Gels

16 pages, 4816 KB

Open AccessArticle

Bioorthogonally Cross-Linked Injectable PEG Hydrogel with Robust Hemostatic and Antibacterial Properties

by Jun Zhai, Qiwen Huang, Lei Ni, Chenming Li, Li Hao, Jian Chen, Cheng Chi, Risheng Li, Yong-Miao Shen, Ronggui Lu and Zhijun Zhang

Gels 2026, 12(6), 556; https://doi.org/10.3390/gels12060556 (registering DOI) - 20 Jun 2026

Abstract

The rapid hemostasis of deep and irregular wounds is of great clinical significance. In this study, an injectable hemostatic hydrogel based on bioorthogonal conjugation was developed. This gel uses thrombin (TMB) as the hemostatic active substance and 4ARM-PEG-N₃ as the crosslinking agent, [...] Read more.

The rapid hemostasis of deep and irregular wounds is of great clinical significance. In this study, an injectable hemostatic hydrogel based on bioorthogonal conjugation was developed. This gel uses thrombin (TMB) as the hemostatic active substance and 4ARM-PEG-N₃ as the crosslinking agent, which undergo orthogonal conjugation via the classic azide–alkyne click reaction to form an injectable hydrogel (TMB-PEG). The resulting hydrogel exhibited a transparent, injectable gel state. TEM images revealed that the hydrogel comprised sheet-like structures and interwoven fibers with a diameter of approximately 100 nanometers. In a puncture bleeding wound model, hemostasis with the TMB-PEG hydrogel required only 25 s, with a blood loss of 1.9 ± 1.3 mg, both approximately one-sixth of that of the control group. Moreover, the hemostatic performance of the TMB-PEG hydrogel was far superior to that of three other commonly used hemostatic materials. Furthermore, cephalosporin antibiotics were conjugated to the hemostatic gel via orthogonal reactions, endowing it with significant broad-spectrum antibacterial activity, achieving over 99% antibacterial efficacy against both Gram-negative and Gram-positive bacteria. Full article

(This article belongs to the Topic Advanced Nanomaterials and Technologies for Sustainable Development)

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15 pages, 6283 KB

Open AccessArticle

Robust Polyurethane Hydrogels Based on Dynamic Disulfide Bonds and Pendant Tertiary Amines with Room-Temperature Self-Healing and pH Responsiveness

by Xia Ding, Bing Yang, Xinyi Si, Lei Ni, Chao Fang and Zhaosheng Hou

Gels 2026, 12(6), 555; https://doi.org/10.3390/gels12060555 (registering DOI) - 20 Jun 2026

Abstract

Hydrogels have garnered significant attention due to their tunable structures and broad applicability in biomedical and smart materials. However, achieving a balance between excellent mechanical performance and multifunctionality remains a major challenge. In this study, a series of multifunctional polyurethane hydrogels (PUGs) was [...] Read more.

Hydrogels have garnered significant attention due to their tunable structures and broad applicability in biomedical and smart materials. However, achieving a balance between excellent mechanical performance and multifunctionality remains a major challenge. In this study, a series of multifunctional polyurethane hydrogels (PUGs) was developed by integrating dynamic disulfide bonds and pendant tertiary amine groups into poly(ethylene glycol)-based networks using a solvent-exchange method. Structural characterization confirmed the successful formation of a crosslinked porous network. The hydrogels demonstrated remarkable mechanical properties, with PUG–II exhibiting a tensile strength of 448 kPa and an elongation at break of 489%, as well as exceptional compressibility (371 kPa at 90% strain) and fatigue resistance. Meanwhile, the PUGs displayed efficient room-temperature self-healing with a healing efficiency of up to 94.5%. The reversible protonation of tertiary amine groups imparted pronounced pH-responsive swelling behavior, with the equilibrium swelling ratio of PUG–I at pH 2.0 being 5.8 times higher than that at pH 12.0. This study provides a promising strategy for developing PU-based hydrogels that combine robust mechanical performance and multifunctionality, offering potential for advanced smart material applications. Full article

(This article belongs to the Special Issue Novel Polymer-Based Smart Hydrogels: Design, Properties and Applications)

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15 pages, 20083 KB

Open AccessArticle

An Environmentally Tolerant 5A Hydrogel with Photothermal Effect for Frostbite Treatment

by Jianmei Chen, Yifan Wu, Tiantian Zhu, Hongyu Wu, Meiling Su and Zongguang Liu

Gels 2026, 12(6), 554; https://doi.org/10.3390/gels12060554 (registering DOI) - 20 Jun 2026

Abstract

Rapid rewarming is the most conventional and primary treatment for frostbite, yet effective adjunctive strategies remain absent. Conventional wound dressings, such as therapeutic hydrogels, tend to freeze and lack the necessary rewarming ability, rendering them unsuitable for direct application. Herein, we engineered an [...] Read more.

Rapid rewarming is the most conventional and primary treatment for frostbite, yet effective adjunctive strategies remain absent. Conventional wound dressings, such as therapeutic hydrogels, tend to freeze and lack the necessary rewarming ability, rendering them unsuitable for direct application. Herein, we engineered an environmentally tolerant photothermal hydrogel, named 5A-Gel, featuring anti-swelling, anti-pressure, antioxidant, anti-freezing, and anti-drying capacities, for the treatment of frostbite. 5A-Gel was formed via dynamic crosslinking between gelatin and tea polyphenols in a glycerol/water solvent system. The incorporation of glycerol endowed the hydrogel with superior anti-swelling, anti-freezing, and anti-drying performance (remaining flexible at −20 °C and 37 °C for at least 60 days), along with concentration-dependent antioxidant activity due to tea polyphenols. Furthermore, 5A-Gel exhibited excellent photothermal effects, maintaining stable temperature and softness under 808 nm laser irradiation with robust cyclic durability. In addition, 5A-Gel showed slow degradability, excellent hemocompatibility, and favorable in vivo biosafety. Functionally, in a mouse frostbite wound model, photothermal rewarming therapy using 5A-Gel markedly expedited frostbite healing, promoting re-epithelialization, enhancing collagen deposition, alleviating inflammatory response, and stimulating neovascularization. Therefore, the as-prepared 5A-Gel serves as a competent therapeutic platform for in situ frostbite treatment and offers innovative principles for the rational engineering of high-performance hydrogel systems targeting frostbite tissue injuries. Full article

(This article belongs to the Special Issue Novel Hydrogels for Drug Delivery and Regenerative Medicine)

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38 pages, 3286 KB

Open AccessReview

Rational Design of Carbon Aerogels for Alkali-Metal-Ion Batteries: Controlled Synthesis, Heteroatom Doping, and Energy Storage Applications

by Anrui Li, Simin Hua, Le Sun, Qinsi Shao, Delun Zhu and Ruicheng Bai

Gels 2026, 12(6), 553; https://doi.org/10.3390/gels12060553 (registering DOI) - 19 Jun 2026

Abstract

Carbon aerogels possess continuous three-dimensional conductive networks, hierarchical pore architectures, and tunable surface chemistry. These structural characteristics make them suitable electrode materials for alkali-metal-ion batteries. This review examines the controlled synthesis and heteroatom doping of carbon aerogels. The discussion links framework construction, electronic-structure [...] Read more.

Carbon aerogels possess continuous three-dimensional conductive networks, hierarchical pore architectures, and tunable surface chemistry. These structural characteristics make them suitable electrode materials for alkali-metal-ion batteries. This review examines the controlled synthesis and heteroatom doping of carbon aerogels. The discussion links framework construction, electronic-structure modulation, and storage mechanism matching with their electrochemical behavior. The rational design of carbon aerogels should move beyond the simple pursuit of high specific surface area or high dopant content. Effective electrodes require the coordinated regulation of pore architecture, conductive continuity, heteroatom-doped sites, and ion-storage pathways. The current application status of carbon aerogels in alkali-metal-ion batteries is also analyzed from an industrial perspective. A mechanism-oriented and application-oriented framework is therefore required to translate carbon aerogel-based electrodes from structural optimization to a practical battery. Full article

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

15 pages, 7271 KB

Open AccessArticle

Application of ECIS to Evaluate the Effects of Porcine Urinary Bladder Matrix Hydrogels on Caco-2 Cell Attachment, Migration, and Barrier Formation

by Wei-Ling Chen, Chi-Tien Chen, Huynh-Quang-Dieu Nguyen, Phenpitcha Charoensaensuk, Chen-Yu Kao and Chun-Min Lo

Gels 2026, 12(6), 552; https://doi.org/10.3390/gels12060552 (registering DOI) - 19 Jun 2026

Abstract

Recent studies have highlighted the potential of urinary bladder matrix (UBM) derived from decellularized porcine urinary bladder as a bioactive hydrogel. Despite its complex composition of over 100 proteins, Type I collagen is the primary constituent of UBM. Caco-2 cells are widely used [...] Read more.

Recent studies have highlighted the potential of urinary bladder matrix (UBM) derived from decellularized porcine urinary bladder as a bioactive hydrogel. Despite its complex composition of over 100 proteins, Type I collagen is the primary constituent of UBM. Caco-2 cells are widely used as an in vitro model of the intestinal epithelium; however, to date, no published study has evaluated the effects of UBM on Caco-2 cells. In this study, Electric Cell–Substrate Impedance Sensing (ECIS) was used to measure Caco-2 cell attachment and wound-healing migration on UBM-coated microelectrodes. Our results demonstrate that UBM hydrogel coating at 0.2 mg/mL significantly accelerates cell attachment and enhances migration rates compared to uncoated controls. These stimulatory effects were comparable to those observed with 0.2 mg/mL Type I collagen, suggesting that UBM can function as effectively as Type I collagen. We further monitored barrier formation in Caco-2 cells cultured on UBM-coated transwell membrane inserts using TEER measurements and scanning electron microscopy. The TEER values reached 300 Ω·cm² within three days, indicating the rapid establishment of mature tight junctions. Overall, these results show that UBM hydrogel coatings are effective substrates for Caco-2 cells, performing as well as Type I collagen in all our tests. Full article

(This article belongs to the Special Issue Advances in Hydrogels for Regenerative Medicine (2nd Edition))

28 pages, 15345 KB

Open AccessArticle

Preliminary Assessment of BNC Membranes as Solvent Delivery Systems for the Cleaning of Mural Paintings: Comparison with Traditional Gel Systems

by Francesco Menconi, Ulderico Santamaria, Alessandro Cardarelli, Eleonora Imperio and Sara Iafrate

Gels 2026, 12(6), 551; https://doi.org/10.3390/gels12060551 (registering DOI) - 19 Jun 2026

Abstract

Growing demand for greener and more sustainable materials in cultural heritage conservation has prompted the investigation of bio-based alternatives for cleaning applications. This study presents a preliminary evaluation of bacterial nanocellulose (BNC) membranes for the removal of acrylic resins from mural paintings, comparing [...] Read more.

Growing demand for greener and more sustainable materials in cultural heritage conservation has prompted the investigation of bio-based alternatives for cleaning applications. This study presents a preliminary evaluation of bacterial nanocellulose (BNC) membranes for the removal of acrylic resins from mural paintings, comparing commercial medical-grade and laboratory-produced BNC with conventional gel systems under simulated application conditions. Both BNC types were characterized in terms of composition, pH, electrical conductivity, Water Holding Capacity and Water Retention Rate. Acetone loading via solvent exchange was assessed by thermogravimetric analysis (TGA), while mechanical behavior before and after solvent loading was evaluated through tensile testing and optical density measurements of the immersion media. The performance of BNCs and reference delivery systems was comparatively assessed in terms of solvent retention, solvent penetration depth into the substrate and residue release. Cleaning performance was investigated through FTIR spectroscopy and semi-quantitative image analysis as indirect indicators of residual resin content, on both mock-up samples and in situ applications. Under the tested conditions, both BNC membranes were compatible with acetone loading and maintained mechanical integrity after solvent exposure. FTIR analysis showed a reduction in the acrylic carbonyl band after treatment with acetone-loaded BNC, which exhibited greater solvent diffusion depth; the underlying removal mechanism, including the possible contribution of solvent-driven redistribution phenomena, remains to be clarified. Differences in reproducibility were observed between medical-grade and laboratory-produced BNC. Overall, the study provides experimental data contributing to the assessment of BNC membranes as bio-based solvent delivery systems for conservation practice. Full article

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

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16 pages, 14998 KB

Open AccessArticle

Gradient Anisotropic Natural Rubber-PNIPAM Composite Hydrogels for Programmable NIR-Responsive Actuation

by Qing Zhang, Xueliang Feng, Yuxin Yan, Lin Chen, Honghua Fan, Wenjing Zhou, Kaipeng Li, Xiaohong Yang, Xueyu Du and Chunxin Ma

Gels 2026, 12(6), 550; https://doi.org/10.3390/gels12060550 (registering DOI) - 19 Jun 2026

Abstract

Heterogeneous hydrogels capable of complex, programmable deformation are highly desirable for soft actuators, yet general strategies that simultaneously impart structural anisotropy, rapid responsiveness, and mechanical robustness remain limited. Here, a gradient anisotropic natural rubber-poly(N-isopropylacrylamide) (NR-PNIPAM) composite hydrogel is developed through a simple one-pot [...] Read more.

Heterogeneous hydrogels capable of complex, programmable deformation are highly desirable for soft actuators, yet general strategies that simultaneously impart structural anisotropy, rapid responsiveness, and mechanical robustness remain limited. Here, a gradient anisotropic natural rubber-poly(N-isopropylacrylamide) (NR-PNIPAM) composite hydrogel is developed through a simple one-pot polymerization strategy by coupling pH-regulated colloidal stability with gravity-directed redistribution of natural rubber latex particles. Under an optimized pH window, NR nanoparticles gradually migrate during gelation and are fixed as a continuous gradient within the PNIPAM network, generating built-in structural asymmetry for nonuniform deformation. Meanwhile, NR nanoparticles act as soft reinforcing domains to improve mechanical strength, while water-soluble graphene nanosheets provide efficient photothermal conversion for remotely-controlled near-infrared (NIR)-responsive actuation. Benefiting from this synergistic design, the hydrogel exhibits programmable bending and localized folding with high actuation rates of 129° s⁻¹ and 46° s⁻¹, respectively, along with a tensile strength of 0.32 MPa and an active lifting capability exceeding 70 times its own weight. The material further enables biomimetic gripping and lifting under NIR stimulation. This work establishes a general route to robust gradient hydrogels by integrating colloidal regulation, structural anisotropy, and photothermal actuation, offering a versatile platform for high-performance soft intelligent systems. Full article

(This article belongs to the Special Issue Advances in Functional Gel (3rd Edition))

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17 pages, 1700 KB

Open AccessArticle

Olive Mill Wastewater-Loaded Polysaccharide Hydrogels as Potential Antibacterial Films for Wound Healing

by Eleonora Russo, Carla Villa, Anna Maria Schito and Debora Caviglia

Gels 2026, 12(6), 549; https://doi.org/10.3390/gels12060549 (registering DOI) - 19 Jun 2026

Abstract

Polysaccharide-based hydrogels represent promising platforms for the development of bioactive wound dressings due to their biocompatibility, bioadhesive properties, and ability to maintain a moist environment at the wound interface. In this study, polymeric films were developed from natural polysaccharides incorporating olive mill wastewater [...] Read more.

Polysaccharide-based hydrogels represent promising platforms for the development of bioactive wound dressings due to their biocompatibility, bioadhesive properties, and ability to maintain a moist environment at the wound interface. In this study, polymeric films were developed from natural polysaccharides incorporating olive mill wastewater (OMW) as a natural antibacterial agent. Chitosan (medium molecular weight), sodium alginate, sodium hyaluronate, and xanthan gum were selected to prepare hydrogel formulations either as single polymers or binary mixtures. Hydrogels were prepared by aqueous dispersion under magnetic stirring and subsequently converted into films using a solvent casting method. The resulting films were characterized in terms of rheological behavior, pH, morphology, thickness and water content. The obtained hydrogel films showed good casting ability, producing smooth and homogeneous matrices with adequate deformability and skin adhesion. Furthermore, they demonstrated a suitable capacity to absorb and retain water, mimicking the management of wound exudate. OMW was incorporated into the hydrogel formulations as a source of phenolic compounds with well-known antioxidant and antimicrobial properties. The presence of these bioactive compounds provides the films with potential antibacterial and antibiofilm activity against clinically relevant multidrug-resistant staphylococcal strains. These findings suggest that OMW-loaded polysaccharide hydrogels represent a promising and sustainable strategy for the development of antibacterial films for wound healing applications. Full article

(This article belongs to the Special Issue Polysaccharide-Based Gels)

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23 pages, 4333 KB

Open AccessArticle

Effects of Acid Modification on Physicochemical Properties of Soybean and Citrus Dietary Fibers and Their Application in Probiotic-Fermented Soy Protein Gels

by Youxin Yan, Meixin Wang, Yuan Zhang, Ke Zhang and Feng Xue

Gels 2026, 12(6), 548; https://doi.org/10.3390/gels12060548 (registering DOI) - 19 Jun 2026

Abstract

Dietary fibers are valuable food components with documented health benefits, yet their native compact and highly crystalline structures often result in low water hydration, poor adsorption capacity, and limited bioactivity. Chemical modification offers a promising strategy to overcome these functional limitations by disrupting [...] Read more.

Dietary fibers are valuable food components with documented health benefits, yet their native compact and highly crystalline structures often result in low water hydration, poor adsorption capacity, and limited bioactivity. Chemical modification offers a promising strategy to overcome these functional limitations by disrupting the dense structure and exposing active groups. This study aimed to investigate the effects of acid modification on the physicochemical properties of soybean and citrus dietary fibers and to evaluate the performance of the modified fibers in probiotic-fermented soy protein gels. Compared with native fibers, modified fibers exhibited reduced particle size, rougher and more porous microstructures, and increased exposure of hydroxyl groups. Consequently, they showed significantly (p < 0.05) enhanced hydration capacity (increased by 92–541%), antioxidant activity (increased by 15–65%), cholesterol adsorption (increased by 16–75%), and α-amylase inhibition (increased by 26–62%). When incorporated into soy protein-based gels, the modified fibers, particularly those from soybean, lowered gel pH, increased water holding capacity, gel strength, apparent viscosity, and storage modulus, while reducing strain, indicating improved gel network integrity. These findings indicate that acid modification effectively unlocks the functional potential of dietary fibers, positioning the modified fibers, especially from soybean, as promising prebiotic ingredients for plant-based fermented gel products. Full article

(This article belongs to the Special Issue Food Gels: Gelling Property in Food Processing and Engineering)

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15 pages, 7330 KB

Open AccessArticle

Frontal Polymerization-Enabled Rapid Fabrication of Gelatin-Containing Hydrogels with Good Mechanical and Biological Properties

by Fucheng Li, Weixiong Yuan, Yonglin Chen, Chang Liu, Cai-Feng Wang and Su Chen

Gels 2026, 12(6), 547; https://doi.org/10.3390/gels12060547 (registering DOI) - 19 Jun 2026

Abstract

A time-saving approach to gelatin-based hydrogels with versatile properties is highly desirable. Herein, we report the rapid fabrication of new gelatin-containing hydrogels with favorable mechanical properties, biocompatibility and antibacterial capability. Frontal polymerization (FP) of acrylic acid (AA), acrylamide (AM), hydroxypropyl acrylate (HPA) with [...] Read more.

A time-saving approach to gelatin-based hydrogels with versatile properties is highly desirable. Herein, we report the rapid fabrication of new gelatin-containing hydrogels with favorable mechanical properties, biocompatibility and antibacterial capability. Frontal polymerization (FP) of acrylic acid (AA), acrylamide (AM), hydroxypropyl acrylate (HPA) with gelatin methacryloyl (GelMA) enables the rapid formation of multifunctional hydrogels within 7 min, providing a highly efficient route for gelatin-based hydrogel fabrication. The effect of GelMA content on FP features and hydrogel properties was systematically investigated. The resultant hydrogels show attractive collective properties with tensile strength up to 101.3 kPa, elongation at break up to 227.7%, cell viability of 96% after 24 h, and antibacterial activity against S. aureus (92.2%). In addition, the FP of the hydrogels with use of forsythia-derived carbon dots (F-CDs) as bioactive nanofillers is explored, conferring the hydrogels with enhanced mechanical performance and biocompatibility, demonstrating the applicability of this FP strategy upon incorporating functional additives. This work provides a simple and effective approach for the rapid preparation of gelatin-containing hydrogels with versatile functions promising for biomedical applications such as wound healing and tissue engineering. Full article

(This article belongs to the Special Issue Hydrogels: Properties and Application in Biomedicine)

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14 pages, 5145 KB

Open AccessArticle

Luminescent Nanoparticles of Gd₂O₃:Eu³⁺ Encapsulated Within SiO₂–PMMA Gel–Polymer Hybrid Matrix: Synthesis and Optical Properties

by Martin Rodolfo Palomino Merino, Juan de la Cruz Quiroga, Oliver Isac Ruiz Hernández, Oscar Mario Martínez Bravo, Benito de Celis Alonso, Angélica Gutiérrez Franco, Miller Toledo Solano, Claudia Mendoza Barrera and Humberto Salazar Ibargüen

Gels 2026, 12(6), 546; https://doi.org/10.3390/gels12060546 (registering DOI) - 18 Jun 2026

Abstract

Luminescent gadolinium oxide nanoparticles doped with europium were synthesized through a precipitation reaction using gadolinium and europium nitrates as precursors. The europium-doped gadolinium oxide nanoparticles were incorporated first into a gel matrix of silicon dioxide and second by mixing with polymethyl methacrylate. Both [...] Read more.

Luminescent gadolinium oxide nanoparticles doped with europium were synthesized through a precipitation reaction using gadolinium and europium nitrates as precursors. The europium-doped gadolinium oxide nanoparticles were incorporated first into a gel matrix of silicon dioxide and second by mixing with polymethyl methacrylate. Both processes are synthesized by the simultaneous hydrolysis of tetraethyl orthosilicate and polymerization of 3-(Trimethoxysilyl) propyl methacrylate. The solid samples obtained are round in shape with a size of about 2.5 cm, which makes the material easy to handle to test different applications. The inclusion of Gd₂O₃:Eu³⁺ nanoparticles increases the level of absorbance in the ultraviolet region, which allows for the improved emission of the material at a wavelength of around 610 nm. Furthermore, it enables easy doping of the material and the fabrication of thin films and monoliths with potential optical applications. Full article

(This article belongs to the Special Issue Advances in Hybrid and Functional Gels: Design, Characterization, and Emerging Applications)

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17 pages, 534 KB

Open AccessArticle

Reformulation of Emulsion-Type Pork Sausage Using Collagen and Plasma Proteins as Soy Protein Substitutes for Soy-Free Product Development

by Ionela Ramona Gheorghe (Pîrvu), Violeta Nour and Georgiana Gabriela Codină

Gels 2026, 12(6), 545; https://doi.org/10.3390/gels12060545 - 18 Jun 2026

Abstract

The present study evaluated the feasibility of replacing soy protein isolate with collagen and plasma proteins, either individually or in combination with κ-carrageenan, xanthan gum, and sodium tripolyphosphate, in an emulsion-type pork sausage, based on selected physicochemical, compositional, and textural quality parameters. Six [...] Read more.

The present study evaluated the feasibility of replacing soy protein isolate with collagen and plasma proteins, either individually or in combination with κ-carrageenan, xanthan gum, and sodium tripolyphosphate, in an emulsion-type pork sausage, based on selected physicochemical, compositional, and textural quality parameters. Six formulations were produced, including a control and five reformulated variants in which soy protein was fully replaced by a mixture of collagen (1.88%) and plasma proteins (3.4%), used alone or supplemented with κ-carrageenan (1.0%), xanthan gum (0.2%), and sodium tripolyphosphate (0.2%). Moisture, protein, fat and collagen contents, color, pH, and sensory properties were analyzed after processing, while TBARS values and textural properties were assessed initially and after 30 days of storage. As a result of the reformulation, collagen content increased by 32.35–40.33%, while the collagen-to-protein ratio remained within legal limits (<20%). Soy protein replacement increased textural parameters, including hardness, cohesiveness, gumminess, chewiness, and shear force. Carrageenan and sodium tripolyphosphate enhanced texture and oxidative stability, whereas xanthan gum negatively affected texture quality and sensory acceptance. The formulation containing collagen, plasma proteins, carrageenan (1%) and sodium tripolyphosphate (0.2%) achieved the highest sensory scores, comparable to those of the control. The results show that replacing soy protein in an emulsion-type pork sausage is feasible when using optimized combinations of collagen, plasma proteins, and κ-carrageenan systems. Full article

(This article belongs to the Special Issue Advances in Food Gels: Structure, Processing and Applications)

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19 pages, 4982 KB

Open AccessArticle

Alginate–Chitosan Gel Microbeads for PhiKZ Encapsulation as a Model of Bacteriophage Delivery to Combat Pseudomonas aeruginosa

by Liubov I. Popova, Elizaveta A. Akoulina, Evgeniia Yu. Parshina, Timofey A. Tarasov, Hejia Yue, Qing Peng, Ying Zhang, Andrei A. Dudun, Anton P. Bonartsev, Olga S. Sokolova and Tolbert Osire

Gels 2026, 12(6), 544; https://doi.org/10.3390/gels12060544 - 17 Jun 2026

Abstract

Wound infections due to antibiotic resistance pose a global public health problem. Phage therapy is a promising approach to address this issue. To improve localization, phage stability, delivery, and antibacterial performance, we propose polymer mix gel microbeads encapsulated with phages as a model [...] Read more.

Wound infections due to antibiotic resistance pose a global public health problem. Phage therapy is a promising approach to address this issue. To improve localization, phage stability, delivery, and antibacterial performance, we propose polymer mix gel microbeads encapsulated with phages as a model for the delivery of phiKZ bacteriophage to combat Pseudomonas aeruginosa. Phages were loaded into the alginate pre-gel under magnetic stirring, with further cross-linking by chitosan and/or Ca²⁺ ions. The obtained gel microbeads were characterized using FTIR and Raman spectroscopy, and their cytotoxicity and antimicrobial properties were evaluated. This study demonstrated the efficient loading of high-titer phage lysate, achieving up to 99% encapsulation efficiency for alginate–chitosan microbeads. The key characteristics of the microbeads include stable physicochemical properties, slow but continuous phage release over 48 h in physiological saline, and low cytotoxicity. The phage-loaded microbeads demonstrated strong in vitro antimicrobial activity against P. aeruginosa PAO1, resulting in mean reductions of 6.9 log₁₀ and 4.8 log₁₀ CFU/mL for alginate and alginate–chitosan formulations, respectively. This corresponded to a decrease in bacterial concentration from approximately 1.1 × 10¹¹ CFU/mL in untreated controls to 1.1 × 10⁵ CFU/mL and 7.7 × 10⁶ CFU/mL for alginate and alginate–chitosan formulations after 3 h of incubation. Full article

(This article belongs to the Special Issue Polysaccharide-Based Gels)

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24 pages, 8169 KB

Open AccessArticle

Reservoir Equilibrium Development Method by Combined Conformance Control of Polymer/Gel-Dispersed Fluids

by Xin Chen, Jiayi Zhu, Yiqiang Li, Zheyu Liu, Jianbin Liu, Houfeng He and Shun Liu

Gels 2026, 12(6), 543; https://doi.org/10.3390/gels12060543 - 17 Jun 2026

Abstract

Reservoir conformance control is a necessary production measure in the oil field, which significantly impacts the efficiency of enhanced oil recovery (EOR). Polymers, hydrophobic associating polymers (HAPs), polymer microgels (MGs), and preformed particle gel (PPG) are typical polymer/gel dispersion fluids that are widely [...] Read more.

Reservoir conformance control is a necessary production measure in the oil field, which significantly impacts the efficiency of enhanced oil recovery (EOR). Polymers, hydrophobic associating polymers (HAPs), polymer microgels (MGs), and preformed particle gel (PPG) are typical polymer/gel dispersion fluids that are widely used as conformance control agents. Currently, there is still no combined conformance control method to realize the equilibrium production of the reservoir. This paper first evaluates the reservoir adaptability of polymers, HAPs, and MGs by the three-parallel core displacement experiments. Then, the displacement equilibrium factor (DEF) was established by comprehensively considering the profile improvement, oil increment, and oil recovery to optimize the fluid switching time. Based on the above oil displacement experiments, a scatter plot of the DEF with respect to the ultimate recovery of each layer can be plotted, which has an inflection point when the DEF is 45%. When the DEF is lower than 45%, the difference in the oil displacement effect of each layer is enhanced. Therefore, the best time to switch the injection fluid is when the DEF is reduced to 45%. Finally, based on the above results, a graph guiding the combined conformance control method under different reservoir variation coefficients and reservoir median permeability was established, and an equilibrium production method for heterogeneous reservoirs was developed. The five-parallel core flooding experiments with the DEF < 45% as the switching guidance can increase the oil recovery by 17.79% based on association polymer flooding, which is 9.68% higher than that of the conventional conformance control method. This paper can provide theoretical and experimental support for the optimal design of conformance control in oilfields. Full article

(This article belongs to the Special Issue Advances and Application of Polymer Gels for Subsurface Energy and Storage)

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28 pages, 7751 KB

Open AccessArticle

Mild Heat Stimulating and Microenvironment Reprogramming Hydrogel for Accelerating Diabetic Wound Healing

by Xueting Xiao, Yannan Liu, Dan Li, Lebin Wang, Zirui Hu, Xinliang Xing, Yali Ding, Xurun Wang, Ruifan Zhang, Jing Yang and Xiaoxuan Ma

Gels 2026, 12(6), 542; https://doi.org/10.3390/gels12060542 - 17 Jun 2026

Abstract

Diabetic wounds are characterized by persistent hyperglycemia, excessive ROS accumulation, sustained inflammation, and impaired angiogenesis, yet current treatments remain suboptimal. To address these challenges, we developed a mild heat stimulating and microenvironment reprogramming hydrogel (termed C-4-N) via a green synthetic strategy. L-Arginine (L-Arg) [...] Read more.

Diabetic wounds are characterized by persistent hyperglycemia, excessive ROS accumulation, sustained inflammation, and impaired angiogenesis, yet current treatments remain suboptimal. To address these challenges, we developed a mild heat stimulating and microenvironment reprogramming hydrogel (termed C-4-N) via a green synthetic strategy. L-Arginine (L-Arg) triggered the spontaneous self-polymerization of protocatechuic aldehyde (PA) into poly (protocatechuic aldehyde) (PPA) nanoparticles, onto which ginsenoside Compound K (CK) was subsequently loaded, yielding CK/L-Arg/PPA nanoparticles. These nanoparticles were then uniformly embedded into a dynamic disulfide network composed of α-lipoic acid (LA)-modified chitosan (CS-LA) and 4-arm-PEG-SH under UV irradiation without toxic photo-initiators, forming the C-4-N hydrogel. The C-4-N hydrogel reprogrammed the diabetic wound microenvironment through three synergistic mechanisms, lowering blood glucose and scavenging ROS via the coordinated actions of LA, CK and PPA, promoting M1-to-M2 macrophage polarization via downregulation of pro-inflammatory cytokines (TNF-α, IL-6) and upregulation of anti-inflammatory cytokines (IL-10, TGF-β1), further amplified by mild photothermal stimulation of 40–43 °C. In a diabetic rat model, the C-4-N hydrogel achieved a near-complete wound closure rate of 99.49 ± 0.10% on day 13 upon mild photothermal stimulation, accompanied by enhanced re-epithelialization, organized collagen deposition, vascular maturation, and systemic glucose regulation. In summary, this green synthesized, mild heat-stimulating hydrogel establishes a synergistic microenvironment reprogramming paradigm for chronic diabetic wound managements. Full article

(This article belongs to the Special Issue Hydrogels with Appropriate/Tunable Properties for Biomedical Applications (3rd Edition))

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34 pages, 4785 KB

Open AccessArticle

Multifunctional 3D-Printed Alginate Emulgel Patches Incorporating Plant Extracts for Potential Burn Wound Applications

by Roxana Colette Sandulovici, Ion Mircioiu, Mariana Panțuroiu, Corneliu Dan Blendea, Mirela Claudia Rîmbu, Daniel Cord, Carmen Elisabeta Manea, Carmen Marinela Mihăilescu, Mirela Antonela Mihăilă, Iulian Sârbu, Horia Sebastian Iliescu, Manuel Ovidiu Amzoiu, Adina Boldeiu, Vasilica Țucureanu, Oana Brîncoveanu, Luiza Mădălina Cima and Mona Luciana Gălățanu

Gels 2026, 12(6), 541; https://doi.org/10.3390/gels12060541 - 17 Jun 2026

Abstract

Multifunctional dressings capable of maintaining a moist environment, supporting tissue regeneration, and delivering bioactive compounds are increasingly being explored as promising strategies for burn wound management. In this study, alginate-based emulgel patches incorporating hydrophilic and lipophilic plant extracts were developed by extrusion-based 3D [...] Read more.

Multifunctional dressings capable of maintaining a moist environment, supporting tissue regeneration, and delivering bioactive compounds are increasingly being explored as promising strategies for burn wound management. In this study, alginate-based emulgel patches incorporating hydrophilic and lipophilic plant extracts were developed by extrusion-based 3D printing as potential topical systems for burn wound applications. The formulation included sodium alginate, hyaluronic acid, and hydroglyceric extracts of Calendula officinalis, Matricaria chamomilla, and Plantago major, as well as oily extracts of Hippophae rhamnoides and Hypericum perforatum. The emulgel was evaluated for pH, rheological behaviour, spreadability, physical stability, apparent hydrodynamic size distribution, zeta potential, total polyphenol content, and antioxidant activity. Following Ca²⁺-induced crosslinking, uniform and flexible 3D-printed patches were obtained and further characterised for pharmacotechnical, physicochemical, structural, functional, and biological properties. The emulgel exhibited suitable characteristics for extrusion-based printing, while the resulting patches showed good dimensional uniformity, flexibility, swelling capacity, water vapour transmission, and surface pH compatible with topical application. FTIR, DLS, SEM, and SEM–EDX analyses supported the formation of a Ca²⁺-crosslinked alginate network and confirmed the presence of structurally heterogeneous domains with homogeneous calcium distribution. The patches retained plant-derived bioactive compounds, with a total polyphenol content of 0.2878 ± 0.016 mg GAE/g hydrated patch, and showed improved antioxidant activity compared with the corresponding emulgel. In vitro release studies indicated the time-dependent diffusion of polyphenols over 24 h, with cumulative release reaching 64.42%. The patches also exhibited a water vapour transmission rate of 1270 ± 93 g/m²/24 h, indicating adequate moisture regulation. HaCaT cell viability remained above 90% at lower tested concentrations, demonstrating a favourable biocompatibility profile. Overall, the developed 3D-printed alginate emulgel patches represent promising multifunctional systems for potential burn wound management and warrant further preclinical investigation. Full article

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

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16 pages, 1630 KB

Open AccessArticle

Designing Tunable GelMA Hydrogels by Integrating Mammalian and Non-Mammalian Gelatins

by Cristina Padilla, Vanessa Campos, Eduardo González, Francisco Kirhman and Javier Enrione

Gels 2026, 12(6), 540; https://doi.org/10.3390/gels12060540 - 15 Jun 2026

Abstract

Modulating the physical crosslink architecture of gelatin methacryloyl (GelMA) hydrogels without altering total polymer concentration or introducing exogenous components remains a central challenge in biomaterial design. Here, we present a source blending strategy in which porcine skin gelatin (PG) and salmon skin gelatin [...] Read more.

Modulating the physical crosslink architecture of gelatin methacryloyl (GelMA) hydrogels without altering total polymer concentration or introducing exogenous components remains a central challenge in biomaterial design. Here, we present a source blending strategy in which porcine skin gelatin (PG) and salmon skin gelatin (SG), two gelatins with markedly different proline and hydroxyproline contents, are combined at seven compositional ratios (PG weight fractions 0–1.0) and subsequently functionalized to GelMA under standardized conditions (8% v/v methacrylic anhydride, 60 °C, 3 h). Near-complete degrees of substitution (95–98%) were achieved across all formulations, as confirmed by both TNBS and ¹H-NMR analyses. In the parent gelatin mixtures, increasing PG fraction progressively increased viscosity, elastic modulus (G′), gelation temperature (Tgel), and compression modulus at 4 °C, with DSC revealing independent SG (0–15 °C) and PG (20–40 °C) endothermic transitions that suggest partial hindrance of PG triple-helix formation by high SG fractions. These composition-dependent trends were preserved after functionalization to GelMA, albeit with attenuated physical crosslinking due to steric impairment by the methacrylate groups. Photocrosslinked GelMA hydrogels fabricated after pre-incubation at 4 °C exhibited systematically higher compression moduli and lower swelling degrees with increasing PG content, demonstrating that the PG/SG ratio provides an effective means for independently tuning hydrogel mechanics and mesh architecture. In vitro release assays using Rhodamine 6G further demonstrated that pre-incubation at 4 °C prior to photocrosslinking effectively modulates transport kinetics in SG-PG GelMA hydrogels. This strategy delayed characteristic release times and constrained Weibull shape parameters to the anomalous-transport regime (0.75 < β < 1), where diffusion is governed by network chain relaxation. This effect was most pronounced in the 0.4SG:0.6PG formulation, where lower SG content permitted unhindered triple-helix formation, as corroborated by DSC and compression studies. Ultimately, adjusting the pre-incubation temperature and gelatin source combination provides a straightforward, processing-additive-free strategy to achieve programmable release profiles via controlled matrix tortuosity. Full article

(This article belongs to the Special Issue Hydrogels: Properties and Application in Biomedicine)

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Graphical abstract

12 pages, 3996 KB

Open AccessArticle

Development of Antiseptic and Epidermal Growth Factor Co-Loaded Thermoresponsive Composite Hydrogel for Wound Healing: Fabrication, Characterization, and In Vitro Functional Assessment

by Ting-Jui Wang, Chieh-An Chen and Yu-Hsiang Lee

Gels 2026, 12(6), 539; https://doi.org/10.3390/gels12060539 - 15 Jun 2026

Abstract

Deep wounds often lead to severe complications such as persistent infection, biofilm formation, and high patient morbidity. While skin injuries can usually be managed with functional dressings, wounds in deep layers without sufficient treatment may serve as primary entry points for bacterial infection, [...] Read more.

Deep wounds often lead to severe complications such as persistent infection, biofilm formation, and high patient morbidity. While skin injuries can usually be managed with functional dressings, wounds in deep layers without sufficient treatment may serve as primary entry points for bacterial infection, thereby posing a significant life-threatening risk to patients. With the rising prevalence of chronic diseases and an aging population, effective strategies for enhanced wound healing are still in high demand. In this study, an injectable and thermoresponsive hexamethylene diisocyanate–Pluronic F127 copolymer–hyaluronic acid composite hydrogel loaded with polyhexamethylene biguanide (PHMB) and epidermal growth factor (EGF), named PEHHPG, was developed for joint therapy of deep wounds. PEHHPG self-gels at 37 °C and stabilizes both agents in the gel matrix. Based on the results of microbial colony assay and analysis of fibroblast growth kinetics, PEHHPG with ≥200 ppm of PHMB and ≥0.15 μg/mL of EGF can eradicate bacteria and enhance cell proliferation in vitro, illustrating the functionalities of PEHHPG. Given the aforementioned effects, together with the recognized advantages of injectable hydrogels such as wound shape/depth adaptation, low adhesiveness, exudate absorptiveness, and moisture maintenance, the developed PEHHPG is anticipated to be a feasible dressing material for deep wound treatment after further in vivo examinations. Full article

(This article belongs to the Special Issue Polymeric Hydrogels for Biomedical Application (2nd Edition))

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18 pages, 2110 KB

Open AccessArticle

Self-Healing Bilayer Hydrogel Solid-State Electrochemical Platform: Time-Resolved In Situ Dynamic Monitoring of Escherichia coli Activity

by Ye Li, Chaofan Zhang, Miao Zhang, Shi Zhou, Yanping Yu, Xiaoyan Yu, Ximing Cui and Xiangge Qin

Gels 2026, 12(6), 538; https://doi.org/10.3390/gels12060538 - 15 Jun 2026

Abstract

Achieving in situ and time-resolved monitoring of microbial metabolites without disrupting the microbial growth environment remains a key challenge in electrochemical biosensing. Herein, we propose a self-healing bilayer hydrogel-based solid-state electrochemical sensing platform for the in situ, time-resolved analysis of purine metabolites produced [...] Read more.

Achieving in situ and time-resolved monitoring of microbial metabolites without disrupting the microbial growth environment remains a key challenge in electrochemical biosensing. Herein, we propose a self-healing bilayer hydrogel-based solid-state electrochemical sensing platform for the in situ, time-resolved analysis of purine metabolites produced by Escherichia coli (E. coli). This platform integrates an upper Agar culture module and a lower borax-crosslinked poly(vinyl alcohol) (PVA) detection module, forming a contiguous structure that allows metabolites (e.g., guanine, xanthine, hypoxanthine) to migrate across the solid–solid interface for sensitive electrochemical detection. The detection layer exhibits excellent ionic conductivity; when coupled with its robust structural self-healing capacity, the platform achieved a detection limit of 0.05 µM for guanine. For E. coli detection, a linear response range of 1.1 × 10⁶ to 9.5 × 10⁶ CFU·mL⁻¹ (R² = 0.9974) was obtained, and relative standard deviations (RSDs) of less than 2.34% even after two weeks of storage. Leveraging this integrated design, the platform enables continuous, label-free tracking of bacterial metabolic dynamics throughout all growth phases. Notably, it detects metabolic transition points earlier than traditional plate counting methods and accurately evaluates antibiotic inhibition trends, with results consistent with colony-forming unit (CFU) analysis. This integrated culture–detection architecture thus provides a versatile strategy for functional microbial analysis and rapid antimicrobial susceptibility testing. Full article

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

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