Gels | December 2025 - Browse Articles

14 pages, 6502 KB

Open AccessArticle

Study on the Structure, Thermal Properties and Antibacterial Properties of Phosphorus-Modified PVA/TiO₂ Composite Films

by Alina-Mirela Ipate, Diana Serbezeanu, Ioana-Antonia Iftimie, Gabriela Lisa, Cristina-Mihaela Rîmbu and Tăchiță Vlad-Bubulac

Gels 2025, 11(12), 1020; https://doi.org/10.3390/gels11121020 - 18 Dec 2025

Cited by 1 | Viewed by 598

Abstract

Phosphorus-modified poly(vinyl alcohol) (PVA) has recently gained increasing attention as a functional polymeric matrix suitable for gel-based systems, owing to its biocompatibility, film-forming ability, and capacity to develop semi-interpenetrating networks. In this work, PVA was chemically modified through the nucleophilic substitution of its [...] Read more.

Phosphorus-modified poly(vinyl alcohol) (PVA) has recently gained increasing attention as a functional polymeric matrix suitable for gel-based systems, owing to its biocompatibility, film-forming ability, and capacity to develop semi-interpenetrating networks. In this work, PVA was chemically modified through the nucleophilic substitution of its hydroxyl groups with the chloride groups of phenyl dichlorophosphate, following a literature-reported method carried out in N,N-dimethylformamide (DMF) as reaction medium, resulting in phosphorus-containing PVA networks (PVA-OP3). Hybrid gel-like films were then prepared by incorporating titanium dioxide nanoparticles (TiO₂ NPs), known for their antimicrobial activity, low toxicity, and high stability. The resulting composites were structurally, morphologically, and thermally characterized using FTIR, SEM, and thermogravimetric analysis. The incorporation of TiO₂ NPs significantly improved the thermal stability, with T₅% increasing from 240 °C for neat PVA-OP3 to 288 °C for the optimal composite, increased the char residue from 4.5% for the neat polymer to 30.1% for PVA-OP3/TiO₂-4, and enhanced antimicrobial activity against both Gram-positive and Gram-negative bacteria. These findings demonstrate that PVA-OP3/TiO₂ hybrid films possess promising potential as advanced biomaterials for biomedical, protective, and environmental applications. Full article

(This article belongs to the Special Issue Advances in Gel Films (2nd Edition))

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23 pages, 10481 KB

Open AccessArticle

Synergistic Effect of Aminated Sodium Alginate Composite Material on Selective Adsorption of Sb: Experimental and Density Functional Theory Study

by Lan Yang, Pingshu Wang, Xin Sun, Kai Li, Meijie Ren, Fansong Liu, Fawei Tang, Ping Ning and Yimin Huang

Gels 2025, 11(12), 1019; https://doi.org/10.3390/gels11121019 - 18 Dec 2025

Viewed by 523

Abstract

Pollution by Sb, which is widely used in industry and agriculture, poses serious threats to ecosystems. This study demonstrates, for the first time, that sodium alginate (ALG) modified by polyethyleneimine (PEI) has good adsorption capacity for Sb(III) (the theoretical maximum adsorption capacity was [...] Read more.

Pollution by Sb, which is widely used in industry and agriculture, poses serious threats to ecosystems. This study demonstrates, for the first time, that sodium alginate (ALG) modified by polyethyleneimine (PEI) has good adsorption capacity for Sb(III) (the theoretical maximum adsorption capacity was 978 mg/g, and the actual maximum adsorption capacity was 743 mg/g) and can retain 90–98% of the initial removal rate after eight cycles of reuse. The inorganic ions and humic acid in Sb(III)-containing wastewater do not affect the adsorption capacity of PEI/ALG within a certain pH range. However, it was also found that the adsorption was interfered with by Sb(III) precipitation, phosphate ions, and some coexisting cations/metalloids such as Ni, Cd, Pb, and As under higher pH conditions, and the recovery rate of antimony in the desorption process needs to be further improved. Density functional theory calculations reveal that the -OH, -COOH, -NH₂, -NH-, and -N= in PEI/ALG show strong binding with Sb (−56.85, −28.39, −17.98, −25.76, and −17.98 kcal/mol, respectively), enabling these functional groups to easily form stable composite structures with Sb(III). This characteristic enables PEI/ALG to selectively adsorb Sb(III) under certain conditions. Combining these findings with the characterization analysis results indicates that the mechanism of PEI/ALG adsorption of Sb(III) is mainly the formation of H bonds and coordination between -OH, -COOH, and Sb(III). The selective adsorption mechanism of PEI/ALG for Sb(III) has not been investigated previously, and our research results indicate the high potential of this approach. Full article

(This article belongs to the Section Gel Applications)

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15 pages, 2987 KB

Open AccessArticle

A Novel Phenolic Resin Aerogel Modified by SiO₂-ZrO₂ for Efficient Thermal Protection and Insulation

by Yifan Zhan, Chunhui Zhang, Liangjun Li, Mengle Huang, Sian Chen, Yonggang Jiang, Junzong Feng, Yijie Hu and Jian Feng

Gels 2025, 11(12), 1018; https://doi.org/10.3390/gels11121018 - 18 Dec 2025

Cited by 1 | Viewed by 848

Abstract

Phenolic aerogel holds great promise for applications in thermal protection against ablation, and constructing inorganic–organic hybrid networks is an effective strategy to enhance its oxidation and ablation resistance. This study introduces a stepwise hybridization strategy for the preparation of SiO₂–ZrO₂ [...] Read more.

Phenolic aerogel holds great promise for applications in thermal protection against ablation, and constructing inorganic–organic hybrid networks is an effective strategy to enhance its oxidation and ablation resistance. This study introduces a stepwise hybridization strategy for the preparation of SiO₂–ZrO₂–phenolic resin aerogels (SZPA). First, nano-silica sol and nanometer-scale zirconia were physically blended to form a uniformly dispersed mixture. Subsequently, the modified silica was incorporated into a phenolic resin solution to construct a three-dimensional hybrid silica–phenolic network framework. Nano-sized zirconia was then uniformly dispersed within the matrix as a physical reinforcing phase through high-shear dispersion. Finally, the SZPA with a hierarchical nanoporous structure was obtained via ambient-pressure drying. Owing to its unique hybrid network structure, the aerogel exhibits markedly improved properties: the thermal conductivity is as low as 0.0419–0.0431 W/(m·K) (a reduction of approximately 24%), and the specific surface area is as high as 190–232 m²/g (an increase of approximately 83%). Meanwhile, the inorganic network considerably enhances the residual mass at elevated temperatures, as well as the oxidation resistance and thermal stability of the matrix. Among the tested materials, the SZPA-4 exhibited outstanding thermal insulation capability at high temperatures; its back surface temperature reached only 74.4 °C after 600 s of exposure to a 1200 °C butane flame. This study provides a feasible route for the preparation of high-performance phenolic-based composite aerogels for aerospace thermal protection systems, thereby expanding their potential applications in extreme thermal environments. Full article

(This article belongs to the Section Gel Processing and Engineering)

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15 pages, 2382 KB

Open AccessArticle

From Vegetable Waste to By-Product: Rheological Analysis of a Potential High-Protein Vegetable Burger

by Olga Mileti, Francesco Filice, Francesca R. Lupi, Domenico Gabriele and Noemi Baldino

Gels 2025, 11(12), 1017; https://doi.org/10.3390/gels11121017 - 18 Dec 2025

Viewed by 479

Abstract

(1) Foods with attractive shapes have been receiving increasing interest from researchers, particularly for foods for children. The ability to particularize foods by imparting attractive aspects to nutritious and less attractive food ingredients, such as vegetables or proteins, is an interesting challenge for [...] Read more.

(1) Foods with attractive shapes have been receiving increasing interest from researchers, particularly for foods for children. The ability to particularize foods by imparting attractive aspects to nutritious and less attractive food ingredients, such as vegetables or proteins, is an interesting challenge for the food industry. In this context, the rheological characteristics of food doughs are fundamental for obtaining form-forming foods that are able to maintain a shape of their own. (2) Broccoli, pumpkin, carrot and zucchini wastes (stems, leaves, and off-gauge veggies), which are still rich in nutrients, from the food industry were used in this work to enrich burgers with vegetable proteins. The doughs were characterized by rheological analysis using a frequency sweep test and a temperature ramp test. They were also shaped with attractive molds and baked. (3) From the frequency sweep test, the formulation with brown rice proteins resulted in better consistency; all samples showed a solid-like behavior. (4) Workable doughs were formulated using vegetal wastes from the food industry. Among the proteins used, those from brown rice were found to be the most suitable for the preparation of a vegetable burger. Full article

(This article belongs to the Special Issue Recent Advances on the Use of Different Gels Type in the Food Industry (2nd Edition))

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3 pages, 3188 KB

Open AccessCorrection

Correction: Kovacevic et al. The Effect of Deoxycholic Acid on Chitosan-Enabled Matrices for Tissue Scaffolding and Injectable Nanogels. Gels 2022, 8, 358

by Bozica Kovacevic, Corina Mihaela Ionescu, Melissa Jones, Susbin Raj Wagle, Michael Lewkowicz, Maja Đanić, Momir Mikov, Armin Mooranian and Hani Al-Salami

Gels 2025, 11(12), 1016; https://doi.org/10.3390/gels11121016 - 18 Dec 2025

Viewed by 333

Abstract

In Figure 1b [...] Full article

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21 pages, 4109 KB

Open AccessArticle

Engineering Inhalable Carboxymethyl Chitosan-Swellable Microgels for Pulmonary Delivery of Charged Hydrophilic Molecules

by David Encinas-Basurto, Kiley McCombs, Ernest L. Vallorz, Maria F. Acosta, Rick G. Schnellmann and Heidi M. Mansour

Gels 2025, 11(12), 1015; https://doi.org/10.3390/gels11121015 - 17 Dec 2025

Cited by 1 | Viewed by 758

Abstract

Swellable microparticles are a promising strategy for pulmonary drug delivery. They provide good aerosol performance in the dry state and enlarge after deposition in the lungs. In this study, we aimed to develop and characterize spray-dried microparticles composed of carboxymethyl chitosan (CMC), L-leucine, [...] Read more.

Swellable microparticles are a promising strategy for pulmonary drug delivery. They provide good aerosol performance in the dry state and enlarge after deposition in the lungs. In this study, we aimed to develop and characterize spray-dried microparticles composed of carboxymethyl chitosan (CMC), L-leucine, and suramin, a hydrophilic polyanionic drug. Microparticles were obtained by co-spray drying (Co-SD) formulations with increasing leucine content (0–10% w/w) and evaluated for morphology, thermal behavior, crystallinity, swelling, aerodynamic deposition using a Next Generation Impactor (NGI), and cytocompatibility in pulmonary epithelial cells. The 10% leucine formulation produced the highest fine particle fraction (35.2 ± 1.1%) and the lowest mass median aerodynamic diameter (1.0 ± 0.4 µm). These values indicate efficient in vitro deep lung deposition. XRPD and DSC showed that the Co-SD formulations were predominantly amorphous. Hydration studies revealed rapid water uptake and a clear increase in particle size, leading to the formation of swollen microgels. Cell viability assays demonstrated >85% viability up to 100 µM suramin, suggesting that CMC–leucine microgels enable efficient pulmonary delivery of hydrophilic drugs by combining respirable dry-state properties with in situ swelling and reducing immunological clearance. Future in vivo studies will be needed to assess long-term stability, macrophage interaction, and the translational potential of this delivery system. Full article

(This article belongs to the Special Issue Gels: 10th Anniversary)

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17 pages, 883 KB

Open AccessArticle

Effect of a Home Bleaching Gel Containing Chitosan and Theobromine on Tooth Surface Roughness, Microhardness, and Colour Change

by Safıya Temizyurek and Derya Gursel Surmelioglu

Gels 2025, 11(12), 1014; https://doi.org/10.3390/gels11121014 - 17 Dec 2025

Cited by 1 | Viewed by 557

Abstract

This study aimed to evaluate the effect of experimental bleaching gels containing chitosan and theobromine and compare their performance in terms of tooth surface roughness, microhardness, and colour change with the bleaching gels BioWhiten ProHome and FGM Whiteness Perfect. One hundred and forty-four [...] Read more.

This study aimed to evaluate the effect of experimental bleaching gels containing chitosan and theobromine and compare their performance in terms of tooth surface roughness, microhardness, and colour change with the bleaching gels BioWhiten ProHome and FGM Whiteness Perfect. One hundred and forty-four upper central incisors were used for microhardness, surface roughness, and colour change analyses (n = 12). Prior to bleaching, surface roughness was measured using a profilometer, microhardness was analysed using a Vickers hardness test, and colour was measured using a spectrophotometer. For Group 1, the treatment consisted of an experimental gel containing chitosan–theobromine (16% CP); for Group 2, it was an experimental gel containing chitosan–theobromine (6% HP); for Group 3, it consisted of BioWhiten ProHome (6% HP); and for Group 4, it consisted of FGM Whiteness Perfect (16% CP). Microhardness and surface roughness tests were performed under the same conditions before bleaching, after bleaching, and 14 days after the initial treatment. Colour analysis was performed before the bleaching, during the application, 24 h after bleaching, and at 7 and 14 days after treatment. p < 0.05 was considered significant. No statistically significant increase in microhardness values after bleaching was detected in any group (p > 0.05), effective bleaching was detected in all groups, and the highest efficacy was observed in Group 4 (p < 0.05). The experimental gels containing theobromine and chitosan resulted in effective bleaching and did not exert any negative effects regarding surface roughness or microhardness. Full article

(This article belongs to the Special Issue Functional Gels for Dental Applications)

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25 pages, 1029 KB

Open AccessReview

Eutectogels: Recent Advances, Design Strategies, and Emerging Applications in Biotechnology

by Liane Meneses and Ana Rita Jesus

Gels 2025, 11(12), 1013; https://doi.org/10.3390/gels11121013 - 17 Dec 2025

Cited by 2 | Viewed by 1813

Abstract

Eutectogels, obtained from the combination of deep eutectic systems (DESs) or natural deep eutectic systems (NADESs) with polymers, represent a new class of sustainable soft materials. Combining the tunable properties of DESs, such as low volatility, ionic conductivity, and biocompatibility, with the structural [...] Read more.

Eutectogels, obtained from the combination of deep eutectic systems (DESs) or natural deep eutectic systems (NADESs) with polymers, represent a new class of sustainable soft materials. Combining the tunable properties of DESs, such as low volatility, ionic conductivity, and biocompatibility, with the structural integrity of gels, these materials can be designed to have improved mechanical flexibility, self-healing ability, and environmental stability. Recent research focused on understanding how the composition of DESs, polymer type, or crosslinking mechanisms influence the physicochemical behavior and performance of eutectogels. Advances in this field enabled their use in diverse biotechnological applications, particularly in drug delivery, transdermal systems, wound healing, and tissue engineering, where they demonstrate improved biofunctionality and adaptability compared to traditional hydrogels. Nevertheless, challenges related to scalability, reproducibility, long-term stability, and toxicity must be addressed to reach their full potential. Progress in this area relies on multidisciplinary efforts between green chemistry, materials science, and bioengineering. Overcoming these hurdles could allow eutectogels to evolve from academic concepts into a new generation of sustainable, high-performance soft materials with broad applicability in the biotechnology field. Full article

(This article belongs to the Special Issue Current Research on Eutectogels)

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21 pages, 20035 KB

Open AccessArticle

Camellia Saponin-Enhanced Sodium Alginate Hydrogels for Sustainable Fruit Preservation

by Lisong Hu, Hongdan Rao, Borong Zhu, Menghao Du, Keqin Xu and Haili Gao

Gels 2025, 11(12), 1012; https://doi.org/10.3390/gels11121012 - 16 Dec 2025

Cited by 3 | Viewed by 833

Abstract

It is well known that food waste, especially perishable fruits, is one of the pressing issues worldwide, and as much as 50% of harvested fruits are wasted in developing countries as a result of poor preservation methods. Other traditional options such as plastic [...] Read more.

It is well known that food waste, especially perishable fruits, is one of the pressing issues worldwide, and as much as 50% of harvested fruits are wasted in developing countries as a result of poor preservation methods. Other traditional options such as plastic films or chemical preservatives are harmful to the environment and to our health. In this work, the limitations are overcome through the fabrication of an innovative camellia saponin/sodium alginate (CS/SA) composite hydrogel film that not only recycles agricultural waste but also improves fruit protection. CS/SA films were prepared by ionic crosslinking with CaCl₂ with different CS content (0–10% w/v, corresponding to 0–3.1 wt% in air-dried films). Detailed SEM, FTIR, XRD and rheological studies indicated that CS addition led to a gradual microstructural densification, stronger intermolecular interactions (involving hydrogen bonding and electrostatic complexation) and superior viscoelasticity, with the best performance at 8% CS (2.5 wt% in dried film). Mechanical tests confirmed that the stable CS/SA film showed higher tensile strength (152 kPa) and compressive strength (353 kPa) than pure SA (10 kPa) with a relatively low Young’s modulus (0.82 MPa) and high elongation at break (116.33%), which could be easily peeled off from fruit surfaces—an essential benefit of this over stiff chitosan/alginate composites. Structure: The composite film exhibited lower porosity (103.2%), reduced moisture content (94.7%), a controlled swelling ratio (800%) and improved barrier property with a water vapor permeability of 1.3

\times 10^{- 6}

g·m⁻¹·s⁻¹·kPa⁻¹ and an oxygen permeability of 1.9 × cm³

\cdot μ

m·m⁻²·d⁻¹·kPa⁻¹. The 8% CS film showed very strong antioxidant activity (86% DPPH scavenging). Results of application tests on bananas and strawberries indicated that the ripening process was delayed by the CS/SA coatings, the decay rate was decreased from 99.9% (uncoated control) to 55.6% after 9 days, the weight loss was reduced to 29.3%, and the fruit’s firmness and titratable acidity were maintained. This degradable, multifunctional hydrogel film has the potential to be a sustainable measure to simultaneously mitigate food waste, valorize agricultural byproducts, and protect the environment, which could offer substantial benefit for enhancing global food security as well as fruit shelf life. Full article

(This article belongs to the Special Issue Gel-Related Materials: Challenges and Opportunities (2nd Edition))

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20 pages, 2610 KB

Open AccessArticle

The Influence of Synthesis Parameters on the Properties of Dextran-Based Hydrogels for Colon-Targeted Antitumor Drug Delivery Part I: Room Temperature Synthesis of Dextran/Inulin Hydrogels for Colon-Targeted Antitumor Drug Delivery

by Tamara Erceg, Miloš Radosavljević, Milorad Miljić, Aleksandra Cvetanović Kljakić, Sebastian Baloš, Katarina Mišković Špoljarić, Ivan Ćorić, Ljubica Glavaš-Obrovac and Aleksandra Torbica

Gels 2025, 11(12), 1011; https://doi.org/10.3390/gels11121011 - 16 Dec 2025

Cited by 2 | Viewed by 897

Abstract

This research successfully developed novel hydrogels composed of methacrylated dextran and inulin for targeted drug delivery in colorectal cancer therapy. The formulation exploits the natural degradation of both biopolymers by the large intestine’s microflora. A key achievement was the development of a room-temperature [...] Read more.

This research successfully developed novel hydrogels composed of methacrylated dextran and inulin for targeted drug delivery in colorectal cancer therapy. The formulation exploits the natural degradation of both biopolymers by the large intestine’s microflora. A key achievement was the development of a room-temperature free radical polymerization synthesis method. The study thoroughly investigated how varying inulin content (10 and 20 wt%) influenced the hydrogels’ properties. The formulation with 20 wt% inulin exhibited the highest swelling ability at both pH 3 and pH 6, and consequently the lowest elastic modulus, measured by a newly established technique for granulated hydrogels. Using uracil as a model drug, in situ incorporated, confirmed that the greatest drug release occurs in the colorectal region for the neat dextran-based hydrogel, triggered by specific microbial enzymes. Notably, the addition of inulin did not enhance biodegradation-driven drug release in combination with dextran; instead, inulin primarily acted as a protective component against premature hydrolysis in the gastric medium. These findings strongly confirm that the targeted action is predominantly governed by the dextran component. The synthesized hydrogels, particularly the dextran-only formulation, therefore show strong potential as effective carriers for colon-targeted drug delivery. The primary objective of this study was to evaluate the feasibility of modified and unmodified dextran and inulin as biodegradable carriers for enzyme-triggered, colon-targeted drug delivery. Full article

(This article belongs to the Special Issue Biopolymer Hydrogels: Synthesis, Properties and Applications)

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22 pages, 6048 KB

Open AccessArticle

Impact of CeO₂-Doped Bioactive Glass on the Properties of CMC/PEG Hydrogels Intended for Wound Treatment

by Sofia Pacheco, Inês Alexandra Marques, Ana Salomé Pires, Maria Filomena Botelho, Sílvia Soreto Teixeira, Manuel Graça and Sílvia Gavinho

Gels 2025, 11(12), 1010; https://doi.org/10.3390/gels11121010 - 16 Dec 2025

Viewed by 878

Abstract

Diabetes mellitus is a serious public health problem, mainly due to the difficulty in healing chronic wounds, which present an inflammatory response for long periods of time and are more vulnerable to infections. Hydrogels are a promising therapeutic solution due to their biocompatibility, [...] Read more.

Diabetes mellitus is a serious public health problem, mainly due to the difficulty in healing chronic wounds, which present an inflammatory response for long periods of time and are more vulnerable to infections. Hydrogels are a promising therapeutic solution due to their biocompatibility, biodegradability, and ability to allow controlled release of therapeutic agents. The addition of bioactive glasses doped with therapeutic ions to hydrogels can also provide specific biological responses to the system and thus improve tissue regeneration. In this study, a hydrogel based on carboxymethylcellulose and polyethylene glycol with different degrees of crosslinking and enriched with 10% by weight of CeO₂-doped Bioglass 45S5 was developed. Structural, morphological, mechanical, and biological characterizations were performed on bioactive glass, hydrogels, and hydrogels enriched with bioactive glass. Structural analyses confirmed the preservation of the typical amorphous structure of Bioglass 45S5, even after the incorporation of 5% molar CeO₂, as well as the effectiveness of the polymer matrix crosslinking process. Structural analyses demonstrated the preservation of the typical amorphous structure of Bioglass 45S5, even after the incorporation of 5 mol% CeO₂, as well as the effectiveness of the polymer matrix cross-linking process. The hydrogels exhibited distinct behaviours in terms of water absorption and degradation, showing that the sample with the lowest concentration of crosslinkers and bioactive glass allowed for a higher expansion rate and a higher degradation rate. The hydrogel with 10 wt% BG did not compromise cell viability and showed structural integrity after being subjected to cyclic flexible deformations, indicating its safety and suitability for use in tissue engineering. Full article

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19 pages, 5484 KB

Open AccessArticle

Smart pH/Near-Infrared Light-Responsive Carboxymethyl Chitosan/Sodium Alginate/MXene Hydrogel Beads for Targeted Tea Polyphenols Delivery

by Kun Fang, Pei Li, Hanbing Wang, Xiangrui Huang, Yihan Li and Bo Luo

Gels 2025, 11(12), 1009; https://doi.org/10.3390/gels11121009 - 16 Dec 2025

Cited by 2 | Viewed by 983

Abstract

Tea polyphenols (TP) offer health benefits, but their stability is compromised by sensitivity to environmental factors, limiting their applications. Developing stimulus-responsive delivery systems that precisely control TP release is essential. This study prepared novel hydrogel beads encompassing carboxymethyl chitosan (CMC), sodium alginate (SA), [...] Read more.

Tea polyphenols (TP) offer health benefits, but their stability is compromised by sensitivity to environmental factors, limiting their applications. Developing stimulus-responsive delivery systems that precisely control TP release is essential. This study prepared novel hydrogel beads encompassing carboxymethyl chitosan (CMC), sodium alginate (SA), and MXene (Ti₃C₂T_x) using a blending method for the sustained release of TP. After being exposed to 808 nm near-infrared (NIR) radiation, the beads demonstrated excellent stability in simulated gastric conditions, resulting from the pH-dependent solubilization, facilitating controlled TP release under simulated intestinal conditions. The drug release kinetics conformed to the Ritger–Peppas model. Notably, CMC-SA-MXene@TP exhibited strong antioxidant activity and antimicrobial properties, effectively inhibiting the growth of S. aureus (ATCC 6538) and E. coli (ATCC 25922). Additionally, according to in vitro cellular assays, they exhibited good biocompatibility with normal liver cells (HL-7702) and could effectively inhibit hepatocellular carcinoma cells (HepG2). These hydrogel beads, featuring excellent pH and NIR responsiveness, biocompatibility, drug loading efficiency, antioxidant capability, and antibacterial activity, represent promising candidates for advanced wound dressings or oral drug delivery systems for modulating intestinal flora. Full article

(This article belongs to the Special Issue Recent Research on Alginate Hydrogels in Bioengineering Applications)

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17 pages, 3770 KB

Open AccessArticle

Structural Features and Mechanical Properties of Hydrogels Based on PVP Copolymers, Obtained in the Presence of a Solvent

by Oleksandr Grytsenko, Petro Pukach, Myroslava Vovk and Nataliia Baran

Gels 2025, 11(12), 1008; https://doi.org/10.3390/gels11121008 - 13 Dec 2025

Viewed by 722

Abstract

The paper analyses the effect of the solvent amount and nature on the structure and mechanical properties of hydrogels based on copolymers of 2-hydroxyethylmethacrylate (HEMA) with polyvinylpyrrolidone (PVP). The synthesis of pHEMA-gr-PVP copolymers was carried out by the copolymerization method in the presence [...] Read more.

The paper analyses the effect of the solvent amount and nature on the structure and mechanical properties of hydrogels based on copolymers of 2-hydroxyethylmethacrylate (HEMA) with polyvinylpyrrolidone (PVP). The synthesis of pHEMA-gr-PVP copolymers was carried out by the copolymerization method in the presence of metal ions of variable oxidation states in solvents with various nature: water, dimethyl sulfoxide (DMSO), diethylene glycol (DEG), and cyclohexanol (HOCy). The structure of the copolymers was evaluated by the PVP grafting efficiency, its actual content in the copolymer, and the molecular weight between crosslinks (M_C). Taking the example of water, an increase in the solvent content up to 50 mass parts causes an increase in the efficiency of PVP grafting, which occurs due to enhanced macromolecule mobility through the dilution of the starting composition, hence the decrease in its viscosity. It was established that the nature of the solvent significantly affects the crosslinking density of the polymer network in the series H₂O, DEG, DMSO, HOCy, an increase in the M_C is observed causing a decrease in the hardness and elasticity of hydrogels and an increase in their water-retention capacity and swelling coefficient. The obtained results prove the possibility of targeted regulation within wide limits of the structure and properties of hydrogels based on pHEMA-gr-PVP copolymers through control of polymerization conditions (selection of the type and concentration of solvent). Full article

(This article belongs to the Special Issue Physicochemical Properties and Applications of Gel Materials)

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12 pages, 5211 KB

Open AccessArticle

H₂O₂-Assisted Fabrication of Stiff and Tough Hydrogel Using Natural Cysteine-Rich Protein

by Mengting Fan, Beizhe Huang, Yuhan Li, Ting Zhang, Ranjith Kumar Kankala and Jianting Zhang

Gels 2025, 11(12), 1007; https://doi.org/10.3390/gels11121007 - 13 Dec 2025

Viewed by 558

Abstract

Protein-based hydrogels have emerged as an important class of materials for biomedical applications. However, these hydrogels often exhibit inferior mechanical properties, significantly limiting their potential applicability. Herein, a simplified yet efficient soaking method is developed to broaden the scope of constructing stiff and [...] Read more.

Protein-based hydrogels have emerged as an important class of materials for biomedical applications. However, these hydrogels often exhibit inferior mechanical properties, significantly limiting their potential applicability. Herein, a simplified yet efficient soaking method is developed to broaden the scope of constructing stiff and tough pure protein hydrogels, using natural cysteine-rich proteins, such as lactoferrin (LF). The preformed, soft and brittle, unfolded protein hydrogels transformed into highly stretchable and compressible elastomers after soaking in H₂O₂ due to chain entanglement and self-crosslinking via interchain disulfide bonds. As a result, the H₂O₂-treated LF hydrogels exhibited an extraordinary ultimate strength (compressive and tensile strains of over 90% and 400%, respectively, and stresses of 20 and 1.5 MPa). In addition, these rubber-like hydrogels exhibited exceptional self-recovery and fatigue resistance capabilities. Furthermore, the relationship between protein structure and the mechanical properties of the hydrogel was investigated. Together, these revelations could serve as a guiding principle for advancing the design of biocompatible, tough protein hydrogels without chemical modification or mechanical reinforcing fillers. Full article

(This article belongs to the Special Issue Advances in Protein Gels and Their Applications)

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22 pages, 1973 KB

Open AccessReview

Comparative Evaluation of Spreadability Measurement Methods for Topical Semisolid Formulations/A Scoping Review

by Elham Y. Al-Barghouthy, Saja Hamed, Ghadeer F. Mehyar and Hatim S. AlKhatib

Gels 2025, 11(12), 1006; https://doi.org/10.3390/gels11121006 - 12 Dec 2025

Cited by 8 | Viewed by 3535

Abstract

Background: Spreadability is a critical performance attribute for semisolid formulations, influencing patient compliance, dose uniformity, and product acceptability. Despite its importance, there is no standardized method for its assessment across pharmaceutical and cosmetic applications. Objective: This review uniquely integrates systematic literature mapping with [...] Read more.

Background: Spreadability is a critical performance attribute for semisolid formulations, influencing patient compliance, dose uniformity, and product acceptability. Despite its importance, there is no standardized method for its assessment across pharmaceutical and cosmetic applications. Objective: This review uniquely integrates systematic literature mapping with an experimental comparison of five spreadability assessment techniques, providing evidence-based recommendations for harmonizing protocols and improving reproducibility in semisolid formulation testing. Methods: A systematic search of PubMed, Scopus, and Web of Science identified 211 records, of which 14 studies met the inclusion criteria. Techniques reviewed included parallel-plate, slip-and-drag, rheometry (flow curve and amplitude sweep), texture analysis, and frictiometry. An experimental comparison was conducted on ten commercial formulations using all five techniques to assess inter-method variability and formulation-dependent behavior. Results: Texture analyzer and amplitude sweep rheometry emerged as the most reproducible and predictive methods, showing strong correlation (r = 0.74) in both literature and experimental data. Flow curve yield stress negatively correlated with parallel-plate spreadability (r = −0.796). Frictiometry results varied significantly with formulation type, particularly for ointments. Creams consistently ranked highest in spreadability across methods. Conclusion: No single method universally captures spreadability. Amplitude sweep rheometry correlated well with texture analysis, while flow curve values were more variable. Parallel-plate testing showed strong agreement with rheological and tribological methods, though texture analysis diverged, capturing distinct mechanical attributes. A tiered approach integrating parallel-plate, amplitude sweep, and frictiometry is recommended, with flow curve retained for regulatory compliance. Texture analysis provides valuable orthogonal information. Standardization of parallel-plate protocols is needed to establish unified spreadability indices. Full article

(This article belongs to the Section Gel Analysis and Characterization)

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18 pages, 2597 KB

Open AccessArticle

Eco-Friendly Hydrogels from Natural Gums and Cellulose Citrate: Formulations and Properties

by Giuseppina Anna Corrente, Fabian Ernesto Arias Arias, Eugenia Giorno, Paolino Caputo, Nicolas Godbert, Cesare Oliviero Rossi, Iolinda Aiello, Candida Milone and Amerigo Beneduci

Gels 2025, 11(12), 1005; https://doi.org/10.3390/gels11121005 - 12 Dec 2025

Viewed by 713

Abstract

The design of sustainable hydrogel materials with tunable mechanical and thermal properties is essential for emerging applications in flexible and wearable electronics. In this study, hydrogels based on natural gums such as Guar, Tara, and Xanthan and their composites with Cellulose Citrate were [...] Read more.

The design of sustainable hydrogel materials with tunable mechanical and thermal properties is essential for emerging applications in flexible and wearable electronics. In this study, hydrogels based on natural gums such as Guar, Tara, and Xanthan and their composites with Cellulose Citrate were developed through a mild physical crosslinking process, ensuring environmental compatibility and structural integrity. The effect of cellulose citrate pretreatment under different alkaline conditions (0.04%, 5%, and 10% NaOH) was systematically investigated using Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), and dynamic rheology. Overall, the results show that the composites exhibit different properties of the hydrogel networks compared to the pure hydrogel gums, strongly depending on the alkaline treatment. In all composite hydrogels, a significant increase in the number of interacting rheological units occurs, though the strength of the interactions decreases in Guar and Tara composites, which exhibit partial structural destabilization. In contrast, Xanthan–Cellulose Citrate hydrogels display enhanced strong gel character, and crosslinking density. These improvements reflect stronger intermolecular associations and a more compact polymer network, due to the favorable H-bonding and ionic interactions among Xanthan, Cellulose and Citrate mediated by water and sodium ions. Overall, the results demonstrate that Xanthan–Cellulose Citrate systems represent a new class of eco-friendly, mechanically robust hydrogels with controllable viscoelastic and thermal responses, features highly relevant for the next generation of flexible, self-supporting, and responsive soft materials suitable for wearable and stretchable electronic devices. Full article

(This article belongs to the Special Issue Application of Smart Gel Material in Flexible and Wearable Electronic (2nd Edition))

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21 pages, 6002 KB

Open AccessArticle

Effect of Ultrasonic Treatment of Dispersed Carbon Nanocomposite Media on the Formation, Electrical Conductivity, and Degradation of a Hydrogel for Metallic Stimulation Electrodes

by Mikhail Savelyev, Artem Kuksin, Denis Murashko, Ekaterina Otsupko, Victoria Suchkova, Kristina Efremova, Pavel Vasilevsky, Ulyana Kurilova, Sergey Selishchev and Alexander Gerasimenko

Gels 2025, 11(12), 1004; https://doi.org/10.3390/gels11121004 - 12 Dec 2025

Viewed by 591

Abstract

This study investigates the impact of ultrasonic treatment on the deagglomeration of aggregates of single-walled carbon nanotubes (SWCNTs) and reduced graphene oxide (rGO). The aim of the research is to enhance the electrical conductivity of a biopolymer hydrogel designed for coating metallic neurostimulation [...] Read more.

This study investigates the impact of ultrasonic treatment on the deagglomeration of aggregates of single-walled carbon nanotubes (SWCNTs) and reduced graphene oxide (rGO). The aim of the research is to enhance the electrical conductivity of a biopolymer hydrogel designed for coating metallic neurostimulation electrodes. Biocompatible coating materials are essential for the safe long-term function of implants within the body, enabling the transmission of nerve impulses to external devices for signal conversion and neurostimulation. Dynamic light scattering (DLS) was employed to monitor the dispersion state, in conjunction with measurements of specific electrical conductivity. The mass loss and swelling capacity were evaluated over an 80-day period to account for the effects of degradation during in vitro studies. Samples of flexible–elastic hydrogels for electrodes with complex geometry were formed by the photopolymerization of a photopolymerizable medium, similar to a photoresist. Analysis of the dependence of temperature and normalized optical transmittance on the duration of laser photopolymerization made it possible to determine the optimal polymerization temperature for the photopolymerizable medium as −28 °C. This temperature regime ensures maximum reproducibility of hydrogel formation and eliminates the presence of unpolymerized areas. The article presents a biopolymer hydrogel with SWCNTs and rGO nanoparticles in a 1:1 ratio. It was found that sufficient specific electrical conductivity is achieved using SWCNTs with a characteristic hydrodynamic radius of R = 490 nm and rGO with R = 210 nm (sample Col/BSA/CS/Eosin Y/SWCNTs (490 nm)/rGO 4). The photopolymerized hydrogel 4 demonstrated sufficient biocompatibility, exceeding the control sample by 16%. According to the results of in vitro studies over 80 days, this sample exhibited moderate degradation of 45% while retaining its swelling ability. The swelling degree decreased by 50% compared to the initial value of 170%. The presented hydrogel 4 is a promising coating material for implantable metallic neurostimulation electrodes, enhancing their stability in the physiological environment. Full article

(This article belongs to the Special Issue Innovative Gels: Structure, Properties, and Emerging Applications)

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26 pages, 6335 KB

Open AccessArticle

Integration of Nonlinear Rheology and CFD Simulation to Elucidate the Influence of Saturated Oil on Soy Protein Concentrate Behavior During High-Moisture Extrusion

by Timilehin Martins Oyinloye, Chae-Jin Lee and Won Byong Yoon

Gels 2025, 11(12), 1003; https://doi.org/10.3390/gels11121003 - 12 Dec 2025

Cited by 1 | Viewed by 728

Abstract

This study investigated the influence of coconut oil concentration (0–2%) on the nonlinear rheological and thermal behavior of soy protein concentrate (SPC) mixtures and integrated these data into computational fluid dynamics (CFD) models to predict flow behavior during high-moisture extrusion. Temperature sweep tests [...] Read more.

This study investigated the influence of coconut oil concentration (0–2%) on the nonlinear rheological and thermal behavior of soy protein concentrate (SPC) mixtures and integrated these data into computational fluid dynamics (CFD) models to predict flow behavior during high-moisture extrusion. Temperature sweep tests revealed that increasing oil content elevated the onset and peak gelation temperatures from 64.13 to 70.21 °C and 70.29 to 76.08 °C, respectively, while decreasing gelation enthalpy from 4.05 J/g to 2.81 J/g. Large-amplitude oscillatory shear (LAOS) analysis showed a shift from strain-stiffening (e₃/e₁ > 0.15) behavior to strain-thinning (e₃/e₁ < 0.05) behavior with increasing oil, accompanied by enhanced shear-thinning behavior (v₃/v₁ < 0). Integrating these nonlinear parameters into the CFD simulations enhanced model accuracy relative to the SAOS-based approach, resulting in lower RMSE values (≤4.41 kPa for pressure and ≤0.11 mm/s for velocity) and enabling more realistic prediction of deformation and flow under extrusion-relevant conditions, a capability that conventional SAOS-based models could not achieve. Predicted outlet melt temperatures averaged 70.27 ± 1.55 °C, consistent with experimental results. The findings demonstrate that oil addition modulates protein network formation and flow resistance, and that nonlinear rheology-coupled CFD models enable reliable prediction of extrusion behavior. Overall, this study provides a novel rheology-driven modeling strategy for enhancing the design and optimization of oil-enriched plant-protein extrusion processes. Full article

(This article belongs to the Special Issue Recent Developments in Food Gels (3rd Edition))

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5 pages, 241 KB

Open AccessEditorial

Research Progress and Application Prospects of Gel Electrolytes

by Andrea Zille and Ana Isabel Ribeiro

Gels 2025, 11(12), 1002; https://doi.org/10.3390/gels11121002 - 12 Dec 2025

Viewed by 649

Abstract

Gel electrolytes have rapidly emerged as indispensable components in modern electrochemical systems, bridging the performance gap between liquid and solid electrolytes [...] Full article

(This article belongs to the Special Issue Research Progress and Application Prospects of Gel Electrolytes)

32 pages, 11529 KB

Open AccessEditor’s ChoiceReview

Flexible Polymer Hydrogel Materials for Next-Generation Wearable Energy Storage Technologies

by Thirukumaran Periyasamy, Shakila Parveen Asrafali and Jaewoong Lee

Gels 2025, 11(12), 999; https://doi.org/10.3390/gels11120999 - 11 Dec 2025

Viewed by 1626

Abstract

The rapid advancement of wearable technology has created an increasing demand for efficient, high-performance energy storage systems that also offer key characteristics such as flexibility, lightweight, and durability. Among the emerging materials, polymer hydrogels have garnered significant attention due to their unique combination [...] Read more.

The rapid advancement of wearable technology has created an increasing demand for efficient, high-performance energy storage systems that also offer key characteristics such as flexibility, lightweight, and durability. Among the emerging materials, polymer hydrogels have garnered significant attention due to their unique combination of viscoelasticity, low density, and tunable porous nanostructures. These materials exhibit adaptable surface and structural properties, making them promising candidates for next-generation flexible and wearable energy storage devices. This work provides an overview of recent progress and innovations in the application of polymer hydrogels for the development of flexible energy storage systems. The intrinsic three-dimensional architecture and porous morphology of these hydrogels offer a versatile platform for constructing high-performance supercapacitors, rechargeable batteries, and personal thermal management devices. Various types of polymer hydrogels and their principal fabrication methods are discussed in detail, along with the structural factors that influence their electrochemical and mechanical performance. Furthermore, recent advancements in integrating polymer hydrogel materials into wearable and flexible technologies—such as energy storage devices, thermal regulation systems, and multifunctional energy platforms—are comprehensively reviewed and analyzed. Full article

(This article belongs to the Special Issue Energy Storage and Conductive Gel Polymers)

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13 pages, 1974 KB

Open AccessArticle

Cryoelectrospun Elastin-Alginate Scaffolds Support In Vitro 3D Epithelial-Stromal Cocultures for Salivary Tissue Engineering

by Pujhitha Ramesh, James Castracane, Melinda Larsen, Deirdre A. Nelson, Susan T. Sharfstein and Yubing Xie

Gels 2025, 11(12), 998; https://doi.org/10.3390/gels11120998 - 11 Dec 2025

Cited by 1 | Viewed by 1603

Abstract

Bioengineered functional salivary tissues can advance regenerative therapies, preclinical drug testing, and the fundamental understanding of salivary gland dysfunction. Current salivary tissue models are typically Matrigel-based, hydrogel-based or scaffold-free organoid systems, with limited physiological relevance or mimicry of cell-cell and cell-extracellular matrix (ECM) [...] Read more.

Bioengineered functional salivary tissues can advance regenerative therapies, preclinical drug testing, and the fundamental understanding of salivary gland dysfunction. Current salivary tissue models are typically Matrigel-based, hydrogel-based or scaffold-free organoid systems, with limited physiological relevance or mimicry of cell-cell and cell-extracellular matrix (ECM) interactions. We previously developed elastin-alginate cryoelectrospun scaffolds (CES) that resemble the topography and viscoelastic properties of healthy salivary ECM, and validated their potential for stromal cell culture, delivery, and in vitro fibrosis modeling. Here, we evaluated the utility of CES to support 3D cocultures of salivary gland epithelial and mesenchymal cells in vitro. We compared CES with honeycomb-like topography (CES-H) to densely packed electrospun nanofibers (NFs) and CES with fibrous topography (CES-F) for their ability to support SIMS epithelial cell attachment, morphology, 3D clustering, phenotype and organization into distinct clusters when cocultured with stromal cells. Both CES-F and CES-H supported epithelial cell attachment and clustering; in particular, CES-H most effectively supported the self-organization of epithelial and stromal cells into distinct 3D clusters resembling the structure of native salivary tissue. Stromal cells were essential for maintaining the phenotype of epithelial cells cultured on CES-H, laying the foundation for the development of in vitro tissue models. Full article

(This article belongs to the Special Issue Advanced Hydrogels for Tissue Engineering and Drug Delivery (2nd Edition))

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17 pages, 3370 KB

Open AccessArticle

Physicochemical, Thermal and Textural Characterization of Olive Pomace Oil and Argan Oil Oleogels Prepared with Different Oleogelators

by Mine Kırkyol, Ahmet Akköse, Şeyma Şişik Oğraş, Zeynep Feyza Yılmaz Oral, Güzin Kaban and Mükerrem Kaya

Gels 2025, 11(12), 997; https://doi.org/10.3390/gels11120997 - 11 Dec 2025

Viewed by 681

Abstract

The physicochemical, thermal and textural properties of oleogels formed from olive pomace oil and argan oil using carnauba (KW), candelilla (CW) and sunflower (AW) waxes and their combinations (KCW: 50% carnauba + 50% candelilla wax, KAW: 50% carnauba + 50% sunflower wax, CAW: [...] Read more.

The physicochemical, thermal and textural properties of oleogels formed from olive pomace oil and argan oil using carnauba (KW), candelilla (CW) and sunflower (AW) waxes and their combinations (KCW: 50% carnauba + 50% candelilla wax, KAW: 50% carnauba + 50% sunflower wax, CAW: 50% candelilla + 50% sunflower wax) were investigated. The highest mean L* value, peroxide value and time of crystallization formation were found in AW oleogelator. Argan oil + AW had the lowest mean L* value. Sunflower wax differed from the other waxes in terms of major fatty acids, and oleogels containing argan oil and olive pomace oil exhibited a different major fatty acid profile from each other; in particular, there were higher values of oleic acid content in the groups where olive pomace oil was used. It was determined that KW and the oleogels containing KW had higher melting and crystallization temperatures and enthalpy values compared to other waxes. The hardness, adhesiveness, gumminess, cohesiveness and springiness values of the oleogels were affected by the oils and waxes used. The oleogels using sunflower wax were different in terms of texture profile from oleogels formed with carnauba and candelilla waxes. Full article

(This article belongs to the Section Gel Chemistry and Physics)

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13 pages, 3057 KB

Open AccessArticle

Injectable Hydrogels with Tissue-Adaptive Gelation and Mechanical Properties: Enhancing Softness and Stability

by Jessica Garcia, Foad Vashahi, Akmal Z. Umarov, Evgeniy V. Dubrovin, Apollinariya Yu. Konyakhina, Elena N. Subcheva, Dimitri A. Ivanov, Andrey V. Dobrynin and Sergei S. Sheiko

Gels 2025, 11(12), 996; https://doi.org/10.3390/gels11120996 - 11 Dec 2025

Viewed by 728

Abstract

Ultra-soft injectable hydrogels are paramount in biomedical applications such as tissue fillers, drug depots, and tissue regeneration scaffolds. Synthetic approaches relying on linear polymers are confronted by the necessity for significant dilution of polymer solutions to reduce chain entanglements. Bottlebrush polymers offer an [...] Read more.

Ultra-soft injectable hydrogels are paramount in biomedical applications such as tissue fillers, drug depots, and tissue regeneration scaffolds. Synthetic approaches relying on linear polymers are confronted by the necessity for significant dilution of polymer solutions to reduce chain entanglements. Bottlebrush polymers offer an alternative approach due to suppressed chain overlap and entanglements, which facilitates lower solution viscosities and increased gel softness. Leveraging the bottlebrush architecture in linear-bottlebrush-linear (LBL) block copolymer systems, where L is a thermosensitive linear poly(N-isopropylacrylamide) block, and B is a hydrophilic polyethylene glycol brush block, injectable hydrogels were designed to mimic tissues as soft as the extracellular matrix at high polymer concentrations. Compared to an analogous system with shorter brush side chains, increasing the side chain length enables a decrease in modulus by up to two orders of magnitude within 1–100 Pa at 20 wt% polymer concentrations, near to the physiological water content of ~70%. This system further exhibits thermal hysteresis, enabling stability with inherent body temperature fluctuations. The observed features are ascribed to kinetically hindered network formation by bulky macromolecules. Full article

(This article belongs to the Section Gel Chemistry and Physics)

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33 pages, 31820 KB

Open AccessArticle

Confined Fluids in Gel Matrices for the Selective Cleaning of a Tibetan Altar Table

by Chiara Biribicchi, Jessica Chasen and Laura Maccarelli

Gels 2025, 11(12), 1001; https://doi.org/10.3390/gels11121001 - 11 Dec 2025

Viewed by 755

Abstract

LACMA’s 19th-century Tibetan Altar Table with Auspicious Symbols is characterized by a complex stratigraphy comprising animal glue-based ground and paint layers, a presumably original tung oil-based varnish, and a dark surface layer composed of a complex mixture of paraffinic wax, shellac, and rapeseed [...] Read more.

LACMA’s 19th-century Tibetan Altar Table with Auspicious Symbols is characterized by a complex stratigraphy comprising animal glue-based ground and paint layers, a presumably original tung oil-based varnish, and a dark surface layer composed of a complex mixture of paraffinic wax, shellac, and rapeseed oil, which obscures the object’s original decorative scheme. This study examines the use of nanostructured fluids and organic solvents confined within hydrogels and organogels for the selective removal of the dark surface layer while preserving the underlying paint and varnish. Following the analysis of the artwork’s constituent materials, cleaning tests were conducted and evaluated using visible and ultraviolet fluorescence (UVF) imaging, spectrophotometry, and digital microscopy. The homogeneous absorption of solvent mixtures by the organogels was assessed through gas chromatography–mass spectrometry (GC–MS). Results indicate that confining cleaning fluids within the gels’ porous networks significantly improved solvent retention and control of fluid release. While conventional cleaning methods proved insufficiently selective, the gradual release of a nanostructured fluid containing a small amount of benzyl alcohol, combined with the nanostructural properties of the poly(vinyl alcohol)–sebacic acid (PSA2) hydrogel, enabled targeted removal of the surface layer while preserving the integrity of the underlying layers. Full article

(This article belongs to the Special Issue Advances in the Design and Application of Gels in Heritage Conservation)

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13 pages, 5510 KB

Open AccessArticle

Highly Sensitive MXene/MMT-Based Hydrogel for Wearable Sensors and Flexible Supercapacitors

by Haiyan Zhao, Ziqi Wang, Chaohao Yin, Chu Chen, Li Wang, Xin Zhang and Zhuo Wang

Gels 2025, 11(12), 1000; https://doi.org/10.3390/gels11121000 - 11 Dec 2025

Viewed by 809

Abstract

In this work, a flexible, stretchable, tough, highly ionic conductive, and anti-freezing hydrogel based on acrylamide/two-dimensional transition metal carbide (MXene)/montmorillonite (MMT) was precisely designed. In the hydrogel, MXene and MMT acted as both cross-linking agents and conductive fillers, delivering high stretchability (1037%) with [...] Read more.

In this work, a flexible, stretchable, tough, highly ionic conductive, and anti-freezing hydrogel based on acrylamide/two-dimensional transition metal carbide (MXene)/montmorillonite (MMT) was precisely designed. In the hydrogel, MXene and MMT acted as both cross-linking agents and conductive fillers, delivering high stretchability (1037%) with a strength of up to approximately 67 kPa and high conductivity. As a result, the usual trade-off between conductivity and mechanical properties of hydrogels could be alleviated to some extent. Therefore, the hydrogel could be used as an electrolyte for supercapacitors (SCs) and strain sensors to monitor physical signals. The hydrogel-based SC exhibited outstanding electrochemical performance over a wide temperature range. Moreover, it could easily withstand various deformations, such as bending, twisting, and compression. The hydrogel also exhibited excellent sensing properties, with a short tensile response time and a high-sensitivity factor (GF = 14.8) in the 0–400% range (0 denotes the original state, where both the strain and stretch are zero as there is no deformation at this point). Due to its high conductivity, the prepared hydrogel could be used as a flexible electrode to replace commercial electrodes and record electromyographic (EMG) signals. This work proposes a novel approach for balancing the conductivity and mechanical strength of hydrogels. Full article

(This article belongs to the Special Issue Stretchable Conductive Hydrogel Materials for Flexible Sensors and Bioelectronics)

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21 pages, 3960 KB

Open AccessArticle

The Design and Development of an Injectable Thermoresponsive Hydrogel for Controlled Simvastatin Release in Bone Repair Applications

by Christopher R. Simpson, Helena M. Kelly and Ciara M. Murphy

Gels 2025, 11(12), 995; https://doi.org/10.3390/gels11120995 - 10 Dec 2025

Cited by 3 | Viewed by 757

Abstract

Osteoporotic vertebrae are a uniquely challenging tissue for local delivery due to the complex geometry of cancellous bone, the proximity of the spinal cord, and the need for reliable site retention. These challenges can be met with the use of stimuli responsive, state [...] Read more.

Osteoporotic vertebrae are a uniquely challenging tissue for local delivery due to the complex geometry of cancellous bone, the proximity of the spinal cord, and the need for reliable site retention. These challenges can be met with the use of stimuli responsive, state transiting formulations by leveraging their unique capacity for minimally invasive implantation as a liquid, sol–gel transition in response to stimuli, and finally, release of a loaded therapeutic. Here, we present the formulation development of a thermosensitive methylcellulose–collagen hydrogel, functionalised with controlled release simvastatin, recently shown to enhance osteogenesis while also impeding osteoclast activity. We first optimised a formulation with collagen content of 0.4% w/v to achieve a thermosensitive system with sol–gel transition at 29 °C, shear-thinning/injectable properties, low cytotoxicity, and high biocompatibility. Incorporation of nano-hydroxyapatite for enhanced bone tissue mimicry revealed optimal performance at 100% w/collagen content, showing long-term hydrolytic stability, maintaining more than 100% of its mass after 28 days. A loading concentration of 1 mg of simvastatin to 1 g of hydrogel displayed sustained release of simvastatin over 35 days. Finally, the release of simvastatin from the hydrogel into in vitro conditions prevented the formation of osteoclasts but failed to boost osteogenesis. Together these findings reveal a series of desirable stimuli-responsive hydrogel properties, achieving minimally invasive application coupled with sustained release of a hydrophobic compound, which is potentially useful for spatially complex bone regeneration. Further this work demonstrates the challenge of dosing sustained release systems to achieve simultaneous osteogenesis and anti-osteoclastogenic effects. Full article

(This article belongs to the Special Issue Biopolymer-Based Gels for Drug Delivery and Tissue Engineering (2nd Edition))

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32 pages, 798 KB

Open AccessSystematic Review

Platelet-Rich Plasma in Veterinary Orthopedic Surgery: A Systematic Review and Quality Evaluation on Liquid- and Gel-Based Therapies in Dogs

by Francisco Vidal-Negreira, Mario García-González, Victoria Valiño-Cultelli and Antonio González-Cantalapiedra

Gels 2025, 11(12), 994; https://doi.org/10.3390/gels11120994 - 10 Dec 2025

Viewed by 1331

Abstract

The clinical use of platelet-rich plasma (PRP) has gained increasing attention as a regenerative strategy in veterinary orthopedic surgery, yet its efficacy beyond osteoarthritis remains unclear. This systematic review aimed to evaluate the therapeutic potential of liquid and gel PRP formulations as adjuncts [...] Read more.

The clinical use of platelet-rich plasma (PRP) has gained increasing attention as a regenerative strategy in veterinary orthopedic surgery, yet its efficacy beyond osteoarthritis remains unclear. This systematic review aimed to evaluate the therapeutic potential of liquid and gel PRP formulations as adjuncts in canine orthopedic procedures and to assess the methodological quality of the available evidence. A comprehensive search of PubMed, Scopus, and Web of Science was conducted following PRISMA guidelines. Fourteen eligible studies (six experimental in vivo and eight clinical investigations) including in vivo and clinical investigations of fracture and osteotomy repair and tendon or ligament reconstruction were critically analyzed. Overall, PRP demonstrated safety and biological activity, with early-phase improvements in tissue regeneration and inflammatory modulation; however, long-term functional outcomes were often similar to controls. Gel PRP showed practical advantages in handling, local retention, and the sustained release of growth factors, acting as a transient fibrin scaffold. Quality and risk-of-bias assessments following ARRIVE 2.0, CONSORT, and RoB 2.0 guidelines revealed moderate methodological rigor, with frequent omissions in blinding, sample-size calculation, and preregistration. However, the marked heterogeneity in PRP preparations and outcomes across studies, together with weak evidence for consistent long-term benefits, limits the strength of these conclusions. These findings highlight PRP, particularly in gel form, as a promising biological adjuvant for orthopedic repair in dogs, while emphasizing the need for standardized preparation protocols and harmonized outcome measures to advance its translational application. Full article

(This article belongs to the Special Issue Biopolymeric Gels: Advancements in Sustainable Multifunctional Materials)

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49 pages, 8174 KB

Open AccessReview

Biocompatible Stimuli-Sensitive Natural Hydrogels: Recent Advances in Biomedical Applications

by Jose M. Calderon Moreno, Mariana Chelu and Monica Popa

Gels 2025, 11(12), 993; https://doi.org/10.3390/gels11120993 - 10 Dec 2025

Cited by 12 | Viewed by 2554

Abstract

Biocompatible stimuli-sensitive hydrogels are a versatile and promising class of materials with significant potential for various biomedical applications. These ‘’smart’’ hydrogels can dynamically respond to external environmental stimuli such as pH, temperature, enzymes, or biomolecular interactions, enabling controlled drug release, tissue regeneration, wound [...] Read more.

Biocompatible stimuli-sensitive hydrogels are a versatile and promising class of materials with significant potential for various biomedical applications. These ‘’smart’’ hydrogels can dynamically respond to external environmental stimuli such as pH, temperature, enzymes, or biomolecular interactions, enabling controlled drug release, tissue regeneration, wound healing, and biosensing applications. Hydrogels derived from natural polymers, including chitosan, alginate, collagen, and hyaluronic acid, offer key advantages such as intrinsic biocompatibility, biodegradability, and the ability to mimic the extracellular matrix. Their ability to respond to environmental stimuli—including pH, temperature, redox potential, and enzymatic activity—enables control over drug release and tissue regeneration processes. This review explores the fundamental principles governing the design, properties, and mechanisms of responsiveness of natural stimuli-sensitive hydrogels. It also highlights recent advancements in their biomedical applications, discusses existing challenges, and outlines future research directions aimed at improving their functional performance and therapeutic potential for sustainable healthcare solutions. Full article

(This article belongs to the Special Issue Innovative Approaches of Biopolymer-Based Hydrogels: Development, Characterization, and Biomedical Applications)

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23 pages, 6275 KB

Open AccessArticle

Epoxy Resin Highly Loaded with an Ionic Liquid: Morphology, Rheology, and Thermophysical Properties

by Svetlana O. Ilyina, Irina Y. Gorbunova, Michael L. Kerber and Sergey O. Ilyin

Gels 2025, 11(12), 992; https://doi.org/10.3390/gels11120992 - 10 Dec 2025

Cited by 1 | Viewed by 938

Abstract

An epoxy resin can be crosslinked with an imidazole-based ionic liquid (IL), whose excess, provided its high melting temperature, can potentially form a dispersed phase to store thermal energy and produce a phase-change material (PCM). This work investigates the crosslinking of diglycidyl ether [...] Read more.

An epoxy resin can be crosslinked with an imidazole-based ionic liquid (IL), whose excess, provided its high melting temperature, can potentially form a dispersed phase to store thermal energy and produce a phase-change material (PCM). This work investigates the crosslinking of diglycidyl ether of bisphenol A (DGEBA) using 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) at its mass fractions of 5, 10, 20, 40, and 60%. The effect of [EMIM]Cl on the viscosity, curing rate, and curing degree was studied, and the thermophysical properties and morphology of the resulting crosslinked epoxy polymer were investigated. During the curing, [EMIM]Cl changes its role from a crosslinking agent (an initiator of homopolymerization) and a diluent of the epoxy resin to a plasticizer of the cured epoxy polymer and a dispersed phase-change agent. An increase in the [EMIM]Cl content accelerates the curing firstly because of the growth in the number of reaction centers, and then the curing slows down because of the action of the IL as a diluent, which reduces the concentration of reacting substances. In addition, a rise in the proportion of [EMIM]Cl led to the predominance of the initiation over the chain growth, causing the formation of short non-crosslinked molecules. The IL content of 5% allowed for curing the epoxy resin and elevating the stiffness of the crosslinked product by almost 7 times compared to tetraethylenetriamine as a usual aliphatic amine hardener (6.95 GPa versus 1.1 GPa). The [EMIM]Cl content of 20–40% resulted in a thermoplastic epoxy polymer capable of flowing and molding at elevated temperatures. The formation of IL emulsion in the epoxy matrix occurred at 60% [EMIM]Cl, but its hygroscopicity and absorption of water from surrounding air reduced the crystallinity of dispersed [EMIM]Cl, not allowing for an effective phase-change material to be obtained. Full article

(This article belongs to the Special Issue Energy Storage and Conductive Gel Polymers)

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11 pages, 1289 KB

Open AccessArticle

Pasting and Gel Behavior of Durum Wheat Derivatives

by Diogo Salvati, Laura Moreno, Juan Manuel Antolín-Rodríguez and Manuel Gómez

Gels 2025, 11(12), 991; https://doi.org/10.3390/gels11120991 - 10 Dec 2025

Viewed by 516

Abstract

Durum wheat (Triticum durum) is one of the main raw materials in the food industry, used primarily in the production of pasta. During milling, semolina and flour are obtained with different size distributions, and different compositional and functional characteristics, which influence [...] Read more.

Durum wheat (Triticum durum) is one of the main raw materials in the food industry, used primarily in the production of pasta. During milling, semolina and flour are obtained with different size distributions, and different compositional and functional characteristics, which influence processes such as gelatinization, retrogradation and the final texture of the products. Understanding these changes is essential for optimizing the technological quality and shelf life of processed foods. The aim was to evaluate how particle size, composition, temperature, and treatment time affect gelatinization, retrogradation, and gel texture. Samples included common wheat flour (control), durum wheat semolina, durum wheat flour, and re-milled semolina (<180 μm). Hydrothermal tests were conducted at 95 °C with varying holding times, and at 140 °C with extended cooling to observe retrogradation. Composition and particle size were found to determine rheological behavior. Semolina showed higher retrogradation and produced firmer gels, while durum wheat flour, with higher protein and ash content, showed atypical profiles and less consistent gels. Increased temperature and time enhanced breakdown and reduced final viscosity, indicating starch thermal degradation. A correlation was observed between final viscosity and gel hardness. This study provides information useful for optimizing the milling, cooking, and development of durum wheat-based products with improved texture and shelf life. Full article

(This article belongs to the Special Issue Food Hydrocolloids and Hydrogels: Rheology and Texture Analysis)

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