Journal Description
Gels
Gels
is an international, peer-reviewed, open access journal on physical and chemical gels. Gels is published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High visibility: indexed within Scopus, SCIE (Web of Science), PubMed, PMC, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q1 (Polymer Science)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 10 days after submission; acceptance to publication is undertaken in 2.9 days (median values for papers published in this journal in the first half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Testimonials: See what our editors and authors say about the Gels.
Impact Factor:
4.6 (2022);
5-Year Impact Factor:
5.2 (2022)
Latest Articles
Design of Pectin-Based Hydrogel Microspheres for Targeted Pulmonary Delivery
Gels 2023, 9(9), 707; https://doi.org/10.3390/gels9090707 (registering DOI) - 01 Sep 2023
Abstract
Pulmonary drug delivery via microspheres has gained growing interest as a noninvasive method for therapy. However, drug delivery through the lungs via inhalation faces great challenges due to the natural defense mechanisms of the respiratory tract, such as the removal or deactivation of
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Pulmonary drug delivery via microspheres has gained growing interest as a noninvasive method for therapy. However, drug delivery through the lungs via inhalation faces great challenges due to the natural defense mechanisms of the respiratory tract, such as the removal or deactivation of drugs. This study aims to develop a natural polymer-based microsphere system with a diameter of around 3 μm for encapsulating pulmonary drugs and facilitating their delivery to the deep lungs. Pectin was chosen as the foundational material due to its biocompatibility and degradability in physiological environments. Electrospray was used to produce the pectin-based hydrogel microspheres, and Design-Expert software was used to optimize the production process for microsphere size and uniformity. The optimized conditions were determined to be as follows: pectin/PEO ratio of 3:1, voltage of 14.4 kV, distance of 18.2 cm, and flow rate of 0.95 mL/h. The stability and responsiveness of the pectin-based hydrogel microspheres can be altered through coatings such as gelatin. Furthermore, the potential of the microspheres for pulmonary drug delivery (i.e., their responsiveness to the deep lung environment) was investigated. Successfully coated microspheres with 0.75% gelatin in 0.3 M mannitol exhibited improved stability while retaining high responsiveness in the simulated lung fluid (Gamble’s solution). A gelatin-coated pectin-based microsphere system was developed, which could potentially be used for targeted drug delivery to reach the deep lungs and rapid release of the drug.
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(This article belongs to the Special Issue Hydrogels with Appropriate/Tunable Properties for Biomedical Applications (2nd Edition))
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A SEM-EDX Study on the Structure of Phenyl Phosphinic Hybrids Containing Boron and Zirconium
Gels 2023, 9(9), 706; https://doi.org/10.3390/gels9090706 (registering DOI) - 01 Sep 2023
Abstract
The SEM-EDX method was used to investigate the structure and morphology of organic–inorganic hybrids containing zirconium, boron and phosphorus compounds, synthesized by the sol–gel method. We started by using, for the first time together, zirconyl chloride hexa-hydrate (ZrOCl2·6H2O), phenyl
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The SEM-EDX method was used to investigate the structure and morphology of organic–inorganic hybrids containing zirconium, boron and phosphorus compounds, synthesized by the sol–gel method. We started by using, for the first time together, zirconyl chloride hexa-hydrate (ZrOCl2·6H2O), phenyl phosphinic acid and triethyl borate as precursors and reagents, at different molar ratios. The obtained hybrids showed a very high thermal stability and are not soluble in water or in organic solvents. As a consequence, such hybrid solid materials are suitable for applications at high temperatures. The obtained hybrids have complex 3D structures and form organic–inorganic networks containing Zr-O-Zr, Zr-O-P and Zr-O-B bridges. Such organic–inorganic networks are also expected to form supramolecular structures and to have many potential applications in different fields of great interest such as catalysis, medicine, agriculture, energy storage, fuel cells, sensors, electrochemical devices and supramolecular chemistry.
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(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))
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Carrageenan-Based Crowding and Confinement Combination Approach to Increase Collagen Deposition for In Vitro Tissue Development
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, , , , and
Gels 2023, 9(9), 705; https://doi.org/10.3390/gels9090705 (registering DOI) - 01 Sep 2023
Abstract
Connective tissue models grown from cell monolayers can be instrumental in a variety of biomedical fields such as drug screening, wound healing, and regenerative engineering. However, while connective tissues contain abundant fibrillar collagen, achieving a sufficient assembly and retention of fibrillar collagen in
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Connective tissue models grown from cell monolayers can be instrumental in a variety of biomedical fields such as drug screening, wound healing, and regenerative engineering. However, while connective tissues contain abundant fibrillar collagen, achieving a sufficient assembly and retention of fibrillar collagen in vitro is challenging. Unlike the dilute cell culture environment, the body’s environment is characterized by a high density of soluble macromolecules (crowding) and macromolecular networks (confinement), which contribute to extracellular matrix (ECM) assembly in vivo. Consequently, macromolecular crowding (MMC) has been successfully used to enhance the processing of type I procollagen, leading to significant increases in fibrillar collagen assembly and accumulation during in vitro culture of a variety of cell types. In this study, we developed a combination approach using a carrageenan hydrogel, which released soluble macromolecules and served as a confinement barrier. We first evaluated the local carrageenan release and then confirmed the effectiveness of this combination approach on collagen accumulation by the human MG-63 bone cell line. Additionally, computational modeling of oxygen and glucose transport within the culture system showed no negative effects of the hydrogel and its releasates on cell viability.
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(This article belongs to the Special Issue Hydrogels with Appropriate/Tunable Properties for Biomedical Applications (2nd Edition))
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Mechanistic Study of the Formation of Multicomponent Oxide Porous Microspheres (MICROSCAFS®) by Cryo-Scanning Electron Microscopy
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and
Gels 2023, 9(9), 704; https://doi.org/10.3390/gels9090704 (registering DOI) - 01 Sep 2023
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Multicomponent oxide microspheres with interconnected macroporosity (MICROSCAFS®) are new materials with great potential as support materials for photocatalysis, optimized for real life applications and for other uses that are still being explored. They are obtained from an adapted sol–gel process combined
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Multicomponent oxide microspheres with interconnected macroporosity (MICROSCAFS®) are new materials with great potential as support materials for photocatalysis, optimized for real life applications and for other uses that are still being explored. They are obtained from an adapted sol–gel process combined with phase separation phenomena that occur within the water droplets of an emulsion. We present here a methodology based on cryogenic scanning electron microscopy (cryo-SEM) that allows, with minimal specimen preparation, the direct and in situ visualization of ‘wet’ alkoxide-derived microstructures, for the mechanistic study of the complex process of MICROSCAFS® generation. It is simultaneously combined with energy dispersive X-ray spectroscopy (EDS) to visualize phase separation phenomena and study the chemical elemental composition at specific regions of the sample and reaction times.
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Sulfonated Hydrogel Formed via CO2-in-Water Emulsion: Potential in Antibiotic Removal
Gels 2023, 9(9), 703; https://doi.org/10.3390/gels9090703 (registering DOI) - 31 Aug 2023
Abstract
Herein, a green, carbon dioxide-in-water high-internal-phase emulsion (C/W HIPEs) was developed and stabilized with polyvinyl alcohol (PVA) for the formation of chitosan oligosaccharide/poly(acrylamide-co-sodium 4-styrene sulfonate) [COS/P(AM-co-SSS)] monolithic porous hydrogel. The obtained monolith was characterized via FT-IR and SEM. The SEM patterns depicted that
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Herein, a green, carbon dioxide-in-water high-internal-phase emulsion (C/W HIPEs) was developed and stabilized with polyvinyl alcohol (PVA) for the formation of chitosan oligosaccharide/poly(acrylamide-co-sodium 4-styrene sulfonate) [COS/P(AM-co-SSS)] monolithic porous hydrogel. The obtained monolith was characterized via FT-IR and SEM. The SEM patterns depicted that the monoliths were interconnected, the void sizes were 78.5 µm, and the interconnected pore throats were 28 μm approximately. Mechanical measurement results indicated that the maximum compress stress of the monolith could reach 334.4 kPa at 90% strain, and it exhibited good mechanical stability. After 200 cycles of compression, it could still recover its original shape without cracking. The obtained COS-based monolith was selected to remove tetracycline (TC) for evaluating the adsorptive features of the interpenetrating pore-containing monolith. The monolithic COS/P(AM-co-SSS) hydrogel behaved with strong antibiotic adsorption capacity (1600.4 mg/g for TC). The adsorption process agreed well with the pseudo-second-order kinetic and Langmuir isothermal models. In addition, the porous monolith had a strong electrostatic force on TC according to the thermodynamic study. This work provides a green route for the development of novel monolithic hydrogels and highlights its potential application in the treatment of antibiotic-containing wastewater.
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(This article belongs to the Special Issue Synthesis and Applications of Hydrogels)
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Effective Removal of Cu2+ Ions from Aqueous Media Using Poly(acrylamide-co-itaconic acid) Hydrogels in a Semi-Continuous Process
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, , and
Gels 2023, 9(9), 702; https://doi.org/10.3390/gels9090702 - 30 Aug 2023
Abstract
Adsorption is one of the most crucial processes in water treatment today. It offers a low-cost solution that does not require specialized equipment or state-of-the-art technology while efficiently removing dissolved contaminants, including heavy metals. This process allows for the utilization of natural or
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Adsorption is one of the most crucial processes in water treatment today. It offers a low-cost solution that does not require specialized equipment or state-of-the-art technology while efficiently removing dissolved contaminants, including heavy metals. This process allows for the utilization of natural or artificial adsorbents or a combination of both. In this context, polymeric materials play a fundamental role, as they enable the development of adsorbent materials using biopolymers and synthetic polymers. The latter can be used multiple times and can absorb large amounts of water per gram of polymer. This paper focuses on utilizing adsorption through hydrogels composed of poly(acrylamide-co-itaconic acid) for removing Cu2+ ions dissolved in aqueous media in a semi-continuous process. The synthesized hydrogels were first immersed in 0.1 M NaOH aqueous solutions, enabling OH− ions to enter the gel matrix and incorporate into the polymer surface. Consequently, the copper ions were recovered as Cu(OH)2 on the surface of the hydrogel rather than within it, allowing the solid precipitates to be easily separated by decantation. Remarkably, the hydrogels demonstrated an impressive 98% removal efficiency of the ions from the solution in unstirred conditions at 30 °C within 48 h. A subsequent study involved a serial process, demonstrating the hydrogels’ reusability for up to eight cycles while maintaining their Cu2+ ion recovery capacity above 80%. Additionally, these hydrogels showcased their capability to remove Cu2+ ions even from media with ion concentrations below 100 ppm.
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(This article belongs to the Special Issue Gels for Removal and Adsorption)
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Carbonization of Corn Leaf Waste for Na-Ion Storage Application Using Water-Soluble Carboxymethyl Cellulose Binder
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and
Gels 2023, 9(9), 701; https://doi.org/10.3390/gels9090701 - 30 Aug 2023
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Hard carbon materials are considered to be the most practical anode materials for sodium ion batteries because of the rich availability of their resources and potentially low cost. Here, the conversion of corn leaf biomass, a largely available agricultural waste, into carbonaceous materials
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Hard carbon materials are considered to be the most practical anode materials for sodium ion batteries because of the rich availability of their resources and potentially low cost. Here, the conversion of corn leaf biomass, a largely available agricultural waste, into carbonaceous materials for Na-ion storage application is reported. Thermal analysis investigation determines the presence of exothermic events occurring during the thermal treatment of the biomass. Accordingly, various temperatures of 400, 500, and 600 °C are selected to perform carbonization treatment trials, leading to the formation of various biocarbons. The materials obtained are characterized by a combination of methods, including X-ray diffraction, electron microscopy, surface evaluation, Raman spectroscopy, and electrochemical characterizations. The Na-ion storage performances of these materials are investigated using water-soluble carboxymethyl cellulose binder, highlighting the influence of the carbonization temperature on the electrochemical performance of biocarbons. Moreover, the influence of post-mechanochemical treatment on the Na-ion storage performance of biocarbons is studied through kinetic evaluations. It is confirmed that reducing the particle sizes and increasing the carbon purity of biocarbons and the formation of gel polymeric networks would improve the Na-ion storage capacity, as well as the pseudocapacitive contribution to the total current. At a high-current density of 500 mA g−1, a specific Na-ion storage capacity of 134 mAh g−1 is recorded on the biocarbon prepared at 600 °C, followed by ball-milling and washing treatment, exhibiting a reduced charge transfer resistance of 49 Ω and an improved Na-ion diffusion coefficient of 4.8 × 10−19 cm2 s−1. This article proposes a simple and effective technique for the preparation of low-cost biocarbons to be used as the anode of Na-ion batteries.
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Electrosprayed Stearic-Acid-Coated Ethylcellulose Microparticles for an Improved Sustained Release of Anticancer Drug
Gels 2023, 9(9), 700; https://doi.org/10.3390/gels9090700 - 29 Aug 2023
Abstract
Sustained release is highly desired for “efficacious, safe and convenient” drug delivery, particularly for those anticancer drug molecules with toxicity. In this study, a modified coaxial electrospraying process was developed to coat a hydrophobic lipid, i.e., stearic acid (SA), on composites composed of
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Sustained release is highly desired for “efficacious, safe and convenient” drug delivery, particularly for those anticancer drug molecules with toxicity. In this study, a modified coaxial electrospraying process was developed to coat a hydrophobic lipid, i.e., stearic acid (SA), on composites composed of the anticancer drug tamoxifen citrate (TC) and insoluble polymeric matrix ethylcellulose (EC). Compared with the electrosprayed TC-EC composite microparticles M1, the electrosprayed SA-coated hybrid microparticles M2 were able to provide an improved TC sustained-release profile. The 30% and 90% loaded drug sustained-release time periods were extended to 3.21 h and 19.43 h for M2, respectively, which were significantly longer than those provided by M1 (0.88 h and 9.98 h, respectively). The morphology, inner structure, physical state, and compatibility of the components of the particles M1 and M2 were disclosed through SEM, TEM, XRD, and FTIR. Based on the analyses, the drug sustained-release mechanism of multiple factors co-acting for microparticles M2 is suggested, which include the reasonable selections and organizations of lipid and polymeric excipient, the blank SA shell drug loading, the regularly round shape, and also the high density. The reported protocols pioneered a brand-new manner for developing sustained drug delivery hybrids through a combination of insoluble cellulose gels and lipid using modified coaxial electrospraying.
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(This article belongs to the Special Issue Hydrogel for Sustained Delivery of Therapeutic Agents)
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Self-Healing Oxalamide Organogelators of Vegetable Oil
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, , , , and
Gels 2023, 9(9), 699; https://doi.org/10.3390/gels9090699 - 29 Aug 2023
Abstract
The aim of this study was to assess the gelling potential of chiral oxalamide derivatives in vegetable oils. Special emphasis was given to the potential applications of the examined oil gels as sustained delivery systems and as fat substitutes in food products. The
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The aim of this study was to assess the gelling potential of chiral oxalamide derivatives in vegetable oils. Special emphasis was given to the potential applications of the examined oil gels as sustained delivery systems and as fat substitutes in food products. The applicability of oil gelators is envisaged in food, cosmetics, and the pharmaceutical industry. The regulations requiring the elimination of saturated fats and rising concerns among consumers health motivated us to investigate small organic molecules capable of efficiently transforming from liquid oil to a gel state. The oxalamide organogelators showed remarkable gelation efficiency in vegetable oils, thermal and mechanical stability, self-healing properties, and a long period of stability. The physical properties of the gels were analysed by TEM microscopy, DSC calorimetry, and oscillatory rheology. The controlled release properties of acetylsalicylic acid, ibuprofen, and hydrocortisone were analysed by the LC–MS method. The influence of the oil type (sunflower, soybean, and olive oil) on gelation efficiency of diverse oxalamide derivatives was examined by oscillatory rheology. The oxalamide gelators showed thermoreversible and thixotropic properties in vegetable oils with a minimum gelation concentration of just 0.025 wt%. The substitution of palm fats with gelled sunflower oil applied in cocoa and milk spreads at gelator concentrations lower than 0.2 wt% have shown promising viscoelastic properties compared to that of the original food products.
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(This article belongs to the Collection Recent Advances and Future Perspectives in Organogels and Organogelators Research)
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Role of Chitosan Hydrogels in Clinical Dentistry
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, , , , , , , , , , and
Gels 2023, 9(9), 698; https://doi.org/10.3390/gels9090698 - 29 Aug 2023
Abstract
Biopolymers are organic polymers that can be treated into intricate designs with porous characteristics that mimic essential biologic components. Due to their superior biosafety, biodegradability, biocompatibility, etc., they have been utilized immensely in biomedical engineering, regeneration, and drug delivery. To obtain the greatest
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Biopolymers are organic polymers that can be treated into intricate designs with porous characteristics that mimic essential biologic components. Due to their superior biosafety, biodegradability, biocompatibility, etc., they have been utilized immensely in biomedical engineering, regeneration, and drug delivery. To obtain the greatest number of results, a literature search was undertaken in scientific search engines utilizing keywords. Chitosan is used in a variety of medical sectors, with the goal of emphasizing its applications and benefits in the clinical dental industry. Chitosan can be dissolved in liquid form and combined with other substances to create a variety of products, including fibers, hydrogels, membranes, microspheres, resins, sponges, pastes, tablets, and micro granules. Chitosan has been studied in a variety of dental applications. Chitosan is used in the prevention of caries and wear, in pulpotomy to accelerate osteogenesis in guided tissue regeneration due to its hemostatic property, and primarily to benefit from its antimicrobial activity by adding it to materials, such as glass ionomer cement, calcium hydroxide, and adhesive systems. With its antibacterial activity and biocompatibility, chitosan is leading the pack as a promising ingredient in the production of dental materials. The current review provides an update on the background, fundamentals, and wide range of uses of chitosan and its gels in dental science.
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(This article belongs to the Special Issue Chitosan-Containing Hydrogels and Their Applications)
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Novel Hydrolytic Degradable Crosslinked Interpenetrating Polymeric Networks (IPNs): An Efficient Hybrid System to Manage the Controlled Release and Degradation of Misoprostol
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, , , , , and
Gels 2023, 9(9), 697; https://doi.org/10.3390/gels9090697 (registering DOI) - 29 Aug 2023
Abstract
Purpose: The goal of this study was to make pH-sensitive HPMC/Neocel C19-based interpenetrating polymeric networks (IPNs) that could be used to treat different diseases. An assembled novel carrier system was demonstrated in this study to achieve multiple functions such as drug protection and
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Purpose: The goal of this study was to make pH-sensitive HPMC/Neocel C19-based interpenetrating polymeric networks (IPNs) that could be used to treat different diseases. An assembled novel carrier system was demonstrated in this study to achieve multiple functions such as drug protection and self-regulated release. Methods: Misoprostol (MPT) was incorporated as a model drug in hydroxyl-propyl-methylcellulose (HPMC)- and Neocel C19-based IPNs for controlled release. HPMC- and Neocel C19-based IPNs were fabricated through an aqueous polymerization method by utilizing the polymers HPMC and Neocel C19, the initiator ammonium peroxodisulfate (APS), the crosslinker methylenebisacrylamide (MBA), and the monomer methacrylic acid (MAA). An IPN based on these materials was created using an aqueous polymerization technique. Samples of IPN were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC), thermal analysis (TGA), and powder X-ray diffraction (PXRD). The effects of the pH levels 1.2 and 7.4 on these polymeric networks were also studied in vitro and through swelling experiments. We also performed in vivo studies on rabbits using commercial tablets and hydrogels. Results: The thermal stability measured using TGA and DSC for the revised formulation was higher than that of the individual components. Crystallinity was low and amorphousness was high in the polymeric networks, as revealed using powder X-ray diffraction (PXRD). The results from the SEM analysis demonstrated that the surface of the polymeric networks is uneven and porous. Better swelling and in vitro results were achieved at a high pH (7.4), which endorses the pH-responsive characteristics of IPN. Drug release was also increased in 7.4 pH (80% in hours). The pharmacokinetic properties of the drugs showed improvement in our work with hydrogel. The tablet MRT was 13.17 h, which was decreased in the hydrogels, and its AUC was increased from 314.41 ng h/mL to 400.50 ng h/mL in hydrogels. The blood compatibility of the IPN hydrogel was measured using different weights (100 mg, 200 mg, 400 mg, and 600 mg; 5.34%, 12.51%, 20.23%, and 29.37%, respectively). Conclusions: As a result, IPN composed of HPMC and Neocel C19 was successfully synthesized, and it is now possible to use it for the controlled release of MPT.
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(This article belongs to the Special Issue Hydrogels: Synthesis, Characterization and Applications)
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Comparative Studies on the Organogel Formation of a Polyester in Three Different Base Oils by X-ray Analysis, Rheology and Infrared Spectroscopy
Gels 2023, 9(9), 696; https://doi.org/10.3390/gels9090696 - 29 Aug 2023
Abstract
High-performance greases typically consist of a base oil and polyurea as a thickener material. To date, few alternatives to polyureas have been investigated. Polyesters could be one such alternative; however, little is known about the gelation of such polyesters because, unlike polyureas, they
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High-performance greases typically consist of a base oil and polyurea as a thickener material. To date, few alternatives to polyureas have been investigated. Polyesters could be one such alternative; however, little is known about the gelation of such polyesters because, unlike polyureas, they cannot form hydrogen bonds between the polymer chains. Here, we present studies on the gel formation of a polyester based thickener poly(hexane dodecanoate) with 1-octanol endgroups in three different base oils, i.e., a mineral oil (Brightstock 150), a synthetic Polyalphaolefin (Spectrasyn 40) and castor oil (85 to 90 wt.% ricinoleic acid triglyceride). Small- and wide-angle X-ray scattering measurements indicate a strong interaction of the polyester with castor oil and an increase in the crystalline fraction, with an increasing polymer amount from 5 to 40 wt.%. Moreover, infrared analysis of the polyester in castor oil showed gel formation at a minimum concentration of 20 wt.%. The strong interaction of the polyester with castor oil compared to the other two base oils led to an increase in the yield point γF as a measure of the mechanical stability of the gel, which was determined to be 5.9% compared to 0.8% and 1.0% in Brightstock and Spectrasyn, respectively.
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(This article belongs to the Special Issue Functional Gel Materials and Applications)
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Tough, Stretchable, and Thermoresponsive Smart Hydrogels
Gels 2023, 9(9), 695; https://doi.org/10.3390/gels9090695 - 28 Aug 2023
Abstract
Self-healing, thermoresponsive hydrogels with a triple network (TN) were obtained by copolymerizing N-isopropyl acryl amide (NiPAAm) with polyvinyl alkohol (PVA) functionalized with methacrylic acid and N,N′-methylene bis(acryl amide) crosslinker in the presence of low amounts (<1 wt.%) of tannic acid (TA). The final
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Self-healing, thermoresponsive hydrogels with a triple network (TN) were obtained by copolymerizing N-isopropyl acryl amide (NiPAAm) with polyvinyl alkohol (PVA) functionalized with methacrylic acid and N,N′-methylene bis(acryl amide) crosslinker in the presence of low amounts (<1 wt.%) of tannic acid (TA). The final gels were obtained by crystalizing the PVA in a freeze-thaw procedure. XRD, DCS, and SEM imaging indicate that the crystallinity is lower and the size of the PVA crystals is smaller at higher TA concentrations. A gel with 0.5 wt.% TA has an elongation at a break of 880% at a tension of 1.39 MPa. It has the best self-healing efficiency of 81% after cutting and losing the chemical network. Step-sweep strain experiments show that the gel has thixotropic properties, which are related to the TA/PVA part of the triple network. The low amount of TA leaves the gel with good thermal responsiveness (equilibrium swelling ratio of 13.3). Swelling-deswelling loop tests show enhanced dimensional robustness of the hydrogel, with a substantial constancy after two cycles.
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(This article belongs to the Special Issue Physical and Mechanical Properties of Polymer Gels)
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Progress of Hydrogel Dressings with Wound Monitoring and Treatment Functions
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, , , , , , , and
Gels 2023, 9(9), 694; https://doi.org/10.3390/gels9090694 - 28 Aug 2023
Abstract
Hydrogels are widely used in wound dressings due to their moisturizing properties and biocompatibility. However, traditional hydrogel dressings cannot monitor wounds and provide accurate treatment. Recent advancements focus on hydrogel dressings with integrated monitoring and treatment functions, using sensors or intelligent materials to
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Hydrogels are widely used in wound dressings due to their moisturizing properties and biocompatibility. However, traditional hydrogel dressings cannot monitor wounds and provide accurate treatment. Recent advancements focus on hydrogel dressings with integrated monitoring and treatment functions, using sensors or intelligent materials to detect changes in the wound microenvironment. These dressings enable responsive treatment to promote wound healing. They can carry out responsive dynamic treatment in time to effectively promote wound healing. However, there is still a lack of comprehensive reviews of hydrogel wound dressings that incorporate both wound micro-environment monitoring and treatment functions. Therefore, this review categorizes hydrogel dressings according to wound types and examines their current status, progress, challenges, and future trends. It discusses various wound types, including infected wounds, burns, and diabetic and pressure ulcers, and explores the wound healing process. The review presents hydrogel dressings that monitor wound conditions and provide tailored treatment, such as pH-sensitive, temperature-sensitive, glucose-sensitive, pressure-sensitive, and nano-composite hydrogel dressings. Challenges include developing dressings that meet the standards of excellent biocompatibility, improving monitoring accuracy and sensitivity, and overcoming obstacles to production and commercialization. Furthermore, it provides the current status, progress, challenges, and future trends in this field, aiming to give a clear view of its past, present, and future.
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(This article belongs to the Special Issue Synthesis and Applications of Hydrogels)
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Thermosensitive Intravitreal In Situ Implant of Cefuroxime Based on Poloxamer 407 and Hyaluronic Acid
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, , , , , , and
Gels 2023, 9(9), 693; https://doi.org/10.3390/gels9090693 - 28 Aug 2023
Abstract
The main method of treatment and prevention of endophthalmitis is a combination of intravitreal and topical administration of antibiotics, such as cefuroxime moxifloxacin or vancomycin. However, this method is ineffective due to the rapid elimination of the drug. This problem can be solved
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The main method of treatment and prevention of endophthalmitis is a combination of intravitreal and topical administration of antibiotics, such as cefuroxime moxifloxacin or vancomycin. However, this method is ineffective due to the rapid elimination of the drug. This problem can be solved with the help of intravitreal in situ injection systems, which are injected with a syringe into the vitreous body and provide prolonged action of the drug at the focus of inflammation. Under the influence of temperature, the liquid drug undergoes a phase transition and turns into a gel after injection. This ensures its prolonged action. The study aimed to develop an intravitreal in situ cefuroxime delivery system for the treatment of endophthalmitis based on a thermosensitive biodegradable composition of poloxamer 407 and hyaluronic acid. A combination of poloxamer Kolliphor® P407, Kolliphor® P188, and PrincipHYAL® hyaluronic acids of different molecular weights was used as a delivery system. The potency of cefuroxime solid dispersion with polyvinylpyrrolidone-10000, polyethylene glycol-400, and polyethylene glycol-1500 in a 1:2 ratio was studied for prolonged action compared to cefuroxime substance. The experimental formulations were studied for the parameters of gelation temperature in a long-term test (4 months), pH, and release of cefuroxime using dialysis bags. To study the distribution parameter in the vitreous body, an in vitro model (1/13) was developed, which was a hollow agar sphere filled with 1% (w/v) polyacrylate gel. For the superior formulations, a HET-CAM test (chorioallantoic membrane test) was performed to determine the absence of irritant effects. According to the study results, a formulation containing a solid dispersion of cefuroxime:PEG-400 (1:2), the matrix of which contained 18% (w/v) Kolliphor® P407 poloxamer, 3% (w/v) Kolliphor® P188 poloxamer, and 0.5% (w/v) hyaluronic acid (1400–1800), was selected. This sample had an average gelation temperature of 34.6 °C, pH 6.7 ± 0.5, and a pronounced prolonged effect. Only 7.6% was released in 3 h of the experiment, whereas about 38% of cefuroxime was released in 72 h. No irritant effect on the chorioallantoic membrane was observed for any formulations studied.
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(This article belongs to the Special Issue Research on Hydrogels for Controlled Drug Delivery)
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Preparation of Amino-Functionalized Poly(N-isopropylacrylamide)-Based Microgel Particles
Gels 2023, 9(9), 692; https://doi.org/10.3390/gels9090692 - 28 Aug 2023
Abstract
Responsive cationic microgels are a promising building block in several diagnostic and therapeutic applications, like transfection and RNA or enzyme packaging. Although the direct synthesis of cationic poly(N-isopropylacrylamide) (PNIPAm) microgel particles has a long history, these procedures typically resulted in low
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Responsive cationic microgels are a promising building block in several diagnostic and therapeutic applications, like transfection and RNA or enzyme packaging. Although the direct synthesis of cationic poly(N-isopropylacrylamide) (PNIPAm) microgel particles has a long history, these procedures typically resulted in low yield, low incorporation of the cationic comonomer, increased polydispersity, and pure size control. In this study, we investigated the possibility of the post-polymerization modification of P(NIPAm-co-acrylic acid) microgels to prepare primary amine functionalized microgels. To achieve this goal, we used 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) mediated coupling of a diamine to the carboxyl groups. We found that by controlling the EDC excess in the reaction mixture, the amine functionalization of the carboxyl functionalized microgel could be varied and as much as 6–7 mol% amine content could be incorporated into the microgels. Importantly, the reaction was conducted at room temperature in an aqueous medium and it was found to be time efficient, making it a practical and convenient approach for synthesizing primary amine functionalized PNIPAm microgel particles.
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(This article belongs to the Special Issue Recent Advances in Microgels)
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Anomalous Magnetorheological Response for Carrageenan Magnetic Hydrogels Prepared by Natural Cooling
Gels 2023, 9(9), 691; https://doi.org/10.3390/gels9090691 - 28 Aug 2023
Abstract
The effect of the cooling rate on magnetorheological response was investigated for magnetic hydrogels consisting of carrageenan and carbonyl iron particles with a concentration of 50 wt.%. For magnetic gels prepared via natural cooling, the storage moduli at 0 and 50 mT were
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The effect of the cooling rate on magnetorheological response was investigated for magnetic hydrogels consisting of carrageenan and carbonyl iron particles with a concentration of 50 wt.%. For magnetic gels prepared via natural cooling, the storage moduli at 0 and 50 mT were 3.7 × 104 Pa and 5.6 × 104 Pa, respectively, and the change in the modulus was 1.9 × 104 Pa. For magnetic gels prepared via rapid cooling, the storage moduli at 0 and 50 mT were 1.2 × 104 Pa and 1.8 × 104 Pa, respectively, and the change in the modulus was 6.2 × 103 Pa, which was 1/3 of that for the magnetic gel prepared by natural cooling. The critical strains, where G′ is equal to G″ on the strain dependence of the storage modulus, for magnetic gels prepared by natural cooling and rapid cooling, were 0.023 and 0.034, respectively, indicating that the magnetic gel prepared by rapid cooling has a hard structure compared to that prepared by natural cooling. Opposite to this, the change in the storage modulus at 500 mT for the magnetic gel prepared by rapid cooling was 1.6 × 105 Pa, which was 2.5 times higher than that prepared by natural cooling. SEM images revealed that many small aggregations of the carrageenan network were found in the magnetic gel prepared by natural cooling, and continuous phases of carrageenan network with large sizes were found in the magnetic gel prepared by rapid cooling. It was revealed that magnetic particles in the magnetic gel prepared by rapid cooling can move and form a chain structure at high magnetic fields by breaking the restriction from the continuous phases of carrageenan.
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(This article belongs to the Special Issue Advances in Polymer Rheology)
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Actinide Ion (Americium-241 and Uranium-232) Interaction with Hybrid Silica–Hyperbranched Poly(ethylene imine) Nanoparticles and Xerogels
Gels 2023, 9(9), 690; https://doi.org/10.3390/gels9090690 - 27 Aug 2023
Abstract
The binding of actinide ions (Am(III) and U(VI)) in aqueous solutions by hybrid silica–hyperbranched poly(ethylene imine) nanoparticles (NPs) and xerogels (XGs) has been studied by means of batch experiments at different pH values (4, 7, and 9) under ambient atmospheric conditions. Both materials
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The binding of actinide ions (Am(III) and U(VI)) in aqueous solutions by hybrid silica–hyperbranched poly(ethylene imine) nanoparticles (NPs) and xerogels (XGs) has been studied by means of batch experiments at different pH values (4, 7, and 9) under ambient atmospheric conditions. Both materials present relatively high removal efficiency at pH 4 and pH 7 (>70%) for Am(III) and U(VI). The lower removal efficiency for the nanoparticles is basically associated with the compact structure of the nanoparticles and the lower permeability and access to active amine groups compared to xerogels, and the negative charge of the radionuclide species is formed under alkaline conditions (e.g., UO2(CO3)34− and Am(CO3)2−). Generally, the adsorption process is relatively slow due to the very low radionuclide concentrations used in the study and is basically governed by the actinide diffusion from the aqueous phase to the solid surface. On the other hand, adsorption is favored with increasing temperature, assuming that the reaction is endothermic and entropy-driven, which is associated with increasing randomness at the solid–liquid interphase upon actinide adsorption. To the best of our knowledge, this is the first study on hybrid silica–hyperbranched poly(ethylene imine) nanoparticle and xerogel materials used as adsorbents for americium and uranium at ultra-trace levels. Compared to other adsorbent materials used for binding americium and uranium ions, both materials show far higher binding efficiency. Xerogels could remove both actinides even from seawater by almost 90%, whereas nanoparticles could remove uranium by 80% and americium by 70%. The above, along with their simple derivatization to increase the selectivity towards a specific radionuclide and their easy processing to be included in separation technologies, could make these materials attractive candidates for the treatment of radionuclide/actinide-contaminated water.
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(This article belongs to the Special Issue Advances in Xerogels: From Design to Applications (2nd Edition))
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Temperature-Controlled 3D Cryoprinting Inks Made of Mixtures of Alginate and Agar
by
and
Gels 2023, 9(9), 689; https://doi.org/10.3390/gels9090689 - 26 Aug 2023
Abstract
Temperature-controlled 3D cryoprinting (TCC) is an emerging tissue engineering technology aimed at overcoming limitations of conventional 3D printing for large organs: (a) size constraints due to low print rigidity and (b) the preservation of living cells during printing and subsequent tissue storage. TCC
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Temperature-controlled 3D cryoprinting (TCC) is an emerging tissue engineering technology aimed at overcoming limitations of conventional 3D printing for large organs: (a) size constraints due to low print rigidity and (b) the preservation of living cells during printing and subsequent tissue storage. TCC addresses these challenges by freezing each printed voxel with controlled cooling rates during deposition. This generates a rigid structure upon printing and ensures cell cryopreservation as an integral part of the process. Previous studies used alginate-based ink, which has limitations: (a) low diffusivity of the CaCl2 crosslinker during TCC’s crosslinking process and (b) typical loss of print fidelity with alginate ink. This study explores the use of an ink made of agar and alginate to overcome TCC protocol limitations. When an agar/alginate voxel is deposited, agar first gels at above-freezing temperatures, capturing the desired structure without compromising fidelity, while alginate remains uncrosslinked. During subsequent freezing, both frozen agar and alginate maintain the structure. However, agar gel loses its gel form and water-retaining ability. In TCC, alginate crosslinking occurs by immersing the frozen structure in a warm crosslinking bath. This enables CaCl2 diffusion into the crosslinked alginate congruent with the melting process. Melted agar domains, with reduced water-binding ability, enhance crosslinker diffusivity, reducing TCC procedure duration. Additionally, agar overcomes the typical fidelity loss associated with alginate ink printing.
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(This article belongs to the Special Issue Hydrogel and Cryogel Scaffolds)
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Development and Characterization of Gel-Based Buccoadhesive Bilayer Formulation of Nifedipine
by
, , , , , and
Gels 2023, 9(9), 688; https://doi.org/10.3390/gels9090688 - 26 Aug 2023
Abstract
A promising controlled drug delivery system has been developed based on polymeric buccoadhesive bilayered formulation that uses a drug-free backing layer and a polymeric hydrophilic gel buccoadhesive core layer containing nifedipine. The DSC thermogravimetric analysis confirms the drug’s entrapment in the gel layer
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A promising controlled drug delivery system has been developed based on polymeric buccoadhesive bilayered formulation that uses a drug-free backing layer and a polymeric hydrophilic gel buccoadhesive core layer containing nifedipine. The DSC thermogravimetric analysis confirms the drug’s entrapment in the gel layer and reveals no evidence of a potential interaction. Various ratios of bioadhesive polymers, including HPMC K100, PVP K30, SCMC, and CP 934, were combined with EC as an impermeable backing layer to ensure unidirectional drug release towards the buccal mucosa. The polymeric compositions of hydrophilic gel-natured HPMC, SCMC, and CP formed a matrix layer by surrounding the core nifedipine during compression. Preformulation studies were performed for all of the ingredients in order to evaluate their physical and flow characteristics. Ex vivo buccoadhesive strength, surface pH, swelling index, in vitro and in vivo drug release, and ex vivo permeation investigations were performed to evaluate the produced gel-based system. Rapid temperature variations had no appreciable impact on the substance’s physical properties, pharmacological content, or buccoadhesive strength during stability testing using actual human saliva. It was clear from a histological examination of the ex vivo mucosa that the developed system did not cause any irritation or inflammation at the site of administration. The formulation NT5 was the best one, with a correlation coefficient of 0.9966. The in vitro and in vivo drug release profiles were well correlated, and they mimic the in vitro drug release pattern via the biological membrane. Thus, the developed gel-based formulation was found to be novel, stable, and useful for the targeted delivery of nifedipine.
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(This article belongs to the Special Issue Functional Gel Materials and Applications)
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