogel Research Articles

Sweat-adaptive adhesive hydrogel electronics enabled by dynamic hydrogen bond networks

Adhesive hydrogels offer an appealing way to the demand for flexible epidermal electronics. Despite the significant advances of adhesive hydrogel electronics, the unavoidable degradation of adhesion and associated diminished detection on sweaty skin are two long-standing bottlenecks for their practical applications. Herein, we present a sweat-adaptive adhesive poly(acrylamide)/cellulose (PAAm/Cel) hydrogel electronic via dynamic hydrogen bond networks. Increased sweat promotes the decoupling of hydrogen bonds within the hydrogel between PAAm and cellulose, leading to enhanced skin-hydrogel interfacial adhesion due to the strong binding of exposed abundant polar groups to the skin. The resulting PAAm/Cel hydrogel exhibits robust bioadhesion on sweating skin, with 268.3 J m−2 in interfacial toughness, 201.7 kPa in tensile strength, and 31.7 kPa in shear strength. Furthermore, the conformable and adhesive PAAm/Cel hydrogel electronics are demonstrated to produce high-quality and stable electromyogram (EMG) signals worked on persistent sweating skin. We believe that our designed adhesive hydrogel with dynamic hydrogen bond networks coupled with sweat is promising for tough bioadhesive electronics and enables bioadhesive technologies with high-level adaptivity in daily activities.

Wood-inspired anisotropic hydrogel electrolyte with large modulus and low tortuosity realizing durable dendrite-free zinc-ion batteries

While aqueous zinc-ion batteries exhibit great potential, their performance is impeded by zinc dendrites. Existing literature has proposed the use of hydrogel electrolytes to ameliorate this issue. Nevertheless, the mechanical attributes of hydrogel electrolytes, particularly their modulus, are suboptimal, primarily ascribed to the substantial water content. This drawback would severely restrict the dendrite-inhibiting efficacy, especially under large mass loadings of active materials. Inspired by the structural characteristics of wood, this study endeavors to fabricate the anisotropic carboxymethyl cellulose hydrogel electrolyte through directional freezing, salting-out effect, and compression reinforcement, aiming to maximize the modulus along the direction perpendicular to the electrode surface. The heightened modulus concurrently serves to suppress the vertical deposition of the intermediate product at the cathode. Meanwhile, the oriented channels with low tortuosity enabled by the anisotropic structure are beneficial to the ionic transport between the anode and cathode. Comparative analysis with an isotropic hydrogel sample reveals a marked enhancement in both modulus and ionic conductivity in the anisotropic hydrogel. This enhancement contributes to significantly improved zinc stripping/plating reversibility and mitigated electrochemical polarization. Additionally, a durable quasi-solid-state Zn//MnO2 battery with noteworthy volumetric energy density is realized. This study offers unique perspectives for designing hydrogel electrolytes and augmenting battery performance.

Molecularly imprinted beads based on modified cellulose hydrogel:A novel solid phase extraction filler for specific adsorption of camptothecin

Traditional solid phase extraction (SPE) suffers from a lack of specific adsorption. To overcome this problem, a combination of adsorption method and molecular imprinting technology by polydopamine modification was proposed to realize specific recognition of target compounds in SPE, which is of great significance to improve the separation efficiency of SPE. Cellulose hydrogel beads were prepared by dual cross-linking curing method and modified with polydopamine to make them hydrophilic and biocompatible. Subsequently, cellulose hydrogel-based molecularly imprinted beads (MIBs) were synthesized by surface molecular imprinting technology and used as novel column fillers in SPE to achieve efficient adsorption (34.16 mg·g−1) with specific selectivity towards camptothecin (CPT) in 120 min. The simulation and NMR analysis revealed that recognition mechanism of MIBs involved hydrogen bond interactions and Van der Waals effect. The MIBs were successful used in separating CPT from Camptotheca acuminata fruits, exhibiting impressive adsorption capacity (1.19 mg·g−1) and efficient recovery of CPT (81.54 %). Thus, an environmentally friendly column filler for SPE was developed, offering a promising avenue for utilizing cellulose-based materials in the selective separation of natural products.

Chitosan-reinforced nanocrystalline cellulose hydrogels containing activated carbon as antitoxin wound dressing

Chitosan-reinforced nanocrystalline cellulose hydrogels containing activated carbon as antitoxin wound dressing

Porous molecularly imprinted beads for highly specific separation of 10-hydroxycamptothecine: An imprinted strategy based on modified cellulose hydrogel

10-hydroxycamptothecine (HCPT), known as a natural alkaloid with significant anti-cancer properties in Camptotheca acuminata, has valuable application prospects in health and medicine and has attracted worldwide attention especially in the field of cancer research. In this study, a porous cellulose hydrogel-based molecularly imprinted bead (PCH@MIBs) with high affinity and selectivity was prepared and served as novel fillers of solid phase extraction (SPE) for selectively separating HCPT. The combination of polydopamine (PDA) modified cellulose hydrogel and highly selective molecular imprinting technology enabled the efficient and targeted adsorption for template molecules. The mixture of nano-calcium carbonate and cellulose solution underwent a reaction with an acidic coagulation bath, which endowed the cellulose hydrogel beads with porous structures. Porous cellulose hydrogel beads were coated with a PDA layer, followed by the preparation of PCH@MIBs using HCPT as template molecules and acrylamide (AM) as functional monomers, resulting in hydrogel-based materials with specific adsorption cavities matched to HCPT. The PCH@MIBs exhibited excellent adsorption capacity (57.87 mg·g−1) and adsorption selectivity (IF = 3.75), as well as good reusability (5 of cycles). The PCH@MIBs were successfully used to separate HCPT from C. acuminata fruits, with an impressive adsorption capacity (0.0974 mg·g−1) and recovery of HCPT (91.27 %). Mechanism analysis demonstrated that the recognition of PCH@MIBs was primarily achieved through non-covalent interactions between AM and HCPT, specifically hydrogen bonds and Van der Waals forces. This work proposes a novel strategy for constructing porous cellulose-based molecularly imprinted hydrogel beads to specific capture targeted compound, which have broad potential for practical application.

Biomimetic design of platelet-rich plasma controlled release bacterial cellulose/hydroxyapatite composite hydrogel for bone tissue engineering

Bacterial cellulose (BC) hydrogel is renowned in the field of tissue engineering for its high biocompatibility, excellent mechanical strength, and eco-friendliness. Herein, we present a biomimetic mineralization method for preparing BC/hydroxyapatite (HAP) composite hydrogel scaffolds with different mineralization time and ion concentration of the mineralized solution. Spherical HAP reinforcement enhanced bone mineralization, thereby imparting increased bioactivity to BC matrix materials. Subsequently, platelet-rich plasma (PRP) was introduced into the scaffold. The PRP-loaded hydrogel enhanced the release of growth factors, which promoted cell adhesion, growth, and bone healing. After 3 weeks of MC3T3-E1 cell-induced osteogenesis, PRP positively affected cell differentiation in BC/HAP@PRP scaffolds. Overall, these scaffolds exhibited excellent biocompatibility, mineralized nodule formation, and controlled release in vitro, demonstrating great potential for application in bone tissue repair.

Flaw sensitivity of bacterial cellulose hydrogel under monotonic and cyclic loadings

The presence of flaw in solid materials can lead to stress concentration, resulting in the reduction of rupture stress and stretchability of material. When the flaw is sufficiently smaller than a material-specific length, referred to as flaw sensitivity length, the material exhibits flaw insensitivity. The flaw sensitivity length is a critical material property that reflects how the material is sensitive or insensitive to crack. However, the impact of crack length on the load-bearing process of material remains an open problem. In this work, we characterize the flaw sensitivity of a stretchable material, bacterial cellulose hydrogel, under monotonic and cyclic loadings. Through fracture and fatigue tests, we first determine that the hydrogel exhibits high fracture toughness and fatigue resistance. We next characterize the flaw sensitivity of the hydrogel through two visualized experimental methods. Photoelasticity observation on the stress distribution in samples during loading shows that the samples with cracks below 2 mm exhibit uniform stress distribution during the deformation process, while those with cracks above 2 mm experience stress concentration at crack tip. Scanning electron microscope observation on the microstructure morphology of samples under fixed stretch shows that the samples with cracks below 2 mm exhibit uniform alignment of nanofibers, while those with cracks above 2 mm exhibit more intense alignment and even bundling of nanofibers at crack tip. Similar trends are observed in the samples under cyclic loading, where the transition length is also about 2 mm. Notably, the flaw sensitivity lengths obtained by the visualized methods agree well with that obtained by direct measurement of rupture stress and theoretical estimations under monotonic and cyclic loadings. The methods offer novel way to study the flaw sensitivity of materials, thereby contributing to the exploration of failure mechanisms.

Preparation and characterization of cellulose fluorescent material: Experiment and simulation

The extensive use of fossil based materials has caused serious pollution problems, the full utilization of biomass resources to prepare high value-added new materials is of great significance for the environmental protection and sustainable social development. For this purpose, this study explored the preparation process and molecular dynamics simulation of cellulose fluorescent materials. Firstly, bacterial cellulose was dissolved in a solution of NaOH and urea at low temperature, followed by a solution blending and hot pressing with hyperbranched polyamide. It was found that the addition of hyperbranched polyamide could effectively filled in the internal pores of cellulose hydrogel, thereby enhancing the fluorescence effects and tensile properties, especially the elongation at break of cellulose materials. The optimal amount of hyperbranched polyamide added was 5 wt%. Molecular dynamics simulation showed that the hydrogen bonds and interaction with cellulose increased as the concentration of hyperbranched polyamide increased.

Construction of cellulose-based hybrid hydrogel beads containing carbon dots and their high performance in the adsorption and detection of mercury ions in water

Cellulose-based adsorbents have been extensively developed in heavy metal capture and wastewater treatment. However, most of the reported powder adsorbents suffer from the difficulties in recycling due to their small sizes and limitations in detecting the targets for the lack of sensitive sensor moieties in the structure. Accordingly, carbon dots (CDs) were proposed to be encapsulated in cellulosic hydrogel beads to realize the simultaneous detection and adsorption of Hg (II) in water due to their excellent fluorescence sensing performance. Besides, the molding of cellulose was beneficial to its recycling and further reduced the potential environmental risk generated by secondary pollution caused by adsorbent decomposition. In addition, the detection limit of the hydrogel beads towards Hg (II) reached as low as 8.8 × 10−8 M, which was below the mercury effluent standard declared by WHO, exhibiting excellent practicability in Hg (II) detection and water treatment. The maximum adsorption capacity of CB-50 % for Hg (II) was 290.70 mg/g. Moreover, the adsorbent materials also had preeminent stability that the hydrogel beads could maintain sensitive and selective sensing performance towards Hg (II) after 2 months of storage. Additionally, only 3.3% of the CDs leaked out after 2 weeks of immersion in water, ensuring the accuracy of Hg (II) evaluation. Notably, the adsorbent retained over 80% of its original adsorption capacity after five consecutive regeneration cycles, underscoring its robustness and potential for sustainable environmental applications.

Zwitterionic modified and freeze-thaw reinforced foldable hydrogel as intraocular lens for posterior capsule opacification prevention

Posterior capsule opacification (PCO) is a predominant postoperative complication, often leading to visual impairment due to the aberrant proliferation and adhesion of lens epithelial cells (LECs) and protein precipitates subsequent to intraocular lens (IOL) implantation. To address this clinical issue, a foldable and antifouling sharp-edged IOL implant based on naturally-derived cellulose hydrogel is synthesized. The mechanical strength and transparency of the hydrogel is enhanced via repeated freeze-thaw (FT) cycles. The incorporated zwitterionic modifications can remarkably prevent the incidence of PCO by exhibiting proteins repulsion and cell anti-adhesion properties. The graft of dopamine onto both the haptic and the periphery of the posterior surface ensures the adhesion of the hydrogel to the posterior capsule and impedes the migration of LECs without compromising transparency. In in vivo study, the zwitterionic modified foldable hydrogel exhibits uveal and capsular biocompatibility synchronously with no signs of inflammatory response and prevent PCO formation, better than that of commercialized and PEG-modified IOL. With foldability, endurability, antifouling effect, and adhesive to posterior capsule, the reported hydrogel featuring heterogeneous surface design displays great potential to eradicate PCO and attain post-operative efficacy after cataract surgery.

Photorewriting, Time-Resolved Encryption, and Unclonable Anticounterfeiting with Artificial Intelligence Authentication via a Reversible Photoswitchable System.

In the fields of photolithographic patterning, optical anticounterfeiting, and information encryption, reversible photochromic materials with solid-state fluorescence are emerging as a potential class of systems. A design strategy for reversible photochromic materials has been proposed and synthesized through the introduction of photoactive thiophene groups into the molecular backbone of aryl vinyls, compounds with unique aggregation-induced emission properties, and solid-state reversible photocontrollable fluorescence and color-changing properties. This work develops novel photochromic inks, films, and cellulose hydrogels for enhancing the security of information encryption and anticounterfeiting technologies. They achieve rapid and reversible color change under ultraviolet light irradiation. Dependent upon the rate of color change, higher levels of time-resolved security can be achieved. This feature is important for enhancing the confidentiality of encrypted information and the reliability of security labels. Color-changing cellulose hydrogels, inks, and films consisting of three photochromic fluorescent molecules have quick photoactivity, great photoreversibility and photostability, and good processability, making them ideal for time-delayed anticounterfeiting and smart encryption. Furthermore, specialized algorithms are used to construct convolutional neural networks, and image analysis is performed on these systems, thus solving the current problem of the time-consuming information decryption process. This artificial intelligence method offers new opportunities for enhanced data encryption.

A bacterial cellulose/polyvinyl alcohol/nitro graphene oxide double layer network hydrogel efficiency antibacterial and promotes wound healing

In this study, graphene oxide (GO) was chemically modified utilizing concentrated nitric acid to produce a nitrated graphene oxide derivative (NGO) with enhanced oxidation level, improved dispersibility, and increased antibacterial activity. A double-layer composite hydrogel material (BC/PVA/NGO) with a core-shell structure was fabricated by utilizing bacterial cellulose (BC) and polyvinyl alcohol (PVA) binary composite hydrogel scaffold as the inner network template, and hydrophilic polymer (PVA) loaded with antibacterial material (NGO) as the outer network. The fabrication process involved physical crosslinking based on repeated freezing and thawing. The resulting BC/PVA/NGO hydrogel exhibited a porous structure, favorable mechanical properties, antibacterial efficacy, and biocompatibility. Subsequently, the performance of BC/PVA/NGO hydrogel in promoting wound healing was evaluated using a mouse skin injury model. The findings demonstrated that the BC/PVA/NGO hydrogel treatment group facilitated improved wound healing in the mouse skin injury model compared to the control group and the BC/PVA group. This enhanced wound healing capability was attributed primarily to the excellent antibacterial and tissue repair properties of the BC/PVA/NGO hydrogel.

Assessment of the ability of Pseudomonas aeruginosa and Staphylococcus aureus to create biofilms during wound healing in a rat model treated with carboxymethyl cellulose/carboxymethyl chitosan hydrogel containing EDTA.

The primary objective of this study was to develop a carboxymethyl cellulose (CMC) and carboxymethyl chitosan (CMCS) hydrogel containing ethylene diamine tetra acetic acid (EDTA) as the materials for wound healing. CMC and CMCS solutions were prepared with a concentration of 4% (w/v). These solutions were made using normal saline serum with a concentration of 0.5% (v/v). Additionally, EDTA with the concentrations of 0.01%, 0.05%, 0.1%, 0.5%, 1%, and 2% (w/v) was included in the prepared polymer solution. The analysis of the hydrogels revealed that they possess porous structures with interconnected pores, with average in size 88.71 ± 5.93 μm. The hydrogels exhibited a swelling capacity of up to 60% of their initial weight within 24 h, as indicated by the weight loss and swelling measurements. The antibacterial experiments showed that the formulated CMC/CMCS/EDTA 0.5% hydrogel inhibited the growth of Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, the produced hydrogels were haemocompatible and biocompatible. At the last stage, the evaluation of wound healing in the animal model demonstrated that the use of the produced hydrogels significantly improved the process of wound healing. Finally, the findings substantiated the effectiveness of the formulated hydrogels as the materials for promoting wound healing and antibacterial agents.

Enhancing storage and gastroprotective viability of Lactiplantibacillus plantarum encapsulated by sodium caseinate-inulin-soy protein isolates composites carried within carboxymethyl cellulose hydrogel

Probiotics are subjected to various edible coatings, especially proteins and polysaccharides, which serve as the predominant wall materials, with ultrasound, a sustainable green technology. Herein, sodium caseinate, inulin, and soy protein isolate composites were produced using multi-frequency ultrasound and utilized to encapsulateLactiplantibacillus plantarumto enhance its storage, thermal, and gastrointestinal viability. The physicochemical analyses revealed that the composites with 5 % soy protein isolate treated with ultrasound at 50 kHz exhibited enough repulsion forces to maintain stability, pH resistance, and the ability to encapsulate larger particles and possessed the highest encapsulation efficiency (95.95 %). The structural analyses showed changes in the composite structure at CC, CH, CO, and amino acid residual levels. Rheology, texture, and water-holding capacity demonstrated the production of soft hydrogels with mild chewing and gummy properties, carried the microcapsules without coagulation or sedimentation. Moreover, the viability attributes ofL. plantarumevinced superior encapsulation, protecting them for at least eight weeks and against heat (63 °C), reactive oxidative species (H2O2), and GI conditions.

Optimization of method for cross-section hydrogels preparation using high-pressure freezing.

High-pressure water freeze fracturing is a method for preparing water-containing samples such as hydrogels for scanning electron microscopy (SEM), in which a sample is placed in a divisible pressure vessel, filled with water, sealed, frozen with liquid nitrogen and then vacuum dried after the vessel is divided. The pressure (∼200 MPa) generated by the phase transition from water to ice is expected to inhibit ice crystal formation that causes large deformation of microstructure in the sample. To maximize the useable sample size, where SEM observation is not affected by ice crystal growth, preparation conditions including the size of pressure vessel were examined in this work. Using pressure vessels 8.0 mm, 5.5 mm and 4.5 mm in diameter, agarose gel, gelatin gel, wheat starch hydrogel, wheat flour noodle and cellulose hydrogel were used to prepare SEM samples. With agarose gel, an area of 3.6 mm in diameter in the 5.5 mm vessel was achieved as the maximum size of the area observable without ice crystal growth. The observable size of other samples was comparable, except for gelatin gel. As a result, observation of the three-dimensional network structure of hydrogels could be performed over a wider range than with the conventional method without shredding or chemical treatment of the samples. Additionally, usability of agarose gel for sample support matrix in high-pressure water freeze fracturing was demonstrated.

Preclinical assessment of an antibiotic-free cationic surfactant-based cellulose hydrogel for sexually and perinatally transmitted infections

Preclinical assessment of an antibiotic-free cationic surfactant-based cellulose hydrogel for sexually and perinatally transmitted infections

Development of eugenol loaded cellulose-chitosan based hydrogels; in-vitro and in-vivo evaluation for wound healing

Recent years have demonstrated that biopolymers can serve as effective woundhealing agents. We hereby report chitosan-oxidized cellulose (CS.OMCC) based hydrogels loaded with eugenol with distinctive antimicrobial, biocompatible, and angiogenic characteristics. CS.OMCC hydrogels in four different ratios were synthesized through Schiff base (-CN) between chitosan (CS) and oxidized microcrystalline cellulose (OMCC). The swelling and degradation study analyzed the maximum absorption strength and weight loss of 1165% and 56.8 %, respectively. Hydrogels were potent against E. coli and S. aureus. The zones of inhibition were dependent upon the chitosan and eugenol, where 30 % eugenol (Eu) loaded CS.OMCC 4:1 hydrogel revealed greater zones (17 mm). The hydrogels demonstrated favorable biocompatibility, adhesion, and migration potential of mouse fibroblast cells. Moreover, the in-vivo potential by Chorioallantoic membrane (CAM) assay displayed an increase in the number, length, and size of blood vessels, contributing superior angiogenic potential. Increased expression in the case of VEGF further supported the role of hydrogels in promoting angiogenesis. Our study presents eugenol loaded chitosan-oxidized cellulose hydrogels that presented a promising solution to target bacterial infection and promote angiogenesis, thereby promoting the wound healing process.

Tailoring of Bilosomal Nanogel for Augmenting the Off-Label Use of Sildenafil Citrate in Pediatric Pulmonary Hypertension.

Pediatric pulmonary hypertension is a serious syndrome with significant morbidity and mortality. Sildenafil is widely used off-label in pediatric patients with pulmonary arterial hypertension. In this study, bile salt-stabilized nanovesicles (bilosomes) were screened for their efficacy to enhance the transdermal delivery of the phosphodiesterase type 5 inhibitor, sildenafil citrate, in an attempt to augment its therapeutic efficacy in pediatric pulmonary hypertension. A response surface methodology was implemented for fabricating and optimizing a bilosomal formulation of sildenafil (SDF-BS). The optimized SDF-BS formulation was characterized in terms of its entrapment efficiency (EE), zeta potential, vesicle size, and in vitro release profile. The optimized formula was then loaded onto hydroxypropyl methyl cellulose (HPMC) hydrogel and assessed for skin permeation, in vivo pharmacokinetics, and pharmacodynamic studies. The optimized SDF-BS showed the following characteristic features; EE of 88.7 ± 1.1%, vesicle size of 185.0 + 9.2 nm, zeta potential of -20.4 ± 1.1 mV, and efficiently sustained SDF release for 12 h. Skin permeation study revealed a remarkable improvement in SDF penetration from bilosomal gel compared to plain SDF gel. In addition, pharmacokinetic results revealed that encapsulating SDF within bilosomal vesicles significantly enhanced its systemic bioavailability (∼3 folds), compared to SDF oral suspension. In addition, pharmacodynamic investigation revealed that, compared to plain SDF gel or oral drug suspension, SDF-BS gel applied topically triggered a significant elevation (p < 0.05) in cGMP serum levels, underscoring the superior therapeutic efficacy of SDF-BS gel. Conclusively, bilosomes can be viewed as a promising nanocarrier for transdermal delivery of SDF that would grant higher therapeutic efficiency while alleviating the limitations encountered with SDF oral administration.

Degradable, anti-swelling, high-strength cellulosic hydrogels via salting-out and ionic coordination

Cellulosic hydrogels are widely used in various applications, as they are natural raw materials and have excellent degradability. However, their poor mechanical properties restrict their practical application. This study presents a facile approach for fabricating cellulosic hydrogels with high strength by synergistically utilizing salting-out and ionic coordination, thereby inducing the collapse and aggregation of cellulose chains to form a cross-linked network structure. Cellulosic hydrogels are prepared by soaking cellulose in an Al2(SO4)3 solution, which is both strong (compressive strength of up to 16.99 MPa) and tough (compressive toughness of up to 2.86 MJ/m3). The prepared cellulosic hydrogels exhibit resistance to swelling in different solutions and good biodegradability in soil. The cellulosic hydrogels are incorporated into strain sensors for human-motion monitoring by introducing AgNWs. Thus, the study offers a promising, simple, and scalable approach for preparing strong, degradable, and anti-swelling hydrogels using common biomass resources with considerable potential for various applications.

Versatile and recyclable double-network PVA/cellulose hydrogels for strain sensors and triboelectric nanogenerators under harsh conditions

Versatile and recyclable conductive hydrogels with long-term environmental adaptability and mechanical stability have attracted tremendous attention in wearable smart electronics. Here, double-network (DN) polyvinyl alcohol (PVA)/cellulose hydrogels were constructed after introducing a conductive rigid cellulose/Zn2+/Ca2+ network into a soft PVA/borax network. The resultant hydrogels possessed good mechanical and self-adhesive properties, along with transparency, recyclability, and remarkable resistance to freezing. They showed 30-day non-drying properties due to the presence of hygroscopic salts through a dynamic moisture adsorption and desorption process. Dehydrated hydrogels can return to their original states via self-regeneration under high relative humidity. Hydrogel-based strain sensors retained good sensitivity and a wide sensing range during the wide working temperature ranging from −40 °C to 50 °C and after recycling. Additionally, conductive hydrogels were integrated into triboelectric nanogenerators (TENGs) functioning as energy harvesters for powering electronics. TENGs retained stable electrical outputs even under harsh conditions and after recycling. Hydrogels were also assembled into flexible self-powered biomechanical sensors and tactile sensors. Thermally reversible interactions in composite hydrogels enabled their good recyclability, thereby reducing economic costs and environmental impacts caused by e-wastes. This work demonstrates the great potential of versatile and recyclable hydrogels with good environmental and mechanical stability in wearable smart electronics under harsh conditions.