Preparation Of Composite Hydrogels Research Articles

Preparation of Composite Hydrogels Based on Cysteine-Silver Sol and Methylene Blue as Promising Systems for Anticancer Photodynamic Therapy.

In this study, a novel supramolecular composite, "photogels", was synthesized by mixing of cysteine-silver sol (CSS) and methylene blue (MB). A complex of modern physico-chemical methods of analysis such as viscosimetry, UV spectroscopy, dynamic and electrophoretic light scattering, scanning electron microscopy and energy-dispersive X-ray spectroscopy showed that MB molecules are uniformly localized mainly in the space between fibers of the gel-network formed by CSS particles. Molecules of the dye also bind with the surface of CSS particles by non-covalent interactions. This fact is reflected in the appearance of a synergistic anticancer effect of gels against human squamous cell carcinoma even in the absence of light irradiation. A mild toxic influence of hydrogels was observed in normal keratinocyte cells. Photodynamic exposure significantly increased gel activity, and there remained a synergistic effect. The study of free-radical oxidation in cells has shown that gels are not only capable of generating reactive oxygen species, but also have other targets of action. Flow cytometric analysis allowed us to find out that obtained hydrogels caused cell cycle arrest both without irradiation and with light exposure. The obtained gels are of considerable interest both from the point of view of academics and applied science, for example, in the photodynamic therapy of superficial neoplasms.

Green preparation of composite hydrogel coated hydrophobic long-chain carboxylic acid-bonded silica microspheres for mixed-mode chromatography

Combining composite hydrogel with silica gel can endow hydrogel with new application possibilities. In this work, polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) were combined into a composite hydrogel, which was then wrapped on the surface of 1-undecenoic acid (UA) bonded silica microspheres. As a result, a novel PVP/PVA composite hydrogel-functionalized silica stationary phase (PVP/PVA@Sil-UA) was prepared by a green and facile method. Specifically, the thiol-ene click reaction was preferentially used to bond a hydrophobic long-chain carboxylic acid (UA) on the surface of thiolated silica gel in deep eutectic solvent, which was able to provide abundant hydrogen bonding sites for the further coating of PVP/PVA composite hydrogel. The hydrophobic long alkyl chain not only improved the separation selectivity, but also effectively alleviated the swelling of hydrogel. It was discovered that the prepared PVP/PVA@Sil-UA showed outstanding separation performance for a wide range of samples. The study of retention behavior proved that the PVP/PVA@Sil-UA was a mixed-mode chromatographic stationary phase, possessing hydrophilic and hydrophobic retention characteristics. In summary, an eco-friendly method was applied to realize the effective combination of composite hydrogel and SiO2 due to the fact that no harmful organic solvents were used in the preparation process, which provided a novel idea for the application of composite hydrogel in the field of chromatographic separation.

Preparation of Composite Hydrogels with Silica Nanoparticles by Photoinitiated Polymerization Reaction

In this study, (3-mercaptopropyl) trimethoxysilane (MPTMS) modified silica nanoparticles (SiO2-MPTMS) were successfully prepared. The average size of SiO2-MPTMS nanoparticles was measured by Dynamic Light Scattering (DLS) as 341 nm in ethanol, while Scanning Transmission Electron Microscopy (STEM) analyzes confirmed that the nanoparticles were nano-sized and revealed that their shapes were spherical. Then, 3D nanocomposite hydrogels were prepared by incorporating SiO2-MPTMS nanoparticles in various ratios (0.25, 0.50, 0.75 and 1.0 wt %) into an acrylate resin consisting of N-isopropyl acrylamide (NIPAM) and polyethylene glychol diacrylate (PEGDA; as a crosslinker) by the photoinitiated polymerization reaction with Dimethoxy-2-phenylacetophenone (DMPA; as a photoinitiator). By Thermal Gravimetric Analyzer (TGA) measurements, it was determined that the nanocomposite hydrogels maintained their thermal stability up to 330 0C and the thermal degradation steps were close to each other. Scanning Electron Microscopy (SEM) study showed that the neat and nanocomposite hydrogels’ morphological structures were in the porous and smooth scaffold, and also that the SiO2-MPTMS nanoparticles (0.50 wt %) were homogeneously distributed in the network structures of hydrogels, localized in the bonds.

Application of UV responsive SiO2/PVP composite hydrogels as intelligent controlled drug release patches

Designing and preparing smart drug release systems are important in the field of medicine. A composite hydrogel preparation method is presented here to address the critical need and provide a practical perspective for local drug release. Photoresponsive silica polyvinylpyrrolidone (SiO2-PVP) composite hydrogels were prepared based on the crosslinking effect of partially hydrolyzed tetraethyloxysilane and the flexibility of PVP to combine the advantage of SiO2 framework with more space and excellent deformation ability of PVP. Thus, the hydrogel prepared under optimized conditions was able to withstand 160% elongation and swell to 600%. In addition, relatively high drug loading and long-term release of ibuprofen for up to 10 h in solution were achieved. The hydrogel could even release drugs through the simulated skin and show a faster release rate under UV light irradiation and a higher surrounding temperature. The smart hydrogels had also been demonstrated to be biocompatible and non-toxic. The unique combination of strong mechanical properties, biocompatibility, and drug release properties may facilitate the application of hydrogels as skin patches.

Preparation of composite hydrogel with high mechanical strength and reusability for removal of Cu(II) and Pb(II) from water

An adsorbent with good reusability, rapid adsorption kinetics, cost-effectiveness, and high adsorption capacity is desired in practical adsorption processes. A new strategy was proposed herein, combining the ball-milling biochar (MBC) and double network to synthesize a composite hydrogel. The ball-milling biochar /carboxymethylcellulose/polyacrylic acid (MBC/CMC/PAA) composite hydrogel was prepared using a one-step method. Both the carboxymethylcellulose (CMC) and polyacrylic acid (PAA) were used to form double networks, immobilized and crosslinked with MBC. The MBC/CMC/PAA possessed a higher allowable compression force of 133.52 N. The FTIR and XPS results confirmed that -COOH, -OH, and -NH- functional groups were the main adsorption sites. The proposed adsorbent maintained a stable removal efficiency of 100 % for Cu2+ and Pb2+ within five cycles of use. Thomas model better described the Cu2+ and Pb2+ in the individual dynamic adsorption process. In the alternate fixed-bed column experiments, the treatment volume of Cu2+-containing water reached 13.7 L and produced 300 mL eluent. This work not only developed a new strategy for preparing composite hydrogel but also verified that the MBC/CMC/PAA could have great applicability for removing Cu2+ and Pb2+ in real solutions.

Preparation of composite hydrogels containing fly ash as low-cost adsorbent material and its use in dye adsorption

Preparation of composite hydrogels containing fly ash as low-cost adsorbent material and its use in dye adsorption

High strength and low swelling composite hydrogels from gelatin and delignified wood

A delignified wood template with hydrophilic characteristics and high porosity was obtained by removal of lignin. Gelatin was infiltrated into the delignified wood and further crosslinked with a natural crosslinker genipin to form hydrogels. The composite hydrogels showed high mechanical strength under compression and low swelling in physiological condition. The effect of genipin concentrations (1, 50 and 100 mM) on structure and properties of the composite hydrogels were studied. A porous honeycomb structure with tunable pore size and porosity was observed in the freeze-dried composite hydrogels. High elastic modulus of 11.82 ± 1.51 MPa and high compressive yield stress of 689.3 ± 34.9 kPa were achieved for the composite hydrogel with a water content as high as 81%. The equilibrium water uptake of the freeze-dried hydrogel in phosphate buffered saline at 37 °C was as low as 407.5%. These enables the delignified wood structure an excellent template in composite hydrogel preparation by using infiltration and in-situ synthesis, particularly when high mechanical strength and stiffness are desired.

Preparation, Characterization, and Cytotoxicity Evaluation of Zinc Oxide–Bacterial Cellulose–Chitosan Hydrogels for Antibacterial Dressing

AbstractIn this work, a kind of novel antibacterial and biocompatible composite hydrogels composed of zinc oxide, bacterial cellulose (BC), and chitosan (CS) are prepared via immersing the oxidized BC hydrogels in CS solution and then combining zinc oxide in alkaline environment. The structure and properties of the composite hydrogels are characterized by different techniques. The results of Fourier transform infrared spectroscopy and X‐ray diffraction prove the successful preparation of composite hydrogels. Scanning electron microscopy is used to study the microscopic morphology of hydrogels. The results show that the zinc oxide particles are successfully attached to the bacterial cellulose. From the results of thermogravimetric analysis, it can be seen that the hydrogels exhibit well thermal stability. For 0.03m zinc oxide @bacterial cellulose‐chitosan (ZnO@BCCS) hydrogels, the compressive stress is as high as 440 kPa at a deformation of 60%, which is 15 times that of BC hydrogels. Its maximum tensile stress is 880 kPa. The maximum inhibition rates of 0.05mZnO@BCCS hydrogels against Escherichia coli and Staphylococcus aureus are 78.9% and 77.6%, respectively. The cytotoxicity evaluation results show that the hydrogels have low cytotoxicity and good cell compatibility.

Preparation of composite hydrogel (PCG) and its adsorption performance for uranium(VI)

In this work, a novel composite hydrogel (PCG) was constructed by mixing amidoxime polyacrylonitrile, chitosan and graphene oxide. The structure characterization of PCG was successfully investigated by FTIR, SEM. The effects of the pH, initial concentration of metal ion and contact time were conducted by a batch of experiments. PCG showed higher adsorption selectivity for U(VI) and its maximum adsorption capacity can reach up 247 mg/g. PCG can be completely separate from the aqueous solution and displayed excellent regeneration ability which would not cause secondary pollution to water bodies. The sorption kinetics of PCG for U(VI) followed pseudo-second order model well and Langmuir model were used to describe the equilibrium data well, which indicated that a monolayer adsorption occurred on PCG and the chemisorption was the main rate-limiting step. This work proved that PCG could be considered as the effective and promising material for removal of U(VI) from aqueous solution.

Multifunctional Role of MoS2 in Preparation of Composite Hydrogels: Radical Initiation and Cross-Linking.

This paper describes the multifunctional effect of molybdenum disulfide (MoS2) that enables the rapid and accessible preparation of nanocomposite hydrogels via a bottom-up design. The MoS2 nanoplatelet forms radical species through a redox reaction with persulfate under aqueous conditions while initiating the polymerization of acrylic monomers and providing noncovalent cross-linking points without requiring external stimuli or extra cross-linkers, leading to the formation of hydrogels that are in situ embedded with inorganic flakes. Furthermore, the addition of MoS2 could induce more rigid and elastic networks compared to those in control hydrogels using a typical cross-linker at the same level; for example, 0.08 wt % MoS2 resulted in a composite hydrogel of which the elastic modulus was 2.5 times greater than that from a hydrogel using N,N'-methylenebis(acrylamide) as the showing phase transition during polymerization. The composite hydrogels are self-healable, taking advantage of reversible physical cross-links. Thus, two cut hydrogel strips could be readily rejoined by heating at 70 °C, and the resulting whole strip showed mechanical strength similar to that of the pristine sample before it was cut. This synthetic approach would give way to the modular design of MoS2-containing composite hydrogels.

High-Strength, Self-Healable, Temperature-Sensitive, MXene-Containing Composite Hydrogel as a Smart Compression Sensor.

As a new two-dimensional material similar to graphene, MXene has attracted extensive attention in the field of electrochemical materials such as supercapacitors because of its excellent mechanical properties, electrical conductivity, and thermal conductivity. What is better than graphene is that the few-layer MXene material obtained by proper treatment has good water dispersibility and can be used as an ideal nanomaterial to enhance the conductivity of hydrogels. However, the articles about the few-layer MXene material used in the preparation of composite hydrogels are rare. In this paper, MXene was synthesized by Yury mild method. Poly(N-isopropyl acrylamide) (PNIPAM) hydrogel and physical cross-linking hydrogel were used as the matrix to prepare composite hydrogels with temperature sensitivity and stress-sensing properties. The composite hydrogels exhibited excellent mechanical properties: it could be stretched to over 14 times the original length and achieved a 0.4 MPa tensile strength while showing good self-healing ability, which was of great significance for the practical application of hydrogels. The conductivity of the composite hydrogel was 1.092 S/m, which was about 15 times that of the control hydrogel without MXene. The potential of the composite hydrogel as a smart compression sensor was also verified by the conductivity tests.

3D bioprinting of scaffolds with living Schwann cells for potential nerve tissue engineering applications

Three-dimensional bioprinting of biomaterials shows great potential for producing cell-encapsulated scaffolds to repair nerves after injury or disease. For this, preparation of biomaterials and bioprinting itself are critical to create scaffolds with both biological and mechanical properties appropriate for nerve regeneration, yet remain unachievable. This paper presents our study on bioprinting Schwann cell-encapsulated scaffolds using composite hydrogels of alginate, fibrin, hyaluronic acid, and/or RGD peptide, for nerve tissue engineering applications. For the preparation of composite hydrogels, suitable hydrogel combinations were identified and prepared by adjusting the concentration of fibrin based on the morphological spreading of Schwann cells. In bioprinting, the effects of various printing process parameters (including the air pressure for dispensing, dispensing head movement speed, and crosslinking conditions) on printed structures were investigated and, by regulating these parameters, mechanically-stable scaffolds with fully interconnected pores were printed. The performance of Schwann cells within the printed scaffolds were examined in terms of viability, proliferation, orientation, and ability to produce laminin. Our results show that the printed scaffolds can promote the alignment of Schwann cells inside scaffolds and thus provide haptotactic cues to direct the extension of dorsal root ganglion neurites along the printed strands, demonstrating their great potential for applications in the field of nerve tissue engineering.

Preparation and characterization of chitosan – collagen peptide / oxidized konjac glucomannan hydrogel

In this paper, the microbial transglutaminase (MTGase) was used as a catalyst to graft the collagen peptide (COP) molecules on the amino group of chitosan to obtain water-soluble chitosan-collagen peptide (CS-COP) derivatives. The preparation of composite hydrogel was via the Schiff-base reaction between the amino of CS-COP and the aldehyde of oxidized konjac glucomannan (OKGM). The hydrogels were characterized by various techniques including Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The results of SEM showed that the hydrogel sample had a clear and stable three-dimensional network structure. Meanwhile, these effects of the addition of OKGM on gelation time, swelling behaviors, water evaporation rate and blood coagulation capacity were investigated. The shortest gelation time for hydrogels was 99.3s. The hydrogels showed a good swelling ability and appropriate water retention capacity. The maximum swelling ratio of the hydrogel was 265%. Dynamic blood clotting test showed that the hydrogels materials had good blood coagulation capacity. Moreover, The biocompatibility of hydrogels was evaluated with NIH-3T3 cells by MTT method. The results indicated that the hydrogels exhibited better biocompatibility. Therefore, this hydrogel has a promising potential to be applied as wound dressing.

Acrylated Composite Hydrogel Preparation and Adsorption Kinetics of Methylene Blue.

By using cyclodextrin (α-CD) self-assembly into a hydrogel with the triblock copolymer Pluronic F127, nanomicrocrystalline cellulose was introduced into a gel system to form a composite CNC-β-CD/α-CD/Pluronic F127 hydrogel (CCH). CCH was modified further by grafting acrylic acid to form a novel acrylated composite hydrogel (ACH). The swelling degree of ACH was 156 g/g. Adsorption isotherms show that the adsorption process for methylene blue proximity fitted the Freundlich model. The adsorption kinetics showed that ACH followed a quasi-second-order kinetic model. Methylene blue desorption showed that ACH was a temperature- and pH-dependent gel. Repeated adsorption and desorption experiments were carried out three times, and the removal rate of methylene blue at 75 mg/L was still 70.1%.

Preparation of Hydrophilic Encapsulated Carbon Nanotubes with Polymer Brushes and Its Application in Composite Hydrogels.

Carbon nanotubes can be used as promising reinforcement materials to improve the mechanical properties of hydrogels, but their poor dispersibility in aqueous solution severely limits their application in preparation of composite hydrogels. Therefore, to develop method for modification of carbon nanotubes is still highly desired. In this paper, a facile approach for preparation of the hydrophilic carbon nanotube was reported. The encapsulated multiwalled carbon nanotubes (E-CNT-PAA) with cross-linked shell structure were obatined through the self-assembly of the amphipathic azide diblock copolymers poly(acrylic acid)-b-poly(4-vinylbenzyl azide-co-styrene) (PAA-b-(PVBA-co-PS)), and the cross-linking of inside azide groups under UV irradiation. The encapsulated MWCNT was characterized by FT-IR, Raman and TEM. It was demonstrated that the dispersibility of the hydrophilic encapsulated MWCNTs was related to the length of the poly(acrylic acid) brushes. Subsequently, thermal-responsive composite hydrogels (PNIPAM/E-CNT-PAA) were prepared by in situ polymerization of N-isopropylacrylamide (NIPAM) in the solution of dispersed E-CNT-PAA. The results showed that the composite hydrogels possessed high mechanical properties compared to the pure PNIPAM hydrogel. The tensile strength and elongation of the composite hydrogels were highly dependent on the content of the modified MWCNTs. The composite hydrogels with 0.46 wt % MWCNTs exhibited tensile strength of 97.7 kPa and elongation of 465%, which were at least 3.5× higher than those of the PNIPAM hydrogel. Moreover, the composite hydrogels displayed significant and reversible stimuli-responsiveness.

Preparation of Composite Hydrogels for Medical Applications: Experimental Study and Modeling of Mass Transfers

The aim of this work is to prepare wound dressing hydrogels permitting (i) to cure chronicle pathologies; (ii) to remove unsuitable odors coming from healing. Thus, chitosan, a natural polymer with biological properties, and activated carbon (AC), a well-known adsorbent, are mixed within a composite hydrogel. To get a suitable porous structure for healing, the vapor induced phase separation process (VIPS) is used. It permits to slow down mass transfers kinetics compared to other elaboration processes such as the wet process. Hence, a better control of the final porous matrix is reached throughout the elaboration process.In this work, the mass transfers occurring through the elaboration of the composites were studied thanks to gravimetric measurements carried out during the VIPS process. Results showed there were two main steps in the gelation process. A weight intake, due to an ammonia flux allowing the gelation to happen, was followed by a weight loss, mainly controlled by a water outtake. This second part could be compared to a slow drying in smooth conditions. Gelation with a color indicator was also performed, which provided complementary experimental information on mass transfers barrier.A modeling of mass transfers mechanisms occurring during the gel elaboration is presented to get an overview of limiting phenomena leading to the final composite structures. It involves a coupling between chemical reactions, external mass transfers and internal diffusion within the polymeric matrix. Results show that internal diffusion is the main barrier to gelation.To qualify the gel structure, drying kinetics were compared on the elaborated gels. Whatever the gel, the drying kinetics were globally the same and could be divided into three steps. Considering the process used and this result, it was believed that the matrixes prepared were homogeneous and rather symmetric. They could constitute the first layer of wound dressings.