Gels

17 pages, 1128 KiB

Open AccessSystematic Review

Biopolymers for Liver Tissue Engineering: A Systematic Review

by John Ong, Jacky Junzhe Zhao, Carla Swift and Athina E. Markaki

Gels 2025, 11(7), 525; https://doi.org/10.3390/gels11070525 - 7 Jul 2025

Stem cell-derived liver cells, organoids, and lab-grown liver tissue are promising regenerative therapies for liver disease. However, current culture conditions are sub-optimal, producing end-target cells and tissue phenotypes that are immature or unstable when compared to primary liver cells and tissue. Biopolymers used [...] Read more.

Stem cell-derived liver cells, organoids, and lab-grown liver tissue are promising regenerative therapies for liver disease. However, current culture conditions are sub-optimal, producing end-target cells and tissue phenotypes that are immature or unstable when compared to primary liver cells and tissue. Biopolymers used in culture substrates and scaffolds for tissue engineering significantly impact the quality of the end-target cells and tissue, influencing the efficacy of regenerative treatments. In addition, the biochemical properties of some biopolymers may preclude the translation of downstream bioengineered products into clinical practice. Therefore, this systematic review aims to evaluate the recent advances in biopolymers within liver tissue engineering, providing an overview of the current usage in the field and highlighting novel substrates that have strong potential to be translated into clinical therapy. Full article

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

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13 pages, 1890 KiB

Open AccessArticle

Compound Salt-Based Coagulants for Tofu Gel Production: Balancing Quality and Protein Digestibility

by Zhaolu Li, Sisi Zhang, Zihan Gao, Xinyue Guo, Ruohan Wang, Maoqiang Zheng and Guangliang Xing

Gels 2025, 11(7), 524; https://doi.org/10.3390/gels11070524 - 6 Jul 2025

Abstract

Tofu quality is critically influenced by coagulants, though their impact on protein digestibility remains underexplored. This study aimed to investigate the effects of calcium sulfate (CaSO₄), magnesium chloride (MgCl₂), and their combination (CaSO₄ + MgCl₂) on [...] Read more.

Tofu quality is critically influenced by coagulants, though their impact on protein digestibility remains underexplored. This study aimed to investigate the effects of calcium sulfate (CaSO₄), magnesium chloride (MgCl₂), and their combination (CaSO₄ + MgCl₂) on the physicochemical properties and protein digestibility of tofu. Water-holding capacity, cooking loss, texture, protein composition, and protein digestibility were analyzed. The results showed that the CaSO₄ + MgCl₂ combination yielded a water-holding capacity of 99.16%, significantly higher than CaSO₄ tofu (93.73%) and MgCl₂ tofu (96.82%), while reducing cooking loss to 2.03% and yielding the highest hardness (897.27 g) and gumminess (765.72). Electrophoresis revealed distinct protein retention patterns, with MgCl₂ (0.6% w/v) forming denser gels that minimized protein leakage into soy whey. During in vitro digestion, MgCl₂-coagulated tofu exhibited superior soluble protein release (5.33 mg/mL after gastric digestion) and higher intestinal peptide (5.89 mg/mL) and total amino acid (123.06 μmol/mL) levels, indicating enhanced digestibility. Conversely, the CaSO₄ + MgCl₂ combination showed delayed proteolysis in electrophoresis analysis. These findings demonstrate that coagulant selection directly modulates tofu’s texture, water retention, and protein bioavailability, with MgCl₂ favoring digestibility and the hybrid coagulant optimizing physical properties. This provides strategic insights for developing nutritionally enhanced tofu products. Full article

(This article belongs to the Special Issue Food Gel-Based Systems: Gel-Forming and Food Applications)

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19 pages, 3030 KiB

Open AccessArticle

Effect of Chitosan Properties and Dissolution State on Solution Rheology and Film Performance in Triboelectric Nanogenerators

by Francisca Araújo, Solange Magalhães, Bruno Medronho, Alireza Eivazi, Christina Dahlström, Magnus Norgren and Luís Alves

Gels 2025, 11(7), 523; https://doi.org/10.3390/gels11070523 - 5 Jul 2025

Abstract

Chitosan films with potential application in triboelectric nanogenerators (TENGs) represent a promising approach to replace non-biobased materials in these innovative devices. In the present work, chitosan with varying molecular weights (MW) and degrees of deacetylation was dissolved in aqueous acetic acid (AA) at [...] Read more.

Chitosan films with potential application in triboelectric nanogenerators (TENGs) represent a promising approach to replace non-biobased materials in these innovative devices. In the present work, chitosan with varying molecular weights (MW) and degrees of deacetylation was dissolved in aqueous acetic acid (AA) at different acid concentrations. It was observed that the MW had a greater influence on the viscosity of the solution compared to either the acid concentration or deacetylation degree. Gel formation occurred in high-MW chitosan solutions prepared with low AA concentration. Films prepared from chitosan solutions, through solvent-casting, were used to prepare TENGs. The power output of the TENGs increased with higher concentrations of AA used in the chitosan dissolution process. Similarly, the residual AA content in the dried films also increased with higher initial AA concentrations. Additionally, hot-pressing of the films significantly improves the TENG power output due to the decrease in morphological defects of the films. It was demonstrated that a good selection of the acid concentration not only facilitates the dissolution of chitosan but also plays a key role in defining the properties of the resulting solutions and films, thereby directly impacting the performance of the TENGs. Full article

(This article belongs to the Special Issue Advances in Chitin- and Chitosan-Based Hydrogels (2nd Edition))

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11 pages, 2099 KiB

Open AccessArticle

Biocompatible Composite Protective Thin Layer Containing Cellulose Fibers and Silica Cryogel

by Marius Horvath and Katalin Sinkó

Gels 2025, 11(7), 522; https://doi.org/10.3390/gels11070522 - 5 Jul 2025

Abstract

The aim of the present research was to synthesize protective composite layers from biodegradable cellulose and biocompatible, sol–gel-derived silica cryogel. An important task in the present work was to achieve good applicability on distinct (smooth and rough) surfaces of various materials (from metallic [...] Read more.

The aim of the present research was to synthesize protective composite layers from biodegradable cellulose and biocompatible, sol–gel-derived silica cryogel. An important task in the present work was to achieve good applicability on distinct (smooth and rough) surfaces of various materials (from metallic to ceramic). The aim was to utilize the composite layers as thermal and electric insulation coating. The investigation put some effort into the enhancement of mechanical strength and the elasticity of the thin layer as well as a reduction in its water solubility. The removal of the alkali content leads successfully to a significant reduction in water solubility (97 wt% → 1–3 wt%). Adhesion properties were measured using a specialized measurement technique developed in our laboratory. Treatments of the substrate surface, such as alkaline or acidic etching (i.e., Na₂CO₃, HF, water glass), mechanical roughening, or the application of a thin alkali-containing primer layer, strongly increase adhesion. SEM analyses revealed the interactions between the matrix and the reinforcement phase and their morphology. Full article

(This article belongs to the Special Issue Advances and Current Applications in Gel-Based Membranes)

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16 pages, 2293 KiB

Open AccessArticle

Molecular Dynamics Simulation of the Thermosensitive Gelation Mechanism of Phosphorylcholine Groups-Conjugated Methylcellulose Hydrogel

by Hongyu Mei, Yaqing Huang, Juzhen Yi, Wencheng Chen, Peng Guan, Shanyue Guan, Xiaohong Chen, Wei Li and Liqun Yang

Gels 2025, 11(7), 521; https://doi.org/10.3390/gels11070521 - 4 Jul 2025

Abstract

The intelligently thermosensitive 2-methacryloyloxyethyl phosphorylcholine (MPC) groups-conjugated methylcellulose (MC) hydrogel, abbreviated as MPC-g-MC, exhibits good potential for prevention of postoperative adhesions. However, its thermosensitive gelation mechanism and why the MPC-g-MC hydrogel shows a lower gelation temperature than that of MC hydrogel are still [...] Read more.

The intelligently thermosensitive 2-methacryloyloxyethyl phosphorylcholine (MPC) groups-conjugated methylcellulose (MC) hydrogel, abbreviated as MPC-g-MC, exhibits good potential for prevention of postoperative adhesions. However, its thermosensitive gelation mechanism and why the MPC-g-MC hydrogel shows a lower gelation temperature than that of MC hydrogel are still unclear. Molecular dynamics (MD) simulation was thus used to investigate these mechanisms in this work. After a fully atomistic MPC-g-MC molecular model was constructed, MD simulations during the thermal simulation process and at constant temperatures were performed using GROMACS 2022.3 software. The results indicated that the hydrophobic interactions between the MPC-g-MC molecular chains increased, the interactions between the MPC-g-MC molecular chains and H₂O molecules decreased with the rise in temperature, and the hydrogen bonding structures were changed during the thermal simulation process. As a result, the MPC-g-MC molecular chains began to aggregate at about 33 °C (close to the gelation temperature of 33 °C determined by the rheological measurement), bringing about the formation of the MPC-g-MC hydrogel in the macroscopic state. The mechanism of MPC-g-MC hydrogel formation showed that its lower gelation temperature than that of the MC hydrogel is attributed to the increase in the interactions (including hydrophobic interactions, hydrogen bonding interactions, Van der Waals and Coulomb forces) induced by the side MPC groups of MPC-g-MC molecules. The thermosensitive gelation mechanism revealed in this study provides an important reference for the development of novel thermosensitive MC-derived hydrogels with gelation temperatures close to human body temperature. Full article

(This article belongs to the Special Issue Advances in Functional and Intelligent Hydrogels)

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39 pages, 5423 KiB

Open AccessReview

Dual-Drug Delivery Systems Using Hydrogel–Nanoparticle Composites: Recent Advances and Key Applications

by Moon Sup Yoon, Jae Min Lee, Min Jeong Jo, Su Jeong Kang, Myeong Kyun Yoo, So Yeon Park, Sunghyun Bong, Chan-Su Park, Chun-Woong Park, Jin-Seok Kim, Sang-Bae Han, Hye Jin Lee and Dae Hwan Shin

Gels 2025, 11(7), 520; https://doi.org/10.3390/gels11070520 - 3 Jul 2025

Abstract

Dual-drug delivery systems using hydrogel–nanoparticle composites have emerged as a versatile platform for achieving controlled, targeted, and efficient delivery of two distinct therapeutic agents. This approach combines the high loading capacity and tunable release properties of hydrogels with the enhanced stability and targeting [...] Read more.

Dual-drug delivery systems using hydrogel–nanoparticle composites have emerged as a versatile platform for achieving controlled, targeted, and efficient delivery of two distinct therapeutic agents. This approach combines the high loading capacity and tunable release properties of hydrogels with the enhanced stability and targeting ability of nanoparticles, providing synergistic benefits in various biomedical applications. While significant progress has been made, previous research has primarily focused on single-drug systems or simple co-delivery strategies, often lacking precise spatial and temporal control. This gap underscores the need for more sophisticated composite designs that enable programmable, multi-phase release. This review discusses representative fabrication methods, including physical embedding, covalent integration, and layer-by-layer assembly, to offer insights into practical implementation strategies. Also we present recent studies focusing on key applications—including wound healing, cancer therapy, infection prevention, transplant immunosuppression, and tissue regeneration—with an emphasis on composite design and formulation strategies, types of hydrogels and nanoparticles, and mechanisms of dual-drug release and evaluation. Recent advances in nanoparticle engineering and hydrogel formulation have enabled precise control over drug release and improved therapeutic outcomes. Dual-drug delivery systems using hydrogel–nanoparticle composites present a promising approach for overcoming the limitations of conventional monotherapy and achieving synergistic therapeutic effects. Ongoing research continues to optimize the design, efficacy, and safety of these systems, paving the way for their clinical translation. Full article

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

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5 pages, 251 KiB

Open AccessEditorial

Recent Advances in Gels for Water Treatment

by Anita-Laura Chiriac, Andrei Sarbu and Anamaria Zaharia

Gels 2025, 11(7), 519; https://doi.org/10.3390/gels11070519 - 3 Jul 2025

Abstract

Water is a vital resource for all known life forms on our planet, and essential for human health, economic development, and maintaining ecological balance [...] Full article

(This article belongs to the Special Issue Gels for Water Treatment)

24 pages, 5036 KiB

Open AccessArticle

Eugenol@natural Zeolite vs. Citral@natural Zeolite Nanohybrids for Gelatin-Based Edible-Active Packaging Films

by Achilleas Kechagias, Areti A. Leontiou, Yelyzaveta K. Oliinychenko, Alexandros Ch. Stratakos, Konstantinos Zaharioudakis, Katerina Katerinopoulou, Maria Baikousi, Nikolaos D. Andritsos, Charalampos Proestos, Nikolaos Chalmpes, Aris E. Giannakas and Constantinos E. Salmas

Gels 2025, 11(7), 518; https://doi.org/10.3390/gels11070518 - 3 Jul 2025

Abstract

In this study, aligned with the principles of the circular economy and sustainability, novel eugenol@natural zeolite (EG@NZ) and citral@natural zeolite (CT@NZ) nanohybrids were developed. These nanohybrids were successfully incorporated into a pork gelatin (Gel)/glycerol (Gl) composite matrix using an extrusion–compression molding method to [...] Read more.

In this study, aligned with the principles of the circular economy and sustainability, novel eugenol@natural zeolite (EG@NZ) and citral@natural zeolite (CT@NZ) nanohybrids were developed. These nanohybrids were successfully incorporated into a pork gelatin (Gel)/glycerol (Gl) composite matrix using an extrusion–compression molding method to produce innovative active packaging films: Gel/Gl/xEG@NZ (where x = 5, 10, and 15%wt.) and Gel/Gl/xCT@NZ (where x = 5 and 10%wt.). All films exhibited zero oxygen barrier properties. Release kinetic studies showed that both EG@NZ and CT@NZ nanohybrids adsorbed up to 58%wt. of their respective active compounds. However, EG@NZ exhibited a slow and nearly complete release of eugenol, whereas CT@NZ released approximately half of its citral content at a faster rate. Consequently, the obtained Gel/Gl/xEG@NZ films demonstrated significantly higher antioxidant activity as measured by the 2,2-diphenyl-1-picrylhydrazylradical (DPPH) assay and superior antibacterial effectiveness against Escherichia coli and Listeria monocytogenes compared to their CT-based counterparts. Overall, the Gel/Gl/xEG@NZ films show strong potential for applications as active pads for fresh pork ham slices, offering zero oxygen permeability, enhanced antioxidant and antibacterial properties, and effective control of total viable count (TVC) growth, maintaining a low and steady rate beyond the 10th day of a 26-day storage period. Full article

(This article belongs to the Special Issue Edible Gel Coatings and Membranes)

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17 pages, 2822 KiB

Open AccessArticle

Rat Islet pECM Hydrogel-Based Microencapsulation: A Protective Niche for Xenotransplantation

by Michal Skitel Moshe, Stasia Krishtul, Anastasia Brandis, Rotem Hayam, Shani Hamias, Mazal Faraj, Tzila Davidov, Inna Kovrigina, Limor Baruch and Marcelle Machluf

Gels 2025, 11(7), 517; https://doi.org/10.3390/gels11070517 - 2 Jul 2025

Abstract

Type 1 diabetes (T1D) is caused by autoimmune-mediated destruction of pancreatic β-cells, resulting in insulin deficiency. While islet transplantation presents a potential therapeutic approach, its clinical application is impeded by limited donor availability and the risk of immune rejection. This study proposes an [...] Read more.

Type 1 diabetes (T1D) is caused by autoimmune-mediated destruction of pancreatic β-cells, resulting in insulin deficiency. While islet transplantation presents a potential therapeutic approach, its clinical application is impeded by limited donor availability and the risk of immune rejection. This study proposes an innovative islet encapsulation strategy that utilizes decellularized porcine pancreatic extracellular matrix (pECM) as the sole biomaterial to engineer bioactive, immunoprotective microcapsules. Rat islets were encapsulated within pECM-based microcapsules using the electrospray technology and were compared to conventional alginate-based microcapsules in terms of viability, function, and response to hypoxic stress. The pECM microcapsules maintained a spherical morphology, demonstrating mechanical robustness, and preserving essential ECM components (collagen I/IV, laminin, fibronectin). Encapsulated islets exhibited sustained viability and superior insulin secretion over a two-week period compared to alginate controls. The expression of key β-cell transcription factors (PDX1, MAFA) and structural integrity were preserved. Under hypoxic conditions, pECM microcapsules significantly reduced islet apoptosis, improved structural retention, and promoted functional recovery, likely due to antioxidant and ECM-derived cues inherent to the pECM. In vivo transplantation in immunocompetent mice confirmed the biocompatibility of pECM microcapsules, with minimal immune responses, stable insulin/glucagon expression, and no adverse systemic effects. These findings position pECM-based microencapsulation as a promising strategy for creating immunoprotective, bioactive niches for xenogeneic islet transplantation, with the potential to overcome current limitations in cell-based diabetes therapy. Full article

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

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33 pages, 13987 KiB

Open AccessReview

Insights into Carbon-Based Aerogels Toward High-Performance Lithium–Sulfur Batteries: A Review of Strategies for Sulfur Incorporation Within Carbon Aerogel Frameworks

by Yue Gao, Dun Liu, Yi Zhao, Dongdi Yang, Lugang Zhang, Fei Sun and Xiaoxiao Wang

Gels 2025, 11(7), 516; https://doi.org/10.3390/gels11070516 - 2 Jul 2025

Abstract

Lithium–sulfur batteries (LSBs), possessing excellent theoretical capacities, advanced theoretical energy densities, low cost, and nontoxicity, are one of the most promising energy storage battery systems. However, some issues, including poor conductivity of elemental S, the “shuttle effect” of high-order lithium polysulfides (LiPSs), and [...] Read more.

Lithium–sulfur batteries (LSBs), possessing excellent theoretical capacities, advanced theoretical energy densities, low cost, and nontoxicity, are one of the most promising energy storage battery systems. However, some issues, including poor conductivity of elemental S, the “shuttle effect” of high-order lithium polysulfides (LiPSs), and sluggish reaction kinetics, hinder the commercialization of LSBs. To solve these problems, various carbon-based aerogels with developed surface morphology, tunable pores, and electrical conductivity have been examined for immobilizing sulfur, mitigating its volume variation and enhancing its electrochemical kinetics. In this paper, an extensive generalization about the effective preparation methods of carbon-based aerogels comprising the combined method of carbonization with the gelation of precursors and drying processes (ambient pressure drying, freeze-drying, and supercritical drying) is proposed. And we summarize various carbon carbon-based aerogels, mainly including graphene aerogels (Gas) and carbon nanofiber (CNF) and carbon nanotube (CNT) aerogels as cathodes, separators, and interlayers in LSBs. In addition, the mechanism of action of carbon-based aerogels in LSBs is described. Finally, we conclude with an outlook section to provide some insights into the application of carbon-based aerogels in electrochemical energy storage devices. Based on the discussion and proposed recommendations, we provide more approaches on nanomaterials in high-performance liquid or state LSBs with high electrochemical performance in the future. Full article

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

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16 pages, 1343 KiB

Open AccessArticle

The Effect of Light on the Germination of Raphanus sativus Seeds and the Use of Sprout Extracts in the Development of a Dermatocosmetic Gel

by Mihaela Carmen Eremia, Ramona Daniela Pavaloiu, Oana Livadariu, Anca Daniela Raiciu, Fawzia Sha’at, Corina Bubueanu and Dana Maria Miu

Gels 2025, 11(7), 515; https://doi.org/10.3390/gels11070515 - 2 Jul 2025

Abstract

This study investigates the influence of different light sources (sunlight, green, red, and white LED) on the germination of Raphanus sativus L. sprouts and the potential use of their sprout extracts in the development of natural dermatocosmetic gels. The bioactive fractions were extracted [...] Read more.

This study investigates the influence of different light sources (sunlight, green, red, and white LED) on the germination of Raphanus sativus L. sprouts and the potential use of their sprout extracts in the development of natural dermatocosmetic gels. The bioactive fractions were extracted using simple methods and analyzed for total polyphenol content and antioxidant activity. Statistical analysis of weight, total phenolic content, and antioxidant activity of Raphanus sativus L. sprouts was performed using ANOVA. Sprouts exposed to green LED light showed the highest biomass (16.13 ± 0.38 g), while red LED light resulted in the highest total polyphenol content (3.28 ± 0.03 mg GAE/g fresh weight). The highest antioxidant activity (6.60 ± 0.08 mM Trolox/g fresh weight) was obtained under white LED. Although variations were observed, ANOVA analysis revealed that only sprout weight differed significantly among treatments (p < 0.001), while differences in polyphenol content and antioxidant activity were not statistically significant (p > 0.05). The extract with the highest antioxidant activity was incorporated as an active ingredient into Carbopol-based hydrogel formulations containing natural gelling agents and gentle preservatives. The resulting gels demonstrated favorable pH (4.85–5.05), texture, and stability. The results indicate that the light spectrum influences the germination process and the initial development of seedlings. Moreover, radish sprout extracts, rich in bioactive compounds, show promise for dermatocosmetic applications due to their antioxidant, soothing, and antimicrobial properties. This study supports the use of natural resources in the development of care products, in line with current trends in green cosmetics. Full article

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26 pages, 8710 KiB

Open AccessArticle

MOFs—Combining Fully Synthetic Injectable Hydrogel Scaffolds Exhibiting Higher Skeletal Muscle Regenerative Efficiency than Matrigel

by Sobuj Shahidul Islam, Tatsuya Dode, Soma Kawashima, Myu Fukuoka, Takaaki Tsuruoka and Koji Nagahama

Gels 2025, 11(7), 514; https://doi.org/10.3390/gels11070514 - 2 Jul 2025

Abstract

Due to its sarcoma-derived origin and the associated carcinogenic risks, as well as its lack of tissue-specific extracellular matrix biochemical cues, the use of the injectable gel scaffold Matrigel is generally restricted to research applications. Therefore, the development of new fully synthetic injectable [...] Read more.

Due to its sarcoma-derived origin and the associated carcinogenic risks, as well as its lack of tissue-specific extracellular matrix biochemical cues, the use of the injectable gel scaffold Matrigel is generally restricted to research applications. Therefore, the development of new fully synthetic injectable gel scaffolds that exhibit performance comparable to Matrigel is a high priority. In this study, we developed a novel fully synthetic injectable gel scaffold by combining a biodegradable PLGA-PEG-PLGA copolymer, clay nanoparticle LAPONITE®, and L-arginine-loaded metal–organic frameworks (NU-1000) at the nano level. An aqueous solution of the developed hybrid scaffold (PLGA-PEG-PLGA/LAPONITE®/L-Arg@NU-1000) exhibited rapid sol–gel transition at body temperature following simple injection and formed a continuous bulk-sized gel, demonstrating good injectability. Long-term sustained slow release of L-arginine from the resultant gels can be achieved because NU-1000 is a suitable reservoir for L-arginine. PLGA-PEG-PLGA/LAPONITE®/L-Arg@NU-1000 hybrid gels exhibited good compatibility with and promoted the growth of human skeletal muscle satellite cells. Importantly, in vivo experiments using skeletal muscle injury model mice demonstrated that the tissue regeneration efficiency of PLGA-PEG-PLGA/LAPONITE®/L-Arg@NU-1000 gels is higher than that of Matrigel. Specifically, we judged the higher tissue regeneration efficacy of our gels by histological analysis, including MYH3 immunofluorescent staining, H&E staining, and Masson’s trichrome staining. Taken together, these data suggest that novel hybrid hydrogels could serve as injectable hydrogel scaffolds for in vivo tissue engineering and ultimately replace Matrigel. Full article

(This article belongs to the Section Gel Applications)

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17 pages, 2132 KiB

Open AccessArticle

Development, Characterization, and Stability of Margarine Containing Oleogels Based on Olive Oil, Coconut Oil, Starch, and Beeswax

by Bárbara Viana Barbosa Naves, Thais Lomonaco Teodoro da Silva, Cleiton Antônio Nunes, Felipe Furtini Haddad and Sabrina Carvalho Bastos

Gels 2025, 11(7), 513; https://doi.org/10.3390/gels11070513 - 2 Jul 2025

Abstract

The removal of partially hydrogenated fats, as well as the substitution of saturated fats with healthier alternatives, has become increasingly common due to their well-established association with adverse health effects. As a result, the demand for alternative formulations in the food industry has [...] Read more.

The removal of partially hydrogenated fats, as well as the substitution of saturated fats with healthier alternatives, has become increasingly common due to their well-established association with adverse health effects. As a result, the demand for alternative formulations in the food industry has driven the development of a promising emerging technology: oleogels. Oleogels are a semi-solid material made by trapping liquid oil within a three-dimensional network formed by structuring agents. Within this context, this study aimed to develop and characterize margarines prepared with oleogels formulated from extra virgin olive oil, coconut oil, starch, and beeswax at varying concentrations. The proposed oleogel-based formulations exhibited a high melting temperature range and lower enthalpy. Although lipid oxidation levels differed between the commercial and oleogel-based margarines, they remained within acceptable limits. A significant difference in color was observed, with the oleogel formulations imparting a slight greenish hue compared to the commercial margarine. In terms of microstructure, the commercial margarine presented smaller and more uniformly distributed water droplets. Oleogel-based margarines demonstrated technological feasibility. Considering consumers’ growing interest in food innovation and health-conscious products, olive oil-based oleogel margarines represent a promising alternative, particularly due to the nutritional benefits associated with olive oil. Full article

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

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13 pages, 2631 KiB

Open AccessArticle

TEMPO-Oxidized Cellulose Hydrogels Loaded with Copper Nanoparticles as Highly Efficient and Reusable Catalysts for Organic Pollutant Reduction

by Yangyang Zhang, Yuanyuan Li and Xuejun Yu

Gels 2025, 11(7), 512; https://doi.org/10.3390/gels11070512 - 1 Jul 2025

Abstract

To successfully prepare cellulose hydrogels through a dissolution–regeneration process, 60 wt% LiBr aqueous solution was used as a green solvent. Carboxyl groups were precisely introduced onto the surface of the cellulose hydrogels through a TEMPO-mediated oxidation reaction, while the three-dimensional network structure and [...] Read more.

To successfully prepare cellulose hydrogels through a dissolution–regeneration process, 60 wt% LiBr aqueous solution was used as a green solvent. Carboxyl groups were precisely introduced onto the surface of the cellulose hydrogels through a TEMPO-mediated oxidation reaction, while the three-dimensional network structure and open pore morphology were completely retained. This modification strategy significantly enhanced the loading capacity of the hydrogels with copper nanoparticles (Cu NPs). The experimental results show that the LiBr aqueous solution can efficiently dissolve cellulose, and the TEMPO oxidation introduces carboxyl groups without destroying the stability of the hydrogels. Cu NPs are uniformly dispersed and highly loaded on the surface of the hydrogel because of the anchoring effect of the carboxyl groups. Cu NP-loaded hydrogels exhibit excellent catalytic activity in the NaBH₄ reduction of 4-nitrophenol (4-NP). Cu NP-loaded hydrogels maintain their complete structure and good catalytic performance after five consecutive cycles. Moreover, Cu NP-loaded hydrogels demonstrate high efficiency in degrading organic dyes such as methyl orange and Congo red. This study successfully developed efficient, low-cost, and environmentally friendly Cu NP-loaded hydrogel catalysts through the synergistic effect of LiBr green solvent and TEMPO oxidation modification, providing a feasible alternative to noble metal catalysts. Full article

(This article belongs to the Special Issue Advances in Cellulose-Based Hydrogels (3rd Edition))

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14 pages, 2481 KiB

Open AccessArticle

Insights on the Influence of the Drying Method and Surface Wettability on the Final Properties of Silica Aerogels

by Beatriz Merillas, Maria Inês Roque, Cláudio M. R. Almeida, Miguel Ángel Rodríguez-Pérez and Luisa Durães

Gels 2025, 11(7), 511; https://doi.org/10.3390/gels11070511 - 1 Jul 2025

Abstract

In the synthesis of aerogels, the influence of the drying process on the nanostructure is an issue of utmost relevance for tailoring the final properties of these materials. Among the complex parameters affecting this process, the hydrophobicity of the aerogel structure plays a [...] Read more.

In the synthesis of aerogels, the influence of the drying process on the nanostructure is an issue of utmost relevance for tailoring the final properties of these materials. Among the complex parameters affecting this process, the hydrophobicity of the aerogel structure plays a key role. Thus, herein, four different silica aerogel formulations based on tetraethyl orthosilicate and trimethoxymethylsilane were employed to produce aerogels with different wettability properties (from hydrophilic samples to highly hydrophobic). The synthesized gels were dried by three methods, namely freeze-drying, high-temperature supercritical drying with ethanol, and low-temperature supercritical drying with carbon dioxide, and the influence of each procedure on bulk density, porosity, pore size, and specific surface area of the resulting aerogels was analyzed in detail. The direct correlation between the surface hydrophobicity/hydrophilicity of the silica gels and the effects of each drying technique was analyzed, providing insights into a proper selection of the drying method depending on both the water affinity of the gel and the desired textural properties and structures. Full article

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

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19 pages, 2575 KiB

Open AccessArticle

Formulation-Dependent Extrudability of Highly Filled Alginate System for Vaginal Drug Delivery

by Arianna Chiappa, Alice Fusari, Marco Uboldi, Fabiana Cavarzan, Paola Petrini, Lucia Zema, Alice Melocchi and Francesco Briatico Vangosa

Gels 2025, 11(7), 510; https://doi.org/10.3390/gels11070510 - 1 Jul 2025

Abstract

The incorporation of solid particles as a filler to a hydrogel is a strategy to modulate its properties for specific applications, or even to introduce new functionalities to the hydrogel itself. The efficacy of such a modification depends on the filler content and [...] Read more.

The incorporation of solid particles as a filler to a hydrogel is a strategy to modulate its properties for specific applications, or even to introduce new functionalities to the hydrogel itself. The efficacy of such a modification depends on the filler content and its interaction with the hydrogel matrix. In drug delivery applications, solid particles can be added to hydrogels to improve drug loading capacity, enable the inclusion of poorly soluble drugs, and modulate release kinetics. This work focuses on the case of alginate (ALG)-based hydrogels, obtained following an internal gelation procedure using CaCO₃ as the Ca²⁺ source and containing a high solid volume fraction (up to 50%) of metronidazole (MTZ), a drug with low water solubility, as a potential extrusion-based drug delivery system. The impact of the hydrogel precursor composition (ALG and MTZ content) on the rheological behavior of the filled hydrogel and precursor suspension were investigated, as well as the hydrogel stability and MTZ dissolution. In the absence of solid MTZ, the precursor solutions showed a slightly shear thinning behavior, more accentuated with the increase in ALG concentration. The addition of drugs exceeding the saturation concentration in the precursor suspension resulted in a substantial increase (about one order of magnitude) in the low-shear viscosity and, for the highest MTZ loadings, a yield stress. Despite the significant changes, precursor formulations retained their extrudability, as confirmed by both numerical estimates and experimental validation. MTZ particles did not affect the crosslinking of the precursors to form the hydrogel, but they did control its viscoelastic behavior. In unfilled hydrogels, the ALG concentration controls stability (from 70 h for the lowest concentration to 650 h for the highest) upon immersion in acetate buffer at pH 4.5, determining the MTZ release/hydrogel dissolution behavior. The correlations between composition and material properties offer a basis for building predictive models for fine-tuning their composition of highly filled hydrogel systems. Full article

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

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14 pages, 3148 KiB

Open AccessArticle

Polymorphic Control in Pharmaceutical Gel-Mediated Crystallization: Exploiting Solvent–Gelator Synergy in FmocFF Organogels

by Dong Chen, Koen Robeyns, Tom Leyssens, Basanta Saikia and Stijn Van Cleuvenbergen

Gels 2025, 11(7), 509; https://doi.org/10.3390/gels11070509 - 1 Jul 2025

Abstract

FmocFF is a highly versatile gelator whose π–π-stacking fluorenyl group and hydrogen-bonded peptide backbone permit gelation in a wide spectrum of solvents, providing a rich scaffold for crystal engineering. This study explores the synergistic effects of FmocFF organogels and solvent selection on controlling [...] Read more.

FmocFF is a highly versatile gelator whose π–π-stacking fluorenyl group and hydrogen-bonded peptide backbone permit gelation in a wide spectrum of solvents, providing a rich scaffold for crystal engineering. This study explores the synergistic effects of FmocFF organogels and solvent selection on controlling the polymorphic outcomes of nilutamide, a nonsteroidal antiandrogen drug with complex polymorphism. By systematically varying process parameters such as solvent type and concentration, we demonstrate remarkable control over crystal nucleation and growth pathways. Most significantly, we report the first ambient-temperature isolation of pure nilutamide Form II through acetonitrile-based FmocFF organogel, highlighting the unique interplay between solvent properties and gel fiber networks. Thermal analysis reveals that the organogel not only selectively templates Form II but also affects its thermal pathway. We also present compelling evidence for a new polymorph exhibiting second-harmonic generation (SHG) activity. This would represent the first non-centrosymmetric nilutamide form discovered, suggesting the gel matrix induces symmetry breaking during crystallization. We also characterize a previously unreported nilutamide–chloroform solvate through multiple analytical techniques including PXRD, DSC, FTIR, SXRD, and SHG microscopy. Our findings demonstrate that solvent-specific molecular recognition within gel matrices enables access to entirely new regions of polymorphic space, establishing gel-mediated crystallization as a broadly applicable platform technology for pharmaceutical solid form discovery under mild conditions. Full article

(This article belongs to the Special Issue Advanced Hydrogels for Biomedical Applications)

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28 pages, 4884 KiB

Open AccessReview

Design, Synthesis, and Morphological Behavior of Polymer Gel-Based Materials for Thermoelectric Devices: Recent Progress and Perspectives

by Md. Mahamudul Hasan Rumon, Mohammad Mizanur Rahman Khan and Md Khairul Amin

Gels 2025, 11(7), 508; https://doi.org/10.3390/gels11070508 - 1 Jul 2025

Abstract

The current level of achievement in obtaining suitable polymer gel-based materials for efficient applications in thermoelectric devices is insufficient, although a substantial amount of research has already been performed. In this context, further investigations are necessary to design and synthesize polymer gel-based materials [...] Read more.

The current level of achievement in obtaining suitable polymer gel-based materials for efficient applications in thermoelectric devices is insufficient, although a substantial amount of research has already been performed. In this context, further investigations are necessary to design and synthesize polymer gel-based materials for ionic thermoelectric device applications. Polymer gel-based materials have attracted extensive consideration because of their multiple benefits, including easy processing, eco-friendly waste, and versatility, making them excellent materials for ionic thermoelectric devices. However, the design and synthesis of suitable polymer gel-based materials for ionic thermoelectric devices are still challenging areas of research. The surface morphological topography of prepared polymer gels is an important issue in thermoelectric device applications. In this review, significant approaches for the design and synthesis of polymer gel-based materials are discussed. This review may provide an important reference for upcoming perceptions on the design and synthesis of polymer gel materials for thermoelectric devices. Full article

(This article belongs to the Special Issue Smart Gels for Sensing Devices and Flexible Electronics)

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16 pages, 3080 KiB

Open AccessArticle

Microwave Curing of FA- and MK-Based Geopolymer Gels: Effects on Pore Structure, Mechanical Strength, and Heavy Metal Leachability

by Yanhui Dong, Runhui Gao, Yefan Li and Fuchen Wang

Gels 2025, 11(7), 507; https://doi.org/10.3390/gels11070507 - 30 Jun 2025

Abstract

Microwave curing has proven to be a highly effective method for enhancing the structural integrity, compressive strength, and heavy metal immobilization performance of geopolymer (GP) gels. For fly ash-based GP gels, optimal compressive strength (126.84 MPa) and minimal heavy metal ion leaching (0.01 [...] Read more.

Microwave curing has proven to be a highly effective method for enhancing the structural integrity, compressive strength, and heavy metal immobilization performance of geopolymer (GP) gels. For fly ash-based GP gels, optimal compressive strength (126.84 MPa) and minimal heavy metal ion leaching (0.01 mg/L) were achieved under microwave irradiation at 100 W for 75 s. Similarly, metakaolin-based GP gels reached peak compressive strength (76.84 MPa) and reduced heavy metal leaching (0.44 mg/L) under 440 W irradiation for 60 s. Microwave energy significantly accelerates geopolymerization by promoting the aggregation of dispersed particles, rapidly forming a dense, block-like matrix. This accelerated densification enhances the mechanical properties of GP gels within minutes. Moreover, the dense matrix structure effectively encapsulates heavy metal ions, minimizing their leaching through a combination of physical encapsulation and chemical bonding. In summary, microwave treatment significantly enhances both mechanical performance and heavy metal immobilization, offering a practical pathway for sustainable applications. Full article

(This article belongs to the Special Issue Rheological Properties and Applications of Gel-Based Materials)

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