Hydrogel

Cetirizine dihydrochloride (CTZ) is a second-generation histamine H1 antagonist, effective for the treatment of a wide range of allergic diseases. It has been utilized for managing the symptoms of chronic urticaria and atopic skin conditions. Thus, two novel semisolid formulations, nanoemulsion (NE) and hydrogel (HG) were developed to study their potential utility as vehicles including cetirizine (CTZ) and evaluate the potential use as topical H1-antihistamines agents. The physicochemical and stability properties of both vehicles were tested. Drug release kinetics and human skin permeation studies were performed using Franz cells. The antihistaminic activity was assayed in New Zealand rabbits and compared with two commercial first generation antihistamines. Both formulations were stable and provided a sustained drug release. Amounts of CTZ remaining in the skin were higher for HG, showing the maximum biological effect at 30 min, similar to topical first generation H1-antihistamines ...

This chapter describes the production of micropatterns of extracellular matrix proteins on a 2D flat polyacrylamide (PAA) gel. The technique is divided into two parts. First, micropatterns are produced on glass or directly on a photomask using deep UV. Then the micropatterns are transferred on acrylamide gel by polymerization of the gel directly on the template coverslip. This procedure is easy to perform and does not require any expensive equipment. It can be performed in no more than 2h once you get your hands on it. It combines the advantages of other existing techniques: good spatial resolution, suitable for very soft gel, no need for the use of chemical crosslinkers for attachment of the proteins to the acrylamide, no modification of the mechanical properties of the gel by the process, and suitable for multiple protein patterning. We also discuss the storage issues of such substrates and provide a brief review of other existing techniques for micropatterning on PAA.

A novel adsorbent was prepared via crosslinking graft copolymerization of 2-(dimethylamino) ethyl
methacrylate (DMAEMA) onto carboxymethyl cellulose (CMC) backbone. Ethylene glycol dimethacrylate
and potassium persulphate were used as crosslinker and initiator, respectively. CMC-g-PDMAEMA
hydrogel was used to remove methyl orange (MO) from aqueous solutions. The adsorption kinetics and
isotherms were found to follow Pseudo-second-order kinetic model and Langmuir model, respectively.
The high maximum adsorption capacity (1825 mg/g) implied that CMC-g-PDMAEMA can be used as
promising adsorbent for the synthetic dyes removal from wastewater.

Wet spinning and radial self-assembly of a carbohydrate low molecular weight gelator into well organized hydrogel fi laments A single biocompatible small molecule, the N-heptyl-D-galactonamide can be spun into well-defi ned hydrogel fi laments. A solution of this molecule in dimethylsulfoxide is injected in water, resulting in the formation of a continuous fi lament. The counter-diff usion of water and dimethylsulfoxide triggers the self-assembly of the molecule into supramolecular nanofi bers. A radial organization of the fi bers was observed in the gel fi laments. This method could be used for making well-defi ned cell culture scaff olds. As featured in: rsc.li/nanoscale

To determine the effect of intraoperative ophthalmic viscosurgical devices (OVDs) on late opacification of the Hydroview hydrogel intraocular lens (IOL) (Bausch & Lomb Surgical). Hamilton Health Sciences, McMaster University, Hamilton, Ontario, Canada. A retrospective study of 949 cases of Hydroview IOL implantations from February 1998 to September 2000 was conducted. Of the 949 implantations, 462 were performed by 1 surgeon (J.H.S.) using Viscoat (sodium chondroitin sulfate 4.0%-sodium hyaluronate 3.0%) and 487 were performed by a second surgeon (W.A.N.) using Biolon (sodium hyaluronate 1.0%). Surgical techniques were identical with the exception of surgeon OVD preference. The number of IOLs opacifying and requiring explantation was determined in each group. Seventy-one Hydroview IOLs had surface calcification deposits that presented a mean of 39 months postoperatively. Twenty-two IOLs opacified sufficiently to warrant a recommendation of IOL explantation; 20 IOLs were explanted, and 2 surgeries were cancelled due to death or disability. In all cases of opacification, Viscoat had been used intraoperatively. This represented a 15.4% incidence of opacification in the Viscoat group, with 31.0% cases severe enough to warrant a recommendation of explantation. The results suggest that the intraoperative use of Viscoat has a facilitating role in the development of late calcification and opacification of the Hydroview IOL.

The development of printable biomaterial inks is critical to the application of 3D printing in biomedicine. To print high-resolution structures with fidelity to a computer-aided design, materials used in 3D printing must be capable of being deposited on a surface and maintaining a printed structure. A dual-cross-linking hyaluronic acid system was studied here as a printable hydrogel ink, which encompassed both shear-thinning and self-healing behaviors via guest−host bonding, as well as covalent cross-linking for stabilization using photopolymerization. When either guest−host assembly or covalent cross-linking was used alone, long-term stable structures were not formed, because of network relaxation after printing or dispersion of the ink filaments prior to stabilization, respectively. The dual-cross-linking hydrogel filaments formed structures with greater than 16 layers that were stable over a month with no loss in mechanical properties and the printed filament size ranged from 100 to 500 μm, depending on printing parameters (needle size, speed, and extrusion flux). Printed structures were further functionalized (i.e., RGD peptide) to support cell adhesion. This work highlights the importance of ink formulation and cross-linking on the printing of stable hydrogel structures.

ABSTRACT Enzyme catalysis: Three dehydrogenases have been engineered to self-assemble into a hydrogel that supports a synthetic metabolic network. The new catalytic biomaterial was used as an anode modification in two enzymatic biobatteries capable of the complete oxidation of methanol to CO(2) .

The use of water holding amendments like hydrogel polymers material for enhancing water and nutrient use efficiency will become more important over time, especially in arid and semiarid regions with limiting water availability, the hydrogel able to retain water and plant nutrients and release it to the plants when surrounding soil near the root zone of plants start to dry up. Nowadays water management is considered one of the major challenges for all countries in arid and semi–arid regions, in fact, by 2030, global water demand is probable to be 50% higher than today, resulting in water scarcity, in the same time agricultural sector
used over 70 percent of freshwater in most regions of the world.
Research evidence suggests that when the soil is treated with water hydrogel composite the water volumetric content of the soil increases significantly and when the surrounding soil dries, the stored water is released back slowly into the soil.
The hydrogel increase efficient water consumption, decreasing irrigation costs and increasing irrigation intervals, also, implement soil’s water holding capacity and soil porosity, providing plants with eventual moisture and nutrients as well as enhancing plant viability and ventilation and root development which provides a conducive atmosphere for better growth of plants and finally increases crop yield.
Hydrogel has various characters like the high swelling and the slow water retention encourage their use as safer release systems for fertilizers and as a soil conditioner in agricultural applications. Hydrogel polymer is particularly valuable in agricultural sector since they can retain water and reduce land erosion.
There are various original publications, papers, reviews, and book chapter focused on the synthesis, properties, and applications of hydrogel polymer. The objectives of this work are to explain the role and applications of hydrogel polymer in agricultural sector i.e. improving soil characters, increasing nutrient use efficiency, and the management of irrigation to reduce water consumption and conservation.

Previous studies have demonstrated deposition of tear proteins onto worn contact lenses. In this study, we used proteomic techniques to analyze the protein deposits extracted from worn daily wear silicone hydrogel contact lenses in combination with different lens care solutions. Worn lenses were collected and protein deposits extracted using urea and surfactant. Protein extracts were desalted, concentrated, and then separated using one-dimensional gel electrophoresis. Individual protein components in extracts were identified using liquid chromatography combined with tandem mass spectrometry (LC-MS-MS) after trypsin digestion. One-dimensional gel electrophoresis revealed that lysozyme and other small proteins (around 20 kDa) were the most abundant proteins in the extracts. LC-MS-MS revealed a wide array of proteins in lens extracts with lysozyme and lipocalin 1 being the most commonly identified in deposit extracts. Worn contact lenses deposit a wide array of proteins from tear film ...

Superoxide dismutase (SOD) was chemically bound to carboxymethyl-cellulose (CMC) polymer.Furthermore, SOD was also trapped into two hydrogels of CMC with 50% and 90% crosslinking degree. The ability of the two SOD-CMC hydrogels to capture SOD and their release kinetics were investigated. ATR FT-IR spectrometry was used to study the conformation of SOD interacting with both CMC polymer and hydrogels. The effect of SOD-CMC polymer conjugate and SOD-CMC hydrogel systems upon human fibroblasts was studied in vitro measuring the cell proliferation inhibition index and evaluating cell morphology. Using the xanthine oxidase-nitroblue tetrazolium assay, the specific activity of bound SOD to CMC polymer or trapped into hydrogels was evaluated. The specific activity of the enzyme was higher in SOD-CMC hydrogels than in SOD-CMC polymer conjugates.

This project compared the effects of hydrocolloid (HC) and hydrogel (HG) occlusive dressings and a polyethylene (PE) semi-occlusive dressing on the healing of acute full-thickness skin wounds on the forelimbs of 10 dogs. All treatments resulted in a similar degree of healing at postoperative days 4 and 7. No significant differences existed in the number of wounds that were more than 90% healed at postoperative day 28 between the group treated with the HG dressing and the group treated with the PE dressing. There were significantly fewer wounds more than 90% healed at postoperative day 28 in the group treated with the HC dressing. Wounds under the HG dressing had the largest mean percentage of contraction at postoperative days 21 and 28. Wounds under the HG dressing also had the largest contraction/re-epithelialization ratio (postoperative days 21 and 28) compared with wounds under the PE and HC dressings. Wounds under the PE dressing had a significantly higher mean percentage of re-epithelialization than wounds under both occlusive dressings on postoperative days 14, 21, and 28. Wounds under the two occlusive dressings had exuberant granulation tissue present more often than wounds under the PE dressing. The two occlusive dressings had significantly higher bacterial counts on wounds compared with wounds under the PE dressing; analysis of variance (ANOVA), P = .0008. Wounds under the HC dressing showed the poorest healing in all parameters.

The biomolecule conjugated macroporous hydrogels have been particularly investigated in
the field of bioseparation, biocatalysts, bioreactor, cell therapy, tissue regeneration and
environmental applications. This review focuses on different types of biological molecules
that have been conjugated on macroporous hydrogels. A variety of techniques are available
for the fabrication of macroporous hydrogels and attachment of biomolecules. The natural
polymers, ECM components, growth factors, peptides and proteins have been widely used for
the functionalization of macroporous hydrogels in various biomedical applications. The
major areas benefited by the incorporation of these biomolecules are separation of cells and
biomolecules (e.g. antibody), tissue repair and regeneration (e.g. peptides and ECM
molecules), biocatalysts (e.g. enzyme) and controlling of environmental pollution.
Additionally, functionalization of macroporous hydrogels with chemical drugs have
demonstrated their controlled drug release capabilities. Moreover, clinically available
biofunctionalized macroporous polymeric products have been briefly discussed.

Hydrogels are being investigated recently for wastewater treatment. These polymeric networks permit their functional group alterations imparting high binding affinity for different contaminants in wastewater. Their innate ability to imbibe huge volume of water qualifies it for a smart material for water remediation. In this review recent advancements in the modifications and types of hydrogels with particular emphasis on adsorption capacity of metal ions and dyes is presented. In addition, through a comparative approach, adsorption mechanism , kinetic, isotherm and related thermodynamics parameters of the modified hydrogels have been discussed. It gives a detailed account of the work done by different authors on the synthesis, composition, func-tionality and contaminant removal mechanism. It also provides an in-depth perspective on the advantages and limitations in the application of hydrogels for wastewater treatment.

This paper describes the methodology and practice-based research underpinning the development of a successful cleaning strategy for Eva Hesse's sculpture Addendum (1967, Tate Collection T02394). Research strands included: technical and art historical investigations to determine the materials and construction of the work of art and to define the aims of the conservation treatment; the production, soiling and accelerated ageing of mock-up samples using contemporary equivalent materials; and the systematic, iterative evaluation of soiling removal systems, which were further refined for appropriate use on the work of art. The comparative cleaning system evaluation was employed to determine options which offered optimal soiling removal efficacy and posed minimal risk to the work of art. Newly developed Nanorestore Gel ® Peggy series (i.e. polyvinyl alcohol (PVA) and polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP)-based hydrogels), designed for the cleaning of modern and contemporary art, were evaluated with a range of other gels, emulsifiers and cosmetic sponges and assessed through a combination of empirical observation, microscopy and spectroscopic techniques. Promising options, combined with tailored aqueous phases derived from trials on mock-up samples, were then evaluated on discreet areas of the sculpture. After extensive testing, the top papier mâché section of Addendum was surface cleaned using an aqueous solution applied with cosmetic sponges, and the ropes were surface cleaned using a modified version of Nanorestore Gel ® Peggy 5 (PVA/PVP) loaded with a tailored aqueous solution. The optimisation of this hydrogel, combined with the extensive supporting research, enabled the successful, low-risk, conservation treatment of Addendum for the first time since acquisition.

In this study, we demonstrate the fabrication of three-dimensional reduced graphene oxide/hydroxyapatite (HA)/Gelatin scaffolds by employing two steps, including a hydrothermal autoclave with hydrogen gas injection to synthesize three-dimensional graphene (3DG)/HA powders and a hydrogel 3D-printing method to fabricate the scaffolds. Evaluations were performed separately for synthesized powders and fabricated scaffolds, which included field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma, Raman spectroscopy, and instrumented compression experiments. The powders characterization results showed that the nanostructured hybrid powders were successfully synthesized. The graphene sheets were stacked in 3D and the HA nanorods were attached on the surface of the graphene. Interface analysis showed that the two phases (HA/Graphene) are connected coherently and various preferential directions played a role in the growth of hydroxyapatite crystals. Characterization of the scaffolds showed that the addition of HA and graphene/HA powders resulted in smaller pores and higher dimensional accuracy of the fabricated scaffolds. Mechanical evaluation showed that the addition of HA (0.3 gr) increased the mechanical properties of the scaffolds. Also, increasing the small amount of graphene (0.0045 gr) made the mechanical properties much higher than that of pure HA.

Tissue engineering is a newly emerging biomedical technology, which aids and increases the repair and regeneration of deficient and injured tissues. It employs the principles from the fields of materials science, cell biology, transplantation, and engineering in an effort to treat or replace damaged tissues. Tissue engineering and development of complex tissues or organs, such as heart, muscle, kidney, liver, and lung, are still a distant milestone in twenty-first century. Generally, there are four main challenges in tissue engineering which need optimization. These include biomaterials, cell sources, vascularization of engineered tissues, and design of drug delivery systems. Biomaterials and cell sources should be specific for the engineering of each tissue or organ. On the other hand, angiogenesis is required not only for the treatment of a variety of ischemic conditions, but it is also a critical component of virtually all tissue-engineering strategies. Therefore, controlling the dose, location, and duration of releasing angiogenic factors via polymeric delivery systems, in order to ultimately better mimic the stem cell niche through scaffolds, will dictate the utility of a variety of biomaterials in tissue regeneration. This review focuses on the use of polymeric vehicles that are made of synthetic and/or natural biomaterials as scaffolds for three-dimensional cell cultures and for locally delivering the inductive growth factors in various formats to provide a method of controlled, localized delivery for the desired time frame and for vascularized tissue-engineering therapies.