Properties Of Composite Hydrogels Research Articles

Diphasic CeO2 Nanocrystal/Bioactive Glass Nanosphere-Based Composite Hydrogel for Diabetic Wound Healing by Reactive Oxygen Species Scavenging and Inflammation Regulation.

Background: Antioxidant therapy aimed at reducing excessive local oxidative stress is one of the most important strategies for promoting diabetic wound repair. The reversible transformation of Ce3+/Ce4+ in ceria (CeO2) can reduce excessive local oxidative stress. However, inducing angiogenesis, local anti-inflammatory effects, and other positive effects are challenging. Therefore, ideal dressings for chronic diabetic wound management must concurrently reduce excessive oxidative stress, promote angiogenesis, and have anti-inflammatory effects. Methods: In this study, Ce-doped borosilicate bioactive glasses (BGs) were prepared using the sol-gel method, and CeO2 nanocrystals (CeO2-NCs) were precipitated on the glass surface by heat treatment to obtain BG-xCe composite glass nanospheres. Subsequently, nanospheres were modified by amino group and combined with dopamine and acrylamide to obtain BG-xCe/polydopamine/polyacrylamide (PDA/PAM) composite hydrogel. Then, the morphology and properties of composite hydrogels were detected, and the properties to treat the diabetic wounds were also evaluated. Results: The results demonstrated that the BG-10Ce/PDA/PAM composite hydrogel possessed excellent tensile and adhesive properties. Invitro, the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) and fibroblasts (L929) were enhanced by reducing reactive oxygen species (ROS) levels in the conditioned medium. Animal experiments have shown that CeO2-NCs in hydrogels effectively scavenge ROS in diabetic wounds, and Sr dissolved from the glassy phase can modulate macrophage polarization to the M2 phenotype. Conclusions: The synergistic effect of both amorphous materials and nanocrystals provides the BG-10Ce/PDA/PAM composite hydrogel with great potential for diabetic wound healing.

Regulate structure and properties of κ-carrageenan/konjac glucomannan composite hydrogel by filling effects of Quillaja saponin-stabilized solid lipid nanostructure

κ-Carrageenan/konjac glucomannan (κ-CA/KGM) composite hydrogels often fail to meet industrial requirements due to their low gel strength and poor mechanical properties, while solid lipid nanoparticles are potential materials to address this challenge due to their good biocompatibility. In the study, we propose using Quillaja saponin-stabilized solid lipid nanoparticle (QSLN) as nanofillers to enhance properties of κ-carrageenan/konjac glucan (κ-CA/KGM) composite hydrogels, and with emphasis on the effect of QSLN filling concentration on the structure and properties of composite hydrogels and the possible mechanisms were investigated. The best performance of QSLN-filled composite hydrogels was achieved at the QSLN concentration of 2.4 %. QSLN was uniformly distributed in the hydrogel matrix and formed electrostatic interactions and hydrogen bonding interactions with the matrix at an appropriate filling level, which enhanced the textural and rheological properties of the hydrogel greatly. In addition, the results of low-field NMR experiments showed that the filling of QSLN reduced the water mobility by enhancing the entanglement of polymer chains in the hydrogel matrix, which improved the freeze-thaw stability and regulated the swelling and deswelling behavior of the composite hydrogel. However, with the increasing of QSLN filling concentration, the above improvements were weakened by the depletion of van der Waals interactions due to the large amount of QSLN aggregation and the weakening of electrostatic interaction. In turn, the hydrogel was found to modulate the crystalline behavior of QSLN by X-ray diffraction and differential scanning calorimeter monitoring. Overall, the optimal synergistic effect between structure and properties could be achieved when the QSLN filling concentration was 2.4 %. These results provide a basis for the development of products that require excellent gel properties and structure.

Constitutive modeling for hydrogel with chain entanglements and application to adaptive hydrogel composite structures

Hydrogel is one of typical smart materials and has been used in many engineering applications, such as flexible electronics, flexible robots, and biomedical engineering. Modern industries with complex working environments require hydrogel to have higher strength without losing flexibility. Many published experimental studies focus on the preparation technique of hydrogel composite with high strength and toughness. However, the theoretical investigation into the influence of entanglements on the hydrogel deformation is rarely reported for the structure analysis and deformation mechanism of hydrogel composite, as a purpose to design of hydrogel devices. In this paper, the constitutive model is developed for thermal responsive hydrogel with chain entanglements, based on Flory-Rehner theory and slip-link model, and numerically solved by a user subroutine in ABAQUS. The uniaxial tensile and compressive simulations of standard specimens are carried out to validate the proposed model and demonstrate the applicability of the hydrogel composite, in which a great agreement is obtained by comparing the simulation results to the experimental data from published work. Subsequently, the hydrogel composites with three types of structure, such as hydrogel grippers, scaffolds and skins, are designed to improve the overall strength and maintain the flexibility of the devices, inspired by the deformation mismatch characteristics of multilayer hydrogels. The results show that the properties of composite hydrogels are closely related to the level of entanglements, cross-link and composite structures. This work may contribute to the preparation of reinforced hydrogels and provide insights for the design of hydrogel multifunctional devices.

Catalytic activity of multi-walled carbon nanotubes decorated with tungsten trioxides nanoparticles against 4-nitrophenol

The fabrication of metallic oxide nanoparticles in a matrix material for use in catalysis has piqued researchers' curiosity, particularly in the aqueous phase. In this work, Multi-walled carbon nanotubes decorated with tungsten trioxide nanocomposites structure exhibit improved catalytic reduction activity in comparison to individual MWCNTs. the nanocomposites structure was prepared in just one step by infrared pulsed laser ablation (Nd:YAG laser, 1064 nm) of tungsten plate immersed in liquid media of functionalized multi-walled carbon nanotubes. Furthermore, the properties of composite hydrogels have been studied by X-ray diffraction, scanning electron microscope, transmission electron microscope, Fourier transforms infrared spectroscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectrometer, and thermal gravimetric analysis. The effective reduction of 4-Nitrophenol to 4-Aminophenol by NaBH4 was studied in the existence of the prepared nanocomposite structure of WO3-decorated MWCNTs. This nanocomposite demonstrated the large-scale possible use of organic catalytic oxidation and disposal of wastewater.

Investigation on the tunable effect of oxidized konjac glucomannan with different molecular weight on gelatin-based composite hydrogels

Herein, oxidized konjac glucomannan (OKG) with different molecular weight (Mw) were prepared as polysaccharide crosslinker to reinforce gelatin-based hydrogels. Then, properties of composite hydrogels with various OKGs were investigated via a series of methods, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), rheology, mechanical and biocompatibility tests. The results confirmed an increased degree of crosslinking and entanglement between gelatin and OKG with higher Mw. Besides, composite hydrogels not only showed increased mechanical strength, but self-healing ability at the same time, which were closely affected by the Mw of OKG. Furthermore, both composite hydrogels could support well proliferation of cells, which showed excellent capacity in tissue engineering and biomedical applications. In brief, this work provides a facile method to promote the overall properties of gelatin-based hydrogels, meanwhile revealed the relationship and mechanism underlying the effects of OKG with different Mw on composite hydrogels.

One-step electrochemically induced counterion exchange to construct free-standing carboxylated cellulose nanofiber/metal composite hydrogels

The fabrication of polymeric composite hydrogel with hierarchical structure in a simple, controllable, and straightforward process poses great importance for manufacturing nanomaterials and subsequent applications. Herein, we report a one-step and template-free counterion exchange method to construct free-standing carboxylated cellulose nanofiber composite hydrogels. Metal ions were electrochemically and locally released from the electrode and chelated with carboxylated cellulose nanofibers, leading to the in-situ formation of composite hydrogels. The properties of composite hydrogels can be easily programmed by the type of electrode, current density, and electrodeposited suspension. Significantly, the composited hydrogels exhibited interconnected nanoporous structure, enhanced thermal degradation, improved mechanical strength and antibacterial activity. The results suggest great potential of anodic electrodeposition to fabricate nanofiber/metal composite hydrogels.

Novel Collagen-Chitosan Based Hydrogels Reinforced with Manganite as Potential Adsorbents of Pb2+ Ions

The contamination of water by Pb2+ ions is a problem that requires an imminent solution. Design of hydrogels based on polymers as well as inorganic phases is an innovative alternative for the generation of matrices with adapted properties. This work proposes the synthesis of a novel composite hydrogel based on collagen-polyurethane-chitosan reinforced with manganite; this inorganic phase increases the velocity of the adsorption process of the Pb2+ ions. The effect of the concentration of manganite on the properties of composite hydrogels is studied. The results indicate that the composite reinforced with manganite presents an amorphous structure, improved mechanical properties and resistance to the both acidic and proteolytic degradation. The hydrogel with 35 wt% of manganite show a removal rate of Pb2+ of 91 ± 6% at 24 h. These hydrogel composites could represent an efficient and sustainable alternative for the removal of Pb2+ ions from contaminated water.

Facile Synthesis of Ag/Pd Nanoparticle-Loaded Poly(ethylene imine) Composite Hydrogels with Highly Efficient Catalytic Reduction of 4-Nitrophenol

Poly(ethylene imine) (PEI) has abundant amino groups in a macromolecular chain and can be used as a graft source for metal nanocomposites, which shows excellent ability to form stable complexes with heavy metal ions. In this work, a simple and convenient method was used to make PEI into a stable hydrogel with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide-N-hydroxysuccinimide and subsequently coprecipitate with silver nitrate solution or palladium chloride solution to form metal-loaded composite hydrogels. In addition, the characterizations of composite hydrogels were investigated by scanning electron microscopy, specific surface area tests (Brunauer–Emmett–Teller), X-ray photoelectron spectroscopy, and ultraviolet spectroscopy. The properties of composite hydrogels on the catalytic reduction of 4-nitrophenol were studied. The results showed that the composite hydrogels could be easily separated from the water environment, which indicated the large-scale potential application in organic catalytic degradation and wastewater treatment.

Influence of fish collagen on viscoelastic properties and sol-gel phase transition of chitosan solutions

The thermosensitive hydrogels are widely used in tissue engineering due to their non-invasive application. Special interest of researchers, due to the specific characteristics of both materials, is aimed at composites of natural origin obtained from chitosan hydrogels combined with collagen. The mechanical properties of the thermosensitive chitosan-fish collagen hydrogels and the sol-gel phase transition parameters were determined by the rotational rheometry measurement techniques. Based on comparison of the obtained storage modulus G' curves, it was found that the addition of collagen negatively affects the mechanical properties of composite scaffolds. The addition of this protein substance decreases their elasticity. Only the smallest concentration (0.25g collagen/1 g chitosan) of collagen improves the mechanical properties of composite hydrogels, from 56 kPa to 61 kPa. Conducted non-isothermal studies allowed to conclude that the addition of collagen causes an increasing temperature of sol-gel phase transition. However, the observed changes are not a monotone function of the biopolymer concentration.

Fabrication and characterization of polyacrylamide/silk fibroin hydrogels for peripheral nerve regeneration

Various hydrogels have been used for repairing peripheral nerve injury; however, the silk fibroin (SF)-based hydrogels in peripheral nerve regeneration are still rarely reported. In this study, the SF/pAM hydrogels with different SF concentrations and ethanol treatment time were developed by solution blending and in situ radical polymerization. The physiochemical properties of composite hydrogels were measured, the cytotoxicity of hydrogels was evaluated by L929 fibroblasts, and the effect on peripheral nerve regeneration was evaluated via Schwann cells culture in vitro. The results showed that the physiochemical properties of SF/pAM hydrogels could be changed by varying SF concentration and ethanol treatment time, and the mechanical property was enhanced with increasing SF concentration, while the presence of SF in pAM hydrogels and ethanol treatment does not affect hydrogels structure in per se. All the composite hydrogels displayed no obvious cytotoxicity, while the SF/pAM composite hydrogels with 10% SF and 60-min ethanol treatment could obviously accelerate the attachment and proliferation of Schwann cells. Therefore, the SF/pAM composite hydrogels possessed the beneficial properties required for in situ cell scaffolding and may have potential application in peripheral nerve regeneration.