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Volume 11
Issue 6
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Gels, Volume 11, Issue 6 (June 2025) – 94 articles

Cover Story (view full-size image): Metal pollution of water resources is a major global problem, with elevated mercury levels being of particular concern due to its persistence and ability to re-enter ecosystems through various exposure pathways. Health risks associated with mercury exposure highlight the urgent need for coordinated public health responses and effective water treatment technologies to address contamination at sources. In this context, mechanically robust, polyurea-crosslinked Ca-alginate (X-Ca-alginate) aerogel beads demonstrate high mercury retention from water at environmentally relevant concentrations with minimal adsorbent usage. After metal recovery, X-Ca-alginate beads can be regenerated and reused over multiple cycles, reducing both waste and operational costs, while offering a sustainable solution for mercury removal in real-world applications. View this paper
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18 pages, 6693 KiB  
Article
Tensile Resistance and Fracture Mechanisms of Silica Aerogels Reinforced by Nanotube–Graphene Hybrid Networks
by Lin Guo, Mu Du, Jiaqian Li, Wei Li, Mingyang Yang and Gongming Xin
Gels 2025, 11(6), 471; https://doi.org/10.3390/gels11060471 - 19 Jun 2025
Viewed by 283
Abstract
Despite their outstanding thermal insulation and ultralight structure, silica aerogels suffer from inherent mechanical fragility, making the investigation of their mechanical behavior crucial for expanding their practical utility in advanced applications. To enhance their mechanical performance, this study introduces a dual-phase reinforcement strategy [...] Read more.
Despite their outstanding thermal insulation and ultralight structure, silica aerogels suffer from inherent mechanical fragility, making the investigation of their mechanical behavior crucial for expanding their practical utility in advanced applications. To enhance their mechanical performance, this study introduces a dual-phase reinforcement strategy by anisotropically incorporating carbon nanotubes (CNTs) and graphene oxide (GO) sheets into the aerogel matrix. Using molecular dynamic simulations, we systematically investigate the tensile behavior and pore structure evolution of these hetero-structured composites. The results reveal a non-monotonic dependence of tensile strength on loading ratio, distinguishing three strain-dependent reinforcement regimes. High loading content (11.1%) significantly improves strength under low strain (0–26%), whereas low loading levels (1.8%) are more effective at preserving structural integrity under large strain (44–50%). Moderate loading (5.1%) yields balanced performance in intermediate regimes. While increasing carbon content reduces initial pore size by partially filling the framework, tensile deformation leads to interfacial debonding and the formation of larger pores due to CNT–GO hybrid structure interactions. This work elucidates a dual reinforcement mechanism—physical pore confinement and interfacial coupling—highlighting the critical role of nanostructure geometry in tuning strain-specific mechanical responses. The findings provide mechanistic insights into anisotropic nanocomposite behavior and offer guidance for designing robust porous materials for structural and functional applications. Full article
(This article belongs to the Special Issue Aerogels: Synthesis and Applications)
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15 pages, 2659 KiB  
Article
The Thermodynamic and Gelation Properties of Ovalbumin and Lysozyme
by Lifeng Wang, Rongcheng Li, Siyi Lv, Yulin Liu, Shuaifu Fang, Jingnan Zang, Mingmin Qing and Yujie Chi
Gels 2025, 11(6), 470; https://doi.org/10.3390/gels11060470 - 19 Jun 2025
Viewed by 281
Abstract
Ovalbumin (OVA) and lysozyme (LYZ) are the predominant globular proteins in egg white and play a crucial role in influencing thermal stability and colloidal behavior. In this study, the thermal and conformational stability of OVA and LYZ under various physicochemical conditions including pH [...] Read more.
Ovalbumin (OVA) and lysozyme (LYZ) are the predominant globular proteins in egg white and play a crucial role in influencing thermal stability and colloidal behavior. In this study, the thermal and conformational stability of OVA and LYZ under various physicochemical conditions including pH (5–9), protein concentrations (5, 10, and 20%), heating rates (2.5, 5, and 10 °C/min), sugars (sucrose and glucose), and salts (NaCl, KCl, and CaCl2) was systematically investigated using differential scanning calorimetry (DSC), aiming to elucidate their behavior within colloidal and gel-forming systems. The denaturation temperatures (Td) of OVA and LYZ in water (5% w/v, 5 °C/min) were 80.22 °C and 77.46 °C, respectively. The Td of LYZ and OVA decreased with protein concentration, heating rate, and CaCl2. OVA thermal stability was improved with increasing pH, but the stability of LYZ was decreased. Sugars enhanced the thermal stability of OVA and LYZ. In contrast, NaCl and KCl increased OVA stability but reduced LYZ stability. LYZ exhibited nearly 100% reversibility during the second heating cycle in water. Sugars maintained reversibility at approximately 90% for LYZ. However, the presence of salts diminished the reversibility. In contrast, OVA was completely denatured in water and sugar and salt solutions. Full article
(This article belongs to the Special Issue Application of Composite Gel in Food Processing and Engineering)
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17 pages, 2763 KiB  
Article
Effect of Cassia Gum on the Gel Properties of Wheat Flour–Tapioca Starch-Based Batter and the Oil Absorption Capacity of Fried Small Yellow Croaker
by Guilian Ran, Qiang Zhang, Yiping Liao, Liufang Xu and Qiang Zou
Gels 2025, 11(6), 469; https://doi.org/10.3390/gels11060469 - 18 Jun 2025
Viewed by 348
Abstract
High oil content in breaded fried small yellow croaker (BFYC) was reduced using composite batter gels consisting of tapioca starch, wheat flour, and different concentrations of cassia gum (CG; 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1%). The effects of CG on the oil absorption [...] Read more.
High oil content in breaded fried small yellow croaker (BFYC) was reduced using composite batter gels consisting of tapioca starch, wheat flour, and different concentrations of cassia gum (CG; 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1%). The effects of CG on the oil absorption capacity of BFYC and potential mechanisms were investigated. Dynamic rheological analysis revealed that CG addition could enhance the viscoelasticity of the batter by increasing its storage modulus and loss modulus. Furthermore, FTIR and X-ray diffraction results demonstrated that CG interacts with starch through noncovalent interactions, increasing the relative crystallinity from 9.29% to 16.49%, which promoted the formation of a gel layer. This structural improvement effectively inhibited oil absorption. Differential scanning calorimetry analysis showed that within the 0–0.8% CG range, the batter’s denaturation temperature increased from 78.23 °C to 82.08 °C with higher CG concentrations, indicating prolonged gelatinization and enhanced thermal stability that further reduced oil penetration. Low-field nuclear magnetic resonance analysis revealed that CG increased the proportion of tightly bound and weakly bound water in the batter, thereby improving water retention capacity and reducing moisture loss during frying. Microscopic structural observations and Sudan Red-staining tests confirmed that at 0.8% CG concentration, the crust exhibited the lowest porosity with approximately 40% reduction in surface fat content compared to the control group. In conclusion, CG addition significantly improves batter properties and reduces oil content in fried products, providing theoretical support for the development of low-fat fried foods. Full article
(This article belongs to the Special Issue Recent Advance in Food Gels (3rd Edition))
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18 pages, 664 KiB  
Review
Hydrogels in Veterinary Vaccine Development: Types, Mechanisms, and Applications
by Peisen Zhao, Yuwei Yang, Lingxue Yu, Guoxin Li and Dandan Zhu
Gels 2025, 11(6), 468; https://doi.org/10.3390/gels11060468 - 18 Jun 2025
Viewed by 361
Abstract
This review examines the potential and challenges of using hydrogel vaccine delivery systems in animal immunization. Traditional methods face issues like low immunogenicity, reliance on cold chains, and inefficient delivery, limiting their use in modern animal husbandry. Hydrogels offer a promising solution due [...] Read more.
This review examines the potential and challenges of using hydrogel vaccine delivery systems in animal immunization. Traditional methods face issues like low immunogenicity, reliance on cold chains, and inefficient delivery, limiting their use in modern animal husbandry. Hydrogels offer a promising solution due to their biocompatibility, controlled drug release, and immune regulation. This paper highlights hydrogels’ benefits, such as mimicking natural infection through sustained antigen release, boosting antigen-presenting cell activity, activating immune responses, and forming barriers at mucosal sites to prevent pathogen invasion. Additionally, innovative delivery methods like microneedle patches and nasal sprays show promise in enhancing convenience and compliance in animal vaccination. By combining interdisciplinary efforts and technological advancements, the hydrogel vaccine delivery system is anticipated to be crucial in preventing animal diseases, supporting sustainable animal husbandry, and ensuring global animal health and food safety. Full article
(This article belongs to the Special Issue Recent Advances in Multi-Functional Polymer-Based Hydrogels)
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12 pages, 2793 KiB  
Article
Varying Synthesis Parameters of Potato Starch Aerogel for Aerospace Applications
by Jacob Staker, Daniel A. Scheiman, Janice Mather, Jamesa L. Stokes and Haiquan Guo
Gels 2025, 11(6), 467; https://doi.org/10.3390/gels11060467 - 18 Jun 2025
Viewed by 243
Abstract
Aerogels have the potential for usage in many daily and high-tech aerospace applications. Silica aerogels are fragile, while organic aerogels are much tougher, but they are both generally synthesized using toxic solvents. Biodegradable aerogels, if they possess similar properties as polymer aerogels, could [...] Read more.
Aerogels have the potential for usage in many daily and high-tech aerospace applications. Silica aerogels are fragile, while organic aerogels are much tougher, but they are both generally synthesized using toxic solvents. Biodegradable aerogels, if they possess similar properties as polymer aerogels, could be widely utilized in many aerospace applications and offer environmental benefits. In this work, potato starch aerogels were systematically studied. The potato starch concentration, the amount of plasticizer (glycerol), and an acid source (acetic acid) were varied. The relationship of the precursors on potato starch aerogel’s properties, such as density, shrinkage, porosity, BET surface area, mechanical properties, and thermal conductivities, were researched. The resulting potato starch aerogels possess suitable density, Young’s modulus, and thermal conductivity for use in many aerospace applications. Full article
(This article belongs to the Special Issue Polymer Aerogels and Aerogel Composites)
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17 pages, 2486 KiB  
Article
Antifouling Mussel-Inspired Hydrogel with Furanone-Loaded ZIF-8 for Quorum Sensing-Mediated Marine Antifouling
by Yanbin Xiong, Junnan Cui, Xiaodan Liu, Haobo Shu and Pan Cao
Gels 2025, 11(6), 466; https://doi.org/10.3390/gels11060466 - 18 Jun 2025
Viewed by 401
Abstract
Marine biofouling, the process of marine microorganisms, algae, and invertebrates attaching to and forming biofilms on ship hulls, underwater infrastructure, and marine equipment in ocean environments, severely impacts shipping and underwater operations by increasing fuel consumption, maintenance costs, and corrosion risks, and by [...] Read more.
Marine biofouling, the process of marine microorganisms, algae, and invertebrates attaching to and forming biofilms on ship hulls, underwater infrastructure, and marine equipment in ocean environments, severely impacts shipping and underwater operations by increasing fuel consumption, maintenance costs, and corrosion risks, and by threatening marine ecosystem stability via invasive species transport. This study reports the development of a hydrogel-metal-organic framework (MOF)-quorum sensing inhibitor (QSI) antifouling coating on 304 stainless steel (SS) substrates. Inspired by mussel adhesion, a hydrophilic bionic hydrogel was first constructed via metal ion coordination. The traditional metal ion source was replaced with a zeolitic imidazolate framework-8 (ZIF-8) loaded with 2-(5H)-furanone (HF, a QSI) without altering coating formation. Physicochemical characterization using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), the Brunauer–Emmett–Teller (BET) method, and the diffraction of x-rays (XRD) confirmed successful HF loading into ZIF-8 with intact crystal structures. Antifouling tests showed HF@ZIF-8 enhanced antibacterial inhibition against Staphylococcus aureus (97.28%) and Escherichia coli (>97%) and suppressed Chromobacterium violaceum CV026 pigment synthesis at 0.25 mg/mL (sub-growth concentration). The reconstructed PG/PVP/PEI/HF@ZIF-8 coating achieved 72.47% corrosion inhibition via synergistic anodic protection and physical shielding. This work provides a novel green approach for surface antifouling and drag reduction, highlighting MOF-loaded QSIs as promising additives to enhance the antifouling performance of hydrogel coatings, anti-corrosion performance, and QSI performance for sustainable marine engineering applications. Full article
(This article belongs to the Section Gel Applications)
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14 pages, 2818 KiB  
Article
Microencapsulation of Lactiplantibacillus plantarum BXM2 in Bamboo Shoot-Derived Nanocellulose Hydrogel to Enhance Its Survivability
by Yajuan Huang, Qiao Guan, Yirui Wu, Chaoyang Zheng, Lingyue Zhong, Wen Xie, Jiaxin Chen, Juqing Huang, Qi Wang and Yafeng Zheng
Gels 2025, 11(6), 465; https://doi.org/10.3390/gels11060465 - 18 Jun 2025
Viewed by 311
Abstract
This study presents a novel approach for enhancing the survivability of Lactiplantibacillus plantarum BXM2 using bamboo shoot-derived nanocellulose hydrogels. Nanocellulose hydrogels, composed of cellulose nanofibers (CNFs), cellulose nanocrystals (CNCs), and polyvinyl alcohol (PVA), were developed as protective matrices for probiotics. Fourier transform infrared [...] Read more.
This study presents a novel approach for enhancing the survivability of Lactiplantibacillus plantarum BXM2 using bamboo shoot-derived nanocellulose hydrogels. Nanocellulose hydrogels, composed of cellulose nanofibers (CNFs), cellulose nanocrystals (CNCs), and polyvinyl alcohol (PVA), were developed as protective matrices for probiotics. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) confirmed the successful formation of hydrogen-bonded networks between PVA and nanocelluloses, while scanning electron microscopy (SEM) revealed that the ternary PVA-CNF-CNC hydrogel exhibited a dense, hierarchical porous structure, effectively encapsulating probiotics with an encapsulation efficiency of 92.56 ± 0.53%. Under simulated gastrointestinal digestion, the encapsulated probiotics maintained 8.04 log CFU/g viability, significantly higher than that of free bacteria (3.54 log CFU/mL). The hydrogel also enhanced heat tolerance (6.58 log CFU/mL at 70 °C) and freeze-drying survival (86.92% viability), outperforming binary systems. During 60-day storage at 4 °C and 25 °C, encapsulated probiotics retained viability above the critical threshold (≥6 log CFU/unit), whereas free cells declined rapidly. These findings highlight the potential of PVA-CNF-CNC hydrogel as an efficient delivery system to improve probiotic stability in food applications. Full article
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15 pages, 8156 KiB  
Article
Interpretable Machine Learning Analysis of Design Factors in Hydrogel Supercapacitors
by Liying Xu, Siqi Liu, Dandan Hu, Junhao Liu, Yuze Zhang, Ziqiang Li, Zichuan Su and Daxin Liang
Gels 2025, 11(6), 464; https://doi.org/10.3390/gels11060464 - 18 Jun 2025
Viewed by 343
Abstract
Understanding the relationships between design factors is crucial for the development of hydrogel supercapacitors, yet the relative importance and interdependencies of material properties and operating conditions remain unclear. This study employs interpretable machine learning to analyze the design factors that affect hydrogel supercapacitor [...] Read more.
Understanding the relationships between design factors is crucial for the development of hydrogel supercapacitors, yet the relative importance and interdependencies of material properties and operating conditions remain unclear. This study employs interpretable machine learning to analyze the design factors that affect hydrogel supercapacitor performance, using 232 experimental samples from 41 recent studies. SHAP analysis was implemented to quantify parameter importance and reveal feature interactions among 16 key design parameters, including polymer types, electrolyte formulations, and operating conditions. Results show that synthetic vinyl polymers most strongly influence specific capacitance, while conductive polymers predominantly affect cycle stability. Ionic conductivity emerged as the most impactful parameter despite moderate feature importance, indicating complex nonlinear relationships. Critical interdependencies between polymer concentration and electrolyte formulation suggest that optimal design requires coordinated parameter selection rather than independent optimization. This interpretable framework provides quantitative insights into design factor hierarchies and parameter interdependencies, offering evidence-based guidelines for rational material selection in hydrogel supercapacitor development. Full article
(This article belongs to the Special Issue Research Progress and Application Prospects of Gel Electrolytes)
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22 pages, 8987 KiB  
Article
Microfluidic Synthesis of Magnetic Silica Aerogels for Efficient Pesticide Removal from Water
by Dana-Ionela Tudorache (Trifa), Adelina-Gabriela Niculescu, Alexandra-Cătălina Bîrcă, Denisa Alexandra Florea, Marius Rădulescu, Bogdan-Ștefan Vasile, Roxana Trușcă, Dan-Eduard Mihaiescu, Tony Hadibarata and Alexandru-Mihai Grumezescu
Gels 2025, 11(6), 463; https://doi.org/10.3390/gels11060463 - 17 Jun 2025
Cited by 1 | Viewed by 608
Abstract
Aerogels have gained much interest in the last decades due to their specific properties, such as high porosity, high surface area, and low density, which have caused them to be used in multiple and varied fields. As the applicability of aerogels is tightly [...] Read more.
Aerogels have gained much interest in the last decades due to their specific properties, such as high porosity, high surface area, and low density, which have caused them to be used in multiple and varied fields. As the applicability of aerogels is tightly correlated to their morpho-structural features, special consideration must be allocated to the fabrication method. An emerging technique for producing nanostructured materials with tailored morphology and dimensions is represented by continuous-flow microfluidics. In this context, this work explores the synergic combination of aerogel-based materials with microfluidic synthesis platforms to generate advanced nanocomposite adsorbents for water decontamination. Specifically, this study presents the novel synthesis of a magnetic silica-based aerogel using a custom-designed 3D microfluidic platform, offering enhanced control over nanoparticle incorporation and gelation compared to conventional sol–gel techniques. The resulting gel was further dried via supercritical CO2 extraction to preserve its unique nanostructure. The multi-faceted physicochemical investigations (XRD, DLS, FT-IR, RAMAN, SEM, and TEM) confirmed the material’s uniform morphology, high porosity, and surface functionalization. The HR-MS FT-ICR analysis has also demonstrated the advanced material’s adsorption capacity for various pesticides, suggesting its adequacy for further environmental applications. An exceptional 93.7% extraction efficiency was registered for triazophos, underscoring the potential of microfluidic synthesis approaches in engineering advanced, eco-friendly adsorbent materials for water decontamination of relevant organic pollutants. Full article
(This article belongs to the Special Issue Silica Aerogel: Synthesis, Properties and Characterization)
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14 pages, 3844 KiB  
Article
Ambient-Dried Silica Xerogels with Enhanced Strength and Thermal Insulation via Calcium Ion-Glycerol Synergistic Crosslinking
by Xiaoyu Xie, Zilin Zhu, Yu Meng, Lijia Wang, Fuquan Zhao, Lingqing Chen, Lijie Jiang, Ming Yan and Xiaofan Zhou
Gels 2025, 11(6), 462; https://doi.org/10.3390/gels11060462 - 16 Jun 2025
Viewed by 398
Abstract
Despite their high porosity and wide applicability, silica xerogels face mechanical strength limitations for high-performance applications. This study presents an ambient-pressure sol-gel strategy utilizing calcium-glycerol synergy to produce robust xerogels with enhanced properties. Physicochemical analyses reveal that controlled Ca2+ incorporation (optimal at [...] Read more.
Despite their high porosity and wide applicability, silica xerogels face mechanical strength limitations for high-performance applications. This study presents an ambient-pressure sol-gel strategy utilizing calcium-glycerol synergy to produce robust xerogels with enhanced properties. Physicochemical analyses reveal that controlled Ca2+ incorporation (optimal at 6 wt.%) accelerates gelation kinetics while establishing a hybrid network through ionic complexation and hydrogen bonding. The resulting xerogels achieve exceptional compressive strength (30.8 MPa) while maintaining uniform mesoporosity (50–90 nm pore size). Remarkably, the as-prepared silica xerogels demonstrate outstanding thermal insulation, maintaining a 220 °C temperature differential in 300 °C environments. These results prove that the ambient-pressure sol-gel strategy utilizing calcium-glycerol synergy can enhance the mechanical performance and thermal insulation performance of silica xerogels with the dual actions of Ca2+-induced network reinforcement via silanol coordination and glycerol-mediated stress relief during ambient drying. Overall, this work can offer a scalable, energy-efficient approach to produce high-performance silica xerogels with huge potential in building envelopes and aerospace systems. Full article
(This article belongs to the Special Issue Silica Aerogel: Synthesis, Properties and Characterization)
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26 pages, 10223 KiB  
Article
Silver–Titania Nanocomposites for Photothermal Applications
by Leonardo Bottacin, Roberto Zambon, Francesca Tajoli, Veronica Zani, Roberto Pilot, Naida El Habra, Silvia Gross and Raffaella Signorini
Gels 2025, 11(6), 461; https://doi.org/10.3390/gels11060461 - 16 Jun 2025
Viewed by 397
Abstract
Local temperature measurement is crucial for understanding nanoscale thermal transport and developing nanodevices for biomedical, photonic, and optoelectronic applications. The rise of photothermal therapy for cancer treatment has increased the demand for high-resolution nanothermometric techniques capable of non-contact intracellular temperature measurement and modification. [...] Read more.
Local temperature measurement is crucial for understanding nanoscale thermal transport and developing nanodevices for biomedical, photonic, and optoelectronic applications. The rise of photothermal therapy for cancer treatment has increased the demand for high-resolution nanothermometric techniques capable of non-contact intracellular temperature measurement and modification. Raman spectroscopy meets this need: the ratio of anti-Stokes to Stokes Raman intensities for a specific vibrational mode correlates with local temperature through the Boltzmann distribution. The present study proposes a novel photothermal therapy agent designed to advance the current state of the art while adhering to green chemistry principles, thereby favoring low-temperature synthesis involving limited energy consumption. A key challenge in this field is to achieve close contact between plasmonic nanosystems, which act as nanoheaters, and local temperature sensors. This is achieved by employing silver nanoparticles as a heat release agent, coated with anatase-phase titanium dioxide, as a local temperature sensor. The proposed synthesis, which combines refluxing and subcritical solvothermal treatments, enables direct anatase formation, despite its metastability under standard conditions, thus eliminating the need for a calcination step. Structural characterization through SAED-HRTEM and Raman spectroscopy confirms the successful crystallization of the desired phase. Moreover, the nanothermometry measurements conducted at various wavelengths ultimately demonstrate both the effectiveness of these nanomaterials as thermometric probes, with a relative sensitivity of about 0.24 K−1%, and their capability as local heaters, with a release of a few tens of degrees. This work demonstrates a new synthetic strategy for these nanocomposites, which offers a promising pathway for the optimization of nanosystems in therapeutic applications. Full article
(This article belongs to the Special Issue Gel-Based Materials for Intelligent Sensors and Self-Powered Nanogenerators)
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19 pages, 1261 KiB  
Review
Advances in Gelatin-Based Tissue Engineering Using HRP/H2O2
by Marino Basha, Ahmad Aburub, Filippos F. Karageorgos, Georgios Tsoulfas and Aleck H. Alexopoulos
Gels 2025, 11(6), 460; https://doi.org/10.3390/gels11060460 - 16 Jun 2025
Viewed by 526
Abstract
Gelatin, a biocompatible and biodegradable polymer, has garnered considerable attention in tissue engineering (TE) due to its diverse applications enabled by its tunable physical properties. Among the various strategies employed for the fabrication of gelatin-based hydrogels, the use of horseradish peroxidase (HRP) and [...] Read more.
Gelatin, a biocompatible and biodegradable polymer, has garnered considerable attention in tissue engineering (TE) due to its diverse applications enabled by its tunable physical properties. Among the various strategies employed for the fabrication of gelatin-based hydrogels, the use of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) as a catalytic system has been highlighted as an effective tool for producing hydrogels with highly modifiable properties. Herein, we explore recent progress in the utilization of the HRP/H2O2 catalytic system for the creation of gelatin-based hydrogels, with an emphasis on TE applications. Particular attention has been given to the interplay between variations in the concentration equilibrium of HRP and H2O2 and the fine-tuning of gel properties tailored for various TE applications. Emerging trends, such as in situ gelation and hybrid bioinks, have also been examined through the lens of their prospective applications, extrapolating from the findings in cell cultures and animal models. A comprehensive review of two databases (Scopus and Web of Science) was conducted. The data extracted from each study included the materials used for each application, methods used for material preparation, cells used in the TE application, laboratory animals used, and whether computational/simulation techniques were implemented. The applications included both homopolymeric hydrogels, using only gelatin as the backbone, and copolymeric hydrogels, with ≥2 polymers. Full article
(This article belongs to the Special Issue Gelatin-Based Materials for Tissue Engineering)
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21 pages, 9127 KiB  
Article
Antibacterial Composites Based on Alginate/Egg White and ZnO Nanoparticles with the Addition of Essential Oils
by Adrian-Ionuț Nicoară, Adelina Valentina Anton, Roxana Doina Trușcă, Alexandra Cătălina Bîrcă, Cornelia-Ioana Ilie and Lia-Mara Dițu
Gels 2025, 11(6), 459; https://doi.org/10.3390/gels11060459 - 16 Jun 2025
Viewed by 352
Abstract
A series of hydrogels containing sodium alginate at different concentrations (2%, 3%, and 4%) and egg white were prepared through ionic cross-linking with calcium chloride (CaCl2) to obtain composite dressing materials. ZnO nanoparticles coated with eucalyptus or lavender essential oil were [...] Read more.
A series of hydrogels containing sodium alginate at different concentrations (2%, 3%, and 4%) and egg white were prepared through ionic cross-linking with calcium chloride (CaCl2) to obtain composite dressing materials. ZnO nanoparticles coated with eucalyptus or lavender essential oil were introduced into the hydrogel matrix to enhance antibacterial properties. The resulting hydrogels were freeze-dried to enhance mechanical properties, increase the porosity of the dressing, and facilitate further evaluations. A variety of analytical methods, including scanning electron microscopy (SEM), X-ray dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the composites. The developed composites exhibited high porosity and a swelling degree exceeding 200% after 3 days. Additionally, water absorption capacity increased with higher alginate concentrations in the samples. Furthermore, they demonstrated significant antibiofilm activity against Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli, with the samples containing 4% alginate showing the best results. Full article
(This article belongs to the Special Issue Gels: 10th Anniversary)
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12 pages, 3155 KiB  
Article
A Case Study on Fish Gelatin/Microcrystalline Cellulose Biomaterial Inks for Extrusion-Based Bioprinting
by Yubo Tao, Jinbao Du, Tong Hu, Peng Li, Ling Pan, Fangong Kong and Jingfa Zhang
Gels 2025, 11(6), 458; https://doi.org/10.3390/gels11060458 - 16 Jun 2025
Viewed by 379
Abstract
The development of printable, biocompatible, biodegradable, and cost-effective bioinks, or biomaterial inks, remains a focal point in extrusion-based bioprinting research. In this study, fish gelatin (FG) was reinforced with microcrystalline cellulose (MCC) to formulate biomaterial inks. These FG/MCC composite inks were fabricated into [...] Read more.
The development of printable, biocompatible, biodegradable, and cost-effective bioinks, or biomaterial inks, remains a focal point in extrusion-based bioprinting research. In this study, fish gelatin (FG) was reinforced with microcrystalline cellulose (MCC) to formulate biomaterial inks. These FG/MCC composite inks were fabricated into 3D scaffolds using an extrusion bioprinter. The influence of MCC concentration on printability was systematically evaluated. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the formation of hydrogen bonds between MCC and FG, indicating molecular-level interactions. Notably, MCC incorporation enhanced the rheological properties of the ink and significantly improved the compressive strength of printed scaffolds. Furthermore, MCC content modulated key scaffold characteristics, including porosity, degradation rate, swelling behavior, and microarchitecture. These findings demonstrate that FG/MCC composite hydrogels exhibit optimal properties for extrusion-based 3D bioprinting, offering a promising platform for tissue engineering applications. Full article
(This article belongs to the Special Issue Application of Hydrogels in 3D Bioprinting for Tissue Engineering)
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17 pages, 3979 KiB  
Article
Sugar Alcohols as Crosslinking Delay Additives for Fracturing Fluids
by Tariq Almubarak, Mohammed I. Alabdrabalnabi, Abdualilah Albaiz and Mohammed Yami
Gels 2025, 11(6), 457; https://doi.org/10.3390/gels11060457 - 15 Jun 2025
Viewed by 453
Abstract
The development of thermally stable fracturing fluids is essential for the effective stimulation of deep and low-permeability reservoirs. The stabilizing additives used in these fluids typically fall into three categories: crosslinking delay molecules, oxygen scavengers, and pH buffers. However, many conventional additives raise [...] Read more.
The development of thermally stable fracturing fluids is essential for the effective stimulation of deep and low-permeability reservoirs. The stabilizing additives used in these fluids typically fall into three categories: crosslinking delay molecules, oxygen scavengers, and pH buffers. However, many conventional additives raise toxicity and environmental concerns, prompting the search for safer alternatives. This study investigates the use of sugar alcohols, commonly used as low-calorie sweeteners, as environmentally responsible additives for high-temperature fracturing fluids. A guar-based fluid system was formulated at a pH of 10 and evaluated using a high-pressure high-temperature (HPHT) rheometer under simulated field pumping conditions at 300 °F for a 90 min period. The viscosity was measured at a shear rate of 100 s−1, with intermittent low-shear rates introduced to assess the structural recovery and fluid integrity. The effect of sugar alcohol concentration on crosslinking delay was examined across systems containing varying amounts of a zirconium-based crosslinker ranging from 1 to 4 gpt. The results demonstrated that sugar alcohols effectively delayed crosslinking, allowing for controlled viscosity development and improved stability at elevated temperatures. When optimized at concentrations of 2 ppt of the sugar alcohol with 4 gpt of the crosslinker, the fluid generated a peak viscosity of 600 cP after 2.5 min and maintained a viscosity above 300 cP throughout the 90 min test. Breaker results showed a controlled viscosity reduction, with final viscosity values reaching 10 cP. The proppant settling experiments confirmed the suspension of more than 95% of the proppant during the treatment window. These findings highlight the potential of sugar alcohols as effective and environmentally safer crosslinking delay additives for hydraulic fracturing applications. Full article
(This article belongs to the Special Issue Polymer Gels for the Oil and Gas Industry)
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5 pages, 931 KiB  
Editorial
Recent Progress in Hydrogel Synthesis and Biomedical Applications
by Luxing Wei and Jun Huang
Gels 2025, 11(6), 456; https://doi.org/10.3390/gels11060456 - 14 Jun 2025
Viewed by 476
Abstract
Hydrogels are three-dimensional network structures formed by hydrophilic polymer chains through chemical or physical cross-linking [...] Full article
(This article belongs to the Special Issue Synthesis and Applications of Hydrogels (2nd Edition))
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19 pages, 1211 KiB  
Systematic Review
Biopolymers in Facial Aesthetics: Gel-Based Applications, Safety, Effectiveness, and Future Prospects—A Systematic Review of the Literature
by Gonzalo Ruiz-de-León, Daniela Cortés-Eslava, Esther Hernández-Pacheco, María-Ángeles Serrera-Figallo, Daniel Torres-Lagares and María Baus-Domínguez
Gels 2025, 11(6), 455; https://doi.org/10.3390/gels11060455 - 13 Jun 2025
Viewed by 392
Abstract
Biopolymer-based dermal fillers have gained attention in facial aesthetics due to their biocompatibility, gel-forming properties, and capacity to stimulate tissue regeneration. However, evidence regarding their clinical performance remains scattered and inconsistent. This systematic review evaluates the current scientific literature on the effectiveness and [...] Read more.
Biopolymer-based dermal fillers have gained attention in facial aesthetics due to their biocompatibility, gel-forming properties, and capacity to stimulate tissue regeneration. However, evidence regarding their clinical performance remains scattered and inconsistent. This systematic review evaluates the current scientific literature on the effectiveness and safety of injectable biopolymers used in facial aesthetic procedures. A systematic search was conducted in PubMed, MEDLINE, and Embase databases for studies published between 2016 and 2024. Only human studies in English assessing clinical efficacy, safety, adverse events, and patient satisfaction were included. Of the 280 articles initially identified, 9 met the inclusion criteria. The selected studies showed improvements in facial volume and wrinkle reduction with gel-based biopolymers such as poly-L-lactic acid (PLLA), polycaprolactone (PCL), and polymethylmethacrylate (PMMA). Most studies reported high patient satisfaction and a low incidence of serious adverse effects. However, methodological heterogeneity and limited long-term data reduced the strength of the evidence. While injectable biopolymers appear to be effective and generally safe, current evidence is limited and variable. Further multicenter randomized trials with standardized protocols and longer follow-up periods are needed. Clinicians should apply these materials with caution, ensuring individualized treatment planning and careful risk assessment. Full article
(This article belongs to the Special Issue Recent Advances in Biopolymer Gels (2nd Edition))
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15 pages, 3873 KiB  
Article
Porous Silica Gels Doped with Gold Nanoparticles: Preparation, Microstructure, Optical and Textural Properties
by Nina Danchova, Dimitar Shandurkov, Roumen Tsekov, Luben Mihaylov, Tony Spassov and Stoyan Gutzov
Gels 2025, 11(6), 454; https://doi.org/10.3390/gels11060454 - 13 Jun 2025
Viewed by 284
Abstract
Porous silica gel powders, doped with gold nanoparticles (AuNPs), were obtained by heating silica gels containing 1-dodecanethiol and tetrachloroauric acid at temperatures of 450 °C, 700 °C and 900 °C, and characterized using X-ray diffraction, TEM/EDS studies, UV/Vis reflectance spectroscopy and DTA/TG investigations. [...] Read more.
Porous silica gel powders, doped with gold nanoparticles (AuNPs), were obtained by heating silica gels containing 1-dodecanethiol and tetrachloroauric acid at temperatures of 450 °C, 700 °C and 900 °C, and characterized using X-ray diffraction, TEM/EDS studies, UV/Vis reflectance spectroscopy and DTA/TG investigations. The color and microstructure of the obtained samples with a composition SiO2:AuNPs (about 0.03% Au) depend on the heating temperature. The UV/Vis reflection spectra of the samples are explained using Mie’s theory. The thermal stability of the obtained samples, as well as the processes occurring in the sol–gel matrix upon heating, were monitored by DTA/TG. The textural properties of the obtained materials were described based on adsorption–desorption isotherms. The obtained nanocomposites are promising pigments for ceramic glazes, similar to the Purple of Cassius. The textural properties of certain samples, SBET = 200–350 m2/g, a mean pore diameter (DAV) of approximately 10 nm and a specific pore volume (Vt) between 0.5 and 0.8 cm3/g, make them promising candidates for catalytic applications, comparable to aerogel-like materials. Full article
(This article belongs to the Special Issue Aerogels—Preparation and Properties)
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23 pages, 8674 KiB  
Article
Porous and Tough Polyacrylamide/Carboxymethyl Cellulose Gels Chemically Crosslinked via Cryo-UV Polymerization for Sustained Drug Release
by Duangkamon Viboonratanasri, Daniel Rudolf King, Tsuyoshi Okumura, Mohamad Alaa Terkawi, Yoshinori Katsuyama, Milena Lama, Tomoki Yasui and Takayuki Kurokawa
Gels 2025, 11(6), 453; https://doi.org/10.3390/gels11060453 - 13 Jun 2025
Viewed by 422
Abstract
While carboxymethyl cellulose (CMC)—a biocompatible and water-soluble cellulose derivative—holds promise for biomedical applications, challenges remain in synthesizing CMC-based hydrogels with covalent crosslinking through free radical polymerization without requiring complex, multi-step processes. In this study, we introduce a facile one-pot strategy that combines CMC [...] Read more.
While carboxymethyl cellulose (CMC)—a biocompatible and water-soluble cellulose derivative—holds promise for biomedical applications, challenges remain in synthesizing CMC-based hydrogels with covalent crosslinking through free radical polymerization without requiring complex, multi-step processes. In this study, we introduce a facile one-pot strategy that combines CMC with acrylamide (AAm) under cryogelation and low-intensity UV irradiation to achieve covalent bonding and a high polymerization yield. The resulting polyacrylamide/carboxymethyl cellulose (PAAm/CMC) porous gels were systematically evaluated for their chemical, physical, thermal, and drug-release properties, with a focus on the effects of AAm concentration and polymerization temperature (frozen vs. room temperature). Notably, the cryogel synthesized with 2.5 M AAm (PC2.5) exhibited significantly enhanced mechanical properties—that is, an 8.4-fold increase in tensile modulus and a 26-fold increase in toughness—compared with the non-cryo gel. Moreover, PC2.5 demonstrated excellent cyclic compression stability in water and phosphate-buffered saline (PBS), with less than 10% reduction in modulus after 100 cycles. These increases in the mechanical properties of PC2.5 are attributed to the formation of macropores with high polymer density and high crosslinking density at the pore walls. PC2.5 also showed slower drug release in PBS and good cytocompatibility. This study presents a simplified and efficient route for fabricating mechanically robust, covalently crosslinked PAAm/CMC cryogels, highlighting their strong potential for biomedical applications in drug delivery systems. Full article
(This article belongs to the Section Gel Analysis and Characterization)
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18 pages, 5357 KiB  
Article
Bio-Gel Formation Through Enzyme-Induced Carbonate Precipitation for Dust Control in Yellow River Silt
by Jingwei Zhang, Hualing Jia, Jia Li, Xuanyu Chen, Lei Wang, Shilong Wang and Lin Liu
Gels 2025, 11(6), 452; https://doi.org/10.3390/gels11060452 - 12 Jun 2025
Viewed by 750
Abstract
This study explored the enzymatic formation of gel-like polymeric matrices through carbonate precipitation for dust suppression in Yellow River silt. The hydrogel-modified EICP method effectively enhanced the compressive strength and resistance to wind–rain erosion by forming a reinforced bio-cemented crust. The optimal cementation [...] Read more.
This study explored the enzymatic formation of gel-like polymeric matrices through carbonate precipitation for dust suppression in Yellow River silt. The hydrogel-modified EICP method effectively enhanced the compressive strength and resistance to wind–rain erosion by forming a reinforced bio-cemented crust. The optimal cementation solution, consisting of urea and CaCl2 at equimolar concentrations of 1.25 mol/L, was applied to improve CaCO3 precipitation uniformity. A spraying volume of 4 L/m2 (first urea-CaCl2 solution, followed by urease solution) yielded a 14.9 mm thick hybrid gel-CaCO3 crust with compressive strength exceeding 752 kPa. SEM analysis confirmed the synergistic interaction between CaCO3 crystals and the gel matrix, where the hydrogel network acted as a nucleation template, enhancing crystal bridging and pore-filling efficiency. XRD analysis further supported the formation of a stable gel-CaCO3 composite structure, which exhibited superior resistance to wind–rain erosion and mechanical wear. These findings suggest that gel-enhanced EICP represents a novel bio-gel composite technology for sustainable dust mitigation in silt soils. Full article
(This article belongs to the Special Issue Synthesis, Properties, and Applications of Novel Polymer-Based Gels)
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28 pages, 2905 KiB  
Review
Gel-Based Self-Powered Nanogenerators: Materials, Mechanisms, and Emerging Opportunities
by Aditya Narayan Singh and Kyung-Wan Nam
Gels 2025, 11(6), 451; https://doi.org/10.3390/gels11060451 - 12 Jun 2025
Viewed by 699
Abstract
With the rapid rise in Internet of Things (IoT) and artificial intelligence (AI) technologies, there is an increasing need for portable, wearable, and self-powered flexible sensing devices. In such scenarios, self-powered nanogenerators have emerged as promising energy harvesters capable of converting ambient mechanical [...] Read more.
With the rapid rise in Internet of Things (IoT) and artificial intelligence (AI) technologies, there is an increasing need for portable, wearable, and self-powered flexible sensing devices. In such scenarios, self-powered nanogenerators have emerged as promising energy harvesters capable of converting ambient mechanical stimuli into electrical energy, enabling the development of autonomous flexible sensors and sustainable systems. This review highlights recent advances in nanogenerator technologies—particularly those based on piezoelectric and triboelectric effects—with a focus on soft, flexible, and gel-based polymer materials. Key mechanisms of energy conversion are discussed alongside strategies to enhance performance through material innovation, structural design, and device integration. Special attention is given to the role of gel-type composites, which offer unique advantages such as mechanical tunability, self-healing ability, and biocompatibility, making them highly suitable for next-generation wearable, biomedical, and environmental sensing applications. We also explore the evolving landscape of energy applications, from microscale sensors to large-area systems, and identify critical challenges and opportunities for future research. By synthesizing progress across materials, mechanisms, and application domains, this review aims to guide the rational design of high-performance, sustainable nanogenerators for the next era of energy technologies. Full article
(This article belongs to the Special Issue Gel-Based Materials for Intelligent Sensors and Self-Powered Nanogenerators)
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20 pages, 3663 KiB  
Article
Sol–Gel Synthesis and Comprehensive Study of Structural, Electrical, and Magnetic Properties of BiBaO3 Perovskite
by Faouzia Tayari, Kais Iben Nassar, João Pedro Carvalho, Sílvia Soreto Teixeira, Imen Hammami, Sílvia Rodrigues Gavinho, Manuel P. F. Graça and Manuel Almeida Valente
Gels 2025, 11(6), 450; https://doi.org/10.3390/gels11060450 - 12 Jun 2025
Cited by 1 | Viewed by 1233
Abstract
In this study, BiBaO3 perovskite was successfully synthesized via the sol–gel method and thoroughly characterized to evaluate its structural, microstructural, dielectric, electrical, and magnetic properties. X-ray diffraction (XRD) confirmed the formation of a single-phase perovskite structure with high crystallinity. Scanning electron microscopy [...] Read more.
In this study, BiBaO3 perovskite was successfully synthesized via the sol–gel method and thoroughly characterized to evaluate its structural, microstructural, dielectric, electrical, and magnetic properties. X-ray diffraction (XRD) confirmed the formation of a single-phase perovskite structure with high crystallinity. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) revealed a uniform grain morphology and elemental composition consistent with the intended stoichiometry. Dielectric measurements exhibited strong frequency-dependent behavior, suggesting potential for capacitive applications. The electrical conductivity displayed thermally activated behavior, indicative of semiconducting characteristics. Magnetic measurements showed weak ferromagnetic behavior at room temperature, an unusual observation for undoped BaBiO3-based systems. This magnetism may stem from subtle structural distortions or compositional variations introduced during synthesis. Comparison with previously reported studies underscores the significant influence of the synthesis route and microstructural features on the multifunctional properties of BiBaO3. Overall, the results highlight the promise of sol–gel-derived BiBaO3 as a candidate for multifunctional electronic and magnetic applications. Full article
(This article belongs to the Special Issue Gels for Efficient Energy Storage and Conversion)
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27 pages, 7784 KiB  
Article
Performance and Mechanism Analysis of an Anti-Skid Wear Layer of Active Slow-Release Ice–Snow Melting Modified by Gels
by Yuanzhao Chen, Zhenxia Li, Tengteng Guo, Chenze Fang, Peng Guo, Chaohui Wang, Bing Bai, Weiguang Zhang, Haobo Yan and Qi Chen
Gels 2025, 11(6), 449; https://doi.org/10.3390/gels11060449 - 11 Jun 2025
Viewed by 484
Abstract
Winter pavement maintenance faces challenges in balancing large-scale upkeep and driving safety, particularly regarding the application of active slow-release materials. This study proposes a gel-modified salt-storing ceramsite asphalt mixture to enhance ice-melting capabilities through controlled salt release. By replacing a conventional coarse aggregate [...] Read more.
Winter pavement maintenance faces challenges in balancing large-scale upkeep and driving safety, particularly regarding the application of active slow-release materials. This study proposes a gel-modified salt-storing ceramsite asphalt mixture to enhance ice-melting capabilities through controlled salt release. By replacing a conventional coarse aggregate with salt-storing ceramsite in SMA-10 graded mixtures (0–80% content), we systematically evaluate its mechanical performance and de-icing functionality. The experimental results demonstrate that 40% salt-storing ceramsite content optimizes high-temperature stability while maintaining acceptable low-temperature performance and water resistance. Microstructural analysis reveals that silicone–acrylic emulsion forms a hydrophobic film on ceramsite surfaces, enabling uniform salt distribution and sustained release. The optimal 10% gel modification achieves effective salt retention and controlled release through pore-structure regulation. These findings establish a 40–60% salt-storing ceramsite content range as the practical range for winter pavement applications, offering insights into the design of durable snow-melting asphalt surfaces. Full article
(This article belongs to the Special Issue Synthesis, Properties, and Applications of Novel Polymer-Based Gels)
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20 pages, 4373 KiB  
Article
Engineering Moxifloxacin-Encapsulated Liposome-Enriched Alginate Hydrogel Films
by Ismail Bal, Meltem Macit, Ali Alasiri, Onur Cem Namli, Muhammad Sohail Arshad, Zeeshan Ahmad, Gulengul Duman and Israfil Kucuk
Gels 2025, 11(6), 448; https://doi.org/10.3390/gels11060448 - 11 Jun 2025
Viewed by 627
Abstract
In the present study, we developed a moxifloxacin (MXF)-encapsulated liposome-enriched alginate nanocomposite hydrogel coating. MXF was encapsulated in soy lecithin (SL:MXF:2:1) via the probe sonication method with an average efficiency of 80%. Two different manufacturing methods, including a micropipetting and a T-shaped microfluidic [...] Read more.
In the present study, we developed a moxifloxacin (MXF)-encapsulated liposome-enriched alginate nanocomposite hydrogel coating. MXF was encapsulated in soy lecithin (SL:MXF:2:1) via the probe sonication method with an average efficiency of 80%. Two different manufacturing methods, including a micropipetting and a T-shaped microfluidic junction (TMJ) device technique, were used to incorporate the MXF-encapsulated liposomes into hydrogel matrices and layered as a coating on polymeric substrate material. Drug encapsulation and its incorporation into the hydrogel matrix significantly enhanced its stability and facilitated a prolonged drug release profile. A relatively rapid drug release was observed in the MXF-encapsulated liposome-loaded polymeric particulate layer developed via the micropipetting than the TMJ device technique. The findings confirmed sustained drug release behavior due to a hydrogel particulate structural uniformity conferred by the micromachine device, TMJ. Thus, these nanocomposite hydrogel coatings achieved can serve as a promising candidate for the treatment of ophthalmic or mucosal membrane infections. Full article
(This article belongs to the Section Gel Processing and Engineering)
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26 pages, 8645 KiB  
Article
Effect of the Gel Drying Method on Properties of Semicrystalline Aerogels Prepared with Different Network Morphologies
by Glenn A. Spiering, Garrett F. Godshall and Robert B. Moore
Gels 2025, 11(6), 447; https://doi.org/10.3390/gels11060447 - 10 Jun 2025
Viewed by 589
Abstract
The purpose of this study was to investigate the effect of different drying methods on the structure and properties of semicrystalline polymer aerogels. Aerogels, consisting of either globular or strut-like morphologies, were prepared from poly(ether ether ketone) (PEEK) or poly(phenylene sulfide) (PPS) and [...] Read more.
The purpose of this study was to investigate the effect of different drying methods on the structure and properties of semicrystalline polymer aerogels. Aerogels, consisting of either globular or strut-like morphologies, were prepared from poly(ether ether ketone) (PEEK) or poly(phenylene sulfide) (PPS) and dried using vacuum drying, freeze-drying, or supercritical CO2 extraction. Vacuum drying was found to result in aerogels with a higher shrinkage, smaller mesopores (with pore widths of 2–50 nm), and smaller surface areas compared to the use of supercritical extraction as the drying method. Freeze-dried aerogels tended to have properties between those of vacuum-dried aerogels and aerogels prepared with supercritical extraction. High network connectivity was found to lead to improved gel modulus, which increased the ability of aerogels to resist network deformation due to stresses induced during drying. The PEEK and PPS aerogel networks consisting of highly connected strut-like features were considerably stiffer than those composed of globular features, and thus shrank less under the forces induced by vacuum drying or freeze-drying. The aerogels prepared from PPS were found to have larger mesopores and smaller surface areas than the aerogels prepared from PEEK. The larger mesopores of the PPS aerogels induced lower capillary stresses on the aerogel network, and thus shrank less. This work demonstrates that preparing PEEK and PPS gels with strut-like features can allow aerogel processing with simpler evaporative drying methods rather than the more complex supercritical drying method. Full article
(This article belongs to the Special Issue Advances in Synthetic and Bio-Based Aerogels: Mechanical Properties, Thermal Insulation, and Environmental Remediation (2nd Edition))
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20 pages, 7474 KiB  
Article
Utilization of Flotation Wastewater for Metal Xanthate Gel Synthesis and Its Role in Polyaniline-Based Supercapacitor Electrode Fabrication
by Atanas Garbev, Elitsa Petkucheva, Galia Ivanova, Mariela Dimitrova, Antonia Stoyanova and Evelina Slavcheva
Gels 2025, 11(6), 446; https://doi.org/10.3390/gels11060446 - 10 Jun 2025
Viewed by 1158
Abstract
The aim of this study is to explore the feasibility of using flotation wastewater from copper–porphyry ore processing to synthesize a gel that serves as a precursor for a polymer nanocomposite used in supercapacitor electrode fabrication. These wastewaters—characterized by high acidity and elevated [...] Read more.
The aim of this study is to explore the feasibility of using flotation wastewater from copper–porphyry ore processing to synthesize a gel that serves as a precursor for a polymer nanocomposite used in supercapacitor electrode fabrication. These wastewaters—characterized by high acidity and elevated concentrations of metal cations (Cu, Ni, Zn, Fe), sulfates, and organic reagents such as xanthates, oil (20 g/t ore), flotation frother (methyl isobutyl carbinol), and pyrite depressant (CaO, 500–1000 g/t), along with residues from molybdenum flotation (sulfuric acid, sodium hydrosulfide, and kerosene)—are byproducts of copper–porphyry gold-bearing ore beneficiation. The reduction of Ni powder in the wastewater induces the degradation and formation of a gel that captures both residual metal ions and organic compounds—particularly xanthates—which play a crucial role in the subsequent steps. The resulting gel is incorporated during the oxidative polymerization of aniline, forming a nanocomposite with a polyaniline matrix and embedded xanthate-based compounds. An asymmetric supercapacitor was assembled using the synthesized material as the cathodic electrode. Electrochemical tests revealed remarkable capacitance and cycling stability, demonstrating the potential of this novel approach both for the valorization of industrial waste streams and for enhancing the performance of energy storage devices. Full article
(This article belongs to the Special Issue Gel-Based Materials for Intelligent Sensors and Self-Powered Nanogenerators)
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22 pages, 12049 KiB  
Article
Biodegradable and Mechanically Resilient Recombinant Collagen/PEG/Catechol Cryogel Hemostat for Deep Non-Compressible Hemorrhage and Wound Healing
by Yuanzhe Zhang, Tianyu Yao, Ru Xu, Pei Ma, Jing Zhao and Yu Mi
Gels 2025, 11(6), 445; https://doi.org/10.3390/gels11060445 - 10 Jun 2025
Viewed by 928
Abstract
Traumatic non-compressible hemorrhage and subsequent wound management remain critical challenges in military and civilian settings to this day. Cryogels have emerged as promising hemostatic materials for non-compressible hemorrhage due to their blood-triggered shape recovery. In this study, a biodegradable and mechanically resilient cryogel [...] Read more.
Traumatic non-compressible hemorrhage and subsequent wound management remain critical challenges in military and civilian settings to this day. Cryogels have emerged as promising hemostatic materials for non-compressible hemorrhage due to their blood-triggered shape recovery. In this study, a biodegradable and mechanically resilient cryogel (CF/PD) was produced via cryopolymerization, employing methacrylated recombinant collagen as a macromolecular crosslinker alongside poly (ethylene glycol) diacrylate (PEGDA) and dopamine methacrylate (DMA). With its interpenetrating macro-porous structure and high hydrophilicity, the CF/PD rapidly absorbs blood and returns to its original shape within 1.5 s. In a rat liver defect model, CF/PD outperformed commercially available gelatin sponges, reducing hemostasis time by 74.4% and blood loss by 76.5%. Moreover, CF/PD cryogels facilitate in situ tissue regeneration by virtue of the bioactivity and degradability of recombinant collagen. This work establishes a bioactive recombinant collagen-driven cryogel platform, offering a transformative solution for managing non-compressible hemorrhage while enabling tissue regeneration. Full article
(This article belongs to the Special Issue Advancing Green Chemistry in Hydrogel Development: Design, Synthesis, and Characterization)
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4 pages, 231 KiB  
Editorial
Editorial for the Special Issue “Functionalized Gels for Environmental Applications 2nd Edition”
by Luca Burratti, Iole Venditti and Paolo Prosposito
Gels 2025, 11(6), 444; https://doi.org/10.3390/gels11060444 - 10 Jun 2025
Viewed by 251
Abstract
Dear readers, the second edition of the Special Issue entitled “Functionalized Gels for Environmental Applications” in the journal Gels was also a great success [...] Full article
(This article belongs to the Special Issue Functionalized Gels for Environmental Applications (2nd Edition))
17 pages, 4687 KiB  
Article
Synthesis of Temperature/pH Dual-Responsive Double-Crosslinked Hydrogel on Medical Titanium Alloy Surface
by Yutong Li, Jiaqi Wang and Shouxin Liu
Gels 2025, 11(6), 443; https://doi.org/10.3390/gels11060443 - 9 Jun 2025
Viewed by 775
Abstract
Medical titanium alloy Ti-6Al-4V (TC4) is widely used as a surgical implant material in biomedical fields owing to its superior biocompatibility, corrosion resistance, and mechanical performance, particularly for osseous integration applications. However, long-term contact of medical titanium-based implants with human soft tissues may [...] Read more.
Medical titanium alloy Ti-6Al-4V (TC4) is widely used as a surgical implant material in biomedical fields owing to its superior biocompatibility, corrosion resistance, and mechanical performance, particularly for osseous integration applications. However, long-term contact of medical titanium-based implants with human soft tissues may induce infection and inflammation. To address these limitations, a drug-loading gel was designed to be synthesized on a TC4 surface to improve biointegration. Considering the critical regulatory roles of temperature and pH in physiological environments, this study synthesized a dual-responsive hydrogel using the temperature-sensitive monomers 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and oligoethylene glycol methacrylate (OEGMA) and the pH-sensitive monomer diethylaminoethyl methacrylate (DEAEMA), employing stereocomplexed polylactic acid as a physical crosslinker and N,N′-methylenebisacrylamide (MBA) as a chemical crosslinker. A polydopamine-based initiator was synthesized via dopamine functionalization with 2-bromoisobutyryl bromide (BIBB). The amphiphilic co-network hydrogel was grafted onto a modified TC4 surface through atom transfer radical polymerization (ATRP). Integration of the drug-loading gel and TC4 gives the implant an “active therapeutic” function by localized drug release. The results demonstrated that the energy storage modulus of the double-crosslinked gel matched that of human soft tissues. The gels exhibited efficient drug release. Full article
(This article belongs to the Section Gel Processing and Engineering)
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33 pages, 11543 KiB  
Review
Recent Progress of Biomaterial-Based Hydrogels for Wearable and Implantable Bioelectronics
by Baojin Chen, Yan Zhu, Renjie Yu, Yunxiang Feng, Zhenpeng Han, Chang Liu, Pengcheng Zhu, Lijun Lu and Yanchao Mao
Gels 2025, 11(6), 442; https://doi.org/10.3390/gels11060442 - 9 Jun 2025
Viewed by 2004
Abstract
Bioelectronics for wearable and implantable biomedical devices has attracted significant attention due to its potential for continuous health monitoring, early disease diagnosis, and real-time therapeutic interventions. Among the various materials explored for bioelectronic applications, hydrogels derived from natural biopolymers have emerged as highly [...] Read more.
Bioelectronics for wearable and implantable biomedical devices has attracted significant attention due to its potential for continuous health monitoring, early disease diagnosis, and real-time therapeutic interventions. Among the various materials explored for bioelectronic applications, hydrogels derived from natural biopolymers have emerged as highly promising candidates, owing to their inherent biocompatibility, mechanical compliance akin to biological tissues, and tunable structural properties. This review provides a comprehensive overview of recent advancements in the design and application of protein-based hydrogels, including gelatin, collagen, silk fibroin, and gluten, as well as carbohydrate-based hydrogels such as chitosan, cellulose, alginate, and starch. Particular emphasis is placed on elucidating their intrinsic material characteristics, modification strategies to improve electrical and mechanical performance, and their applicability for bioelectronic interfaces. The review further explores their diverse applications in physiological and biochemical signal sensing, bioelectric signal recording, and electrical stimulation. Finally, current challenges and future perspectives are discussed to guide the ongoing innovation of hydrogel-based systems for next-generation bioelectronic technologies. Full article
(This article belongs to the Special Issue Stretchable Conductive Hydrogel Materials for Flexible Sensors and Bioelectronics)
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