PEO Hydrogels Research Articles

Highly elastic superabsorbent collagen/PVP/PAA/PEO hydrogels crosslinked via e-beam radiation

In this work, highly elastic and superabsorbent hydrogels of collagen-poly(vinyl pyrrolidone) (PVP)-poly(acrylic acid) (PAA)-poly(ethylene oxide) (PEO) quaternary copolymer were obtained using e-beam crosslinking reaction to be used for soft tissue engineering. This study is focused on the evaluation of rheological, swelling and stability properties under different pH media, offering in the same time an insight on the hydrogel network parameters. Rheological studies confirm that collagen/PVP/PAA/PEO hydrogels present solid behaviour similar with that of most soft tissue as human abdominal fat, skin and dermis and even more of breast gland or brain and liver. Hydrogels revealed superabsorbent capacity, both in deionized water and in simulated biological buffers, 1600% and 4000%. The stability and physical form of hydrogels were maintained for more than 50 h in environments that simulate both the pH of the healthy skin and that of an infected wound. The elastic modulus and the parameters of the network structure of hydrogels showed the formation of hydrogel with permanent network.

Effect of Drug Loading Method and Drug Physicochemical Properties on the Material and Drug Release Properties of Poly (Ethylene Oxide) Hydrogels for Transdermal Delivery.

Novel poly (ethylene oxide) (PEO) hydrogel films were synthesized via UV cross-linking with pentaerythritol tetra-acrylate (PETRA) as cross-linking agent. The purpose of this work was to develop a novel hydrogel film suitable for passive transdermal drug delivery via skin application. Hydrogels were loaded with model drugs (lidocaine hydrochloride (LID), diclofenac sodium (DIC) and ibuprofen (IBU)) via post-loading and in situ loading methods. The effect of loading method and drug physicochemical properties on the material and drug release properties of medicated film samples were characterized using scanning electron microscopy (SEM), swelling studies, differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FT-IR), tensile testing, rheometry, and drug release studies. In situ loaded films showed better drug entrapment within the hydrogel network and also better polymer crystallinity. High drug release was observed from all studied formulations. In situ loaded LID had a plasticizing effect on PEO hydrogel, and films showed excellent mechanical properties and prolonged drug release. The drug release mechanism for the majority of medicated PEO hydrogel formulations was determined as both drug diffusion and polymer chain relaxation, which is highly desirable for controlled release formulations.

In Situ Fabrication of Fiber Reinforced Three-Dimensional Hydrogel Tissue Engineering Scaffolds.

Hydrogels are an important class of biomaterials, but are inherently weak; to overcome this challenge, we report an in situ manufacturing technique to fabricate mechanically robust, fiber-reinforced poly(ethylene oxide) (PEO) hydrogels. Here, a covalent PEO cross-linking scheme was implemented to derive poly(ε-caprolactone) (PCL) fiber reinforced PEO hydrogels from multilayer coextruded PEO/PCL matrix/fiber composites. By varying PCL fiber loading between ∼0.1 vol % and ∼7.8 vol %, hydrogel stiffness was tailored from 0.69 ± 0.04 MPa to 1.94 ± 0.21 MPa. The influence of PCL chain orientation and enhanced mechanics via uniaxial drawing of PCL/PEO composites revealed a further 225% increase in hydrogel stiffness. To further highlight the robust nature of this manufacturing process, we also derived rigid poly(l-lactic acid) (PLLA) fiber-reinforced PEO hydrogels with a stiffness of 8.71 ± 0.21 MPa. Fibroblast cells were injected into the hydrogel volume, which displayed excellent ingrowth, adhesion, and proliferation throughout the fiber reinforced hydrogels. Finally, the range of mechanical properties obtained with fiber-reinforced hydrogels directed differentiation pathways of MC3T3-E1 cells into osteoblasts. This innovative manufacturing approach to achieve randomly aligned, well-distributed, micrometer-scale fibers within a hydrogel matrix with tunable mechanical properties represents a significant avenue of pursuit not only for load-bearing hydrogel applications, but also targeted cellular differentiation.

Comparative study of PEO and PVA hydrogels for removal of methylene blue dye from wastewater

ABSTRACTIn this study, poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) hydrogels were synthesized and evaluated as adsorbent for dye removal from wastewater using methylene blue (MB) in aqueous solution as probe. PEO samples were photochemically prepared by varying irradiation time (1–16 h), while PVA samples were synthetized with different concentration of glutaraldehyde (GA) (0.03–0.48%). The obtained hydrogels were obtained through the analysis of a swelling test, scanning electron microscopy, and adsorption studies. PEO hydrogels adsorption capacity was dependent on the irradiation time, while the PVA hydrogel adsorption capacity reduces with GA concentration. Both hydrogels demonstrated a Langmuir isotherm adsorption model at the equilibrium and pseudo‐second order kinetic fits properly. pH studies showed that when pH reaches 12, the adsorbed MB amount is close to 8 and 2 times higher than pH = 2 both hydrogels. Photochemical preparation of hydrogels shows an easier way of tuning their properties in order to maximize dye removal. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45043.

Gamma-irradiation synthesis of iron oxide nanoparticles in the presence of PEO, PVP or CTAB

Black hydrogels were synthesized using γ-irradiation of poly(ethylene oxide) (PEO)/iron(III) chloride precursor solutions. The magnetic properties of such hydrogels were improved by adding 2-propanol as a hydroxyl scavenger and/or NaBH4 as a strong chemical reducing agent; however, the rigidity and compactness of thus synthesized PEO hydrogels deteriorated. The magnetic suspension containing pure magnetite nanoparticles was obtained using γ-irradiation of an Fe(III)/PEO deoxygenated aqueous solution in the presence of 2-propanol and NaBH4. The γ-irradiation of an iron(III) chloride aqueous precursor solution in the presence of PVP produced a magnetic suspension due to the formation of a small amount of δ-FeOOH (feroxyhyte). The γ-irradiation of Fe(III)/CTAB (cetyltrimethylammonium bromide) aqueous solutions favored the formation of goethite. γ-irradiation in the presence of 2-propanol increased the yield of rod-like goethite nanoparticles. A small amount of δ-FeOOH found in the Fe(III)/PVP and Fe(III)/CTAB suspensions suggests the formation of Fe(OH)2upon γ-irradiation, which then under atmospheric conditions rapidly oxidized into δ-FeOOH.

Laponite® and Laponite®‐PEO hydrogels with enhanced elasticity in phosphate‐buffered saline

Hydrogels of the synthetic clay Laponite® and Laponite®‐poly (ethylene oxide) (PEO) have long been studied as model systems to understand fundamental aspects of colloidal disks and colloid‐polymer systems. More recently, these systems have been explored for a variety of biomedical applications. However, there is limited information in the literature on the fundamental properties of Laponite and Laponite‐polymer gels at pH < 9. Here, we report the rheological behavior of Laponite and Laponite‐PEO systems at biologically relevant conditions (e.g. physiological pH and ionic strength) and examine the effect of phosphate‐buffered saline on the properties of the gel. Our results show that the elastic modulus of both Laponite and Laponite‐PEO gels increases dramatically, in some cases by one order of magnitude or more, after immersing gels in phosphate‐buffered saline. This may be due to an enhanced edge–face interaction between particles in buffered solutions, which would promote a long‐lasting network structure of clay particles. These results are relevant to the design of clay‐polymer gels and nanocomposites hydrogels for biomaterials applications. Copyright © 2015 John Wiley & Sons, Ltd.

Synthesis of chitosan–PEO hydrogels via mesylation and regioselective Cu(I)-catalyzed cycloaddition

In this work, a well-defined hydrogel was developed by coupling chitosan with PEO through “click chemistry”. Azide functionalities were introduced onto chitosan, through mesylation of C-6 hydroxyl groups, and reacted with a di-alkyne PEO by a regioselective Cu(I)-catalyzed cycloaddition.This synthetic approach allowed us to obtain a hydrogel with a controlled crosslinking degree. In fact, the extent of coupling is strictly dependent on the amount of azido groups on chitosan, which in turn can be easily modulated.The obtained hydrogel, with a crosslinking degree of around 90%, showed interesting swelling properties. With respect to chitosan hydrogels reported in literature, a considerably higher equilibrium uptake was reached (940%).The possibility to control the crosslinking degree of hydrogel and its capability to rapidly absorb high amounts of water make this material suitable for several applications, such as controlled drug release and wound healing.

SYNTHESIS OF POLYETHYLENE OXIDE (PEO)–CHITOSAN HYDROGEL PREPARED BY GAMMA RADIATION TECHNIQUE

Crosslinked PEO hydrogel containing chitosan for wound dressing has been prepared by gamma radiation technique. Chitosan solutions with different concentration (0.5-2% w/v) have been blended with 5% aqueous solution of PEO and irradiated at the doses 20-40 kGy by gamma rays. The copolymers were characterized by Fourier transform infra red spectroscopy and their physico-chemical properties of hydrogels were evaluated in terms of gel fraction, swelling ratio, elongation at break and antimicrobial activities. It was found that under maximum condition of incorporation 1% chitosan with irradiation dose of 20 kGy, PEO-chitosan hydrogels with high gel fraction (85%), swelling ratio (10 g/g) and elongation at break (145%) were obtained. The examination of the microbe penetration shows that the prepared hydrogels can be considered as a good barrier against microbes. Thus, PEO-chitosan hydrogel showed satisfactory properties for use as a wound dressing.

Highly Extensible, Tough, and Elastomeric Nanocomposite Hydrogels from Poly(ethylene glycol) and Hydroxyapatite Nanoparticles

Unique combinations of hard and soft components found in biological tissues have inspired researchers to design and develop synthetic nanocomposite gels and hydrogels with elastomeric properties. These elastic materials can potentially be used as synthetic mimics for diverse tissue engineering applications. Here we present a set of elastomeric nanocomposite hydrogels made from poly(ethylene glycol) (PEG) and hydroxyapatite nanoparticles (nHAp). The aqueous nanocomposite PEG-nHAp precursor solutions can be injected and then covalently cross-linked via photopolymerization. The resulting PEG-nHAp hydrogels have interconnected pore sizes ranging from 100 to 300 nm. They have higher extensibilities, fracture stresses, compressive strengths, and toughness when compared with conventional PEO hydrogels. The enhanced mechanical properties are a result of polymer nanoparticle interactions that interfere with the permanent cross-linking of PEG during photopolymerization. The effect of nHAp concentration and temperature on hydrogel swelling kinetics was evaluated under physiological conditions. An increase in nHAp concentration decreased the hydrogel saturated swelling degree. The combination of PEG and nHAp nanoparticles significantly improved the physical and chemical hydrogel properties as well as some biological characteristics such as osteoblast cell adhesion. Further development of these elastomeric materials can potentially lead to use as a matrix for drug delivery and tissue repair especially for orthopedic applications.

Macromolecular transport through nanostructured and porous hydrogels synthesized using the amphiphilic copolymer, PCL- b-PEO- b-PCL

We have studied macromolecular transport through nanostructured and porous hydrogels. These hydrogels were produced by (1) synthesizing poly(ε-caprolactone- b-ethylene oxide- b-ε-caprolactone) (PCL-PEO-PCL) block copolymers, (2) crosslinking the block copolymer in aqueous solutions at high concentrations, and (3) degrading the PCL blocks by hydrolysis. Lamellar morphologies of the PCL- b-PEO- b-PCL were observed using Small Angle X-ray Scattering (SAXS) and Atomic Force Microscopy (AFM). The regions formerly occupied by PCL domains have no spanning PEO chains and thus should allow fast transport of macromolecules without significant entanglement. This work presents Fluorescence Recovery After Photobleaching (FRAP) data showing that macromolecular diffusivities are higher in these nanostructured materials than in comparable homogeneous PEO hydrogels prepared under the same crosslinking conditions to yield similar crosslink density. These materials offer a route to high macromolecular mobility, and so may be useful in bioengineering areas such as drug delivery and protein separation.

The use of poly(ethylene oxide) hydrogels as immobilization matrices for yeast cells

Hydrogels based on high molecular weight poly(ethylene oxide) (PEO) copolymers of ethylene oxide and propylene oxide, PEO/alginate and PEO/chitosan were synthesized by UV crosslinking of polymer aqueous solutions. These hydrogels were then characterized in terms of their gel fraction yield, degree of equilibrium swelling, shear storage and loss moduli. The physico-mechanical properties of the hydrogels were then correlated to their ability to sustain the viability and the activity of immobilized cells. The production of ethanol by immobilized Saccharomyces cerevisiae was used to test the suitability of the PEO based hydrogels as immobilization matrices. The PEO hydrogel with a value of 255 Pa for Gʹ and 11 Pa for Gʹʹ, showed the best mechanical properties of all the gels tested. Scanning electron microscope (SEM) analysis of the imobilized S. cerevisiae showed proliferation of the yeast cells entrapped inside the polymeric matrix.

Synthesis of polyethylene oxide hydrogels by electron radiation

AbstractPoly(ethylene oxide) (PEO) hydrogels were prepared by crosslinking of aqueous PEO 35,000 solutions at a 30% concentration by using electron irradiation. Measurements were performed at different dose rates and irradiation doses. The swelling properties of each sample have been investigated and the network properties of the PEO hydrogels calculated. In particular, the effect of dose rate and dose irradiation on the crosslinking density were investigated. Finally, the experimental results illustrating the effects of the beam parameters on the network properties for a pulsed irradiation are compared to those of a continuum beam. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 820–824, 2006

Effects of cross-linking molecular weights in a hyaluronic acid–poly(ethylene oxide) hydrogel network on its properties

We examined the effects of cross-linking molecular weights on the properties of a hyaluronic acid (HA)–poly(ethylene oxide) (PEO) hydrogel. Swelling behaviors, mechanical strength and rheological behaviors of the HA–PEO hydrogel were evaluated by employing different cross-linking molecular weights (100 kDa and 1.63 mDa) of the HAs in the hydrogel networks. The low molecular weight of HA was obtained in advance by treating high molecular weight HA with a hydrogen chloride solution. Methacrylation of HA was obtained by grafting aminopropylmethacrylate to its caroboxylic acid functional groups. While reduction of the HA molecular weights was confirmed by gel permeation chromatography, the degree of methacrylate grafting to the HA was measured by 1H-nuclear magnetic resonance. Synthesis of the HA–PEO hydrogel was successfully achieved via the Michael-type addition reaction between the methacrylate arm groups in the HA and the six thiol groups in PEO. The hydrogel formation was not dependent upon the HA molecular weights and its gelation behaviors were markedly different. Compared to the properties of the high molecular weight HA-based PEO one, the low molecular weight HA-based hydrogel induced quicker hydrogelation, as observed from the behaviors of the elastic and viscous modulus. Furthermore, the low molecular weight HA-based hydrogel demonstrated stronger mechanical properties as measured with a texture analyzer, lower water absorption as measured with a microbalance and smaller pore sizes on its surface and cross section as observed with scanning electron microscopy. The information about the effects of the cross-linking molecular weights of the gel network on the properties of the HA-based PEO hydrogel may lead to better design of hydrogels, especially in tissue engineering applications.

Synthesis and Characterization of PCL-b-PEO-b-PCL-Based Nanostructured and Porous Hydrogels

Hydrogels with nanoscale structure were synthesized using amphiphilic poly(epsilon-caprolactone)-poly(ethylene oxide)-poly(epsilon-caprolactone) (PCL-b-PEO-b-PCL) triblock copolymers. Small-angle X-ray scattering (SAXS) studies show that the block copolymers form 30-40 nm structures in aqueous solution and that these patterns are retained, with some increase in length scale, following electron beam cross-linking. Lamellar nanostructures were observed by SAXS and atomic force microscopy (AFM), with SAXS indicating cylindrical structure as the block lengths become more different in length. It is demonstrated through Fourier transform infrared spectroscopy (FTIR), mass loss, and differential scanning calorimetry (DSC) that the PCL can be completely removed by hydrolysis in NaOH(aq) to form porous PEO hydrogels. These hydrogels retain active functional groups following PCL removal that serve as sites for further chemical modification.

Preparation and characterization of pH-sensitive poly(ethylene oxide) grafted methacrylic acid and acrylic acid hydrogels by γ-ray irradiation

pH-sensitive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing it in the small intestine. In this study, hydrogels based on poly(ethylene oxide) (PEO) networks grafted with methacrylic acid (MAA) or acrylic acid (AAc) were prepared via a two-step process. PEO hydrogels were prepared by γ-ray irradiation (radiation dose: 50 kGy, dose rate: 7.66 kGy/h), grafted by either MAA or AAc monomers onto the PEO hydrogels and finally underwent irradiation (radiation dose: 5–20 kGy, dose rate: 2.15 kGy/h). These grafted hydrogels showed a pH-sensitive swelling behavior. The grafted hydrogels were used as a carrier for the drug delivery systems for the controlled release of insulin. Drug-loaded hydrogels were placed in simulated gastric fluid (SGF, pH 1.2) for 2 hr and then in simulated intestinal fluid (SIF, pH 6.8). Thein vitro drug release behaviors of these hydrogels were examined by quantification analysis with a UV-Vis spectrophotometer.

Design and in vitro evaluation of an extended-release matrix tablet for once-daily oral administration of oxybutynin

The oral osmotic oxybutynin release system (Oros), allowing once-daily administration, improves the oxybutynin tolerability over the immediate-release formulation. However, Oros manufacture requires a specialized technology. Therefore an attempt was made to design oxybutynin matrix tablets for once-daily administration in the treatment of urinary incontinence. Matrices (weight, 50 mg; diameter, 6 mm; dose, 5 mg) were prepared by compression, and the drug release kinetics in simulated gastric and intestinal fluids (SGF and SIF, respectively) were measured in vitro. Matrices intended to release the drug by diffusion were based on glycerol palmitostearate. This matrix type released the drug only in SGF. In SIF release stopped, due to the conversion, inside the matrix, of the freely water-soluble oxybutynin hydrochloride into the virtually insoluble free base form. Erodible matrices were based on Eudragit L100 (EUD L) or on poly(ethylene oxide) (PEO). Release in SIF from the former was either too slow or non-reproducible, depending on the EUD L fraction in matrix. Erosion-controlled oxybutynin release in SIF from matrices-based on PEO hydrogel was time-independent and depended on polymer MW and on dissolution medium hydrodynamics. A gastroprotected tablet based on a PEO of MW 5000 kDa released the dose in SIF at the rate of about 6%/h, appropriate for once-daily administration.

UV‐Induced Cross‐Linking of Poly(ethylene oxide) in Aqueous Solution

AbstractSummary: Hydrogels of high‐molecular‐weight poly(ethylene oxide) (PEO) have been obtained in situ by applying a very simple procedure that involves UV cross‐linking of PEO in aqueous solution. The efficiency of the photoactivated cross‐linking of thin layers of PEO in aqueous solution in the presence of (4‐benzoylbenzyl) trimethylammonium chloride as a photoinitiator has been determined at room temperature and in a frozen state (−25 °C). It was found that the efficiency varies with the concentration of PEO solution, the molecular weight of PEO, and especially with the temperature. When the UV cross‐linking was performed in the frozen state, porous hydrogels with very high yield of gel fraction (above 90%) and high cross‐linking density were obtained. After drying the hydrogels, films of 50–150 μm thickness were prepared. The films swell extremely fast in water and act as asymmetric membranes.SEM of a dried PEO hydrogel obtained by UV cross‐linking of an aqueous solution at room temperature.magnified imageSEM of a dried PEO hydrogel obtained by UV cross‐linking of an aqueous solution at room temperature.

Hydrogel Networks of Poly(ethylene oxide) Star‐Molecules Supported by Expanded Polytetrafluoroethylene Membranes: Characterization, Biocompatibility Evaluation and Glucose Diffusion Characteristics

The present work discusses the grafting by electron beam irradiation of poly(ethylene oxide) (PEO) star-shaped polymers onto porous expanded polytetrafluoroethylene (EXPTFE) surfaces. The resulting materials are intended to combine the good biocompatible properties of PEO with the outstanding mechanical properties of PTFE. The star-shaped PEOs were synthesized via anionic polymerization. 3 Mev electron beam irradiation was applied to graft these PEO stars onto porous EXPTFE surfaces. The hydrophobic EXPTFE surface had to be pre-modified with N-vinylpyrrolidone. ESCA was used to quantify the amount of grafted star-shaped PEO. Unmodified EXPTFE surfaces are well known, when implanted in a body, to be rapidly covered by a layer of cells and fibrin. The EXPTFE coated with PEO were implanted in the peritoneal cavity of rats (or under the back skin). This implantation did not induce any inflammation reactions and SEM analysis had attested the absence of adsorbed cells and fibrin. The glucose diffusion properties of these membranes were studied by a lag time analysis method and compared to those of pure PEO hydrogels. As expected, glucose diffuses through the hydrogel coated membrane and diffusion is not affected by the presence of the EXPTFE membrane.

Preparation, properties and biological application of pH-sensitive poly(ethylene oxide) (PEO) hydrogels grafted with acrylic acid(AAc) using gamma-ray irradiation

pH-sensitive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing it in the small intestine. In this study, hydrogels based on poly(ethylene oxide) (PEO) networks grafted with acrylic acid (AAc) were prepared via a two-step process. PEO hydrogels were prepared by γ-ray irradiation, and then grafting by AAc monomer onto the PEO hydrogels with the subsequent irradiation (radiation dose: 5–20 kGy, dose rate: 2.15 kGy/h). These grafted hydrogels showed a pH-sensitive swelling behavior. The grafted hydrogels were used as a carrier for the drug delivery systems for the controlled release of insulin. The in vitro drug release behaviors of these hydrogels were examined by quantification analysis with a UV/VIS spectrophotometer. Insulin was loaded into freeze-dried hydrogels (7 mm×3 mm×2.5 mm) and administrated orally to healthy and diabetic Wistar rats. The oral administration of insulin-loaded hydrogels to Wistar rats decreased the blood glucose levels obviously for at least 4 h due to the absorption of insulin in the gastrointestinal tract.

Radiation chemical synthesis of polyethylene oxide hydrogel containing DCH18C6 crown ether: A new approach

Polyethylene oxide hydrogels containing physically immobilized dicyclohexano-18-crown-6 were prepared by radiation chemical synthesis. Doses of gel formation were found to depend on the molecular weight of the polyethylene oxide and were about 20 and 4 kGy for M w of 105 and 3·106, respectively. An increase in the crown ether concentration resulted in the decrease of the efficiency of hydrogel formation, whereas the effect of polymer concentration was less pronounced. It was found that dicyclohexano-18-crown-6 immobilized in the PEO hydrogel showed relatively high resistance toward washout in aqueous media.