Gels

23 pages, 3872 KB

Open AccessArticle

Comparison of the Structure and Properties of Hydroxypropyl Starch/Carrageenan Blends with Different Amylose/Amylopectin Contents

by Xingxing Zhu, Di Wu, Juanjuan Wu, Jinglong Zhao, Yunhe Lian and Yunkai Lv

Gels 2026, 12(5), 423; https://doi.org/10.3390/gels12050423 - 12 May 2026

Abstract

To compare the structure and properties of hydroxypropyl starch/carrageenan blends with different amylose/amylopectin contents, two types of hydroxypropyl starch—a high-amylose type (amylose content > 70%) and a high-amylopectin type (amylopectin content > 95%)—were used. These starches had similar molecular weights, degrees of hydroxypropyl [...] Read more.

To compare the structure and properties of hydroxypropyl starch/carrageenan blends with different amylose/amylopectin contents, two types of hydroxypropyl starch—a high-amylose type (amylose content > 70%) and a high-amylopectin type (amylopectin content > 95%)—were used. These starches had similar molecular weights, degrees of hydroxypropyl substitution, and other properties, differing only in their amylose and amylopectin contents. Each starch was blended with carrageenan via a solution blending method, and the resulting blends were systematically characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis, rheological tests, texture analysis, mechanical property tests, contact angle analysis, and UV-Vis spectrophotometry. The results showed that, upon blending with carrageenan, the hydroxypropyl starch transformed from a weak viscoelastic solution into an elastic, strong gel. FTIR and XRD analyses confirmed that the hydroxypropyl starch and carrageenan formed a homogeneous, compact, three-dimensional network via hydrogen bonding. This significantly enhanced the mechanical strength and stability of the blends. The influence of starch molecular structure on the blend system’s properties exhibited a pronounced state dependence. In the gel state, hydroxypropyl amylopectin effectively filled the carrageenan network due to its high swelling capacity, thereby improving the thermal stability and textural properties of the blends. However, in the film state, hydroxypropyl amylose with higher crystallinity and denser molecular packing contributed to superior tensile strength, hydrophobicity and light transmittance. Furthermore, the optimal mass ratio of hydroxypropyl starch to carrageenan was found to be in the range of 2:1 to 4:1. With this ratio, excessive cross-linking and poor compatibility could be avoided, resulting in improved mechanical performance, hydrophobicity, and light transmittance. This study reveals the relationship between starch molecular structure, system state and macroscopic properties, providing a theoretical basis for the rational design and regulation of the properties of hydroxypropyl starch/carrageenan blends. Full article

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

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17 pages, 1957 KB

Open AccessArticle

Multivariate Temporal Inflammatory–Regenerative Signatures of Bovine Platelet-Rich Gel Supernatants Under Different Storage Temperatures

by Jorge U. Carmona and Catalina López

Gels 2026, 12(5), 422; https://doi.org/10.3390/gels12050422 - 12 May 2026

Abstract

Platelet-rich gel supernatants (PRGS) are increasingly used in veterinary medicine due to their regenerative and immunomodulatory properties; however, most studies focus on individual mediators and provide limited insight into their coordinated biological behavior. This study aimed to characterize the integrated inflammatory–regenerative signatures of [...] Read more.

Platelet-rich gel supernatants (PRGS) are increasingly used in veterinary medicine due to their regenerative and immunomodulatory properties; however, most studies focus on individual mediators and provide limited insight into their coordinated biological behavior. This study aimed to characterize the integrated inflammatory–regenerative signatures of bovine PRGS stored under different temperature conditions using a multivariate approach. Concentrations of transforming growth factor beta-1 (TGF-β1), tumor necrosis factor alpha (TNF-α), interleukin-2 (IL-2), and interleukin-6 (IL-6) were evaluated in PRGS samples from six clinically healthy cows stored at −80, −20, 4, 21, and 37 °C for up to 326 h. Data were standardized and explored using hierarchical clustering and heatmaps, and principal component analysis (PCA) based on area under the concentration–time curve (AUC) was used to integrate temporal behavior. Temperature-dependent multivariate signatures were identified, with frozen PRGS clustering separately from samples stored at moderate temperatures. The first two principal components explained 43.0% and 28.9% of the variance and defined an inflammatory–regenerative gradient contrasting TGF-β1/IL-2 versus TNF-α/IL-6 profiles. Linear mixed-effects modeling showed that PC1 was significantly affected by temperature and time (p < 0.001), whereas PC2 was influenced by temperature, time, and their interaction (p ≤ 0.048). Differences among temperatures were minimal at early time points but became more pronounced from 48 to 96 h onward, following a temperature gradient with higher values at moderate temperatures and lower values under frozen conditions. These findings indicate that storage temperature reshapes the integrated biological profile of PRGS, rather than merely preserving mediator composition. Full article

(This article belongs to the Special Issue Designing Gels for Wound Dressing (2nd Edition))

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2 pages, 588 KB

Open AccessCorrection

Correction: Tallapaneni et al. Growth Factor Loaded Thermo-Responsive Injectable Hydrogel for Enhancing Diabetic Wound Healing. Gels 2023, 9, 27

by Vyshnavi Tallapaneni, Lavanya Mude, Divya Pamu, Vasanth Raj Palanimuthu, Sai Varshini Magham, Veera Venkata Satyanarayana Reddy Karri and Madhukiran Parvathaneni

Gels 2026, 12(5), 421; https://doi.org/10.3390/gels12050421 - 12 May 2026

Abstract

In the original publication [...] Full article

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20 pages, 1408 KB

Open AccessArticle

Comparative Study of Ni-Impregnated Alumina Aerogels and Ni-Al Xerogels for Light-Irradiation-Assisted CO₂ Methanation

by Daniel Estevez, Haritz Etxeberria and Victoria Laura Barrio

Gels 2026, 12(5), 420; https://doi.org/10.3390/gels12050420 - 11 May 2026

Abstract

CO₂ methanation is considered a key process in achieving carbon neutrality. Expanding on our previous study of supercritically dried Ni-Al aerogels, this work compares two gel-based catalyst families prepared via two different routes—supercritically dried Ni impregnated Al aerogel-based catalysts and oven-dried one-pot [...] Read more.

CO₂ methanation is considered a key process in achieving carbon neutrality. Expanding on our previous study of supercritically dried Ni-Al aerogels, this work compares two gel-based catalyst families prepared via two different routes—supercritically dried Ni impregnated Al aerogel-based catalysts and oven-dried one-pot Ni-Al xerogel-based catalysts—to assess how the synthesis route affects catalyst structure and CO₂ methanation performance under light irradiation. The catalysts were subsequently characterized via different techniques, such as ICP-OES, N₂ adsorption–desorption isotherms, XRD, H₂-TPR, UV-vis DRS, XPS, and TEM. Catalytic activity was tested in a photoreactor at a range of temperatures from 300 °C to 450 °C and 10 bar pressure, and two different light sources were used (λ = 365 nm, λ = 470 nm). Both light sources enhanced catalytic activity in most cases; the xerogels with higher Ni loadings were the most active materials. These catalysts reached CO₂ conversions and CH₄ selectivities near 70% and 100%, respectively. The results indicate that drying gels is a promising method for synthesizing catalysts active in the Sabatier reaction, given the properties of the materials. Full article

(This article belongs to the Special Issue Aerogels and Composites Aerogels)

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19 pages, 2007 KB

Open AccessReview

Hydrogel-Based Semiconductors: Principles, Types, and Emerging Applications

by Md Murshed Bhuyan, Kyungjun Lee and Jae-Ho Jeong

Gels 2026, 12(5), 419; https://doi.org/10.3390/gels12050419 - 11 May 2026

Abstract

The world’s current technical developments are mostly dependent on semiconductors. Even though traditional semiconductor materials are important, they have various disadvantages, especially when evaluated against polymer-based alternatives. Hydrogel-based semiconductors provide soft, ionically linked electronic interfaces by combining hydrated, mechanically compliant matrices with electrically [...] Read more.

The world’s current technical developments are mostly dependent on semiconductors. Even though traditional semiconductor materials are important, they have various disadvantages, especially when evaluated against polymer-based alternatives. Hydrogel-based semiconductors provide soft, ionically linked electronic interfaces by combining hydrated, mechanically compliant matrices with electrically active conjugated polymers and composites which can be applied in bioelectronic and thermoelectric generator/cells. Volumetric capacitances are normally in the range of 1–485 F·cm⁻³, demonstrating excellent ion storage, transport capabilities, and electron mobilities for hydrogel semiconductors spanning roughly 0.25 cm²/V·s (measured for n-type P(PyV)-H hydrogel). The fabrication techniques include additive free casting and room-temperature crosslinking, which lower energy input while maintaining electronic performance; typical systems maintain >80% of their conductivity after 10³–10⁴ mechanical cycles. This review study mainly focuses on the design, preparation, application, and prospects of gel/hydrogel-based semiconductors. It gives readers a thorough understanding of the basic ideas that underline their structure and operation. All things considered, this work is a useful tool for engineers and researchers looking to maximize the potential of gel-based semiconductors in next-generation electrical systems. Full article

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

17 pages, 4895 KB

Open AccessArticle

Effects and Mechanisms of Calcium Silicate Hydrate on Microstructure and Thermal Properties of Hybrid MTMS–Silica Aerogels

by Deyu Kong, Stanley Bryan Kurniawan, Mengqing Huang, Qiuhang Chen and Jintao Liu

Gels 2026, 12(5), 418; https://doi.org/10.3390/gels12050418 - 11 May 2026

Abstract

Hybrid MTMS–silica aerogels incorporating calcium silicate hydrate (C–S–H), the primary hydration product in cementitious systems, were synthesized via sol–gel processing followed by freeze-drying. The influence of C–S–H loading on pore structure, density, wettability, and thermal transport was investigated. The lowest thermal conductivity (0.068 [...] Read more.

Hybrid MTMS–silica aerogels incorporating calcium silicate hydrate (C–S–H), the primary hydration product in cementitious systems, were synthesized via sol–gel processing followed by freeze-drying. The influence of C–S–H loading on pore structure, density, wettability, and thermal transport was investigated. The lowest thermal conductivity (0.068 W/m·K) and tap density (0.30 g/cm³) were obtained at 10% C–S–H loading (wM-CSH10), while the thermal conductivity increases to approximately 0.075–0.082 W/m·K at higher C–S–H content. All samples exhibit mesoporous structures with pore diameters in the range of 10–21 nm. Increasing C–S–H content progressively densified the network, reduced mesopore volume, and enhanced high-temperature mass retention up to 540 °C. FTIR analysis confirmed Si–O–Ca interfacial interactions, while nitrogen adsorption demonstrated persistent mesoporosity across all compositions. Thermal conductivity showed a positive correlation with density, indicating that bulk densification governs heat transport in the hybrid system. Beyond structural modification, the incorporation of C–S–H introduces chemical and microstructural features relevant to cement-based materials, suggesting potential compatibility with cementitious matrices. The results highlight the compositional trade-off between insulation efficiency and structural stability and demonstrate the potential of C–S–H-modified MTMS–silica aerogels for future integration into cement-based composites. These findings provide fundamental insight into their possible use in thermal insulation applications, such as building envelope systems (walls, façades, and roofs used for thermal insulation). Full article

(This article belongs to the Special Issue Synthesis, Properties, and Applications of Novel Polymer-Based Gels (2nd Edition))

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23 pages, 8103 KB

Open AccessArticle

Multifunctional Silk Fibroin Hydrogel with Antibacterial and Regenerative Properties for Accelerated Wound Healing

by Yanjiao Wu, Jiayue Chen, Luyao Han, Yiqiong Zhang and Li Wei

Gels 2026, 12(5), 417; https://doi.org/10.3390/gels12050417 - 10 May 2026

Abstract

The emergence of multifunctional wound dressings represents a significant transformation in the care of cutaneous tissue injuries, providing advanced solutions that surpass traditional dressings. This study is poised to fabricate multifunctional hydrogels through dual-dynamic cross-linking, integrating antibacterial and antioxidant properties, which are capable [...] Read more.

The emergence of multifunctional wound dressings represents a significant transformation in the care of cutaneous tissue injuries, providing advanced solutions that surpass traditional dressings. This study is poised to fabricate multifunctional hydrogels through dual-dynamic cross-linking, integrating antibacterial and antioxidant properties, which are capable of accelerating wound healing while improving therapeutic outcomes. The hydrogel, which exhibits excellent adhesion, rapid self-healing ability, and on-demand removability, was synthesized employing poly(vinyl alcohol) (PVA)–borax as the backbone, followed by the incorporation of silk fibroin (SF), tannic acid (TA), and chitosan (CS). Total saponins of Panax notoginseng flower buds (PNF) with anti-inflammatory and angiogenic properties were loaded in porous structural materials yielding the PBCTS@PNF hydrogel. The prepared hydrogel exhibited outstanding antioxidant properties and cytocompatibility, along with favorable antibacterial capabilities, achieving inhibition rates of 84.30 ± 2.34% against Escherichia coli (E. coli) and 98.12 ± 0.76% against Staphylococcus aureus (S. aureus), respectively. Animal experiments demonstrated that PBCTS@PNF significantly reduced inflammation and promoted multidimensional tissue regeneration, encompassing re-epithelialization, neovascularization, and hair follicle regeneration, along with ordered collagen matrix organization, leading to substantially accelerated wound healing. The multifunctional PBCTS@PNF hydrogel provides a potent bioengineered therapeutic platform for wound healing management through the synergistic interplay among antibacterial, anti-inflammatory, and tissue regenerative functionalities. Full article

(This article belongs to the Special Issue Advanced Hydrogels for Regenerative Medicine and Tissue Engineering (4th Edition))

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22 pages, 33328 KB

Open AccessArticle

Development of an Emulsion-Gel System Based on Corn Alcohol-Soluble Protein and Curdlan: Effects of Oil-to-Water Ratio and Shear Parameters

by Shijia Li, Chao Wu, Xiaojing Kang, Ran Wang, Qiang Cui, Yuyu Zhang, Mingkun Liu, Beibei Dou, Yang Liu and Han Chen

Gels 2026, 12(5), 416; https://doi.org/10.3390/gels12050416 - 10 May 2026

Abstract

This study reports the fabrication of Pickering emulsion gels stabilized by zein and curdlan (CU) and systematically elucidates the regulatory mechanisms of oil fraction and shearing parameters (temperature and duration) on their microstructure, mechanical properties, and stability. Results indicated that excessive oil content [...] Read more.

This study reports the fabrication of Pickering emulsion gels stabilized by zein and curdlan (CU) and systematically elucidates the regulatory mechanisms of oil fraction and shearing parameters (temperature and duration) on their microstructure, mechanical properties, and stability. Results indicated that excessive oil content triggered pronounced flocculation and structural collapse, primarily attributed to insufficient interfacial coverage and compromised network continuity. An optimal dense network with superior cohesiveness was established at a shearing temperature of 60 °C, effectively entrapping oil droplets within the continuous phase. Furthermore, extending the shearing duration enhanced long-term stability by reducing droplet size, yielding a maximum oil binding capacity (OBC) of 78.9%. These emulsion gels exhibited remarkable stability against diverse environmental stressors, including thermal treatments, pH variations, and freeze-thaw cycles. This work expands the application of protein-polysaccharide complexes in food colloid science and provides a theoretical foundation for the development of novel low-fat food formulations based on emulsion gel systems. Full article

(This article belongs to the Special Issue Next-Generation Food Colloids: Protein-Based to Emulsion-Based Gel Systems)

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19 pages, 1421 KB

Open AccessArticle

Development of Kamala-Based, a Thai Traditional Remedy, Nanoemulsion Gel and In Vitro Release Behavior of Phenylbutenoid Markers

by Siraporn Mahakoat, Sujaree Panomket, Catheleeya Mekjaruskul and Bunleu Sungthong

Gels 2026, 12(5), 415; https://doi.org/10.3390/gels12050415 - 9 May 2026

Abstract

Kamala is a traditional Thai herbal knee poultice containing phenylbutenoid compounds with potent anti-inflammatory activity; however, its conventional form is inconvenient to use and exhibits variability in active compound content. This study aimed to develop a Kamala-based nanoemulsion gel to enhance dermal delivery [...] Read more.

Kamala is a traditional Thai herbal knee poultice containing phenylbutenoid compounds with potent anti-inflammatory activity; however, its conventional form is inconvenient to use and exhibits variability in active compound content. This study aimed to develop a Kamala-based nanoemulsion gel to enhance dermal delivery and improve formulation consistency. Oils, surfactants, and co-surfactants were screened for their solubilization efficiency of (E)-1-(3,4-dimethoxyphenyl)butadiene (DMPBD) and (E)-4-(3′,4′-dimethoxyphenyl)but-3-en-1-ol (Compound D) using GC–MS. Pseudo-ternary phase diagrams were constructed to identify isotropic regions, and nanoemulsions with different Smix ratios were prepared by ultrasonication. Droplet size, polydispersity index (PDI), and short-term stability were evaluated. The optimized nanoemulsion was incorporated into a gel, and in vitro release was assessed using Franz diffusion cells. Coconut oil exhibited the highest solubilization capacity for both markers. A Tween 80:n-butanol system (2:1) generated the largest isotropic region (22.88%). The optimized formulation (Kamala extract:coconut oil:Smix:water = 1:2:50:47) showed droplet sizes of 77.92 ± 8.34 nm at 0 h and 130.89 ± 29.16 nm at 72 h, with PDI < 0.20. The nanoemulsion gel prepared with Aristoflex Velvet^® (1% w/w) was transparent and physically stable. Franz diffusion studies demonstrated enhanced cumulative release and flux of Compound D in PBS containing 1% Tween 80. These findings indicate that the Kamala nanoemulsion gel is a promising topical delivery system for phenylbutenoid compounds in knee osteoarthritis. Full article

(This article belongs to the Special Issue Functional Gels Loaded with Natural Products (2nd Edition))

1 pages, 608 KB

Open AccessCorrection

Correction: Bahloul et al. Investigating the Wound-Healing Potential of a Nanoemulsion–Gel Formulation of Pituranthos tortuosus Essential Oil. Gels 2024, 10, 155

by Badr Bahloul, Enis Ben Bnina, Assia Hamdi, Luis Castillo Henríquez, Dhaou Baccar, Nesrine Kalboussi, Aïmen Abbassi, Nathalie Mignet, Guido Flamini and José Roberto Vega-Baudrit

Gels 2026, 12(5), 414; https://doi.org/10.3390/gels12050414 - 9 May 2026

Abstract

In the original publication [...] Full article

(This article belongs to the Section Gel Applications)

28 pages, 7783 KB

Open AccessReview

Hydrogels for Agricultural Applications: From Soil Amendment to Crop Enhancement

by Luohui Wang, Jihang Hu, Liyun Wang, Xiaobo Xue, Panrong Guo, Youming Dong, Fei Xiao, Cheng Li and Limin Guo

Gels 2026, 12(5), 413; https://doi.org/10.3390/gels12050413 - 9 May 2026

Abstract

Hydrogels (HGs), three-dimensional cross-linked hydrophilic polymer networks, have emerged as a promising class of functional materials for sustainable agriculture due to their exceptional water retention capacity, responsiveness to environmental stimuli, and favorable biocompatibility. This review systematically summarizes the key functional properties of hydrogels [...] Read more.

Hydrogels (HGs), three-dimensional cross-linked hydrophilic polymer networks, have emerged as a promising class of functional materials for sustainable agriculture due to their exceptional water retention capacity, responsiveness to environmental stimuli, and favorable biocompatibility. This review systematically summarizes the key functional properties of hydrogels and critically examines their multidimensional roles within agricultural systems. The major synergistic benefits of hydrogels are highlighted, including (1) improvement of soil physical structure, chemical properties, and the biological microenvironment, thereby facilitating soil remediation; (2) direct enhancement of seed germination, root development, and crop productivity when employed as soil amendments or seed-coating materials; (3) controlled and sustained release of water, nutrients (N, P, K, and trace elements), and pesticides, leading to significant improvements in resource use efficiency; (4) functional delivery of beneficial microorganisms, enabling precise regulation of their activity and efficacy; and (5) advancement of soilless cultivation technologies through the development of sophisticated hydrogel-based substrates. Furthermore, this review discusses the key challenges that currently limit large-scale agricultural implementation, including insufficient biodegradability, potential ecotoxicological risks, and techno-economic constraints. Finally, future research directions are proposed from an interdisciplinary perspective, emphasizing rational material design, performance optimization, and practical field application. This comprehensive review aims to provide systematic theoretical guidance and practical insights for the development and deployment of hydrogel-based technologies in sustainable agriculture. Full article

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

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21 pages, 2645 KB

Open AccessArticle

Structural, Interfacial, Gelling, and Digestive Properties of Protein from Grifola frondosa Fruiting Body

by Yu Wang, Shuyu Song, Qiuyan Liu, Lihong Chen, Weimin Liu, Juan Wu and Yu Cheng

Gels 2026, 12(5), 412; https://doi.org/10.3390/gels12050412 - 9 May 2026

Abstract

Culture medium formulation influences mushroom yield and composition, but its effect on the properties of edible fungal protein remains unclear. To explore the functional and nutritional properties of proteins from Grifola frondosa (GF) fruiting bodies, the study examined the structural, interfacial, gelling, and [...] Read more.

Culture medium formulation influences mushroom yield and composition, but its effect on the properties of edible fungal protein remains unclear. To explore the functional and nutritional properties of proteins from Grifola frondosa (GF) fruiting bodies, the study examined the structural, interfacial, gelling, and digestive properties of GF proteins grown in four culture media. The four GF proteins obtained were labeled GFP1–GFP4, respectively. The β-turn content and intrinsic fluorescence in GFP1 increased by 41.48% and 36.45% (p < 0.05), respectively, compared to GFP4. GFP4 exhibited higher surface pressure at the air–water interface and lower interfacial force at the oil–water interface. In comparison with GFP4, the other GFPs showed a higher rate of interfacial film formation and greater film elasticity and strength. GFP2 had a minimum gelling concentration of 80 mg/mL, which is a 33.33% reduction from GFP4. The storage modulus (G′) of GFP1 was 58 times higher than that of GFP4 (10 Pa), indicating a significant increase in gel elasticity (p < 0.05). Additionally, compared to GFP4, GFP1 showed a 16.59% increase in total amino acid and a 6.82% increase in free amino group release (p < 0.05), although its digestibility decreased by 5.06% (p < 0.05). These results suggest that the formulation of the culture medium alters the structures and interfacial properties of GFPs, thereby impacting their functionalities and applications in food colloid-based products. Full article

(This article belongs to the Special Issue Food Gels: Fabrication, Characterization, and Application (2nd Edition))

15 pages, 2309 KB

Open AccessArticle

A Novel Polyacrylamide Composite Hydrogel Reinforced with Deep Eutectic Solvent-Pretreated Paulownia Cellulose/Nanocellulose: Preparation, Characterization and Properties

by Hanyin Li, Yi Meng, Luohui Wang, Yan Gao, Youming Dong, Liangdi Zhang, Fei Xiao, Hanmin Wang and Cheng Li

Gels 2026, 12(5), 411; https://doi.org/10.3390/gels12050411 - 8 May 2026

Abstract

Biomass represents a vital and sustainable resource for developing renewable materials with the potential to replace petroleum-based chemicals. Paulownia wood has high cellulose content and a loose wood structure, giving it natural advantages as a biomass material. Therefore, in this study, Paulownia wood [...] Read more.

Biomass represents a vital and sustainable resource for developing renewable materials with the potential to replace petroleum-based chemicals. Paulownia wood has high cellulose content and a loose wood structure, giving it natural advantages as a biomass material. Therefore, in this study, Paulownia wood was selected as a lignocellulosic feedstock. An integrated pretreatment process combining a deep eutectic solvent (DES) with an organic solvent was employed to efficiently remove lignin and hemicellulose, yielding cellulose-enriched residues. Subsequently, high-intensity ultrasonication was applied to convert the residues into cellulose nanofibers and nanocrystals. Using the extracted cellulose and nanocellulose, a dual-crosslinked network composite hydrogel was fabricated. The structural, mechanical, thermal, swelling, and conductive properties of the hydrogel were systematically investigated. The results show that, compared with the blank group hydrogel, the addition of nanocellulose increased the maximum tensile strength and tensile strain of the composite hydrogel by approximately 113% and 81%, respectively; meanwhile, the compressive strengths of the nanocellulose-based hydrogels (0.04575–0.09060 MPa) are higher than that of the blank group hydrogel (0.04235 MPa), confirming that the incorporation of nanocellulose significantly enhances the mechanical strength and elasticity of the hydrogel. The introduction of an AlCl₃/ZnCl₂ solvent system imparts appreciable electrical conductivity. Furthermore, the composite hydrogel maintains structural integrity after full swelling, indicating good dimensional stability and reusability. This work not only presents a green and efficient strategy for valorizing Paulownia biomass but also offers a novel design route for high-performance conductive hydrogel materials, highlighting their potential application in areas such as flexible electronics and energy storage. Full article

(This article belongs to the Special Issue Cellulose-Based Gels: Synthesis, Properties, and Applications (2nd Edition))

60 pages, 13767 KB

Open AccessReview

Cellulose-Based Hydrogels for Chronic Wound Healing: Bridging Biomaterial Design and Clinical Unmet Needs

by Irina Negut and Anita Ioana Visan

Gels 2026, 12(5), 410; https://doi.org/10.3390/gels12050410 - 8 May 2026

Abstract

Chronic wounds remain a persistent clinical challenge, trapped in a cycle of inflammation, infection, and impaired healing. While traditional dressings offer basic protection, they fail to address the complex pathophysiology of non-healing wounds. This review critically examines cellulose-based hydrogels as next-generation therapeutic platforms, [...] Read more.

Chronic wounds remain a persistent clinical challenge, trapped in a cycle of inflammation, infection, and impaired healing. While traditional dressings offer basic protection, they fail to address the complex pathophysiology of non-healing wounds. This review critically examines cellulose-based hydrogels as next-generation therapeutic platforms, analyzing their structure–property relationships, biofunctionalization strategies, and stimuli-responsive capabilities. We synthesize recent advances in antimicrobial, anti-inflammatory, and pro-regenerative hydrogels, highlighting how cellulose’s inherent tunability enables precision wound management. Finally, we confront the translational barriers—including scalability, sterilization, and regulatory hurdles—that must be overcome to bridge the gap between promising biomaterial research and clinical reality. By integrating materials science with wound pathophysiology, this review provides a roadmap for developing clinically viable cellulose-based hydrogels. Full article

(This article belongs to the Special Issue Nanocomposite Hydrogels for Drug Delivery and Wound Healing)

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16 pages, 11432 KB

Open AccessArticle

In Situ Assembly of NiFe-LDH on Porous Sr-Doped LaCoO₃ Scaffolds Using a Gel Template for High-Performance Oxygen Evolution Reaction

by Lina Zhang, Tian Fang, Changhai Liu, Wenchang Wang, Shiying Wang and Zhidong Chen

Gels 2026, 12(5), 409; https://doi.org/10.3390/gels12050409 - 8 May 2026

Abstract

This study reports a dual composition-interface engineering strategy for high-performance La_1−xSr_xCoO₃/NiFe-LDH hierarchical heterojunction. Porous La_1−xSr_xCoO₃ microspheres were synthesized through a gel route. Then it was used as an in situ–formed template to [...] Read more.

This study reports a dual composition-interface engineering strategy for high-performance La_1−xSr_xCoO₃/NiFe-LDH hierarchical heterojunction. Porous La_1−xSr_xCoO₃ microspheres were synthesized through a gel route. Then it was used as an in situ–formed template to grow NiFe-LDH nanosheets. The hierarchical design inhibits nanosheet aggregation and ensures robust interfacial contact, mitigating the intrinsic instability of physical mixtures. The prepared composite displays superior OER performance in 1.0 M KOH, delivering an overpotential of 237.8 mV at 10 mA cm⁻² and a Tafel slope of 85.06 mV dec⁻¹. These values exceed those of the original samples and commercial RuO₂ and the composite exhibits excellent long-term stability under harsh alkaline conditions. Complemented by DFT calculations, we further indicate that Sr doping coupled with the heterointerface induces substantial electronic structure reconstruction. This effectively switches the OER mechanism from conventional AEM to the thermodynamically more favorable LOM, overcoming the intrinsic scaling relation constraints of AEM. Full article

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

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20 pages, 8248 KB

Open AccessArticle

Epoxy Composites Reinforced with Sol–Gel Synthesized Alumina–Silica, Alumina, and Natural Silica Fillers: Comparative Mechanical Performance

by Milica Marković, Marija M. Vuksanović, Miloš Petrović, Željko Radovanović, Radmila Jančić Heinemann and Vera Obradović

Gels 2026, 12(5), 408; https://doi.org/10.3390/gels12050408 - 8 May 2026

Abstract

Epoxy resins are widely used thermosetting polymers, but their limited toughness and flexural resilience restrict broader applications. In this study, diglycidyl ether of bisphenol A (DGEBA) epoxy was reinforced with 5 wt.% ceramic fillers of different origins: sol–gel alumina calcined at 550 °C [...] Read more.

Epoxy resins are widely used thermosetting polymers, but their limited toughness and flexural resilience restrict broader applications. In this study, diglycidyl ether of bisphenol A (DGEBA) epoxy was reinforced with 5 wt.% ceramic fillers of different origins: sol–gel alumina calcined at 550 °C (γ-Al₂O₃) and 1000 °C (α-Al₂O₃), silica derived from rice husk, silica from diatomaceous earth, and a hybrid alumina–silica mixture prepared by sol–gel and calcined at 1000 °C. Fillers were structurally characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field-emission scanning electron microscopy (FESEM). Mechanical properties were evaluated through tensile (ASTM D638) and flexural (ASTM D790) testing. All reinforcements enhanced the performance of neat epoxy. γ-Al₂O₃ provided superior tensile reinforcement compared to α-Al₂O₃, underscoring the importance of particle morphology and surface reactivity. The hybrid alumina–silica filler achieved the highest flexural strength of 50.6 MPa, compared to 9.91 MPa for the neat epoxy. Bio-derived silica showed improved flexural properties, although its tensile reinforcement was less pronounced compared to the sol–gel derived fillers. These results establish clear structure–property relationships and confirm that filler phase, morphology, and calcination temperature critically govern the mechanical performance of epoxy composites. Full article

(This article belongs to the Topic Polymer and Biopolymer Nanocomposites for Emerging Medical, Industrial, and Environmental Applications)

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17 pages, 4750 KB

Open AccessArticle

Design and Evaluation of Alginate-Based Hydrogels for Controlled Release of Cationic and Anionic Model Compounds

by Archana Mishra, Kitz Paul D. Marco, Madeleine M. Melancon, Dominic Karl M. Bolinas, Allan John R. Barcena, Marvin R. Bernardino and Marites P. Melancon

Gels 2026, 12(5), 407; https://doi.org/10.3390/gels12050407 - 8 May 2026

Abstract

Alginate-based hydrogels are well-known materials for drug delivery. However, their sensitivity towards chelators and burst release remain concerns. Polyelectrolyte coatings have been proposed to control drug release from hydrogels, but it remains unclear how the types of coating influence the release kinetics of [...] Read more.

Alginate-based hydrogels are well-known materials for drug delivery. However, their sensitivity towards chelators and burst release remain concerns. Polyelectrolyte coatings have been proposed to control drug release from hydrogels, but it remains unclear how the types of coating influence the release kinetics of drugs with varying ionic properties. Hence, we explored combinations of natural (chitosan, alginate) and synthetic (polyethyleneimine [PEI], polyacrylic acid [PAA]) polyelectrolytes to modulate the release kinetics of alginate-based hydrogel beads. Rhodamine B (RhB, cationic) and trypan blue (TB, anionic) were used as model drugs. PAA resulted in a less porous coating, and PEI effectively reduced swelling. While uncoated beads showed burst release, polyelectrolyte coatings slowed release to varying degrees. Chitosan+alginate and chitosan+PAA coatings showed limited impact on RhB release. In contrast, PEI+alginate and PEI+PAA coatings significantly reduced RhB release from 86% (uncoated) to 61% and 6% after 4 days, respectively. Alginate–TB displayed inherently slower release across all systems, with polymer coatings further reducing cumulative release from 49% (uncoated) to 7% in PEI+PAA-coated beads. Overall, polyelectrolyte coatings had a greater influence on the anionic payload, and PEI+PAA-coated beads emerged as promising carriers for controlled release of both cationic and anionic drugs. Full article

(This article belongs to the Special Issue Alginate-Based Gels: Preparation, Characterization and Application (3rd Edition))

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23 pages, 12059 KB

Open AccessArticle

Electrostatic Protein–Polysaccharide Assembly as a Potential Alternative to Ionic Gelation for Millimeter-Scale Hydrogel Beads: Insights into Accelerated Gelation from an Amaranth Protein–Xanthan Gum System

by María del Carmen Cortez-Trejo, Ramón Román-Doval, Lucía Abadía-García, Sandra O. Mendoza and Silvia L. Amaya-Llano

Gels 2026, 12(5), 406; https://doi.org/10.3390/gels12050406 - 8 May 2026

Abstract

Electrostatic protein–polysaccharide hydrogels are attractive materials formed without thermal denaturation or chemical crosslinkers and at low biopolymer contents. Their broader application in foods, however, has been limited by slow gelation, with network development often requiring many hours (~18 h). In this study, millimeter-scale [...] Read more.

Electrostatic protein–polysaccharide hydrogels are attractive materials formed without thermal denaturation or chemical crosslinkers and at low biopolymer contents. Their broader application in foods, however, has been limited by slow gelation, with network development often requiring many hours (~18 h). In this study, millimeter-scale hydrogel beads were fabricated from amaranth proteins and xanthan gum by extrusion into glucono-δ-lactone (GDL) solutions (1–5 mg/mL) using hardening times of 10 or 30 min. Beads were successfully formed under all conditions (3.07–3.95 mm diameter), and their physicochemical properties, intermolecular interactions, microstructure, and gel strength were evaluated. Electrostatic attraction remained the dominant force driving gelation. Furthermore, 10 min hardening favored interpolymeric electrostatic interactions, whereas longer exposure reduced them and promoted hydrogen bonding and hydrophobic interactions. These molecular rearrangements were accompanied by a decreased size, lower water retention capacity (WRC), and higher mechanical strength. The mildest treatment (1 mg/mL GDL, 10 min) was post-loaded with a coffee pulp phenolic extract and showed reduced gel strength and electrostatic interactions, suggesting competition for binding sites within the macromolecular network. The extrusion of amaranth protein–xanthan gum mixtures into a GDL bath markedly shortens electrostatic gelation time, supporting this approach as a potential alternative to ionic gelation for the production of millimeter-scale hydrogel beads for food applications. Full article

(This article belongs to the Special Issue Gels: Diversity of Structures and Applications in Food Science)

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26 pages, 11651 KB

Open AccessArticle

Hafnium Oxide-Based Nanostructures as Powders and in Polyvinyl Alcohol Hydrogels for Light-Assisted Processes

by Mihai Anastasescu, Polona Umek, Cristina Maria Vladut, Veronica Bratan, Catalin Negrila, Silviu Preda, Luminita Predoana, Catalina Gifu, Cristina Lavinia Nistor, Daniela C. Culita, Daiana Mitrea, Crina Anastasescu, Maria Zaharescu and Ioan Balint

Gels 2026, 12(5), 405; https://doi.org/10.3390/gels12050405 - 8 May 2026

Abstract

Hafnia (hafnium oxide) nanostructures, both unmodified and silica-modified with minor and major silica content, were synthesized using an adapted sol–gel method with D-L tartaric acid as an internal template. After thermal treatment, structural non-stoichiometry and light absorptive properties were identified in the resulting [...] Read more.

Hafnia (hafnium oxide) nanostructures, both unmodified and silica-modified with minor and major silica content, were synthesized using an adapted sol–gel method with D-L tartaric acid as an internal template. After thermal treatment, structural non-stoichiometry and light absorptive properties were identified in the resulting hafnium-based nanostructures, indicating their potential for various applications, including photocatalysis. The ability of these materials to photogenerate reactive oxygen species (ROS), namely superoxide anion radicals (•O₂₋) under simulated solar light (AM 1.5) and singlet oxygen (¹O₂) under visible light (λ > 390 nm), was evaluated and monitored by UV–Vis and photoluminescence spectroscopy. Functionalization of hafnium-based oxides with protoporphyrin IX was employed to enhance singlet oxygen photogeneration. The reactivity of the generated (¹O₂) was assessed by quenching of DL α-tocopherol photoluminescence under visible light irradiation. Photocatalytic experiments conducted under anaerobic conditions demonstrated the ability of the hafnia-based nanostructures to reduce 1,4-benzoquinone (BQ) to 1,4-hydroquinone (H₂Q). Furthermore, embedding the hafnia-based powders into polyvinyl alcohol hydrogels enabled the obtainment of photoactive coatings on glass substrates, for which their mechanical properties were evaluated using force–distance spectroscopy measurements. Morphological and structural characterization of the materials was performed using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), atomic force microscopy (AFM), X-ray diffraction and fluorescence (XRD, XRF), X-ray photoelectron spectroscopy (XPS), N₂ adsorption–desorption measurements, UV–Vis spectroscopy, photoluminescence (PL) spectroscopy, and zeta potential measurements. These investigations revealed that adding silica induces significant modifications in the morphology, texture, and structure of the hafnia, thereby enhancing the functional properties of the resulting materials. Full article

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

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