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Volume 11
Issue 3
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Gels, Volume 11, Issue 3 (March 2025) – 70 articles

Cover Story (view full-size image): Self-healing hydrogels were synthesized using oxidized hydroxybutanoyl glycan (OHbG) and quaternized carboxymethyl chitosan (QCMCS). The successful modification of these polysaccharides was confirmed through 1H NMR analysis. A dual cross-linking mechanism, involving imine bonds and ionic interactions, enhanced the hydrogel’s self-healing ability and thermal stability, with improvements observed as the OHbG concentration increased. The hydrogel exhibited high compressive strength, significant swelling capacity, and pH-dependent drug release behavior. Additionally, it retained its antioxidant and antibacterial properties, as well as the inherent characteristics of the polysaccharides. These findings underscore the biocompatibility and stimuli-responsive nature of the OHbG/QCMCS hydrogel, making it a promising drug carrier for pharmaceutical and biomedical applications. View this paper
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21 pages, 4544 KiB  
Article
Injectable Magnetic-Nanozyme Based Thermosensitive Hydrogel for Multimodal DLBCL Therapy
by Min Yan, Jingcui Peng, Haoan Wu, Ming Ma and Yu Zhang
Gels 2025, 11(3), 218; https://doi.org/10.3390/gels11030218 - 20 Mar 2025
Viewed by 418
Abstract
Diffuse large B-cell lymphoma (DLBCL), accounting for 31% of non-Hodgkin lymphomas, remains recalcitrant to conventional therapies due to chemoresistance, metastatic progression, and immunosuppressive microenvironments. We report a novel injectable Fe3O4@DMSA@Pt@PLGA-PEG-PLGA hydrogel system integrating magnetothermal therapy (MHT), chemodynamic therapy (CDT), [...] Read more.
Diffuse large B-cell lymphoma (DLBCL), accounting for 31% of non-Hodgkin lymphomas, remains recalcitrant to conventional therapies due to chemoresistance, metastatic progression, and immunosuppressive microenvironments. We report a novel injectable Fe3O4@DMSA@Pt@PLGA-PEG-PLGA hydrogel system integrating magnetothermal therapy (MHT), chemodynamic therapy (CDT), and immunomodulation. Under alternating magnetic fields (AMF), the system achieves rapid therapeutic hyperthermia (50 °C within 7 min) while activating pH/temperature-dual responsive peroxidase (POD) -like activity in Fe3O4@DMSA@Pt nanoparticles. Catalytic efficiency under tumor-mimetic conditions was significantly higher than Fe3O4@DMSA controls, generating elevated reactive oxygen species (ROS). Flow cytometry revealed 75.9% apoptotic cell death in A20 lymphoma cells at 50 °C, significantly surpassing CDT alone (24.5%). Importantly, this dual mechanism induced immunogenic cell death (ICD) characterized by 4.1-fold CRT externalization, 68% HMGB1 nuclear depletion, and 40.74 nM ATP secretion. This triggered robust dendritic cell maturation (92% CD86+/CD80+ DCs comparable to LPS controls) and T cell activation (16.9% CD25+/CD69+ ratio, 130-fold baseline). Our findings validate the therapeutic potential of magnetothermal-chemodynamic synergy for DLBCL treatment, paving the way for innovative multi-mechanism therapeutic strategies against DLBCL with potential clinical translation prospects. Full article
(This article belongs to the Special Issue Recent Advances in Gels Engineering for Drug Delivery (2nd Edition))
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17 pages, 3765 KiB  
Article
A Multifunctional γ-Polyglutamic Acid Hydrogel for Combined Tumor Photothermal and Chemotherapy
by Xiaoqing Jia and Shige Wang
Gels 2025, 11(3), 217; https://doi.org/10.3390/gels11030217 - 20 Mar 2025
Cited by 5 | Viewed by 453
Abstract
Efficient and precise cancer therapy remains a challenge due to limitations in current treatment modalities. In this study, we developed a multifunctional hydrogel system that integrates photothermal therapy (PTT) and chemotherapy to achieve combined tumor treatment. The hydrogel, composed of γ-polyglutamic acid (γ-PGA), [...] Read more.
Efficient and precise cancer therapy remains a challenge due to limitations in current treatment modalities. In this study, we developed a multifunctional hydrogel system that integrates photothermal therapy (PTT) and chemotherapy to achieve combined tumor treatment. The hydrogel, composed of γ-polyglutamic acid (γ-PGA), fifth-generation polyamide-amine dendrimers (G5), and polydopamine (PDA) nanoparticles, exhibits high photothermal conversion efficiency and temperature-responsive drug release properties. The hydrogel exhibited a high photothermal conversion efficiency of 45.6% under 808 nm near-infrared (NIR) irradiation. Drug release studies demonstrated a cumulative hydrophilic anticancer drug doxorubicin DOX release of 79.27% within 72 h under mild hyperthermia conditions (50 °C). In vivo experiments revealed a significant tumor inhibition rate of 82.3% with minimal systemic toxicity. Comprehensive in vitro and in vivo evaluations reveal that the hydrogel demonstrates excellent biocompatibility, photothermal stability, and biodegradability. Unlike conventional hydrogel systems, our γ-PGA-based hydrogel uniquely integrates a biocompatible and biodegradable polymer with polydopamine (PDA) nanoparticles, providing a smart and responsive platform for precise cancer therapy. This multifunctional hydrogel system represents a promising platform that combines PTT precision and chemotherapy efficacy, providing a robust strategy for advanced and safer cancer treatment. Full article
(This article belongs to the Special Issue Hydrogels, Microgels, and Nanogels: From Fundamentals to Applications (2nd Edition))
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23 pages, 3379 KiB  
Review
Hydrogel-Based Biomaterials: A Patent Landscape on Innovation Trends and Patterns
by Ahmed Fatimi, Fouad Damiri, Nada El Arrach, Houria Hemdani, Adina Magdalena Musuc and Mohammed Berrada
Gels 2025, 11(3), 216; https://doi.org/10.3390/gels11030216 - 20 Mar 2025
Viewed by 916
Abstract
The hydrogel patent landscape is characterized by rapid growth and diverse applications, particularly in the biomedical field. Advances in material science, chemistry, novel manufacturing techniques, and a deeper understanding of biological systems have revolutionized the development of hydrogel-based biomaterials. These innovations have led [...] Read more.
The hydrogel patent landscape is characterized by rapid growth and diverse applications, particularly in the biomedical field. Advances in material science, chemistry, novel manufacturing techniques, and a deeper understanding of biological systems have revolutionized the development of hydrogel-based biomaterials. These innovations have led to enhanced properties and expanded applications, particularly in regenerative medicine, drug delivery, and tissue engineering, positioning hydrogels as a pivotal material in the future of biomedical engineering. In this study, an updated patent landscape for hydrogel-based biomaterials is proposed. By analyzing patent documents, classifications, jurisdictions, and applicants, an overview is provided to characterize key trends and insights. The analysis reveals that hydrogel-related patents are experiencing significant growth, with a strong focus on biomedical applications. Foundational research in hydrogel formation remains dominant, with 96,987 patent documents highlighting advancements in crosslinking techniques, polysaccharide-based materials, and biologically active hydrogels for wound care and tissue regeneration. The United States and China lead in hydrogel-related patent filings, with notable contributions from Europe and a high number of international patents under the Patent Cooperation Treaty (PCT) system, reflecting the global interest in hydrogel technologies. Moreover, emerging innovations include biodegradable hydrogels designed for tissue regeneration, wearable hydrogel-based sensors, and advanced therapeutic applications such as chemoembolization agents and vascular defect treatments. The increasing integration of bioactive elements in hydrogel systems is driving the development of multifunctional biomaterials tailored to specific medical and environmental needs. While this study focuses on patent trends, the alignment between hydrogel research and patenting activities underscores the role of patents in bridging scientific discoveries with industrial applications. Future research could explore patent citation analysis and impact assessments to gain deeper insights into the technological significance of hydrogel-related inventions. Finally, a selection of the top 10 recent active and granted patents in the field of hydrogel-based biomaterials is presented as an illustrative example of innovation in this area and to illustrate cutting-edge innovations. Full article
(This article belongs to the Special Issue Gel-Related Materials: Challenges and Opportunities)
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19 pages, 2942 KiB  
Article
The Effects of Encapsulating Bioactive Irish Honey into Pluronic-Based Thermoresponsive Hydrogels and Potential Application in Soft Tissue Regeneration
by Daniel P. Fitzpatrick, Emma Browne, Carmel Kealey, Damien Brady, Siobhan Kavanagh, Sinead Devery and Noel Gately
Gels 2025, 11(3), 215; https://doi.org/10.3390/gels11030215 - 19 Mar 2025
Viewed by 407
Abstract
Honey has been recognised for centuries for its potential therapeutic properties, and its application in wound healing has gained attention due to its antimicrobial, anti-inflammatory, and regenerative properties. With the rapid increase in multidrug resistance, there is a need for new or alternative [...] Read more.
Honey has been recognised for centuries for its potential therapeutic properties, and its application in wound healing has gained attention due to its antimicrobial, anti-inflammatory, and regenerative properties. With the rapid increase in multidrug resistance, there is a need for new or alternative approaches to traditional antibiotics. This paper focuses on the physicochemical changes that occur when formulating honey into Pluronic F127 hydrogels. The manual incorporation of honey, irrespective of quality type, presented the amelioration of Pluronic’s capacity to undergo sol–gel transitions, as investigated by parallel plate rheology. This novel finding was attributed to the formation of fractal aggregates via the hydrogen-bonding-induced irreversible aggregation of honey–PF127 micelles, which subsequently dominate the entire hydrogel system to form a gel. The hydrogen bonding of micelles was identified through Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR), Differential Scanning Calorimetry (DSC), and Dynamic Light Scattering (DLS). This is the first known study to provide physicochemical insight into the effects that honey incorporation has on the thermogelation capacity of Pluronic F127 hydrogels for downstream dermal wound applications. Full article
(This article belongs to the Special Issue Customizing Hydrogels: A Journey from Concept to End-Use Properties)
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11 pages, 736 KiB  
Article
Improving Vaginal Health with a Zinc-Containing Vaginal Hydrogel
by Dávid Rátonyi, Barbara Kozma, Attila G. Sipos, Zoárd Tibor Krasznai, Bence Kozma and Peter Takacs
Gels 2025, 11(3), 214; https://doi.org/10.3390/gels11030214 - 19 Mar 2025
Viewed by 575
Abstract
Vulvovaginal symptoms affect up to 39% of women. These symptoms have a significant impact on quality of life and are often linked to imbalances in the vaginal microbiota. This study evaluates the therapeutic efficacy of a zinc-containing hydroxyethyl cellulose-based hydrogel in 37 women [...] Read more.
Vulvovaginal symptoms affect up to 39% of women. These symptoms have a significant impact on quality of life and are often linked to imbalances in the vaginal microbiota. This study evaluates the therapeutic efficacy of a zinc-containing hydroxyethyl cellulose-based hydrogel in 37 women with different vulvovaginal symptoms (itching, burning, irritation, pain, dryness, discharge, and odor). Over 12 weeks, participants applied the gel intravaginally with both assessments conducted at baseline and follow-ups. Results revealed substantial improvements in symptoms, including reductions in vaginal discharge, itching, and burning, as measured by the Vulvovaginal Symptom Questionnaire (VSQ-21), with scores decreasing from 10.78 ± 3.66 at baseline to 3.17 ± 4.16 at week 12 (p < 0.01). Vaginal Health Index (VHI) scores improved significantly, from 20.78 ± 1.74 at baseline to 23.64 ± 2.59 (p < 0.01). Cervicovaginal lavage (CVL) zinc levels decreased from 110 ± 102 µg/L at baseline to 62 ± 48 µg/L at week 4 (p < 0.01), increased to 80 ± 55 µg/L at week 8 (p = 0.04), and reached 99 ± 92 µg/L by week 12 (NS). A correlation analysis showed an inverse relationship between baseline CVL zinc levels and VSQ-21 scores (r = −0.3586, p = 0.034), while no significant correlation was observed with VHI scores (r = −0.0187, p = 0.9545). Vaginal pH levels decreased significantly, dropping from 4.03 ± 0.42 to 3.71 ± 0.48 (p < 0.01). These findings support the gel’s role as an effective, nonhormonal, drug-free, and local adjunct treatment for a variety of vulvovaginal symptoms. Full article
(This article belongs to the Special Issue Advanced Soft Gels with Enhanced Functionality for Biomedical and Additive Manufacturing Applications)
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23 pages, 6412 KiB  
Article
Influence of Cell Seeding Density and Material Stiffness on Chondrogenesis of Human Stem Cells Within Soft Hydrogels, Without the Use of Exogenous Growth Factors
by Arianna De Mori, Nadide Aydin, Giada Lostia, Alessia Manca, Gordon Blunn and Marta Roldo
Gels 2025, 11(3), 213; https://doi.org/10.3390/gels11030213 - 18 Mar 2025
Viewed by 476
Abstract
Mesenchymal stem cells (MSCs) can differentiate into chondrocytes provided with the appropriate environmental cues. In this study, we loaded human adipose-derived stem cells (hAdMSCs) into collagen/alginate hydrogels, which have been shown to induce chondrogenesis in ovine bone marrow stem cells without the use [...] Read more.
Mesenchymal stem cells (MSCs) can differentiate into chondrocytes provided with the appropriate environmental cues. In this study, we loaded human adipose-derived stem cells (hAdMSCs) into collagen/alginate hydrogels, which have been shown to induce chondrogenesis in ovine bone marrow stem cells without the use of any exogenous chondrogenic growth factors. We examined the influence of hydrogel stiffness (5.75 and 6.85 kPa) and cell seeding density (1, 2, 4, and 16 × 106 cells/mL) on the chondrogenic induction of hAdMSCs, without exogenous differentiation growth factors. Over time, the behaviour of the hAdMSCs in the scaffolds was investigated by analysing the amount of DNA; their morphology; their cell viability; the expression of chondrogenic genes (RT-qPCR); and the deposition of collagen I, collagen II, and aggrecan. The results showed that all scaffolds supported the acquisition of a rounded morphology and the formation of cell aggregates, which were larger with higher cell seeding densities. Furthermore, the cells were viable within the hydrogels throughout the experiment, indicating that high cell density did not have a detrimental effect on viability. All the conditions supported the upregulation of chondrogenic genes (SOX9, COL2A1, SOX5, and ACAN). By comparison, only the highest cell seeding density (16 × 106 cells/mL) promoted a superior extracellular matrix deposition composed of collagen II and aggrecan with limited production of collagen I. These molecules were deposited in the pericellular space. Furthermore, no histological difference was noted between the two stiffnesses. Full article
(This article belongs to the Special Issue Synthesis, Characterization and Applications of Collagen-Based Gels)
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16 pages, 3928 KiB  
Article
Combined Effect of pH and Neutralizing Solution Molarity on the Rheological Properties of Chitosan Hydrogels for Biomedical Applications
by Sofia Jansen de Medeiros Alves, Matheus Araújo Santos, João Emídio da Silva Neto, Henrique Nunes da Silva, Milena C. S. Barbosa, Marcus Vinicius Lia Fook, Rômulo Feitosa Navarro and Suédina Maria de Lima Silva
Gels 2025, 11(3), 212; https://doi.org/10.3390/gels11030212 - 18 Mar 2025
Viewed by 342
Abstract
Hydrogels are promising materials for biomedical applications due to their tunable properties. Despite significant research on optimizing the mechanical and rheological properties of chitosan hydrogels, a comprehensive analysis incorporating pH and molarity of the neutralizing solution is still lacking. This study addresses this [...] Read more.
Hydrogels are promising materials for biomedical applications due to their tunable properties. Despite significant research on optimizing the mechanical and rheological properties of chitosan hydrogels, a comprehensive analysis incorporating pH and molarity of the neutralizing solution is still lacking. This study addresses this gap by evaluating how these factors influence the rheological characteristics of chitosan hydrogels. The hydrogels were prepared using an acidic blend and were neutralized with sodium hydroxide solutions. Rheological characterization demonstrated that all samples exhibited pseudoplastic behavior, with viscosity decreasing under shear stress. Hydrogels with higher pH values exhibited lower viscosity, which is attributed to the reduced protonation and weaker electrostatic repulsion between chitosan chains. In contrast, more acidic conditions resulted in increased viscosity and greater chain entanglements. NaOH concentration impacted gel stability; lower concentrations resulted in more stable gels, whereas higher concentrations increased crosslinking but compromised integrity at elevated pH. These findings provide essential insights for optimizing chitosan hydrogels with customized properties, making them highly suitable for specific biomedical applications, such as advanced 3D-printed wound dressings. Full article
(This article belongs to the Special Issue Rheological Properties and Applications of Gel-Based Materials)
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20 pages, 8566 KiB  
Article
Simultaneous Removal of Heavy Metals and Dyes on Sodium Alginate/Polyvinyl Alcohol/κ-Carrageenan Aerogel Beads
by Taesoon Jang, Soyeong Yoon, Jin-Hyuk Choi, Narae Kim and Jeong-Ann Park
Gels 2025, 11(3), 211; https://doi.org/10.3390/gels11030211 - 16 Mar 2025
Viewed by 2330
Abstract
Industrial textile wastewater containing both heavy metals and dyes has been massively produced. In this study, semi-interpenetrating polymer network structures of sodium alginate (SA)/polyvinyl alcohol (PVA)/κ-carrageenan (CG) aerogel beads were synthesized for their simultaneous reduction. The SA/PVA/CG aerogel beads were synthesized through a [...] Read more.
Industrial textile wastewater containing both heavy metals and dyes has been massively produced. In this study, semi-interpenetrating polymer network structures of sodium alginate (SA)/polyvinyl alcohol (PVA)/κ-carrageenan (CG) aerogel beads were synthesized for their simultaneous reduction. The SA/PVA/CG aerogel beads were synthesized through a cost-effective and environmentally friendly method using naturally abundant biopolymers without toxic cross-linkers. The SA/PVA/CG aerogel beads were spheres with a size of 3.8 ± 0.1 mm, exhibiting total pore areas of 15.2 m2/g and porous structures (pore size distribution: 0.04–242.7 μm; porosity: 93.97%) with abundant hydrogen bonding, high water absorption capacity, and chemical resistance. The adsorption capacity and mechanisms of the SA/PVA/CG aerogel beads were investigated through kinetic and isotherm experiments for heavy metals (Cu(II), Pb(II)), cationic dye (methylene blue, MB), and anionic dye (acid blue 25, AB)) in both single and binary systems. The maximum adsorption capacities of the SA/PVA/CG aerogel beads based on the Langmuir model of Cu(II), Pb(II), and MB were 85.17, 265.98, and 1324.30 mg/g, respectively. Pb(II) showed higher adsorption affinity than Cu(II) based on ionic properties, such as electronegativity and hydration radius. The adsorption of Cu(II), Pb(II), and MB on the SA/PVA/CG aerogel beads was spontaneous, with heavy metals and MB exhibiting endothermic and exothermic natures, respectively. Full article
(This article belongs to the Special Issue Eco-Friendly Gels for Adsorption)
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12 pages, 2949 KiB  
Article
Preliminary Investigation into the Use of Amino-Acid-Derived Ionic Liquids for Extracting Cellulose from Waste Biomass to Prepare Cellulose Aerogel Adsorbents
by Yun Deng, Qiusheng Zhao, Shuai Nian, Ziyan Sha, Lin Fu, Ian Beadham, Xiaolan Xiao and Changbo Zhang
Gels 2025, 11(3), 210; https://doi.org/10.3390/gels11030210 - 16 Mar 2025
Viewed by 666
Abstract
To investigate the feasibility of cellulose extraction from lignocellulosic waste biomass using ionic liquids—a sustainable and efficient approach—for preparing cellulose aerogel adsorbents, we employed a fully green amino acid-derived ionic liquid, cysteine nitrate ([Cys][NO3]), for cellulose separation from diverse biomass sources. [...] Read more.
To investigate the feasibility of cellulose extraction from lignocellulosic waste biomass using ionic liquids—a sustainable and efficient approach—for preparing cellulose aerogel adsorbents, we employed a fully green amino acid-derived ionic liquid, cysteine nitrate ([Cys][NO3]), for cellulose separation from diverse biomass sources. The extracted cellulose, with a purity range of 83.8–93.9%, was processed into cellulose aerogels (CAs) via a conventional aerogel preparation protocol. The resulting CA exhibited promising adsorption capacities, including 0.2–11.6 mg/g for Na+, 4.4–19.9 mg/g for Ca2+, 4.15–35.6 mg/g for Mg2+, and 1.85–13.3 mg/g for Cd2+, as well as 9.7–17.7 g/g for engine oil. These results demonstrate the presence of effective mass transfer channels in the CA, proving that the cellulose’s fibrillation capacity was preserved in the pre-treatment. This study illuminates the potential of this green, straightforward method for preparing aerogels from cellulose derived from waste biomass, with promising applications in wastewater treatment and material recovery. Full article
(This article belongs to the Special Issue Aerogels—Preparation and Properties)
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18 pages, 2680 KiB  
Article
Rheology and Printability of Hydroxyapatite/Sodium Alginate Bioinks Added with Bovine or Fish Collagen Peptides
by Mario Milazzo, Roberta Rovelli, Claudio Ricci, Teresa Macchi, Giuseppe Gallone and Serena Danti
Gels 2025, 11(3), 209; https://doi.org/10.3390/gels11030209 - 15 Mar 2025
Viewed by 580
Abstract
The high biocompatibility and the key role of collagen in bone extracellular matrix make it useful for tissue engineering. However, the high demand, costs, and challenges of extracting good-quality collagen have led to the use of collagen derivatives and search for non-human alternatives. [...] Read more.
The high biocompatibility and the key role of collagen in bone extracellular matrix make it useful for tissue engineering. However, the high demand, costs, and challenges of extracting good-quality collagen have led to the use of collagen derivatives and search for non-human alternatives. This study investigates fish and bovine collagen peptides (Collf and Collb, respectively) as sustainable sources for 3D-printed bone scaffolds by developing and characterizing peptide-incorporated alginate/hydroxyapatite-based bioinks. The chemical analysis revealed structural similarities between the peptides, while rheological tests showed a slightly higher viscosity of Collf-based inks, which improved shape fidelity during the printing process. Upon oscillating rheological tests, both the Collf and Collb-based ink formulations demonstrated a solid-like behavior at frequencies higher than 0.4 Hz, which is crucial for maintaining the printed structure integrity during extrusion. Although Collb-based inks exhibited better pore printability, Collf-based inks achieved superior resolution and geometry retention. Macro-porous structures printed from both inks showed good accuracy, with minimal shrinkage attributed to hydroxyapatite. Both the produced inks had a high gel fraction and swelling behavior, with Collb-based outperforming Collf-based inks. Finally, both ink formulations resulted to be cytocompatibile with human dermal fibroblasts. These findings position Collf- and Collb-based inks as promising alternatives for bone tissue scaffolds, offering a sustainable balance between performance and structural stability in 3D printing applications. Full article
(This article belongs to the Special Issue Recent Advances in Hydrogels for Biomedical Application (2nd Edition))
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50 pages, 14462 KiB  
Article
Novel Buccal Xanthan Gum–Hyaluronic Acid Eutectogels with Dual Anti-Inflammatory and Antimicrobial Properties
by Valentina Anuța, Mihaela-Alexandra Nica, Răzvan-Mihai Prisada, Lăcrămioara Popa, Bruno Ștefan Velescu, Ioana Cristina Marinas, Diana-Madalina Gaboreanu, Mihaela Violeta Ghica, Florentina Iuliana Cocoș, Cristian Andi Nicolae and Cristina-Elena Dinu-Pîrvu
Gels 2025, 11(3), 208; https://doi.org/10.3390/gels11030208 - 15 Mar 2025
Viewed by 727
Abstract
Buccal drug delivery systems often struggle with poor drug solubility, limited adhesion, and rapid clearance, leading to suboptimal therapeutic outcomes. To address these limitations, we developed a novel hybrid eutectogel composed of xanthan gum (XTG), hyaluronic acid (HA), and a Natural Deep Eutectic [...] Read more.
Buccal drug delivery systems often struggle with poor drug solubility, limited adhesion, and rapid clearance, leading to suboptimal therapeutic outcomes. To address these limitations, we developed a novel hybrid eutectogel composed of xanthan gum (XTG), hyaluronic acid (HA), and a Natural Deep Eutectic Solvent (NADES) system (choline chloride, sorbitol, and glycerol in 2:1:1 mole ratio), incorporating 2.5% ibuprofen (IBU) as a model drug. The formulation was optimized using a face-centered central composite design to enhance the rheological, textural, and drug release properties. The optimized eutectogels exhibited shear-thinning behavior (flow behavior index, n = 0.26 ± 0.01), high mucoadhesion (adhesiveness: 2.297 ± 0.142 N·s), and sustained drug release over 24 h, governed by Higuchi kinetics (release rate: 237.34 ± 13.61 μg/cm2/min1/2). The ex vivo residence time increased substantially with NADES incorporation, reaching up to 176.7 ± 23.1 min. An in vivo anti-inflammatory evaluation showed that the eutectogel reduced λ-carrageenan-induced paw edema within 1 h and that its efficacy was sustained in the kaolin model up to 24 h (p < 0.05), achieving comparable efficacy to a commercial 5% IBU gel, despite a lower drug concentration. Additionally, the eutectogel presented a minimum inhibitory concentration for Gram-positive bacteria of 25 mg/mL, and through direct contact, it reduced microbial viability by up to 100%. Its efficacy against Bacillus cereus, Enterococcus faecium, and Klebsiella pneumoniae, combined with its significant anti-inflammatory properties, positions the NADES-based eutectogel as a promising multifunctional platform for buccal drug delivery, particularly for inflammatory conditions complicated by bacterial infections. Full article
(This article belongs to the Special Issue Advanced Hydrogels for Regenerative Medicine and Tissue Engineering (3rd Edition))
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39 pages, 4885 KiB  
Review
Smart Poly(N-isopropylacrylamide)-Based Hydrogels: A Tour D’horizon of Biomedical Applications
by Soumya Narayana, B. H. Jaswanth Gowda, Umme Hani, Mohammed Gulzar Ahmed, Zahrah Ali Asiri and Karthika Paul
Gels 2025, 11(3), 207; https://doi.org/10.3390/gels11030207 - 15 Mar 2025
Viewed by 1185
Abstract
Hydrogels are innovative materials characterized by a water-swollen, crosslinked polymeric network capable of retaining substantial amounts of water while maintaining structural integrity. Their unique ability to swell or contract in response to environmental stimuli makes them integral to biomedical applications, including drug delivery, [...] Read more.
Hydrogels are innovative materials characterized by a water-swollen, crosslinked polymeric network capable of retaining substantial amounts of water while maintaining structural integrity. Their unique ability to swell or contract in response to environmental stimuli makes them integral to biomedical applications, including drug delivery, tissue engineering, and wound healing. Among these, “smart” hydrogels, sensitive to stimuli such as pH, temperature, and light, showcase reversible transitions between liquid and semi-solid states. Thermoresponsive hydrogels, exemplified by poly(N-isopropylacrylamide) (PNIPAM), are particularly notable for their sensitivity to temperature changes, transitioning near their lower critical solution temperature (LCST) of approximately 32 °C in water. Structurally, PNIPAM-based hydrogels (PNIPAM-HYDs) are chemically versatile, allowing for modifications that enhance biocompatibility and functional adaptability. These properties enable their application in diverse therapeutic areas such as cancer therapy, phototherapy, wound healing, and tissue engineering. In this review, the unique properties and behavior of smart PNIPAM are explored, with an emphasis on diverse synthesis methods and a brief note on biocompatibility. Furthermore, the structural and functional modifications of PNIPAM-HYDs are detailed, along with their biomedical applications in cancer therapy, phototherapy, wound healing, tissue engineering, skin conditions, ocular diseases, etc. Various delivery routes and patents highlighting therapeutic advancements are also examined. Finally, the future prospects of PNIPAM-HYDs remain promising, with ongoing research focused on enhancing their stability, responsiveness, and clinical applicability. Their continued development is expected to revolutionize biomedical technologies, paving the way for more efficient and targeted therapeutic solutions. Full article
(This article belongs to the Special Issue Advances in Stimulus-Responsive Hydrogels: Theory, Modern Advances, and Applications)
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39 pages, 3751 KiB  
Review
Multifunctional Hydrogel Microneedles (HMNs) in Drug Delivery and Diagnostics
by Hossein Omidian and Sumana Dey Chowdhury
Gels 2025, 11(3), 206; https://doi.org/10.3390/gels11030206 - 15 Mar 2025
Cited by 1 | Viewed by 1401
Abstract
Hydrogel microneedles (HMNs) have emerged as a transformative platform for minimally invasive drug delivery and biosensing, offering enhanced bioavailability, controlled drug release, and real-time biomarker detection. By leveraging swelling hydrogels, nanomaterial integration, and stimuli-responsive properties, HMNs provide precision medicine capabilities across diverse therapeutic [...] Read more.
Hydrogel microneedles (HMNs) have emerged as a transformative platform for minimally invasive drug delivery and biosensing, offering enhanced bioavailability, controlled drug release, and real-time biomarker detection. By leveraging swelling hydrogels, nanomaterial integration, and stimuli-responsive properties, HMNs provide precision medicine capabilities across diverse therapeutic and diagnostic applications. However, challenges remain in mechanical stability, as hydrogel-based MNs must balance flexibility with sufficient strength for skin penetration. Drug retention and controlled release require optimization to prevent premature diffusion and ensure sustained therapeutic effects. Additionally, biosensing accuracy is influenced by variability in interstitial fluid extraction and signal transduction. Clinical translation is hindered by regulatory hurdles, scalability concerns, and the need for extensive safety validation in human trials. This review critically examines the key materials, fabrication techniques, functional properties, and testing frameworks of HMNs while addressing these limitations. Furthermore, we explore future research directions in smart wearable MNs, AI-assisted biosensing, and hybrid drug–device platforms to optimize transdermal medicine. Overcoming these barriers will drive the clinical adoption of HMNs, paving the way for next-generation patient-centered therapeutics and diagnostics. Full article
(This article belongs to the Special Issue Polymeric Hydrogels for Biomedical Application)
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21 pages, 3840 KiB  
Article
Newly Designed Organic-Inorganic Nanocomposite Membrane for Simultaneous Cr and Mn Speciation in Waters
by Penka Vasileva and Irina Karadjova
Gels 2025, 11(3), 205; https://doi.org/10.3390/gels11030205 - 15 Mar 2025
Viewed by 499
Abstract
A sol-gel approach was used to prepare a thin hydrogel membrane based on an organic-inorganic polymer matrix embedded with pre-synthesized gold nanoparticles (AuNPs). The organic polymers utilized were poly(vinyl alcohol) (PVA) and poly(ethylene oxide) 400 (PEO) while tetraethoxysilane (TEOS) served as a precursor [...] Read more.
A sol-gel approach was used to prepare a thin hydrogel membrane based on an organic-inorganic polymer matrix embedded with pre-synthesized gold nanoparticles (AuNPs). The organic polymers utilized were poly(vinyl alcohol) (PVA) and poly(ethylene oxide) 400 (PEO) while tetraethoxysilane (TEOS) served as a precursor for the inorganic silica polymer. AuNPs were synthesized using D-glucose as a reducing agent and starch as a capping agent. A mixture of PVA, PEO, pre-hydrolyzed TEOS, and AuNP dispersions was cast and dried at 50 °C to obtain the hybrid hydrogel membrane. The structure, morphology, and optical properties of the nanocomposite membrane were analyzed using TEM, SEM, XRD, and UV-Vis spectroscopy. The newly designed hybrid hydrogel membrane was utilized as an efficient sorbent for the simultaneous speciation analysis of valence species of chromium and manganese in water samples via solid-phase extraction. This study revealed that Cr(III) and Mn(II) could be simultaneously adsorbed onto the PVA/PEO/SiO2/AuNP membrane at pH 9 while Cr(VI) and Mn(VII) remained in solution due to their inability to bind under these conditions. Under optimized parameters, detection limits and relative standard deviations were determined for chromium and manganese species. The developed analytical method was successfully applied for the simultaneous speciation analysis of chromium and manganese in drinking water and wastewater samples. Full article
(This article belongs to the Special Issue Gel-Related Materials: Challenges and Opportunities)
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20 pages, 6533 KiB  
Article
High-Quality Application of Crayfish Muscle in Surimi Gels: Fortification of Blended Gels by Transglutaminase
by Hongyi Wang, Qiang Li, Mengru Yang, Hong Wang, Mengtao Wang, Lin Lin and Jianfeng Lu
Gels 2025, 11(3), 204; https://doi.org/10.3390/gels11030204 - 14 Mar 2025
Viewed by 413
Abstract
The application of crayfish muscle in surimi products is a potential way to promote their processing and ensure that it is of a high value. In this study, a one-way completely randomized design was used to prepare mixed surimi gels with different proportions [...] Read more.
The application of crayfish muscle in surimi products is a potential way to promote their processing and ensure that it is of a high value. In this study, a one-way completely randomized design was used to prepare mixed surimi gels with different proportions of crayfish muscle. The effect of transglutaminase (TGase) on the improvement in the structural properties, water-binding capacity, micromorphology and protein conformation of blended gels was explored using mass spectrometry, centrifugation, scanning electron microscopy, and Fourier transform infrared spectroscopy. The results of thus study were analyzed by one-way ANOVA showed that in the absence of TGase, crayfish muscle made the microstructure of the blended gel looser and rougher, with a reduction in the strength of the gel and a decrease in the water holding capacity. The addition of 0.6% TGase was able to ameliorate this negative effect by promoting the formation of key chemical bonds and changes in protein conformation, which ultimately led to the enhancement of the crayfish–surimi blended gel properties. Practically, this study provides a viable strategy for incorporating crayfish into surimi products, enabling the development of novel, high-quality seafood products with improved texture and moisture retention, thereby enhancing consumer appeal and reducing waste in crayfish processing. Full article
(This article belongs to the Special Issue Food Gels: Fabrication, Characterization, and Application)
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18 pages, 7158 KiB  
Article
A Robust Natural Rubber–Polyzwitterion Composite Hydrogel for Highly Enhanced Marine Anti-Biofouling
by Ye Sun, Dominic John, Yuxin Yan, Xueliang Feng, Qingrong Wei, Chunxin Ma, Zhenzhong Liu, Haimei Mao, Tuck-Whye Wong and Yun Chen
Gels 2025, 11(3), 203; https://doi.org/10.3390/gels11030203 - 14 Mar 2025
Viewed by 505
Abstract
Polyzwitterion (PZW) hydrogel has excellent marine anti-biofouling performance, but it is difficult to effectively work for a long time in natural seawater due to its weak mechanical strength. In this study, a new natural rubber (NR)-PZW composite hydrogel has been reported for long-term [...] Read more.
Polyzwitterion (PZW) hydrogel has excellent marine anti-biofouling performance, but it is difficult to effectively work for a long time in natural seawater due to its weak mechanical strength. In this study, a new natural rubber (NR)-PZW composite hydrogel has been reported for long-term anti-biofouling by simply dispersing NR latex into the poly(sulfobetaine methacrylate) (PSBMA) hydrogel network. First of all, owing to the PZW hydrogel network having an anti-polyelectrolyte effect, this NR-PZW hydrogel can provide outstanding anti-biofouling performance, including broad-spectrum anti-bacteria, anti-algae, and anti-protein properties in marine environments. Furthermore, it has a composited natural rubber nanoparticle with a hydrophilic negatively charged outer protein membrane, which can uniformly disperse in the hydrogel to significantly improve its mechanical properties. Therefore, this composited hydrogel can provide not only highly enhanced tensile strength (0.52 MPa) but also ultra-high breaking elongation (738%), which can effectually resist harsh seawater environments. As a result, the NR-PZW composite hydrogel can achieve excellent anti-biofouling performance for more than 3 months within a real marine environment. This work can provide an excellent, robust polyzwitterionic hydrogel for long-term marine anti-biofouling, which will also inspire new strategies for anti-biofouling materials. Full article
(This article belongs to the Special Issue Customizing Hydrogels: A Journey from Concept to End-Use Properties)
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12 pages, 5422 KiB  
Article
Revealing the Impact of Gel Electrolytes on the Performance of Organic Electrochemical Transistors
by Mancheng Li, Xiaoci Liang, Chuan Liu and Songjia Han
Gels 2025, 11(3), 202; https://doi.org/10.3390/gels11030202 - 14 Mar 2025
Viewed by 671
Abstract
Gel electrolyte-gated organic electrochemical transistors (OECTs) are promising bioelectronic devices known for their high transconductance, low operating voltage, and integration with biological systems. Despite extensive research on the performance of OECTs, a precise model defining the dependence of OECT performance on gel electrolytes [...] Read more.
Gel electrolyte-gated organic electrochemical transistors (OECTs) are promising bioelectronic devices known for their high transconductance, low operating voltage, and integration with biological systems. Despite extensive research on the performance of OECTs, a precise model defining the dependence of OECT performance on gel electrolytes is still lacking. In this work, we refine the device model to comprehensively account for the electrical double layer (EDL)’s capacitance of the gel electrolyte. Both experimental data and theoretical calculations indicate that the maximum transconductance of the OECT is contingent upon ion concentration, drain voltage, and scan rate, highlighting a strong correlation between the transconductance and the hydrogel electrolyte. Overall, this model serves as a theoretical tool for improving the performance of OECTs, enabling the further development of bioelectronic devices. Full article
(This article belongs to the Special Issue Research on the Applications of Conductive Hydrogels)
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21 pages, 2780 KiB  
Article
Swelling Behavior, Biocompatibility, and Controlled Delivery of Sodium–Diclofenac in New Temperature-Responsive P(OEGMA/OPGMA) Copolymeric Hydrogels
by Zorana Rogic Miladinovic, Maja Krstic and Edin Suljovrujic
Gels 2025, 11(3), 201; https://doi.org/10.3390/gels11030201 - 14 Mar 2025
Viewed by 409
Abstract
This study investigates the synthesis and properties of innovative poly(oligo(alkylene glycol)) methacrylate hydrogels synthesized via gamma radiation-induced copolymerization and the crosslinking of oligo(ethylene glycol) methacrylate (OEGMA) and oligo(propylene glycol) methacrylate (OPGMA) at varying mole fractions. Our primary objective is to investigate the impact [...] Read more.
This study investigates the synthesis and properties of innovative poly(oligo(alkylene glycol)) methacrylate hydrogels synthesized via gamma radiation-induced copolymerization and the crosslinking of oligo(ethylene glycol) methacrylate (OEGMA) and oligo(propylene glycol) methacrylate (OPGMA) at varying mole fractions. Our primary objective is to investigate the impact of copolymerization on the swelling properties of P(OEGMA/OPGMA) hydrogels compared to their homopolymeric counterparts, namely, POEGMA and POPGMA, which exhibit distinct volume phase transition temperatures (VPTTs) of around 70 and 13 °C, respectively, under physiological conditions. To this end, a comprehensive library of smart methacrylate-based hydrogel biomaterials was developed, featuring detailed data on their swelling behavior across different copolymer molar ratios and physiological temperature ranges. To achieve these objectives, we conducted swelling behavior analysis across a wide range of temperatures, assessed the pH sensitivity of hydrogels, utilized scanning electron microscopy for morphological characterization, performed in vitro biocompatibility assessment through cell viability and hemolysis assays, and employed diclofenac sodium as a model drug to control drug delivery testing. Our findings demonstrate that the newly synthesized P(OEGMA40/OPGMA60) copolymeric hydrogel exhibits desirable characteristics, with VPTT close to the physiological temperatures required for controlled drug delivery applications. Full article
(This article belongs to the Special Issue Hydrogels, Oleogels and Bigels Used for Drug Delivery)
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19 pages, 8242 KiB  
Article
Effects of Polyhydroxybutyrate-co-hydroxyvalerate Microparticle Loading on Rheology, Microstructure, and Processability of Hydrogel-Based Inks for Bioprinted and Moulded Scaffolds
by Mercedes Pérez-Recalde, Evelina Pacheco, Beatriz Aráoz and Élida B. Hermida
Gels 2025, 11(3), 200; https://doi.org/10.3390/gels11030200 - 14 Mar 2025
Viewed by 652
Abstract
Resorbable microparticles can be added to hydrogel-based biocompatible scaffolds to improve their mechanical characteristics and allow localised drug delivery, which will aid in tissue repair and regeneration. It is well-known that bioprinting is important for producing scaffolds personalised to patients by loading them [...] Read more.
Resorbable microparticles can be added to hydrogel-based biocompatible scaffolds to improve their mechanical characteristics and allow localised drug delivery, which will aid in tissue repair and regeneration. It is well-known that bioprinting is important for producing scaffolds personalised to patients by loading them with their own cells and printing them with specified shapes and dimensions. The question is how the addition of such particles affects the rheological responsiveness of the hydrogels (which is critical during the printing process) as well as mechanical parameters like the elastic modulus. This study tries to answer this question using a specific system: an alginate-gelatine hydrogel containing polyhydroxybutyrate-co-hydroxyvalerate (PHBV) microparticles. Scaffolds were made by bioprinting and moulding incorporating PHBV microspheres (7–12 μm in diameter) into alginate–gelatine inks (4.5 to 9.0% w/v). The microparticles (MP) were predominantly located within the polymeric matrix at concentrations up to 10 mg MP/mL ink. Higher particle concentrations disrupted their spatial distribution. Inks pre-crosslinked with 15 mM calcium and containingMPat concentrations ranging from 0 to 10 mg/mL demonstrated rheological characteristics appropriate for bioprinting, such as solid-like behaviour (G′ = 1060–1300 Pa, G″ = 720–930 Pa), yield stresses of 320–400 Pa, and pseudoplastic behaviour (static viscosities of 4000–5600 Pa·s and ~100 Pa·s at bioprinting shear rates). Furthermore, these inks allow high printing quality, assessed through scaffold dimensions, filament widths, and printability (Pr > 0.94). The modulus of elasticity in compression (E) of the scaffolds varied according to the content of MP and the manufacturing technique, with values resembling those of soft tissues (200–600 kPa) and exhibiting a maximum reinforcement effect with 3 mg MP/mL ink (bioprinted E = 273 ± 28 kPa; moulded E = 541 ± 66 kPa). Over the course of six days, the sample’s mass and shape remained stable during degradation in simulated body fluid (SBF). Thus, the alginate–gelatine hydrogel loaded with PHBV microspheres inks shows promise for targeted drug delivery in soft tissue bioengineering applications. Full article
(This article belongs to the Special Issue 3D Printing of Gel-Based Materials)
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18 pages, 3350 KiB  
Article
Expansion and Delivery of Human Chondrocytes on Gelatin-Based Cell Carriers
by Krishi Patel, Derya Ozhava and Yong Mao
Gels 2025, 11(3), 199; https://doi.org/10.3390/gels11030199 - 13 Mar 2025
Cited by 2 | Viewed by 483
Abstract
Cartilage damage is common in sports injuries and cartilage-related diseases, such as degenerative joint and rheumatic disorders. Autologous chondrocyte implantation (ACI) is a widely used cell-based therapy for repairing cartilage damage in clinical practice. In this procedure, a patient’s chondrocytes are isolated, cultured [...] Read more.
Cartilage damage is common in sports injuries and cartilage-related diseases, such as degenerative joint and rheumatic disorders. Autologous chondrocyte implantation (ACI) is a widely used cell-based therapy for repairing cartilage damage in clinical practice. In this procedure, a patient’s chondrocytes are isolated, cultured in vitro to expand the cell population, and then implanted into the damaged site. However, in vitro expansion of chondrocytes on standard 2D culture surfaces leads to dedifferentiation (loss of the chondrocyte phenotype), and the delivery of detached cells has proven to be ineffective. To overcome these limitations, the matrix-assisted ACI (MACI) procedure was developed. In MACI, matrices such as hydrogels and microspheres are used as cell carriers or scaffolds to deliver expanded chondrocytes, enhancing cell viability and precision delivery. To streamline the two key steps of MACI—cell expansion and delivery—this study aims to investigate various configurations of gelatin-based hydrogels for their potential to support both cell expansion and delivery as a single step. This study evaluated gelatin microspheres (Gel MS), micronized photo-crosslinked GelMA microparticles (GelMA MP), and bulky GelMA hydrogels containing cells (GelMA HG). Cell growth, maintenance of the chondrocyte phenotype, and cartilage extracellular matrix (ECM) production were assessed in pellet cultures for cells grown on/in these carriers, compared with cells cultured on tissue culture-treated polystyrene (TCP). Our results demonstrate that normal human knee articular chondrocytes exhibit robust growth on Gel MS and form aggregates enriched with glycosaminoglycan-rich ECM. Gel MS outperformed both GelMA MP and GelMA HG as a cell carrier by both supporting long-term cell growth with reduced dedifferentiation and precision delivery. Full article
(This article belongs to the Special Issue Smart Hydrogel for Wound Healing and Tissue Repair)
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25 pages, 1532 KiB  
Review
Polysaccharide Hydrogels as Delivery Platforms for Natural Bioactive Molecules: From Tissue Regeneration to Infection Control
by Fabrizia Sepe, Anna Valentino, Loredana Marcolongo, Orsolina Petillo, Anna Calarco, Sabrina Margarucci, Gianfranco Peluso and Raffaele Conte
Gels 2025, 11(3), 198; https://doi.org/10.3390/gels11030198 - 12 Mar 2025
Viewed by 700
Abstract
Polysaccharide-based hydrogels have emerged as indispensable materials in tissue engineering and wound healing, offering a unique combination of biocompatibility, biodegradability, and structural versatility. Indeed, their three-dimensional polymeric network and high water content closely resemble the natural extracellular matrix, creating a microenvironment for cell [...] Read more.
Polysaccharide-based hydrogels have emerged as indispensable materials in tissue engineering and wound healing, offering a unique combination of biocompatibility, biodegradability, and structural versatility. Indeed, their three-dimensional polymeric network and high water content closely resemble the natural extracellular matrix, creating a microenvironment for cell growth, differentiation, and tissue regeneration. Moreover, their intrinsic biodegradability, tunable chemical structure, non-toxicity, and minimal immunogenicity make them optimal candidates for prolonged drug delivery systems. Notwithstanding numerous advantages, these polysaccharide-based hydrogels are confronted with setbacks such as variability in material qualities depending on their source, susceptibility to microbial contamination, unregulated water absorption, inadequate mechanical strength, and unpredictable degradation patterns which limit their efficacy in real-world applications. This review summarizes recent advancements in the application of polysaccharide-based hydrogels, including cellulose, starch, pectin, zein, dextran, pullulan and hyaluronic acid as innovative solutions in wound healing, drug delivery, tissue engineering, and regenerative medicine. Future research should concentrate on optimizing hydrogel formulations to enhance their effectiveness in regenerative medicine and antimicrobial therapy. Full article
(This article belongs to the Special Issue Hydrogels for Therapeutic Delivery: Current Developments and Future Directions)
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17 pages, 6186 KiB  
Article
Ion-Specific Gelation and Internal Dynamics of Nanocellulose Biocompatible Hybrid Hydrogels: Insights from Fluctuation Analysis
by Arianna Bartolomei, Elvira D’Amato, Marina Scarpa, Greta Bergamaschi, Alessandro Gori and Paolo Bettotti
Gels 2025, 11(3), 197; https://doi.org/10.3390/gels11030197 - 12 Mar 2025
Viewed by 468
Abstract
Hydrogels find widespread use in bioapplications for their ability to retain large amounts of water while maintaining structural integrity. In this article, we investigate hybrid hydrogels made of nanocellulose and either amino–polyethylenglycol or sodium alginates and we present two novel results: (1) the [...] Read more.
Hydrogels find widespread use in bioapplications for their ability to retain large amounts of water while maintaining structural integrity. In this article, we investigate hybrid hydrogels made of nanocellulose and either amino–polyethylenglycol or sodium alginates and we present two novel results: (1) the biocompatibility of the amino-containing hybrid gel synthesized using a simplified receipt does not require any intermediate synthetic step to functionalize either component and (2) the fluctuation in the second-order correlation function of a dynamic light scattering experiment provides relevant information about the characteristic internal dynamics of the materials across the entire sol–gel transition as well as quantitative information about the ion-specific gel formation. This novel approach offers significantly better temporal (tens of μs) and spatial (tens of μm) resolution than many other state-of-the-art techniques commonly used for such analyses (such as rheometry, SAXS, and NMR) and it might find widespread application in the characterization of nano- to microscale dynamics in soft materials. Full article
(This article belongs to the Special Issue Outcomes and Trends in Polymer Gels: Designing, Properties and Applications)
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14 pages, 4212 KiB  
Article
Influence of Gelation Temperature on Structural, Thermal, and Mechanical Properties of Monolithic Silica Gels with Mono- and Bimodal Pore Structure
by Kai Müller, Christian Scherdel, Stephan Vidi, Gudrun Reichenauer, Moritz Boxheimer, Frank Dehn and Dirk Enke
Gels 2025, 11(3), 196; https://doi.org/10.3390/gels11030196 - 12 Mar 2025
Viewed by 448
Abstract
This study explores the impact of pore volume distribution on the structural, thermal, and mechanical properties of spinodal phase-separated silica gels synthesized with poly(ethylene oxide) as a phase-separating agent. By systematically varying gelation temperatures between 20 and 60 °C, we investigate how reaction [...] Read more.
This study explores the impact of pore volume distribution on the structural, thermal, and mechanical properties of spinodal phase-separated silica gels synthesized with poly(ethylene oxide) as a phase-separating agent. By systematically varying gelation temperatures between 20 and 60 °C, we investigate how reaction kinetics influence the resulting pore architecture, thermal conductivity, and elasticity. Nitrogen sorption, mercury intrusion porosimetry, and SEM analysis reveal a transformation from a bimodal pore structure at low temperatures, featuring interconnected macropores, to a predominantly mesoporous network with loss of bimodality. This shift in the diameter of the macropores significantly impacts the thermal insulation properties of the gels as thermal conductivity decreases from 68 to 27 mW (m·K)−1 due to reduced macroporosity, enhanced mesoporosity, and the Knudsen effect. Mechanical testing revealed a substantial decline in Young’s modulus with increasing gelation temperature. These changes are attributed to the interplay of mesoscale structural differences and density variations, driven by increasing gelation temperatures. While higher temperatures lead to reduced strut thickness and the loss of interconnected macropores, the substantial decline in Young’s modulus highlights the critical role of mesoscale structural integrity in maintaining mechanical stability. The findings underscore the importance of an optimized pore volume distribution in tailoring pore structure and performance characteristics, providing a pathway for optimizing silica gels for applications in thermal insulation, filtration, and catalysis. Full article
(This article belongs to the Section Gel Analysis and Characterization)
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14 pages, 3849 KiB  
Article
Tyrosinase-Catalyzed Soy Protein and Tannic Acid Interaction: Effects on Structural and Rheological Properties of Complexes
by Yaqiong Pei, Lei Yuan, Wenjing Zhou and Jun Yang
Gels 2025, 11(3), 195; https://doi.org/10.3390/gels11030195 - 12 Mar 2025
Cited by 1 | Viewed by 528
Abstract
This study investigated the structural, rheological, and microstructural properties of soy protein isolate (SPI) induced by tyrosinase-catalyzed crosslinking with tannic acid (TA) at 25 °C under neutral conditions at pH 6.5. The particle size and polydispersity index of modified SPI progressively increased with [...] Read more.
This study investigated the structural, rheological, and microstructural properties of soy protein isolate (SPI) induced by tyrosinase-catalyzed crosslinking with tannic acid (TA) at 25 °C under neutral conditions at pH 6.5. The particle size and polydispersity index of modified SPI progressively increased with rising TA concentrations. Tyrosinase-induced polymerization significantly impacted the conformational structure of SPI, evidenced by a notable decrease in intrinsic fluorescence, a pronounced red shift, and a remarkable reduction in surface hydrophobicity. FTIR analysis further revealed that, compared to control SPI, the amide I, II, and III bands of SPI incubated with TA and tyrosinase exhibited varying degrees of red-shift or blue-shift. These observations suggested a substantial alteration in the secondary structure of SPI after incubation with TA and tyrosinase. The apparent viscosity, G′, and G″ of the modified SPI increased with higher TA concentrations, indicating that the modification of SPI by TA in the presence of tyrosinase resulted in enhanced covalent crosslinking. Microstructural observations confirmed that higher TA levels promoted the formation of denser and more uniform gel-like networks. The findings demonstrated that tyrosinase-mediated crosslinking improved the functionality of SPI, making it a promising approach for food applications. Full article
(This article belongs to the Section Gel Analysis and Characterization)
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37 pages, 3451 KiB  
Review
A Comprehensive Review of Honey-Containing Hydrogel for Wound Healing Applications
by Andik Nisa Zahra Zainuddin, Nurul Nadhirah Mustakim, Farah Alea Rosemanzailani, Nur Izzah Md Fadilah, Manira Maarof and Mh Busra Fauzi
Gels 2025, 11(3), 194; https://doi.org/10.3390/gels11030194 - 12 Mar 2025
Cited by 1 | Viewed by 1948
Abstract
Honey has long been recognized for its medicinal properties, particularly in wound healing. Recent advancements in material science have led to the development of honey-containing hydrogels, combining the natural healing properties of honey with the versatile characteristics of hydrogel matrices. These hydrogels offer [...] Read more.
Honey has long been recognized for its medicinal properties, particularly in wound healing. Recent advancements in material science have led to the development of honey-containing hydrogels, combining the natural healing properties of honey with the versatile characteristics of hydrogel matrices. These hydrogels offer numerous advantages, including high moisture retention, biocompatibility, and the controlled release of bioactive compounds, making them highly effective for wound healing applications. Hydrogels hold significant potential in advancing medical applications, particularly for cutaneous injuries. The diverse properties of honey, including antimicrobial, anti-inflammatory, and anti-eschar effects, have shown promise in accelerating tissue regeneration. According to studies, they are effective in maintaining a good swelling ratio index, Water Vapour Transmission Rate (WVTR), contact angle, tensile and elongation at break, in vitro biodegradation rate, viscosity and porosity analysis, lowering bacterial infections, and encouraging rapid tissue regeneration with notable FTIR peaks and SEM average pore sizes. However, limitations such as low bioavailability and inefficiencies in direct application reduce their therapeutic effectiveness at the wound site. Integrating honey into hydrogels can help preserve its wound healing mechanisms while enhancing its ability to facilitate skin tissue recovery. This review explores the underlying mechanisms of honey in wound healing management and presents an extensive analysis of honey-containing hydrogels reported in the literature over the past eight years. It emphasizes the physicochemical and mechanical effectiveness and advancements of honey-incorporated hydrogels in promoting skin wound healing and tissue regeneration, supported by evidence from both in vitro and in vivo studies. While honey-based therapies for wound healing have demonstrated promising outcomes in numerous in vitro and animal studies, clinical studies remain limited. Despite that, honey’s incorporation into hydrogel systems, however, offers a potent fusion of contemporary material technology and natural healing qualities, marking a substantial breakthrough in wound treatment. Full article
(This article belongs to the Section Gel Analysis and Characterization)
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17 pages, 7093 KiB  
Article
Hydration Mechanism of Solid Waste Gelling Materials Containing Semi-Dry Desulfurization Ash
by Yunyun Li, Siqi Zhang, Meixiang Huang, Guodong Yang, Jiajie Li, Mengqi Ma, Wentao Hu and Wen Ni
Gels 2025, 11(3), 193; https://doi.org/10.3390/gels11030193 - 11 Mar 2025
Viewed by 610
Abstract
This study investigated the feasibility of using semi-dry desulfurization ash (DA) in combination with blast furnace slag (BFS) to prepare gelling materials, aiming to improve the resource utilization of DA. The effects of DA dosage and mechanical grinding on the compressive strength and [...] Read more.
This study investigated the feasibility of using semi-dry desulfurization ash (DA) in combination with blast furnace slag (BFS) to prepare gelling materials, aiming to improve the resource utilization of DA. The effects of DA dosage and mechanical grinding on the compressive strength and hydration mechanism of BFS-DA gelling materials were investigated. The results showed that the optimum BFS-DA ratio was 60:40, and the compressive strengths were 14.21 MPa, 20.24 MPa, 43.50 MPa, and 46.27 MPa at 3, 7, 28, and 56 days, respectively. Mechanical grinding greatly improved the activity of the gel materials, with the greatest increase in compressive strength at 3, 7, 28, and 90 days for the BFS and DA mixed milled for 30 min, with increases of 89.86%, 66.36%, 24.56%, and 25.68%, respectively, and compressive strength of 26.22 MPa, 35.6 MPa, 58.33 MPa, and 63.97 MPa, respectively. The cumulative heat of hydration of BFS-DA slurry was about 120 J/g. The hydration mechanism showed that the main hydration products formed were ettringite, C-S-H gel, AFm, and Friedel’s salt. Calcium sulfite in DA was participated in the hydration, and a new hydration product, Ca4Al2O6SO3·11H2O, was formed. DA can be effectively used to prepare BFS-based gelling materials, and its performance meets the requirements of GB/T 28294-2024 standard, which provides a potential solution for the utilization of DA resources and the reduction in the impact on the environment. Full article
(This article belongs to the Special Issue Innovative Gels: Structure, Properties, and Emerging Applications)
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26 pages, 2983 KiB  
Review
3D-Printed Hydrogels from Natural Polymers for Biomedical Applications: Conventional Fabrication Methods, Current Developments, Advantages, and Challenges
by Berk Uysal, Ujith S. K. Madduma-Bandarage, Hasani G. Jayasinghe and Sundar Madihally
Gels 2025, 11(3), 192; https://doi.org/10.3390/gels11030192 - 9 Mar 2025
Cited by 1 | Viewed by 1173
Abstract
Hydrogels are network polymers with high water-bearing capacity resembling the extracellular matrix. Recently, many studies have focused on synthesizing hydrogels from natural sources as they are biocompatible, biodegradable, and readily available. However, the structural complexities of biological tissues and organs limit the use [...] Read more.
Hydrogels are network polymers with high water-bearing capacity resembling the extracellular matrix. Recently, many studies have focused on synthesizing hydrogels from natural sources as they are biocompatible, biodegradable, and readily available. However, the structural complexities of biological tissues and organs limit the use of hydrogels fabricated with conventional methods. Since 3D printing can overcome this barrier, more interest has been drawn toward the 3D printing of hydrogels. This review discusses the structure of hydrogels and their potential biomedical applications with more emphasis on natural hydrogels. There is a discussion on various formulations of alginates, chitosan, gelatin, and hyaluronic acid. Furthermore, we discussed the 3D printing techniques available for hydrogels and their advantages and limitations. Full article
(This article belongs to the Special Issue Advances in Hydrogels for Regenerative Medicine)
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33 pages, 1894 KiB  
Review
Bioprinted Hydrogels as Vehicles for the Application of Extracellular Vesicles in Regenerative Medicine
by Marta Camacho-Cardenosa, Victoria Pulido-Escribano, Guadalupe Estrella-Guisado, Gabriel Dorado, Aura D. Herrera-Martínez, María Ángeles Gálvez-Moreno and Antonio Casado-Díaz
Gels 2025, 11(3), 191; https://doi.org/10.3390/gels11030191 - 8 Mar 2025
Viewed by 873
Abstract
Three-dimensional bioprinting is a new advance in tissue engineering and regenerative medicine. Bioprinting allows manufacturing three-dimensional (3D) structures that mimic tissues or organs. The bioinks used are mainly made of natural or synthetic polymers that must be biocompatible, printable, and biodegradable. These bioinks [...] Read more.
Three-dimensional bioprinting is a new advance in tissue engineering and regenerative medicine. Bioprinting allows manufacturing three-dimensional (3D) structures that mimic tissues or organs. The bioinks used are mainly made of natural or synthetic polymers that must be biocompatible, printable, and biodegradable. These bioinks may incorporate progenitor cells, favoring graft implantation and regeneration of injured tissues. However, the natures of biomaterials, bioprinting processes, a lack of vascularization, and immune responses are factors that limit the viability and functionality of implanted cells and the regeneration of damaged tissues. These limitations can be addressed by incorporating extracellular vesicles (EV) into bioinks. Indeed, EV from progenitor cells may have regenerative capacities, being similar to those of their source cells. Therefore, their combinations with biomaterials can be used in cell-free therapies. Likewise, they can complement the manufacture of bioinks by increasing the viability, differentiation, and regenerative ability of incorporated cells. Thus, the main objective of this review is to show how the use of 3D bioprinting technology can be used for the application of EV in regenerative medicine by incorporating these nanovesicles into hydrogels used as bioinks. To this end, the latest advances derived from in vitro and in vivo studies have been described. Together, these studies show the high therapeutic potential of this strategy in regenerative medicine. Full article
(This article belongs to the Special Issue Gels: 10th Anniversary)
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31 pages, 7229 KiB  
Review
Polydopamine Nanocomposite Hydrogel for Drug Slow-Release in Bone Defect Repair: A Review of Research Advances
by Xiaoman Li, Jianhua Tang, Weiwei Guo, Xuan Dong, Kaisen Cao and Fushan Tang
Gels 2025, 11(3), 190; https://doi.org/10.3390/gels11030190 - 8 Mar 2025
Viewed by 871
Abstract
In recent years, hydrogels have emerged as promising candidates for bone defect repair due to their excellent biocompatibility, high porosity, and water-retentive properties. However, conventional hydrogels face significant challenges in clinical translation, including brittleness, low mechanical strength, and poorly controlled drug degradation rates. [...] Read more.
In recent years, hydrogels have emerged as promising candidates for bone defect repair due to their excellent biocompatibility, high porosity, and water-retentive properties. However, conventional hydrogels face significant challenges in clinical translation, including brittleness, low mechanical strength, and poorly controlled drug degradation rates. To address these limitations, as a multifunctional polymer, polydopamine (PDA) has shown great potential in both bone regeneration and drug delivery systems. Its robust adhesive properties, biocompatibility, and responsiveness to photothermal stimulation make it an ideal candidate for enhancing hydrogel performance. Integrating PDA into conventional hydrogels not only improves their mechanical properties but also creates an environment conducive to cell adhesion, proliferation, and differentiation, thereby promoting bone defect repair. Moreover, PDA facilitates controlled drug release, offering a promising approach to optimizing treatment outcomes. This paper first explores the mechanisms through which PDA promotes bone regeneration, laying the foundation for its clinical translation. Additionally, it discusses the application of PDA-based nanocomposite hydrogels as advanced drug delivery systems for bone defect repair, providing valuable insights for both research and clinical translation. Full article
(This article belongs to the Special Issue Hydrogel for Sustained Delivery of Therapeutic Agents (2nd Edition))
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14 pages, 1694 KiB  
Article
Development and Characterization of Cannabidiol Gummy Using 3D Printing
by Arvind Bagde, Mina Messiha and Mandip Singh
Gels 2025, 11(3), 189; https://doi.org/10.3390/gels11030189 - 8 Mar 2025
Viewed by 684
Abstract
Oropharyngeal dysphagia and pain are prevalent concerns in the geriatric population. Therefore, this study investigates advances in the development of cannabidiol (CBD) gummies using 3D printing technology and compares them to commercially available molded gummies for pain management. A gelatin-based CBD formulation was [...] Read more.
Oropharyngeal dysphagia and pain are prevalent concerns in the geriatric population. Therefore, this study investigates advances in the development of cannabidiol (CBD) gummies using 3D printing technology and compares them to commercially available molded gummies for pain management. A gelatin-based CBD formulation was prepared and printed using a syringe-based extrusion 3D printer. The formulation’s rheological properties were assessed, and the printed gummies were characterized using a texture analyzer. Drug content was analyzed using HPLC, and in vitro dissolution studies were conducted in phosphate buffer (pH 1.2 and 6.8). Our results demonstrated that the gelatin-based formulation had shear-thinning rheological properties for 3D printing at a temperature of 38.00 °C, filament diameter of 26 mm and flow of 110%. The optimized printing parameters produced gummies with higher elasticity compared to marketed gummies and comparable toughness. Drug content analysis showed 98.14 ± 1.56 and 97.97 ± 2.14% of CBD in 3D-printed and marketed gummies, respectively. Dissolution studies revealed that both gummy types released 100% of the drug within 30 min in both pH 1.2 and 6.8 buffers. Overall, 3D printing enables customizable CBD gummies with optimized release and offer a personalized and patient-friendly alternative to traditional oral forms for geriatric care. Full article
(This article belongs to the Special Issue State-of-the Art Gel Research in USA)
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