Crosslinked Chitosan Hydrogel Research Articles

Amputation of Remazol brilliant blue dye on crosslinked chitosan hydrogel: Statistical treatment and experimental evaluation

The primary aim of this research is to comprehensively assess the applicability of chitosan biopolymer towards water treatment application and to enhance its adsorption capacity towards Remazol brilliant blue R-19 dye. This has been achieved through physical modification to obtain the material in hydrogel form and chemical modification by crosslinking it with barbituric acid. The characterization of the resulting Chitosan-barbituric acid hydrogel (CBH) was carried out using various analytical techniques such as SEM-EDX, FT-IR, TGA-DTA, XRD, and BET. CBH was employed as the adsorbent to eliminate R-19 dye from aqueous media. Utilizing response surface methodology (RSM), the parameters were fine-tuned, leading to the achievement of more than a 95% removal for R-19 dye. The adsorption behavior closely adhered to the Langmuir isotherm and pseudo-second-order kinetics. An interesting observation indicated that the rise in temperature leads to rise in adsorption capacity of CBH. The maximum adsorption capacities evaluated at 301.15 K, 313.15 K, 318.15 K, and 323.15 K were 566.6 mg g−1, 624.7 mg g−1, 671.3 mg g−1, and 713.5 mg g−1 respectively, in accordance with the Langmuir isotherm model. Examining the thermodynamics of the adsorption process revealed its spontaneous nature (ΔG = −21.14 to −27.09 kJ mol−1) across the entire temperature range. Furthermore, the assessment of the isosteric heat of adsorption (ΔHads) was conducted using the Clausius–Clapeyron equation, with results indicating an increase in ΔHads from 1.85 to 2.16 kJ mol−1 with temperature rise from 301.15 K to 323.15 K due to augmented surface loading. This suggested the existence of lateral interactions between the adsorbed dye molecules. The potential of adsorbent for regeneration was investigated, demonstrating the ability to reuse the material. Sustainability parameter calculated for synthesis process reflected a notably low E-factor value of 0.32 demonstrated the synthesis is environment friendly.

Facile fabrication of high capacity citric acid cross-linked chitosan and carboxymethyl cellulose-based hydrogel for fast kinetics removal of Cu(II)

Facile fabrication of high capacity citric acid cross-linked chitosan and carboxymethyl cellulose-based hydrogel for fast kinetics removal of Cu(II)

Highly efficient and reusable CuAu nanoparticles supported on crosslinked chitosan hydrogels as a plasmonic catalyst for nitroarene reduction

The synthesis of CuAu-based monometallic (MNPs) and bimetallic nanoparticles (BNPs) supported on chitosan-based hydrogels for their application as catalysts is presented. The hydrogels consisted of chitosan chains cross-linked with tripolyphosphate (TPP) in the form of beads with an approximate average diameter of 1.81 mm. The MNPs and BNPs were obtained by the adsorption of metallic ions and their subsequent reduction with hydrazine, achieving a metallic loading of 0.297 mmol per gram of dry sample, with average nanoparticle sizes that were found between 2.6 and 4.4 nm. Both processes, metal adsorption and the stabilization of the nanoparticles, are mainly attributed to the participation of chitosan hydroxyl, amine and amide functional groups. The materials revealed important absorption bands in the visible region of the light spectra, specifically between 520 and 590 nm, mainly attributed to LSPR given the nature of the MNPs and BNPs inside the hydrogels. Subsequently, the hydrogels were evaluated as catalysts against the reduction of 4-nitrophenol (4NP) into 4-aminophenol (4AP), followed by UV–visible spectroscopy. The kinetic advance of the reaction revealed important improvements in the catalytic activity of the materials by synergistic effect of BNPs and plasmonic enhancement under visible light irradiation, given the combination of metals and the light harvesting properties of the nanocomposites. Finally, the catalytic performance of hydrogels containing BNPs CuAu 3:1 showed an important selectivity, recyclability and reusability performance, due to the relevant interaction of the BNPs with the chitosan matrix, highlighting the potential of this nanocomposite as an effective catalyst, with a potential environmental application.

UV-Crosslinked Poly(N-isopropylacrylamide) Interpenetrated into Chitosan Structure with Enhancement of Mechanical Properties Implemented as Anti-Fouling Materials.

High-performance properties of interpenetration polymer network (IPN) hydrogels, based on physically crosslinked chitosan (CS) and chemically crosslinked poly(N-isopropylacrylamide) (PNiPAM), were successfully developed. The IPN of CS/PNiPAM is proposed to overcome the limited mechanical properties of the single CS network. In this study, the viscoelastic behaviors of prepared materials in both solution and gel states were extensively examined, considering the UV exposure time and crosslinker concentration as key factors. The effect of these factors on gel formation, hydrogel structures, thermal stabilities of networks, and HeLa cell adhesion were studied sequentially. The sol-gel transition was effectively demonstrated through the scaling law, which agrees well with Winter and Chambon's theory. By subjecting the CS hydrogel to the process operation in an ethanol solution, its properties can be significantly enhanced with increased crosslinker concentration, including the shear modulus, crosslinking degree, gel strength, and thermal stability in its swollen state. The IPN samples exhibit a smooth and dense surface with irregular pores, allowing for much water absorption. The HeLa cells were adhered to and killed using the CS surface cationic charges and then released through hydrolysis by utilizing the hydrophilic/hydrophobic switchable property or thermo-reversible gelation of the PNiPAM network. The results demonstrated that IPN is a highly attractive candidate for anti-fouling materials.

Viologen Cross-Linked Chitosan Hydrogel as Biobased Antiseptic Surface-Coating Materials

Viologen Cross-Linked Chitosan Hydrogel as Biobased Antiseptic Surface-Coating Materials

Efficient treatment of palladium from wastewater by acrolein cross-linked chitosan hydrogels: Adsorption, kinetics, and mechanisms

Herein we present a study on the preparation and properties of a hydrogel adsorbent for treatment of wasted palladium souring from actial petrochemical industrial wastewater. Chitosan was used as the raw material and acrolein as the cross-linking agent for the hydrogel (A/CS). The adsorption behaviors of the hydrogel for Pd(II) ions were characterized and analyzed. The effect of pH, temperature, adsorption kinetics, and thermodynamics were investigated. Langmuir models were employed to describe the adsorption isotherms, while the pseudo-second-order equation was applied to describe the adsorption kinetics. The experimental results demonstrated that the adsorption was a monolayer chemical adsorption, and the adsorption capacity was found to reach 505.05 mg/g under optimal conditions. In addition, FT-IR and XPS analyses, combined with MS calculations confirmed that chelation and electrostatic attraction were dominated in the adsorption process. Overall, the development of this hydrogel adsorbent will provide a practical approach to the treatment of industrial wastewater containing palladium and have great potential for practical applications.

A multi-functional double cross-linked chitosan hydrogel with tunable mechanical and antibacterial properties for skin wound dressing

Chitosan hydrogels with essential antibacterial properties and biocompatibility have great potential in tissue engineering and regeneration medicine. However, pure chitosan hydrogel could be limited by insufficient mechanical properties. In this work, we designed a multi-functional chitosan hydrogel based on the combination of chitosan methacrylate (CTSMA) and sulfhydrated chitosan (CTSSH), which is cross-linked simultaneously by free-radical polymerization reaction and Thiol-ene reaction. The CTSMA/CTSSH (CMS) hydrogels displayed superior tissue adhesive and mechanical properties when compared to pure CTSMA hydrogel. Additionally, the resulting hydrogels exhibited potent antimicrobial effects against both E. coli and S. aureus. Besides, the CMS hydrogels exhibited good biocompatibility as demonstrated by cytotoxicity and cell proliferation experiments using fibroblasts cells (L929) and adipose-derived stem cells (ADSCs). In vivo experiment, the repairing effect of hydrogels on full-thickness skin defect model in rats was studied. Histological and immunohistochemical staining results showed that CMS hydrogels promoted angiogenesis, dermal repair and epidermal regeneration. Overall, the study highlights the potential of the CMS hydrogels as a promising biomaterial in wound healing applications.

Reinforcement of the antimicrobial activity and biofilm inhibition of novel chitosan-based hydrogels utilizing zinc oxide nanoparticles

Two novel chemically cross-linked chitosan hydrogels were successfully prepared via insertion of oxalyl dihydrazide moieties between chitosan Schiff's base chains (OCsSB) and between chitosan chains (OCs). For more modification, two different concentrations of ZnO nanoparticles (ZnONPs) were loaded into OCs to obtain OCs/ZnONPs-1 % and OCs/ZnONPs-3 % composites. The prepared samples were recognized using elemental analyses, FTIR, XRD, SEM, EDS and TEM. Their inhibitory action against microbes and biofilms were classified as: OCs/ZnONPs-3 % > OCs/ZnONPs-1 % > OCs > OCsSB > chitosan. OCs has inhibition activity similar to Vancomycin of minimum inhibitory concentration (MIC) value of 3.9 μg/mL against P. aeruginosa. OCs exhibited minimum biofilm inhibitory concentration (MBIC) values (from 31.25 to 62.5 μg/mL) less than that of OCsSB (from 62.5 to 250 μg/mL) which lower than that of chitosan (from 500 to 1000 μg/mL) against S. epidermidis, P. aeruginosa and C. albicans. OCs/ZnNPs-3 % showed MIC value (that caused 100 % inhibition of Clostridioides difficile, C. difficile) of 0.48 μg/mL much lower than Vancomycin (1.95 μg/mL). Both OCs and OCs/ZnONPs-3 % composite were safe on normal human cells. Thus, inclusion of oxalyl dihydrazide and ZnONPs into chitosan greatly reinforced its antimicrobial activity. This is a good strategy to accomplish adequate systems for competing traditional antibiotics.

Porous Chitosan Hydrogels Produced by Physical Crosslinking: Physicochemical, Structural, and Cytotoxic Properties.

Chitosan hydrogels are biomaterials with excellent potential for biomedical applications. In this study, chitosan hydrogels were prepared at different concentrations and molecular weights by freeze-drying. The chitosan sponges were physically crosslinked using sodium bicarbonate as a crosslinking agent. The X-ray spectroscopy (XPS and XRD diffraction), equilibrium water content, microstructural morphology (confocal microscopy), rheological properties (temperature sweep test), and cytotoxicity of the chitosan hydrogels (MTT assay) were investigated. XPS analysis confirmed that the chitosan hydrogels obtained were physically crosslinked using sodium bicarbonate. The chitosan samples displayed a semi-crystalline nature and a highly porous structure with mean pore size between 115.7 ± 20.5 and 156.3 ± 21.8 µm. In addition, the chitosan hydrogels exhibited high water absorption, showing equilibrium water content values from 23 to 30 times their mass in PBS buffer and high thermal stability from 5 to 60 °C. Also, chitosan hydrogels were non-cytotoxic, obtaining cell viability values ≥ 100% for the HT29 cells. Thus, physically crosslinked chitosan hydrogels can be great candidates as biomaterials for biomedical applications.

Autoclaving-Triggered Hydrogelation of Chitosan-Gluconic acid Conjugate Aqueous Solution for Wound Healing.

Moist wound healing is known to heal wounds faster than dry wound healing. Hydrogel wound dressings are suitable for moist wound healing because of their hyperhydrous structure. Chitosan, a natural polymer, promotes wound healing by stimulating inflammatory cells and releasing bioactive compounds. Therefore, chitosan hydrogel has great potential as a wound dressing. In our previous study, physically crosslinked chitosan hydrogels were successfully prepared solely by freeze-thawing of chitosan-gluconic acid conjugate (CG) aqueous solution without using any toxic additives. Furthermore, the CG hydrogels could be sterilized by autoclaving (steam sterilization). In this study, we showed that autoclaving (121 °C, 20 min) of a CG aqueous solution simultaneously achieved gelation of the solution and sterilization of the hydrogel. Hydrogelation of CG aqueous solution by autoclaving is also physically crosslinking without any toxic additives. Further, we showed that the CG hydrogels retained favorable biological properties of the CG hydrogels prepared by freeze-thawing and subsequent autoclaving. These results indicated that CG hydrogels prepared by autoclaving were promising as wound dressings.

Water behavior, thermal, structural, and viscoelastic properties of physically cross-linked chitosan hydrogels produced by NaHCO3 as a crosslinking agent

Water behavior, thermal, structural, and viscoelastic properties of physically cross-linked chitosan hydrogels produced by NaHCO3 as a crosslinking agent

Magnetically Powered Chitosan Milliwheels for Rapid Translation, Barrier Function Rescue, and Delivery of Therapeutic Proteins to the Inflamed Gut Epithelium.

Inflammatory bowel disease (IBD) is mediated by an overexpression of tumor necrosis factor-α (TNF) by mononuclear cells in the intestinal mucosa. Intravenous delivery of neutralizing anti-TNF antibodies can cause systemic immunosuppression, and up to one-third of people are non-responsive to treatment. Oral delivery of anti-TNF could reduce adverse effects; however, it is hampered by antibody degradation in the harsh gut environment during transit and poor bioavailability. To overcome these shortcomings, we demonstrate magnetically powered hydrogel particles that roll along mucosal surfaces, provide protection from degradation, and sustain the local release of anti-TNF. Iron oxide particles are embedded into a cross-linked chitosan hydrogel and sieved to produce 100-200 μm particles called milliwheels (m-wheels). Once loaded with anti-TNF, these m-wheels release 10 to 80% of their payload over 1 week at a rate that depends on the cross-linking density and pH. A rotating magnetic field induces a torque on the m-wheels that results in rolling velocities greater than 500 μm/s on glass and mucus-secreting cells. The permeability of the TNF-challenged gut epithelial cell monolayers was rescued in the presence of anti-TNF carrying m-wheels, which both neutralized the TNF and created an impermeable patch over leaky cell junctions. With the ability to translate over mucosal surfaces at high speed, provide sustained release directly to the inflamed epithelium, and provide barrier rescue, m-wheels demonstrate a potential strategy to deliver therapeutic proteins for the treatment of IBD.

Construction and function of robust and moist bilayer chitosan-based hydrogel wound dressing

The main limit of hydrogel used as an independent wound dressing is its poor water retention, brittleness, and weak skin adhesion. Focusing on it, the macromolecular cross-linked chitosan and polyacrylamide double network hydrogel (C-A) is chosen as a functional layer, another robust poly(vinyl alcohol)-polyacrylamide/glycerin (P-A) protective layer is designed to cover its surface, an interfacial reaction happens to link two layers tightly for achieving the function synergy. In this double-layer hydrogel (DH) dressing, the surface P-A layer with strong water locking ability could keep the wound surface moist for a long time, high strength and toughness make the dressing maintain integrity under large deformation and stress to strengthen wound protection, and the C-A layer with modest adhesion ensures the dressing fit the skin, the synergistic swelling ability could guarantee the fast absorption for the wound exudate. Moreover, in vitro and in vivo tests, the DH dressing exhibits excellent antibacterial and cytocompatibility, it could significantly accelerate skin tissue regeneration and wound closure than the commercial hydrocolloid dressings. In general, this DH dressing is easy to prepare and shows superior comprehensive performance, revealing the great potential for use as an independently applied wound dressing.

Cross-linked sodium alginate-carboxymethyl chitosan hydrogel beads for adsorption of Ni(II) ions

Cross-linked sodium alginate-carboxymethyl chitosan hydrogel beads for adsorption of Ni(II) ions

EFFECT OF IONIC AND COVALENT CROSSLINKING OF HYDROGEL CHITOSAN BEADS ON THE ADSORPTION EFFICIENCY OF BASIC VIOLET 10 AND BASIC GREEN 4 DYES FROM AQUEOUS SOLUTIONS

This work investigated the adsorption efficiency of Basic Violet 10 (BV10)and Basic Green 4 (BG4) dyes on ionically and covalently crosslinked chitosan hydrogel beads. The tested ionic crosslinkers were sodium citrate, sodium tripolyphosphate, and sulphosuccinic acid, while the covalent crosslinkers were glutaraldehyde, epichlorohydrin, and trimethylolpropane triglycidyl ether. The scope of the work included investigation of the effect of pH on the adsorption efficiency of dyes and the maximum adsorption capacity of crosslinked chitosan adsorbents. The maximum adsorption capacity of the non-crosslinked chitosan adsorbent was 2.94 mg/g and 44.32 mg/g for BV10 and BG4, respectively. Ionic crosslinking, regardless of the type of crosslinking agent, reduced the adsorption ability of hydrogel chitosan adsorbents in relation to cationic dyes (Qmax = 1.84-2.49 mg/g for BV10; 37.21-38.90 mg/g for BG4). Covalent crosslinking of chitosan slightly increased its adsorption capacity only for BV10 (Qmax = 3.59-3.81 mg/g for BV10; 39.15-40.62 mg/g for BG4).

Synthesis and characterization of 4-formylphenylboronic acid cross-linked chitosan hydrogel with dual action: Glucose-sensitivity and controlled insulin release

The number of people affected by diabetes mellitus is increasing globally in each year. A cause of elevated blood glucose levels can result from a lack of insulin or insufficient utilization of produced insulin. However, diabetes, a metabolic disorder is a serious chronic disease and an acute public health problem. Glucose-sensitive hydrogels that have 3D network structure can act in response to glucose and garners immense attention in biomedical appliance especially for drug delivery. Herein, a novel, glucose- and pH-responsive intelligent hydrogel encompassing chitosan cross-linked to 4-formylphenylboronic acid is prepared via dynamical reversible chemical bonds (imine) between chitosan and 4-formylphenylboronic acid with potential of controlled release of insulin. The characteristic features of such hydrogels are confirmed by Fourier transformed infrared (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and swelling ratio. Of these, the glucose-sensitive polymeric carrier (hydrogel) based on 4-formylphenylboronic acid has the advantages of enhanced stability, long-term storage, reversible response to glucose with high entrapment efficiency and controlled drug release into the physiological condition. In this paper, chitosan cross-linked with 4-formylphenylboronic acid, comprising the realization of Schiff base bearing (–C=N–) linkage, leads to the generation of a hydrogel which works better than normal phenylboronic acid (PBA) under physiological setting. The ensuing outcome implies that the glucose-susceptible hydrogel has prospective appliance as a glucose-receptive matter for insulin transport.

Enhanced Macroporous Cationic Chitosan Hydrogel by Freezing and Thawing Method with Superadsorption Capacity for Anionic Dyes

In this study, we have developed a simple technique to prepare cationic chitosan hydrogel with interconnected porous structure using freeze–thaw process and the obtained hydrogel was named FCS hydrogel. Scanning electron microscopy (SEM) imaging discovered that the synthesized hydrogel demonstrated interconnected porous structure in the scope of 5–20 μm. We also showed that the FCS hydrogel exhibits pH responsiveness behavior, and demonstrated reversible swelling and de-swelling behaviors maintaining their mechanical stability. We demonstrate that the FCS hydrogel swelling capacity decreased at alkaline pH and rose with a decline in pH value. Besides, the FCS hydrogel presented specific surface area of 78.25 ± 8.75 m2 g−1, due to the cryogenic treatment of glutaraldehyde cross-linked chitosan hydrogel could increase the surface area and permeability of composite hydrogel and then strongly increasing the adsorption capacity. Subsequently, the FCS monolithic hydrogel tested dyes removal, which provides a high removal efficiency towards anionic dyes including congo red (CR) and sodium fluorescein (SFL) dyes. Significantly, we show that the FCS hydrogel could be regenerated and reused as an adsorbent for wastewater treatment without significant loss of pollutants removal efficiency over a number of adsorption and washing cycles. This study offers a promising environmental friendly and sustainable interconnected porous hydrogel for anionic dye removal from wastewater.

A non-invasive smart scaffold for bone repair and monitoring.

Existing strategies for bone defect repair are difficult to monitor. Smart scaffold materials that can quantify the efficiency of new bone formation are important for bone regeneration and monitoring. Carbon nanotubes (CNT) have promising bioactivity and electrical conductivity. In this study, a noninvasive and intelligent monitoring scaffold was prepared for bone regeneration and monitoring by integrating carboxylated CNT into chemically cross-linked carboxymethyl chitosan hydrogel. CNT scaffold (0.5% w/v) demonstrated improved mechanical properties with good biocompatibility and electrochemical responsiveness. Cyclic voltammetry and electrochemical impedance spectroscopy of CNT scaffold responded sensitively to seed cell differentiation degree in both cellular and animal levels. Interestingly, the CNT scaffold could make up the easy deactivation shortfall of bone morphogenetic protein 2 by sustainably enhancing stem cell osteogenic differentiation and new bone tissue formation through CNT roles. This research provides new ideas for the development of noninvasive and electrochemically responsive bioactive scaffolds, marking an important step in the development of intelligent tissue engineering.

Synergistic effect of chemical crosslinking and addition of graphene-oxide in Chitosan—Hydrogels, films, and drug delivery

We investigate the synergistic effect of chemical crosslinking by Glutaraldehyde (GA) and physical crosslinking induced by Graphene Oxide (GO) nanosheets addition on Chitosan (CH) to enhance the mechanical strength of CH hydrogels and their films. An increase in the [GA] and GO loading in CH hydrogels increase the G' (Storage Modulus) and τy(Yield Stress) values. The G' of 0.5 wt% GO incorporated 53 mM [GA] crosslinked CH hydrogel is 7.2 times greater than the 53 mM [GA] crosslinked CH hydrogel. The morphology studies by FESEM indicate that the porosity of CH-GA and CH-GO-GA hydrogels improves with an increase in the [GA] and GO loading. The CH-GO (0.1 wt%)-GA(35.3 mM) nanocomposite hydrogel film displays a higher Young's modulus than the pristine CH film by more than 20 times. Drug delivery studies carried on the tetracycline hydrochloride (TH) loaded films show a pH-responsive behavior where the drug elusion is higher at pH 4 than pH 7.4. Sustained drug delivery is observed in 0.1 wt% GO-loaded CH film crosslinked with [GA] = 35 mM. The GA crosslinking and GO nanosheets incorporation play a prominent role in reducing the burst release from the CH films.

Injectable, self-healable and adhesive hydrogels using oxidized Succinoglycan/chitosan for pH-responsive drug delivery

We prepared chitosan (CS) based multifunctional hydrogels using oxidized succinoglycan (OSG) with a semi-dissolving acidified sol-gel transition method. OSG cross-linked CS hydrogels (OSG/CS) was prepared by aldehyde-amine Schiff-base reaction. OSG/CS increased not only thermal stability but also improved mechanical strength by 5.75 times. Through the tensile and strain sweep test, OSG/CS showed excellent self-healing properties by 98.82% and 99.89%, respectively. It showed the high compressive stress of 173 kPa at 60% strain, the adhesive strength of 2763 kPa, and the antibacterial effect of 90%. Furthermore, OSG/CS showed a pH-controlled drug release pattern, where a change of pH from 7.4 to 2.0 accelerated for 5-fluorouracil release from 60% to 90%. WST-8 assay demonstrated that OSG/CS maintained 97.30% cell viability and 98.84% cell proliferation after 7 days, indicating the potential as biocompatible hydrogel materials such as wound healing, tissue engineering and drug release systems.