Gels, Volume 8, Issue 8 (August 2022) – 68 articles

The current study aims to investigate the influence of iron minerals on the amorphous phase content, compressive strengths and the microstructural properties of the geopolymer materials. Geopolymer materials were prepared by the substitution of metakaolin by 10 and 20 wt.% of each iron mineral sample. Sodium waterglass from rice husk ash was used as a hardener, and metakaolin was used as an aluminosilicate source. The X-ray patterns show that the iron minerals denoted FR and FB are associated with hematite and magnetite, respectively. FY contains goethite together with a significant content of kaolinite and quartz. It is observed in the XRD patterns and FTIR absorption spectra that the additions of hematite, magnetite and goethite remain largely unreacted in the geopolymer binder. The compressive strengths of the related geopolymer composites show some significant variations indicating certain effects for mechanical stability obtained: 10 wt.% replacement of metakaolin by hematite increased the compressive strength from 51.1 to 55.5 MPa, while 20 wt.% hematite caused a decrease to 44.9 MPa. Furthermore, 10 and 20 wt.% replacement with FB revealed decreased values 47.0 and 40.3 MPa, respectively. It was also found that 10 and 20 wt.% of FY caused lower values of 30.9 and 39.1 MPa, respectively. The micrographs of geopolymer materials present some voids and cracks. The denser matrix is related to a superior gel formation producing a better glue between the crystalline additions. The unsubstituted geopolymer sample provides with about 50% the highest X-ray-amorphous content, whereas the substituted samples range between 35 and 45%, indicating systematically smaller gel contents without any clear trend with the compressive strength variation, however. The strength dependencies reveal more complex interaction between the gel and crystalline additions. Full article

Nowadays, edible materials such as polysaccharides have gained attention due to their valuable attributes, especially gelling property. Polysaccharide-based edible gels (PEGs) can be classified as (i) hydrogels, (ii) oleogels and bigels, (iii) and aerogels, cryogels and xerogels, respectively. PEGs have different characteristics and benefits depending on the functional groups of polysaccharide chains (e.g., carboxylic, sulphonic, amino, methoxyl) and on the preparation method. However, PEGs are found in the incipient phase of research and most studies are related to their preparation, characterization, sustainable raw materials, and applicability. Furthermore, all these aspects are treated separately for each class of PEG, without offering an overview of those already obtained PEGs. The novelty of this manuscript is to offer an overview of the classification, definition, formulation, and characterization of PEGs. Furthermore, the applicability of PEGs in the food sector (e.g., food packaging, improving food profile agent, delivery systems) and in the medical/pharmaceutical sector is also critically discussed. Ultimately, the correlation between PEG consumption and polysaccharides properties for human health (e.g., intestinal microecology, “bridge effect” in obesity, gut microbiota) are critically discussed for the first time. Bigels may be valuable for use as ink for 3D food printing in personalized diets for human health treatment. PEGs have a significant role in developing smart materials as both ingredients and coatings and methods, and techniques for exploring PEGs are essential. PEGs as carriers of bioactive compounds have a demonstrated effect on obesity. All the physical, chemical, and biological interactions among PEGs and other organic and inorganic structures should be investigated. Full article

The aim of the study was to evaluate the healing process of chronic wounds treated with carboxymethylcellulose loaded with recombinant human epidermal growth factor in patients with diabetes. The case series consisted of 10 patients treated at the university hospital for 12 weeks. Data were analyzed using SPSS version 22.0. according to the intention to treat the principle, without the loss or exclusion of the participants. The sample consisted of 70% (7/10) males with a mean age of 61.9 years (±9.4); all (100%) had diabetes mellitus and 70% (7/10) had systolic hypertension associated with diabetes mellitus. Sixty percent (6/10) presented lesions of diabetic etiology and 40% (4/10) presented lesions of venous etiology; 70% (7/10) had had lesions for less than 5 years. The mean glycated hemoglobin was 7.8% (±2.7%), while the mean ankle-arm index (AAI) was 0.94 (±0.21). The mean initial area of all wounds was 13.4 cm², and the mean final area was 7.8 cm², with a reduction rate of 28.9% over the 12 weeks of treatment. The reduction rate of diabetic ulcers was higher (33.4%) than that of venous ulcers (22.1%). Regarding the type of tissue, there was an increase in granulation and epithelialization, and a decrease in slough and the amount of exudate that were statistically significant (p = 0.021). No participant had severe or local adverse events during the study period. Epidermal growth factor was effective in the treatment of chronic wounds, especially diabetic ulcers, resulting in the reduction of the wound area and the improvement of tissue and exudate quality. Full article

Insecticides and rodenticides form the basis of integrated pest management systems worldwide. As pest resistance continues to increase and entire groups of chemical active ingredients are restricted or banned, manufacturers are looking for new options for more effective formulations and safer application methods for the remaining pesticide ingredients. In addition to new technological adaptations of mainstream formulations in the form of sprays, fumigants, and dusts, the use of gel formulations is becoming increasingly explored and employed. This article summarizes information on the current and potential use of gel (including hydrogel) and paste formulations against harmful arthropods or rodents in specific branches of pest management in the agricultural, food, stored product, structural wood, urban, medical, and public health areas. Due to the worldwide high interest in natural substances, part of the review was devoted to the use of gels for the formulation of pesticide substances of botanical origin, such as essential or edible oils. Gels as emerging formulation of so called “smart insecticides” based on molecular iRNA disruptors are discussed. Full article

Acetaminophen is an odorless and white crystalline powder drug, used in the management of fever, pain, and headache. The half-life of acetaminophen is very short; thus, multiple intakes of acetaminophen are needed in a day to maintain a constant pharmacological action for an extended period of time. Certain severe adverse effects are produced due to the frequent intake of acetaminophen, especially hepatotoxicity and skin rashes. Therefore, a drug carrier system is needed which not only prolongs the release of acetaminophen, but also enhances the patient compliance. Therefore, the authors prepared novel aspartic acid-graft-poly(acrylic acid) hydrogels for the controlled release of acetaminophen. The novelty of the prepared hydrogels is based on the incorporation of pH-sensitive monomer acrylic acid with polymer aspartic acid in the presence of ethylene glycol dimethacrylate. Due to the pH-sensitive nature, the release of acetaminophen was prolonged for an extended period of time by the developed hydrogels. Hence, a series of studies was carried out for the formulated hydrogels including sol-gel fraction, FTIR, dynamic swelling, polymer volume analysis, thermal analysis, percent porosity, SEM, in vitro drug release studies, and PXRD analysis. FTIR analysis confirmed the grafting of acrylic acid onto the backbone of aspartic acid and revealed the development of hydrogels. The thermal studies revealed the high thermal stability of the fabricated hydrogels as compared to pure aspartic acid. An irregular surface with a few pores was indicated by SEM. PXRD revealed the amorphous state of the developed hydrogels and confirmed the reduction in the crystallinity of the unreacted aspartic acid by the formulated hydrogels. An increase in gel fraction was observed with the increasing concentration of aspartic acid, acrylic acid, and ethylene glycol dimethacrylate due to the availability of a high amount of free radicals. The porosity study was influenced by the various compositions of developed hydrogels. Porosity was increased due to the enhancement in the concentrations of aspartic acid and acrylic acid, whereas it decreased with the increase in ethylene glycol dimethacrylate concentration. Similarly, the pH-responsive properties of hydrogels were evaluated by dynamic swelling and in vitro drug release studies at two different pH levels (1.2 and 7.4), and a greater dynamic swelling and acetaminophen release were exhibited at pH 7.4 as compared to pH 1.2. An increase in swelling, drug loading, and drug release was seen with the increased incorporation of aspartic acid and acrylic acid, whereas a decrease was detected with the increase in the concentration of ethylene glycol dimethacrylate. Conclusively, the formulated aspartic acid-based hydrogels could be employed as a suitable nonactive pharmaceutical ingredient for the controlled delivery of acetaminophen. Full article

A rising health concern with saturated fatty acids allowed researchers to look into the science of replacing these fats with unsaturated fatty acids. Oleogelation is a technique to structure edible oil using gelators. The present study looked for the effect of solid emulsifiers; namely, sorbitan monostearate (SP) and stearyl alcohol (SA), on the physicochemical parameters of oleogels. All the oleogels were formulated using 5% sunflower wax (SW) in sunflower oil (SO). The formulated oleogels displayed irregular-shaped wax crystals on their surface. The bright-field and polarized microscopy showed the fiber/needle network of wax crystals. Formulations consisting of 10 mg (0.05% w/w) of both the emulsifiers (SA10 and SP10) in 20 g of oleogels displayed the appearance of a dense wax crystal network. The SP and SA underwent co-crystallization with wax molecules, which enhanced crystal growth and increased the density and size of the wax crystals. The XRD and FTIR studies suggested the presence of a similar β’ polymorph to that of the triacylglycerols’ arrangement. The incorporation of SA and SP in wax crystal packing might have resulted in a lower crystallization rate in SA10 and SP10. Evaluation of the thermal properties of oleogels through DSC showed better gel recurrence of high melting enthalpy. These formulations also displayed a sustained release of curcumin. Despite the variations in several properties (e.g., microstructures, crystallite size, thermal properties, and nutrient release), the emulsifiers did not affect the mechanical properties of the oleogel. The meager amounts of both the emulsifiers were able to modulate the nutrient release from the oleogels without affecting their mechanical properties in comparison to the control sample. Full article

Recently, the development of new materials with the desired characteristics for functional tissue engineering, ensuring tissue architecture and supporting cellular growth, has gained significant attention. Hydrogels, which possess similar properties to natural cellular matrixes, being able to repair or replace biological tissues and support the healing process through cellular proliferation and viability, are a challenge when designing tissue scaffolds. This paper provides new insights into hydrogel-based polymeric blends (hydroxypropyl cellulose/Pluronic F68), aiming to evaluate the contributions of both components in the development of new tissue scaffolds. In order to study the interactions within the hydrogel blends, FTIR and ¹HNMR spectroscopies were used. The porosity and the behavior in moisture medium were highlighted by SEM and DVS analyses. The biodegradability of the hydrogel blends was studied in a simulated biological medium. The hydrogel composition was determinant for the scaffold behavior: the HPC component was found to have a great influence on the BET and GAB areas, on the monolayer values estimated from sorption–desorption isotherms and on mucoadhesivity on small intestine mucosa, while the Pluronic F68 component improved the thermal stability. All blends were also found to have good mechanical strength and increased biocompatibility on the NHDF cell line. Based on their particular compositions and increased mucoadhesivity on small intestine mucosa, these polymeric blends could be effective in the repair or recovery of damaged cell membranes (due to the contribution of Pluronic F68) or in control drug-delivery intestinal formulations. Full article

The rheological behavior of polyvinyl alcohol (PVA) aqueous solution is crucial to optimizing the processing technology and performance of PVA products. In this paper, the dynamic rheological behavior of PVA aqueous solution was investigated in detail. PVA solution with a concentration of 10 wt% showed unnormal rheological behaviors, that is, the liquid-like behavior in the high frequency (ω) region and the solid-like behavior in the low ω region. A storage modulus (G′) plateau appears in the relatively low ω region as a gel with a network structure. Different from conventional hydrogel, this plateau has a low modulus, and the corresponding size of the relaxation unit is estimated to be 554 nm, being higher than the size of a whole PVA chain. It is believed that the network mesh is formed by the intermolecular hydrogen bonding interactions among PVA chains. The relaxation time of these meshes is longer than the reptation time of a PVA chain. Based on the relaxation spectrum and calculation analysis, it is found that the destruction of intermolecular hydrogen bonds, such as by heating up, adding sodium dodecyl sulfate, and shear operation, will make the relaxation unit (mesh) larger and lead to the left shift of the intersection of G′ and loss modulus (G″). In a PVA solution with a high concentration, multiple meshes of various sizes could be formed and thus generate multiple relaxation peaks. The large-sized meshes mainly contribute to the left shift of the intersection of G′ and G″, and the small-sized meshes contribute to the high plateau modulus. The results in this paper offer a new angle to analyze polymer solutions with strong intermolecular interaction. Full article

This study aimed to explore the effects and mechanisms of differently shaped aggregates of ovotransferrin (OVT) particles on oleogel-based Pickering emulsions (OPEs). Medium-chain triglyceride oil-based oleogels were constructed using beeswax, and their gel-sol melting temperatures were investigated. Atomic force microscopy confirmed that both OVT fibrils and OVT spheres were successfully prepared, and the three-phase contact angle measurements indicated that fibrous and spherical aggregates of OVT particles possessed great potential to stabilize the OPEs. Afterward, the oil-in-water OPEs were fabricated using oleogel as the oil phase and OVT fibrils/spheres as the emulsifiers. The results revealed that OPEs stabilized with OVT fibrils (FIB-OPEs) presented a higher degree of emulsification, smaller droplet size, better physical stability and stronger apparent viscosity compared with OPEs stabilized with OVT spheres (SPH-OPEs). The freeze–thaw stability test showed that the FIB-OPEs remained stable after three freeze–thaw cycles, while the SPH-OPEs could barely withstand one freeze–thaw cycle. An in vitro digestion study suggested that OVT fibrils conferred distinctly higher lipolysis (46.0%) and bioaccessibility (62.8%) of curcumin to OPEs. Full article

Micron-sized hard core-soft shell hybrid microgels are promising model systems for studies of soft matter as they enable in-situ optical investigations and their structures/morphologies can be engineered with a great variety. Yet, protocols that yield micron-sized core-shell microgels with a tailorable shell-to-core size ratio are rarely available. In this work, we report on the one-pot synthesis protocol for micron-sized silica-poly(N-isopropylacrylamide) core-shell microgels that has excellent control over the shell-to-core ratio. Small-angle light scattering and microscopy of 2- and 3-dimensional assemblies of the synthesized microgels confirm that the produced microgels are monodisperse and suitable for optical investigation even at high packing fractions. Full article

Hydrogels are nowadays widely used in various biomedical applications, and show great potential for the making of devices such as biosensors, drug- delivery vectors, carriers, or matrices for cell cultures in tissue engineering, etc. In these applications, due to the irregular complex surface of the human body or its organs/structures, the devices are often designed with a small thickness, and are required to be flexible when attached to biological surfaces. The devices will deform as driven by human motion and under external loading. In terms of mechanical modeling, most of these devices can be abstracted as shells. In this paper, we propose a mixed graph-finite element method (FEM) phase field approach to model the fracture of curved shells composed of hydrogels, for biomedical applications. We present herein examples for the fracture of a wearable biosensor, a membrane-coated drug, and a matrix for a cell culture, each made of a hydrogel. Used in combination with experimental material testing, our method opens a new pathway to the efficient modeling of fracture in biomedical devices with surfaces of arbitrary curvature, helping in the design of devices with tunable fracture properties. Full article

We investigated the mechanical properties of corn starch (CS)/poly(vinyl alcohol) (PVA)/borax hydrogels reinforced by clay platelets, silica (SiO₂) nanospheres, or cellulose nanofibers (CNFs). The effects of these reinforcing agents on the tensile properties of the hydrogels were quite different; the fracture stress of SiO₂/CS/PVA/borax composite hydrogels increased with SiO₂ concentration, whereas that of clay/CS/PVA/borax composite hydrogels was high at a low clay concentration but low at high clay concentrations; for CNF/CS/PVA/borax composite hydrogels, although the elastic modulus was highly enhanced by adding CNF, the fracture stress was very low because of the stress relaxation during the elongation. This result came from differences in the dispersibility of each filler and the reinforcing ability. These composite hydrogels were constructed by multi-crosslinking, such as hydrogen bonding between CS and PVA, CS and PVA crystals, complexation between borate and PVA (partly CS), and the crosslinking between each filler and polymer. The self-healing ability of SiO₂ and clay composite hydrogels was examined. As a result, the SiO₂/CS/PVA/borax composite hydrogels possessed an excellent self-healing ability, whereas the clay/CS/PVA/borax composite hydrogels had a poor self-healing ability. Full article

Preparing structures with the sol-gel method often requires control of the basal plane of crystallites, crystallite structures, or the appearance of the voids. One of the critical factors in the formation of a layer are additives, such as aminoalcohols, which increase the control of the sol formation reaction. Since aminoalcohols differ in boiling points and alkalinity, their selection may play a significant role in the dynamics of structure formation. The main aim of this work is to examine the properties of ZnO layers grown using different aminoalcohols at different concentration rates. The layers were grown on various substrates, which would provide additional information on the behavior of the layers on a specific substrate, and the mixture was annealed at a relatively low temperature (400 °C). The research was conducted using monoethanolamine (MEA) and diethanolamine (DEA). The aminoalcohols were added to the solutions in equal concentrations. The microscopic image of the structure and the size of the crystallites were determined using micrographs. X-ray diffractometry and Raman spectroscopy were used for structural studies, phase analysis and to establish the purity of the obtained films. UV-vis absorption and photoluminescence were used to evaluate structural defects. This paper shows the influence of the stabilizer on the morphology of samples and the influence of the morphology and structure on the optical properties. The above comparison may allow the preparation of ZnO samples for specific applications. Full article

This research manuscript’s objective was to develop the Punica granatum extract ethosome gel. The use of nanotechnology can improve transdermal drug delivery permeation of its major bioactive compound β-sitosterol. The optimised and developed formulations were further studied in vitro and in vivo. The assessment of the anti-inflammatory activity of the gel was performed in Albino rats. Methanolic extract was prepared and developed into an ethosome suspension and an ethosome gel. To optimise the formulation’s response in terms of particle size (nm) and entrapment efficiency (%), the central composite design (CCD) was used in 2² levels. The effects of factors such as lecithin (%) and ethanol (mL) in nine formulations were observed. Characterisation of ethosome gel was performed and the results showed the particle size (516.4 nm) and mean zeta potential (−45.4 mV). Evaluations of the gel formulation were performed. The results were good in terms of pH (7.1), viscosity (32,158 cps), spreadability (31.55 g cm/s), and no grittiness. In an in vitro study, the percentages of β-sitosterol release of ethosome gel (91.83%), suspension (82.74%), and extracts (68.15%) at 279 nm were recorded. The effects of the formulated gel on formalin-induced oedema in Albino rats showed good results in terms of anti-inflammatory activity. The comparative anti-inflammatory activity of Punica granatum extract and gel showed that the gel action was good for their topical application. Full article

Aqueous gels formulated using hydrophilic polymers (hydrogels) and those based on stimuli-responsive polymers (in situ gelling or gel-forming systems) attract increasing interest in the treatment of several eye diseases. Their chemical structure enables them to incorporate various ophthalmic medications, achieving their optimal therapeutic doses and providing more clinically relevant time courses (weeks or months as opposed to hours and days), which will inevitably reduce dose frequency, thereby improving patient compliance and clinical outcomes. Due to its chronic course, the treatment of glaucoma may benefit from applying gel technologies as drug-delivering systems and as antifibrotic treatment during and after surgery. Therefore, our purpose is to review current applications of ophthalmic gelling systems with particular emphasis on glaucoma. Full article

Insulation materials play an extremely important role in the thermal protection of aerospace vehicles. Here, aluminum carbon aerogels (AlCAs) are designed for the thermal protection of aerospace. Taking AlCA with a carbonization temperature of 800 °C (AlCA–800) as an example, scanning electron microscopy (SEM) images show an integrated three-dimensional porous frame structure in AlCA–800. In addition, the thermogravimetric test (TGA) reveals that the weight loss of AlCA–800 is only ca. 10%, confirming its desirable thermal stability. Moreover, the thermal conductivity of AlCA–800 ranges from 0.018 W m⁻¹ K⁻¹ to 0.041 W m⁻¹ K⁻¹, revealing an enormous potential for heat insulation applications. In addition, ANSYS numerical simulations are carried out on a composite structure to forecast the thermal protection ability of AlCA–800 acting as a thermal protection layer. The results uncover that the thermal protective performance of the AlCA–800 layer is outstanding, causing a 1185 K temperature drop of the structure surface that is exposed to a heat environment for ten minutes. Briefly, this work unveils a rational fabrication of the aluminum carbon composite aerogel and paves a new way for the efficient thermal protection materials of aerospace via the simple and economical design of the aluminum carbon aerogels under the guidance of ANSYS numerical simulation. Full article

Background: Promising cancer chemotherapy requires the development of suitable drug delivery systems (DDSs). Previous research has indicated that a hydrogel is a powerful DDS for tumor therapy and holds great potential to offer a feasible method for cancer management. Methods: In this study, glutathione-gellan gum conjugate (GSH-GG) was synthesized through chemical reaction. Doxorubicin hydrochloride (DOX) was loaded into GSH-GG to accomplish DOX-loaded GSH-GG. The properties, injectability, drug release, and in vitro and in vivo anticancer effects of DOX-loaded GSH-GG were tested. Results: DOX-loaded GSH-GG showed a temperature-ion dual responsive gelling property with good viscosity, strength, and injectability at an optimized gel concentration of 1.5%. In addition, lower drug release was found under acidic conditions, offering beneficial long-acting drug release in the tumor microenvironment. DOX-loaded GSH-GG presented selective action by exerting substantially higher cytotoxicity on cancer cells (4T1) than on normal epithelial cells (L929), signifying the potential of complete inhibition of tumor progression, without affecting the health quality of the subjects. Conclusions: GSH-GG can be applied as a responsive gelling material for delivering DOX for promising cancer therapy. Full article

Gel fuel potentially combines the advantages of solid fuel and liquid fuel due to its special rheological properties, which have essential impacts on the application of gel fuel in propulsion systems. In this paper, we study the rheological property of organic kerosene gel through a series of measurements on its viscosity as a function of the shear rate, temperature, and shear history. The measured datasets are then fitted with constitutive relationships between the viscosity and shear rate at three different levels: the power law shear-thinning model, the power law dependency on both the temperature and shear rate, and the thixotropic property. It is found that intense pre-shear could exhaust thixotropy and reduce viscosity of the kerosene gel. For the power law shear-thinning model, the consistency index increases with the gellant mass fraction, whereas the power law exponent remains constant. The dependence of viscosity on temperature could be well approximated by an empirical power law relationship. As for the thixotropic property of the kerosene gel, the fitted second-order kinetic model corresponds accurately to the viscosity at different shear rates and shear times. The constitutive models fitted in this work at different levels are consistent with each other and provide useful tools for further applications of organic kerosene gel fuel. Full article

Suitable elastic modulus and particle size of preformed particle gel are the keys to both diverting water flow and avoiding permanent impairment to reservoirs. Therefore, the paper aims at finding the best matched preformed particle gel for given reservoirs using sand-pack displacement experiments. The results show that the injection pressure of preformed particle gel with excessively small size and elastic modulus is relatively low, indicating poor capacity to increase flow resistance and reduce water channeling. On the other hand, if the particle size and elastic modulus of preformed particle gel are excessively large, the reservoir may be plugged and irreversibly damaged, affecting oil development performance. In fact, the best matched particle size and elastic modulus of preformed particle gel increase with the increase in reservoir permeability. Furthermore, the paper establishes a quantitative logarithmic model between the particle size of preformed particle gel and reservoir permeability. Finally, the established matching relationship is validated via microscopic visualization oil displacement experiments using a glass etching model. The validation experiments indicate that the preformed particle gel (60–80 mesh; 2–4 Pa) selected according to the matching relationship can effectively reduce water channeling and increase sweeping efficiency by as much as 55% compared with water flooding in the glass etching model with an average permeability of 2624 × 10⁻³ μm². Therefore, the established matching relationship can provide an effective guide when selecting the best suitable preformed particle gel for a given reservoir in more future applications. Full article

The need to replace conventional, usually single-use, packaging materials, so important for the future of resources and of the environment, has propelled research towards the development of packaging-based on biopolymers, fully biodegradable and even edible. The current study furthers the research on development of such films and tests the modification of the properties of the previously developed biopolymeric material, by adding 10, respectively 20% w/v essential oils of lemon, grapefruit, orange, cinnamon, clove, mint, ginger, eucalypt, and chamomile. Films with a thickness between 53 and 102 µm were obtained, with a roughness ranging between 147 and 366 nm. Most films had a water activity index significantly below what is required for microorganism growth, as low as 0.27, while all essential oils induced microbial growth reduction or 100% inhibition. Tested for the evaluation of physical, optical, microbiological or solubility properties, all the films with the addition of essential oil in the composition showed improved properties compared to the control sample. Full article

We formulated and characterized oleogels based on montmorillonite clay and vegetable oils that could serve as eco-friendly semi-solid lubricants. In particular, we studied the influence of the physical-chemical properties of olive, castor, soybean, linseed, and sunflower oils on the rheological, chemical, thermal, and tribological properties of the semi-solid lubricants. We prepared the oleogels via the highly intensive mixing of vegetable oils with clay at a concentration of 30 wt.%. The oleogels exhibited shear-thinning, thixotropy, structural recovery, and gel-like behavior commonly related to that of a three-dimensional network. The results were corroborated via XRD measurements showing the presence of intercalated nanoclay structures well-dispersed in the vegetable oil. Empirical correlations between the content of saturated (SFAs), unsaturated (UFAs), mono-unsaturated (MUFAs) and poly-unsaturated (PUFAs) fatty acids and the plateau modulus of the aerogels were found. From these experimental results, we can conclude that the fatty acid profile of the vegetable oils exerts an important influence on the rheological and tribological properties of resulting clay and vegetable oil oleogels. Full article

Antibacterial hydrogel has excellent antibacterial property and good biocompatibility, water absorption and water retention, swelling, high oxygen permeability, etc.; therefore, it widely applied in biomedicine, intelligent textiles, cosmetics, and other fields, especially for medical dressing. As a wound dressing, the antibacterial hydrogel has the characteristics of absorbing wound liquid, controlling drug release, being non-toxic, being without side effects, and not causing secondary injury to the wound. Its preparation method is simple, and can crosslink via covalent or non-covalent bond, such as γ-radiation croFsslinking, free radical polymerization, graft copolymerization, etc. The raw materials are easy to obtain; usually these include chondroitin sulfate, sodium alginate, polyvinyl alcohol, etc., with different raw materials being used for different antibacterial modes. According to the hydrogel matrix and antibacterial mode, the preparation method, performance, antibacterial mechanism, and classification of antibacterial hydrogels are summarized in this paper, and the future development direction of the antibacterial hydrogel as wound dressing is proposed. Full article

Particle image velocimetry (PIV) is an optical and contactless measurement method for analyzing fluid blood dynamics in cardiovascular research. The main challenge to visualization investigated in the current research was matching the channel material’s index of refraction (IOR) to that of the fluid. Silicone is typically used as a channel material for these applications, so optical matching cannot be proven. This review considers hydrogel as a new PIV channel material for IOR matching. The advantages of hydrogels are their optical and mechanical properties. Hydrogels swell more than 90 vol% when hydrated in an aqueous solution and have an elastic behavior. This paper aimed to review single, double, and triple networks and nanocomposite hydrogels with suitable optical and mechanical properties to be used as PIV channel material, with a focus on cardiovascular applications. The properties are summarized in seven hydrogel groups: PAMPS, PAA, PVA, PAAm, PEG and PEO, PSA, and PNIPA. The reliability of the optical properties is related to low IORs, which allow higher light transmission. On the other hand, elastic modulus, tensile/compressive stress, and nominal tensile/compressive strain are higher for multiple-cross-linked and nanocomposite hydrogels than single mono-cross-linked gels. This review describes methods for measuring optical and mechanical properties, e.g., refractometry and mechanical testing. Full article

The advantages of cryogels for enzyme immobilization applications include their mechanical and chemical robustness, ease of production, superior porosity, and low cost. Currently, many researchers are exploring porous material-based systems for enzyme immobilization that are more efficient and economically viable. Here, poly(2-Hydroxyethyl methacrylate-co-allyl glycidyl ether) (p(HEMA-co-AGE)) cryogel matrices were synthesized via the free radical cryopolymerization method to be employed as the support material. For the immobilization of the catalase enzyme onto the p(HEMA-co-AGE) cryogel matrix (catalase@p(HEMA-co-AGE), the best possible reaction conditions were determined by altering parameters such as pH, catalase initial concentration, and flow rate. The maximum catalase immobilization amount onto the p(HEMA-co-AGE) cryogel was found to be 48 mg/g cryogel. To determine the advantages of the cryogel matrix, e.g., the stability and reusability of the cryogel matrix, the adsorption–desorption cycles for the catalase enzyme were repeated five times using the same cryogel matrix. At the end of the reusability tests, it was found that the cryogel was very stable and maintained its adsorption capacity with the recovery ratio of 93.8 ± 1.2%. Therefore, the p(HEMA-co-AGE) cryogel matrix affords repeated useability, e.g., up to five times, without decreasing its catalase binding capacities significantly and has promising potential for many industrial applications. Cryogels offer clear distinctive advantages over common materials, e.g., micro/nano particles, hydrogels, films, and composites for these applications. At present, many researchers are working on the design of more effective and economically feasible, porous material-based systems for enzyme immobilization Full article

We successfully synthesized new macroporous hydrogel particles consisting of hyperbranched poly(amidoamine)s (HPAMAM) using the Oil-in-Water-in-Oil (O/W/O) suspension polymerization method at both the 50 mL flask scale and the 5 L reactor scale. The pore sizes and particle sizes were easily tuned by controlling the agitation speeds during the polymerization reaction. Since O/W/O suspension polymerization gives porous architecture to the microparticles, synthesized hydrogel particles having abundant amine groups inside polymers exhibited a high CO₂ absorption capacity (104 mg/g) and a fast absorption rate in a packed-column test. Full article

This study aimed to investigate the effect of camellia saponin (CS) on the structural characteristics, texture properties, rheological properties, and thermal stability of camellia oil body-based oleogel (COBO). In addition, the formation mechanism of COBO was further studied in terms of the microstructure and texture of freeze-dried products, the mobility of hydrogen protons, and the conformation and structure changes of oleosin. The texture and rheological properties of the oleogels were found to be gradually improved with the incorporation of CS. This was attributed to the CS-induced enhancement of oil body interfacial film. CS was likely to bind to oleosin via hydrogen bonding and hydrophobic interactions, thereby forming a thick CS-oleosin complex interface, which was revealed by the oleosin fluorescence quenching and an increase in the ordered structure (α-helix). The composite interface could resist the crystallization damage and air disturbance caused by solidification and sublimation of water during freeze-drying, resulting in a denser and more uniform three-dimensional gel structure to trap the liquid oil, which could be explained by the decreased mobility of hydrogen protons in oleogel. The work offers a new proposal and theoretical basis for the development of saponin-enhanced oleogels using non-thermal processing. Full article

The effect of gel preparation and heat treatment on the structural and optical properties of SiO₂-ZnO materials prepared by the sol–gel method was investigated. Zinc acetate dehydrate, TEOS (tetraethylortosilicate), ethanol, distillated water and HCl were used as a starting material, solvent and catalyst, respectively. Four powders (G1–G4) were prepared in different ways from the starting materials mentioned above. The method of adding Zn precursors during the synthesis differed from one another. For the G1 synthesis, only Zn acetate powder was employed; for the G2 synthesis, Zn acetate was dissolved in distilled water; and for the G3 synthesis, Zn acetate was dissolved in ethanol. When synthesizing G4, TEOS was added last, after Zn acetate had been combined with water and ethanol. The SiO₂-ZnO materials were dried at 200 °C and then heat-treated at 700 °C and 900 °C. All samples were investigated by X-ray diffraction and infrared spectroscopy in order to investigate their structure. SEM measurements were performed to investigate the morphology of materials. Optical properties were influenced by gel preparation and heat treatments. A reflectance of over 60% was obtained for G3 and G4 powders, while for G1 and G2, the reflectance was below 30%. In conclusion, synthesis steps and heat treatment can control the structure and properties of the powders. Full article

During recent decades, the interest in renewable, biodegradable, non-fossil materials has been exponentially increasing. Thus, cellulose and cellulose-derived products have been extensively considered for a wide variety of new potential uses. Due to the sustainability of cellulosic raw materials and their excellent properties, the use and modification of cellulose-based materials can be versatile in the material science and technology community. In this featured article, the fundamentals and background of cellulose-based gels are presented, and approaches, prospects and developments in the field, including their potential future applications, are discussed. Full article

Hydrogels are biocompatible polymers that are tunable to the system under study, allowing them to be widely used in medicine, bioprinting, tissue engineering, and biomechanics. Hydrogels are used to mimic the three-dimensional microenvironment of tissues, which is essential to understanding cell–cell interactions and intracellular signaling pathways (e.g., proliferation, apoptosis, growth, and survival). Emerging evidence suggests that the malignant properties of cancer cells depend on mechanical cues that arise from changes in their microenvironment. These mechanobiological cues include stiffness, shear stress, and pressure, and have an impact on cancer proliferation and invasion. The hydrogels can be tuned to simulate these mechanobiological tissue properties. Although interest in and research on the biomedical applications of hydrogels has increased in the past 25 years, there is still much to learn about the development of biomimetic hydrogels and their potential applications in biomedical and clinical settings. This review highlights the application of hydrogels in developing pre-clinical cancer models and their potential for translation to human disease with a focus on reviewing the utility of such models in studying glioblastoma progression. Full article