Gels

24 pages, 4225 KiB

Open AccessReview

Recent Advances in Plant-Based Emulsion Gels: Preparation, Characterization, Applications, and Future Perspectives

by Yunfei Huang, Chunmei Li and David Julian McClements

Gels 2025, 11(8), 641; https://doi.org/10.3390/gels11080641 - 13 Aug 2025

Plant-based foods have emerged as a major focus of the modern food industry as it tries to create more sustainable, environmentally friendly, and healthy products. Plant-based emulsion gels (PBEGs) can be used to provide valuable structures, textures, and functions in many plant-based food [...] Read more.

Plant-based foods have emerged as a major focus of the modern food industry as it tries to create more sustainable, environmentally friendly, and healthy products. Plant-based emulsion gels (PBEGs) can be used to provide valuable structures, textures, and functions in many plant-based food applications. For instance, they can be used as a matrix to form semi-solid plant-based meat, fish, egg, or dairy analogs, delivery systems for bioactive compounds in functional foods, and edible inks in 3D food printing. The most common PBEGs used in the food industry consist of oil droplets embedded within an aqueous phase containing a biopolymer network. However, PBEGs may also be formed from high-internal-phase emulsions (HIPEs) or aggregated emulsions. PBEGs combine the benefits of emulsions and gels, such as the ability to encapsulate both polar and non-polar functional ingredients, as well as to create desirable textural attributes. This review summarizes recent advances (2017–2025) in the development and application of PBEGs in the food sector, with a focus on their preparation methods, characterization techniques, and potential applications. The future perspectives and challenges associated with PBEGs are also discussed. Overall, this review provides a useful platform for directing future research efforts and for the practical implementation of PBEGs in plant-based food systems. Full article

(This article belongs to the Special Issue Preparation, Structure-Property Relationships, and Applications of Emulsion Gels)

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1 pages, 205 KiB

Open AccessRetraction

RETRACTED: Gupta et al. Self-Gelling Solid Lipid Nanoparticle Hydrogel Containing Simvastatin as Suitable Wound Dressing: An Investigative Study. Gels 2022, 8, 58

by Bhumika Gupta, Garima Sharma, Pratibha Sharma, Simarjot Kaur Sandhu and Indu Pal Kaur

Gels 2025, 11(8), 640; https://doi.org/10.3390/gels11080640 - 13 Aug 2025

Abstract

The journal retracts the article titled “Self-Gelling Solid Lipid Nanoparticle Hydrogel Containing Simvastatin as Suitable Wound Dressing: An Investigative Study” [...] Full article

15 pages, 14782 KiB

Open AccessArticle

Temperature-Mediated Gel Texture Transformation in Starch Noodles: In Respect of Glass Transition Temperature T_g’

by Hongxiao Liu, Qing Hu, Sha Yang, Lina Liu and Xuyan Dong

Gels 2025, 11(8), 639; https://doi.org/10.3390/gels11080639 - 13 Aug 2025

Abstract

Potato starch noodles (PSN), a characteristic gluten-free Asian food, are essentially high-concentration starch gels (about 35% starch) formed through gelatinization and retrogradation. This study systematically investigates freezing temperature effects, particularly across the glass transition temperature, on PSN texture and microstructure. We found that [...] Read more.

Potato starch noodles (PSN), a characteristic gluten-free Asian food, are essentially high-concentration starch gels (about 35% starch) formed through gelatinization and retrogradation. This study systematically investigates freezing temperature effects, particularly across the glass transition temperature, on PSN texture and microstructure. We found that fresh PSN have a freezing point of −1 °C, supercooling temperature of −4.5 °C, and a T_g’ value of −3.1 °C. Freezing significantly reduced the adhesiveness of PSN and increased the hardness. During the 48 h freezing process, noodles frozen at −3 °C, the closest to T_g’, exhibited the highest hardness (14,065.77 g), springiness (0.98), cohesiveness (0.93), chewiness (11,971.06), and resilience (0.84), and the least adhesiveness. PSN frozen within the range near T_g’ (−3 °C) showed superior texture, continuous solid cross-section, and dense surface, attributed to the reverse transformation of starch, high mobility of starch chains, and smaller ice crystals. PSN frozen at −3 °C for 24 h displayed the most compact and desirable texture compared to the other samples. These findings deepen the understanding of the role of glass transition temperature in the texture formation of starch gel during freezing and provide valuable insights for optimizing the frozen processing of starch gel-based food. Full article

(This article belongs to the Special Issue Recent Advances on the Use of Different Gels Type in the Food Industry)

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16 pages, 2603 KiB

Open AccessArticle

Preparation of Uniform-Pore Ceramics from Highly Stable Emulsions via the Sol–Gel Method

by Alena Fedoročková, Dana Ivánová, Gabriel Sučik and Martina Kubovčíková

Gels 2025, 11(8), 638; https://doi.org/10.3390/gels11080638 - 12 Aug 2025

Abstract

A facile and cost-effective sol–gel method for the synthesis of uniformly porous alumina (Al₂O₃) was developed using stable CTAB/hexanol/water microemulsions as soft templates. The phase behavior of the ternary system was investigated to identify compositions that form kinetically stable [...] Read more.

A facile and cost-effective sol–gel method for the synthesis of uniformly porous alumina (Al₂O₃) was developed using stable CTAB/hexanol/water microemulsions as soft templates. The phase behavior of the ternary system was investigated to identify compositions that form kinetically stable microemulsions, with an optimal ratio of 7.5 wt.% CTAB, 5 wt.% hexanol, and 87.5 wt.% water exhibiting minimal droplet size variation over one week. Gelation was induced by partial neutralization to pH 4.2 with ammonium carbonate, promoting the formation of polynuclear Al species and enabling the uniform entrapment of hexanol droplets. Lyophilization preserved the porous network, and calcination at 500 °C yielded η-Al₂O₃ with a large specific surface area (~225 m²·g⁻¹) and a narrow mesopore size distribution centered around 100 nm, consistent with the original droplet size. Mercury porosimetry and SEM analyses confirmed a highly porous, low-density material (0.75 g·cm⁻³) with an interconnected pore morphology. This scalable synthesis method, supported by the high kinetic stability of the microemulsion, provides sufficient processing time and eliminates the need for post-synthesis purification. It shows strong potential for producing advanced alumina materials for use in energy storage, catalysis, and sensor applications. Full article

(This article belongs to the Special Issue Gel Formation Processes and Materials for Functional Thin Films)

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20 pages, 4252 KiB

Open AccessArticle

Salt-Induced Gel Formation by Zwitterionic Polymer for Synergistic Methane Hydrate Inhibition

by Fei Gao, Shijun Tang, Peng Xu, Jiancheng Wu and Xinru Li

Gels 2025, 11(8), 637; https://doi.org/10.3390/gels11080637 - 12 Aug 2025

Abstract

In deepwater drilling operations, inhibiting methane hydrate (MH) formation is critical for wellbore flow assurance. This study synthesized a zwitterionic polymer NDAD and evaluated its hydrate inhibition performance through high-pressure reactor tests, magnetic resonance imaging (MRI), and molecular simulations. Results demonstrate that NDAD [...] Read more.

In deepwater drilling operations, inhibiting methane hydrate (MH) formation is critical for wellbore flow assurance. This study synthesized a zwitterionic polymer NDAD and evaluated its hydrate inhibition performance through high-pressure reactor tests, magnetic resonance imaging (MRI), and molecular simulations. Results demonstrate that NDAD at concentrations of 1.0 wt% extends MH formation time by 4.9 times compared to conventional inhibitor PVCap. Notably, NaCl (10–15 wt%) synergistically enhances inhibition efficiency by inducing NDAD chain stretching to form physical gel networks, increasing solution viscosity by 98%. This gel structure obstructs methane–water diffusion, prolonging hydrate induction time. Response surface methodology (RSM) identifies NDAD dosage as the primary control factor for inhibition efficacy. Molecular simulations confirm that NDAD inhibits hydrate formation through dual pathways: (i) competitive hydration by ionic groups disrupting water cage structures and (ii) gel networks imposing mass transfer resistance to methane diffusion. Full article

(This article belongs to the Section Gel Applications)

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30 pages, 11860 KiB

Open AccessReview

Bioprinting Vascularized Constructs for Clinical Relevance: Engineering Hydrogel Systems for Biological Maturity

by Jeonghyun Son, Siyuan Li and Wonwoo Jeong

Gels 2025, 11(8), 636; https://doi.org/10.3390/gels11080636 - 12 Aug 2025

Abstract

Vascularization remains a critical challenge in tissue engineering, limiting graft survival, integration, and clinical translation. Although bioprinting enables spatial control over vascular architectures, many existing approaches prioritize geometric precision over biological performance. Bioprinted vasculature can be understood as a dynamic and time-dependent system [...] Read more.

Vascularization remains a critical challenge in tissue engineering, limiting graft survival, integration, and clinical translation. Although bioprinting enables spatial control over vascular architectures, many existing approaches prioritize geometric precision over biological performance. Bioprinted vasculature can be understood as a dynamic and time-dependent system that requires tissue-specific maturation. Within this framework, hydrogel systems act as active microenvironments rather than passive scaffolds. Hydrogel platforms vary from natural matrices and synthetic polymers to bioinspired or stimuli-responsive systems, each offering tunable control over stiffness, degradation, and biochemical signaling needed for vascular maturation. The design requirements of large and small vessels differ in terms of mechanical demands, remodeling capacity, and host integration. A key limitation in current models is the absence of time-resolved evaluation, as critical processes such as lumen formation, pericyte recruitment, and flow-induced remodeling occur progressively and are not captured by static endpoints. Advancements in bioprinting technologies are evaluated based on their capacity to support hydrogel-mediated vascularization across varying length scales and structural complexities. A framework for functional assessment is proposed, and translational challenges related to immunogenicity, scalability, and regulatory requirements are discussed. Such integration of hydrogel-driven biological cues and bioprinting fidelity is critical to advancing vascularized constructs toward clinical translation. Full article

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

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11 pages, 3042 KiB

Open AccessArticle

Phase-Conversion Stiffened Dual-Network Hydrogel for Fracture Plugging in Oil-Based Drilling Fluid

by Xinying Cui, Chengwen Wang, Weian Huang, Shifeng Zhang, Haiqun Chen and Bo Wu

Gels 2025, 11(8), 635; https://doi.org/10.3390/gels11080635 - 12 Aug 2025

Abstract

During drilling operations, lost circulation frequently occurs, leading to significant loss of drilling fluids which causes environmental damage and increasing drilling costs. To address the problem of fracture plugging, gel materials have emerged as an ideal solution due to stable physicochemical properties and [...] Read more.

During drilling operations, lost circulation frequently occurs, leading to significant loss of drilling fluids which causes environmental damage and increasing drilling costs. To address the problem of fracture plugging, gel materials have emerged as an ideal solution due to stable physicochemical properties and excellent environmental compatibility. However, most existing gels exhibit poor stability and low mechanical strength under high-temperature conditions. To overcome these limitations, high-temperature-resistant phase-conversion stiffened dual-network hydrogel for oil-based drilling fluids was developed. Phase-conversion was realized by immersing synthesized double-network hydrogel in ethylene glycol (EG), polyethylene glycol (PEG), and glycerol (Gly), optimizing and enhancing its mechanical properties, followed by plugging performance evaluations. Experimental results demonstrated that the phase-conversion stiffened gels achieved significantly improved compressive strength and plugging efficiency at elevated temperature. The GC-MS results indicated that dehydration and reagent exchange occurred during immersion, with change in the solid content of the sample. After being treated by white oil at high temperature, the oil phase almost replaced the water phase in the gel. The results of ATR-IR confirmed the formation of hydrogen bonds in the gel. TGA data revealed that PEG enhanced the thermal stability of the gel, EG negatively affected thermal stability, and Gly had negligible influence. The enhancement in gel strength primarily stems from the increase in solid content caused by phase transformation. Dehydration and multiple hydrogen bonds formed between organic reagent molecules and polymer chains in the gel have a synergistic enhancement effect. Full article

(This article belongs to the Section Gel Applications)

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18 pages, 4753 KiB

Open AccessArticle

Cryogel-Immobilized Catalase as a Biocatalyst with Enhanced Stability Against Microplastics

by Kadir Erol, Mehmet Hüseyin Alkan and İhsan Alacabey

Gels 2025, 11(8), 634; https://doi.org/10.3390/gels11080634 - 12 Aug 2025

Abstract

Catalase is a pivotal antioxidant enzyme that decomposes hydrogen peroxide and reduces oxidative stress. However, its low thermal and operational stability limits applications in challenging environments, particularly those contaminated with emerging pollutants such as polystyrene-based microplastics (PS-MPs). In this study, cryogels composed of [...] Read more.

Catalase is a pivotal antioxidant enzyme that decomposes hydrogen peroxide and reduces oxidative stress. However, its low thermal and operational stability limits applications in challenging environments, particularly those contaminated with emerging pollutants such as polystyrene-based microplastics (PS-MPs). In this study, cryogels composed of Poly(2-hydroxyethyl methacrylate-co-allyl glycidyl ether) [Poly(HEMA-co-AGE)] were synthesized and evaluated as immobilization matrices to enhance catalase stability. Cryogels containing varying AGE concentrations were characterized using FT-IR, SEM, TEM, TGA, and BET analyses. The formulation with 250 µL AGE exhibited optimal physicochemical properties, including improved water retention, increased surface area, and high immobilization capacity (356.3 mg·g⁻¹). Immobilized catalase maintained superior activity under PS-MP-induced stress across a range of concentrations (0–1.0 mg·mL⁻¹), temperatures (4–60 °C), and exposure times (up to 5 h). Kinetic modeling revealed a significant improvement in substrate affinity, with Km decreasing from 54.9 to 17.1 mM, while Vmax decreased moderately. Long-term stability tests showed that immobilized catalase retained ~80% activity after 70 days at 4 °C and 55% after 15 reuse cycles. Desorption studies confirmed the reusability of the cryogel system. These findings suggest that Poly(HEMA-co-AGE) cryogels provide a robust and reusable platform for catalase stabilization, offering potential for applications such as wastewater treatment and biosensing in microplastic-contaminated systems. Full article

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

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23 pages, 2326 KiB

Open AccessReview

Advances in Hydrogel-Based Delivery of RNA Drugs for Antitumor Therapy

by Hui Xu, Yang Fei, Xueya Wang, Wenfeng Jiao and Yong Jin

Gels 2025, 11(8), 633; https://doi.org/10.3390/gels11080633 - 11 Aug 2025

Abstract

Tumors are a major disease that seriously threatens human health, with their incidence and mortality rates increasing year by year. However, traditional therapies such as surgery, chemotherapy, and radiotherapy have significant limitations, including significant side effects and propensity for drug resistance. In recent [...] Read more.

Tumors are a major disease that seriously threatens human health, with their incidence and mortality rates increasing year by year. However, traditional therapies such as surgery, chemotherapy, and radiotherapy have significant limitations, including significant side effects and propensity for drug resistance. In recent years, with the rapid development of medical technology, RNA therapy has shown great potential as an emerging treatment method in anti-tumor therapy, bringing new hope for tumor treatment. RNA therapy mainly includes small interfering RNA, antisense oligonucleotides, and aptamers. Hydrogels, as a polymer material with three-dimensional network structure, have good biocompatibility and can effectively improve the efficiency of RNA delivery. This review specifically focuses on the application of hydrogels as RNA carriers in anti-tumor therapy, along with the classification, delivery advantages, and challenges. However, despite existing deficiencies in safety and targeting, hydrogel-mediated RNA delivery for tumor treatment still shows unique advantages and broad application prospects. In the future, research and cutting-edge innovations are expected to facilitate precision oncology solutions, offering superior treatment options and catalyzing the evolution of cancer management strategies. Full article

(This article belongs to the Special Issue Advanced Hydrogels for Controlled Drug Delivery (2nd Edition))

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16 pages, 9141 KiB

Open AccessArticle

Quantum-Dot-Based Molecularly Imprinted Hydrogel for Rapid Detection of Homocysteine

by Xin Zhang, Jiarong Liang, Binglei Zheng, Pengfei Jiao and Qian Xu

Gels 2025, 11(8), 632; https://doi.org/10.3390/gels11080632 - 11 Aug 2025

Abstract

Elevated levels of homocysteine (Hcy) are associated with various pathological conditions including atherosclerosis, hypertension, and cardiovascular diseases. In this work, quantum-dot-based molecularly imprinted hydrogels (QD@MIHs) were developed by integrating L-cysteine-modified ZnS quantum dots (QDs)with highly selective molecular imprinting technology for rapid homocysteine detection. [...] Read more.

Elevated levels of homocysteine (Hcy) are associated with various pathological conditions including atherosclerosis, hypertension, and cardiovascular diseases. In this work, quantum-dot-based molecularly imprinted hydrogels (QD@MIHs) were developed by integrating L-cysteine-modified ZnS quantum dots (QDs)with highly selective molecular imprinting technology for rapid homocysteine detection. The QD@MIPHs were fabricated using a dual-functional monomer system (acrylamide and methacrylic acid) through surface coating of the Hcy molecularly imprinted polymer gel onto the QDs. Under optimal conditions, the response time of the QD@MIPHs for Hcy detection was 5 min. When the Hcy concentration ranged from 0.1 to 10.0 μM, the fluorescence quenching of the QD@MIHs showed a good linear relationship with Hcy concentration (R² = 0.9972), with a corresponding detection limit of 0.027 μM. In addition, the constructed QD@MIPHs showed no significant response to other interfering substances, demonstrating the high selectivity of the prepared material. Practical sample analysis revealed that the recovery rates of Hcy ranged from 94.34% to 104.1%, with relative standard deviations (RSD, n = 3) between 3.56% and 7.17%. This study provides a novel tool and method for rapid Hcy detection with significant potential in biomedical diagnostics and preventive-healthcare applications. Full article

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

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18 pages, 3280 KiB

Open AccessArticle

Preparation of Agrowaste-Based Nanocellulose by NaOH-Assisted Ball Milling Technique: Influence of Component Intervention

by Yuxi Wang, Yong Yu, Shuhan Hu, Jinyao Yu, Yue Huang and Hongjie Dai

Gels 2025, 11(8), 631; https://doi.org/10.3390/gels11080631 - 11 Aug 2025

Abstract

Pineapple peel cellulose nanofibrils (PCNFs) were facilely prepared by the ball milling method assisted by alkali solution (3 wt% NaOH) and a wet grinding medium, using various treated pineapple peels (hot water treatment (WT), bleaching treatment (BT), alkaline treatment (AT), and baleaching–alkaline treatment [...] Read more.

Pineapple peel cellulose nanofibrils (PCNFs) were facilely prepared by the ball milling method assisted by alkali solution (3 wt% NaOH) and a wet grinding medium, using various treated pineapple peels (hot water treatment (WT), bleaching treatment (BT), alkaline treatment (AT), and baleaching–alkaline treatment (ABT)) as raw materials. The structure of the obtained PCNFs (i.e., WT-PCNF, BT-PCNF, AT-PCNF, and ABT-PCNF) was characterized to analyze the influence of component intervention. The results indicated that NaOH-assisted ball milling did not change the crystal structure of cellulose, and the yield and thermal stability of the PCNFs was improved. The average diameters of WT-PCNF, BT-PCNF, AT-PCNF, and ABT-PCNF were 24.16, 21.53, 23.04, and 19.46 nm, respectively, in which BT-PCNF and ABT-PCNF exhibited a higher defibrillating degree and smaller diameter. Particularly, NaOH-assisted ball milling can promote the removal of non-cellulose components. The viscosity and modulus of BT-PCNF were relatively higher due to the presence of residual hemicellulose as a natural linker of fibers. The current research provides insights for simplifying the preparation and functionalization of nanocellulose. Full article

(This article belongs to the Section Gel Applications)

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17 pages, 2230 KiB

Open AccessArticle

Synthesis of Hydroxyapatite-Gelatin Composite Hydrogel for Bone Tissue Application

by José Luis Barrera Bernal, Íñigo Gaytán Salvatella, Bryan Iván Martín del Campo, Marco Antonio Alvarez Perez and David Masuoka-Ito

Gels 2025, 11(8), 630; https://doi.org/10.3390/gels11080630 - 10 Aug 2025

Abstract

Bone tissue engineering has gained attention recently as a method for regenerating bone critical-size defects. This work aims to synthesize a hydrogel based on gelatin, di-amine polyethylene glycol, Polyethylene Glycol-Polypropylene Glycol-Polyethylene glycol, using genipin as a cross-linker and adding hydroxyapatite as a ceramic [...] Read more.

Bone tissue engineering has gained attention recently as a method for regenerating bone critical-size defects. This work aims to synthesize a hydrogel based on gelatin, di-amine polyethylene glycol, Polyethylene Glycol-Polypropylene Glycol-Polyethylene glycol, using genipin as a cross-linker and adding hydroxyapatite as a ceramic insert that can be used as a cellular scaffold in bone tissue engineering. Characterization was performed using Fourier transform infrared spectroscopy, identifying the leading absorption bands to verify that the hydrogels cross-linked correctly. The hydrogels with elastic modules and resistances that best adapted to the values reported for the mandibular trabecular bone were identified through mechanical tests. Using scanning electron microscopy, the presence of hydroxyapatite in the hydrogels was verified. The hydrogels with the best results were selected to carry out the biological assays. The cell viability assay verified that the osteoblastic cells proliferated better in the hydroxyapatite scaffolds, and the composite hydrogel induced osteoblast differentiation from undifferentiated mesenchymal stem cells. Hydrogels loaded with hydroxyapatite proved to be a promising biomaterial with potential application in bone regeneration. Full article

(This article belongs to the Special Issue Hydrogel for Tissue Engineering and Biomedical Therapeutics)

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15 pages, 2377 KiB

Open AccessArticle

Orodispersible Hydrogel Film Technology for Optimized Galantamine Delivery in the Treatment of Alzheimer’s Disease

by Dilyana Georgieva, Ivana Bogdanova, Rositsa Mihaylova, Mariela Alexandrova, Silvia Bozhilova, Darinka Christova and Bistra Kostova

Gels 2025, 11(8), 629; https://doi.org/10.3390/gels11080629 - 10 Aug 2025

Abstract

Alzheimer’s disease is the most widespread neurodegenerative disease in the world. Galantamine hydrobromide (GH) is one of the drugs used to treat mild to moderate dementia of the Alzheimer type. Due to the fact that the specificity of the disease requires maximally facilitated [...] Read more.

Alzheimer’s disease is the most widespread neurodegenerative disease in the world. Galantamine hydrobromide (GH) is one of the drugs used to treat mild to moderate dementia of the Alzheimer type. Due to the fact that the specificity of the disease requires maximally facilitated intake, orodispersible films present such an opportunity. In the present study orodispersible films based on poly(2-ethyl-2-oxazoline) as well as partially hydrolyzed poly(2-ethyl-2-oxazoline) were prepared and studied as delivery systems for GH. Two samples of partially hydrolyzed PEtOx were synthesized—one of relatively low degree of hydrolysis and another one of relatively high degree of hydrolysis, and studied by Nuclear Magnetic Resonance (NMR). Cytotoxicity assay was performed that validated the low hydrolyzed derivative as biocompatible polymer that maintained desirable physicochemical characteristics without compromising the safety, thereby it was selected for further research. The films were prepared by the solution casting method and characterized by different methods. FTIR was used to determine the potential interactions between the galantamine molecule and the film components. Based on the Thermogravimetric Analysis (TGA) conducted, it was concluded that all films were sufficiently thermally stable, as the component decomposition stage (after initial solvent removal) began above 180 °C. The polymer films were further characterized with the determination of Shore hardness and the results showed that the films containing glycerol as a plasticizer exhibited higher hardness compared to those with PEG as a plasticizer. The disintegration time of the films was determined visually using Petri dishes and it was found that the films disintegrated within the range of 0.52 to 1.58 min, fully meeting the pharmacopoeial requirements. GH release profiles in PBS at 37 °C were obtained, and it was found that by the second minute, 80–90% of the drug were released from the different films, and the release followed an anomalous diffusion mechanism (Case II). Full article

(This article belongs to the Special Issue Properties and Structure of Hydrogel-Related Materials (2nd Edition))

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22 pages, 4015 KiB

Open AccessArticle

Sol–Gel Synthesized CuFe₂O₄-Modified Biochar Derived from Tea Waste for Efficient Ni(II) Removal: Adsorption, Regeneration, and ANN Modeling

by Celal Duran, Sengul Tugba Ozeken, Serdal Seker and Duygu Ozdes

Gels 2025, 11(8), 628; https://doi.org/10.3390/gels11080628 - 10 Aug 2025

Abstract

In the present research, a novel magnetic adsorbent was developed via the sol–gel method by coating CuFe₂O₄ nanoparticles on biochar sourced from brewed tea waste. The synthesized adsorbent was utilized for the removal of Ni(II) ions from aqueous media. The [...] Read more.

In the present research, a novel magnetic adsorbent was developed via the sol–gel method by coating CuFe₂O₄ nanoparticles on biochar sourced from brewed tea waste. The synthesized adsorbent was utilized for the removal of Ni(II) ions from aqueous media. The adsorption efficiency of Ni(II) ions was assessed under crucial experimental conditions such as initial solution pH, contact time, adsorbent dosage, and initial Ni(II) concentration. The adsorbent exhibited rapid adsorption kinetics, achieving equilibrium in approximately 15 min, and maintained high efficiency across a wide pH range. Adsorption experiments were conducted for Ni(II) solutions at their natural pH (5.6) to minimize chemical usage and enhance process simplicity. An impressive maximum adsorption capacity of 232.6 mg g⁻¹ was recorded, outperforming many previously reported adsorbents. Furthermore, desorption studies demonstrated nearly 100% recovery of Ni(II) ions using 1.0 M HCl solution, indicating excellent regeneration potential of the adsorbent. Additionally, the prediction performance of an artificial neural network (ANN) model was evaluated to predict Ni(II) removal efficiency based on experimental variables, showing strong agreement with experimental data. Isotherm and kinetic models were also applied to the data to estimate the adsorption mechanisms. These findings demonstrate the promise of CuFe₂O₄-modified tea waste biochar for sustainable water treatment applications. Full article

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

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18 pages, 6113 KiB

Open AccessArticle

Flow Characteristics and Enhanced Oil Recovery Performance of Anionic and Zwitterionic Viscoelastic Surfactant System

by Chenyue Ling, Yafei Liu, Xuchun Yang, Qi Ye and Desheng Zhou

Gels 2025, 11(8), 627; https://doi.org/10.3390/gels11080627 - 10 Aug 2025

Abstract

Surfactant flooding has shown potential in enhanced oil recovery (EOR), but conventional surfactants often underperform in heterogeneous reservoirs. This study investigates the impact of a surfactant mixture, combining anionic sodium dodecyl sulfate (SDS) and zwitterionic oleylamidopropyl betaine (OAB-30), on two-phase flow behavior and [...] Read more.

Surfactant flooding has shown potential in enhanced oil recovery (EOR), but conventional surfactants often underperform in heterogeneous reservoirs. This study investigates the impact of a surfactant mixture, combining anionic sodium dodecyl sulfate (SDS) and zwitterionic oleylamidopropyl betaine (OAB-30), on two-phase flow behavior and its EOR potential. Six surfactant solutions with varying concentrations were first screened using an idealized dead-end shaped microchannel in combination with interfacial properties and rheological tests. The results showed that 0.2% SDS and 0.6% OAB-30 produced the highest oil recovery in the dead-end structure. Interfacial tension was reduced to 0.374 mN/m and strong viscoelastic behavior was observed using the optimized surfactant mixture. Wettability of the surface tended to be more hydrophilic after the application of the surfactant mixture as well. Subsequently, the microscale oil displacement process was examined using the optimized surfactant mixture via microfluidic devices with an idealized pore–throat network with permeability contrast and realistic pore–throat structure. The application of the optimal surfactant formula resulted in 28.46% and 49.96% improvement over conventional water flooding in a realistic pore–throat structure and idealized pore–throat network. The critical micelle concentration measurements of the mixture suggested favorable micelle formation, contributing to gel-like properties that improved sweep efficiency by lowering the mobility ratio. In heterogenous pore–throat networks, the emulsification, micellar solubilization, wettability alteration, and viscoelastic properties of the surfactant mixture favored the oil recovery process. This work provides experimental evidence and mechanistic insights for the application of viscoelastic surfactants in EOR in heterogeneous reservoirs. Full article

(This article belongs to the Special Issue Applications of Gels for Enhanced Oil Recovery)

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17 pages, 2849 KiB

Open AccessArticle

Synthesis, Characterization, and Properties of Polyvinyl Alcohol/Jackfruit Peel Carboxymethylcellulose/Graphene Oxide/Kaolin Composite Hydrogels

by Shumin Liu, Jing Ma, Fuqi Yang, Hailin Ye, Yu Liang, Yijia Deng, Jianrong Li and Rundong Wang

Gels 2025, 11(8), 626; https://doi.org/10.3390/gels11080626 - 9 Aug 2025

Abstract

This study presents an environmentally benign composite hydrogel system by combining polyvinyl alcohol (PVA) with carboxymethyl cellulose derived from jackfruit peel waste (JCMC), subsequently reinforced with graphene oxide (GO) and Kaolin nanoparticles for enhanced Congo red (CR) adsorption. The structural properties of the [...] Read more.

This study presents an environmentally benign composite hydrogel system by combining polyvinyl alcohol (PVA) with carboxymethyl cellulose derived from jackfruit peel waste (JCMC), subsequently reinforced with graphene oxide (GO) and Kaolin nanoparticles for enhanced Congo red (CR) adsorption. The structural properties of the synthesized hydrogels were comprehensively characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). FTIR analysis confirmed hydrogel formation through hydrogen bonding interactions, while XRD and SEM revealed the uniform dispersion of GO and Kaolin within the polymer matrix, resulting in an improved adsorption performance. Furthermore, the adsorption efficiency of the composite hydrogels was systematically evaluated under varying conditions, including solution pH, contact time, temperature, and initial CR concentration. Optimal CR removal (92.3%) was achieved at pH 8.0, with equilibrium attained within 90 min. The adsorption kinetics were best fitted by the pseudo-second-order model (R² = 0.9998), confirming a chemisorption-dominated process. The equilibrium adsorption data were accurately described by the Langmuir isotherm model, indicating monolayer coverage with an exceptional maximum capacity of 200.80 mg/g. These findings highlight the superior adsorption performance of the PVA/JCMC/GO/Kaolin hydrogels, attributed to their tailored physicochemical properties and synergistic interactions among components. This study offers both sustainable jackfruit peel waste valorization and an effective solution for anionic dye removal in wastewater treatment. Full article

(This article belongs to the Special Issue Food Gels: Structure and Properties (2nd Edition))

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16 pages, 5525 KiB

Open AccessArticle

Preparation of Bismuth Vanadates with Rich Oxygen Vacancies Using Different Sol pH and Their Photocatalytic Behavior in Degradation of Methylene Blue

by Shengli Chen, Yuanyuan Zhong, Jie Yang, Daixiong Yang, Dong Liu, Xiaodong Zhu and Lin Huang

Gels 2025, 11(8), 625; https://doi.org/10.3390/gels11080625 - 9 Aug 2025

Abstract

Gel precursors were formed by reacting bismuth nitrate pentahydrate, acetic acid, sodium metavanadate, and NaOH. pH was adjusted using NaOH solution followed by calcination to obtain bismuth vanadate (BiVO₄) photocatalysts. During synthesis, pH directly influenced the formation and structure of the [...] Read more.

Gel precursors were formed by reacting bismuth nitrate pentahydrate, acetic acid, sodium metavanadate, and NaOH. pH was adjusted using NaOH solution followed by calcination to obtain bismuth vanadate (BiVO₄) photocatalysts. During synthesis, pH directly influenced the formation and structure of the gel network. Therefore, the effects of pH on the microstructure and photocatalytic activity of BiVO₄ were investigated. At pH 3, the sample consisted of microspheres formed by tightly packed small particles. At pH 5, the microspheres transformed into aggregated flakes. Photocatalytic performance was evaluated through methylene blue (MB) degradation, revealing the sample prepared at pH 7 (7-BVO) demonstrated the highest efficiency. The electronic band structure, bandgap, and band edge positions of 7-BVO were probed by density functional theory (DFT) and UV-vis absorption spectra. Furthermore, photoluminescence spectroscopy, electrochemical measurements, active species trapping experiments and liquid chromatography mass spectrometry technique collectively revealed the possible mechanistic pathways for MB photodegradation by 7-BVO. Full article

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17 pages, 2466 KiB

Open AccessArticle

Fabrication, Characterization, and In Vitro Digestion Behavior of Bigel Loaded with Notoginsenoside Rb1

by Yang Luo, Gao Xiong, Xiao Gong, Chunlei Xu, Yingqiu Tian and Guanrong Li

Gels 2025, 11(8), 624; https://doi.org/10.3390/gels11080624 - 9 Aug 2025

Abstract

Notoginsenoside Rb1 (Rb1), a bioactive saponin from Panax notoginseng, exerts cardio-cerebrovascular protective, anti-inflammatory, antioxidant, and glucose homeostasis-regulating effects. However, its oral bioavailability is limited by gastric degradation and poor intestinal permeability. This study presents a food-grade bigel system for encapsulating Rb1 to enhance [...] Read more.

Notoginsenoside Rb1 (Rb1), a bioactive saponin from Panax notoginseng, exerts cardio-cerebrovascular protective, anti-inflammatory, antioxidant, and glucose homeostasis-regulating effects. However, its oral bioavailability is limited by gastric degradation and poor intestinal permeability. This study presents a food-grade bigel system for encapsulating Rb1 to enhance its stability and controlled-release performance. Oleogels were structured using monoglycerides (8%, w/w) in soybean oil. Rb1-loaded binary hydrogels (gellan gum/xanthan gum, 12:1 w/w) were emulsified in 10% Tween-80 (w/w). Bigels were formulated at varying hydrogel-to-oleogel ratios, and a ratio of 4:6 was identified as optimal. Stress-sweep rheological analysis revealed a dense gel structure with a peak storage modulus (G′) of 290.64 Pa—the highest among all tested ratios—indicating superior structural integrity. Confocal microscopy confirmed homogeneous encapsulation of Rb1 within the continuous hydrogel phase, effectively preventing payload leakage. Differential scanning calorimetry (DSC) analysis detected a distinct endothermic transition at 55 °C (ΔH = 6.25 J/g), signifying energy absorption that enables thermal buffering during food processing. The system achieved an encapsulation efficiency of 99.91% and retains both water and oil retention. Effective acid protection and colon-targeted delivery were observed in the digestion test. Effective acid protection and colon-targeted delivery were observed in the digestion test. Less than 5% of Rb1 was released in the gastric phase, and over 90% sustained intestinal release occurred at 4 h. The optimized bigel effectively protected Rb1 from gastric degradation and enabled sustained intestinal release. Its food-grade composition, thermal stability, and tunable rheology offer significant potential for use in functional foods and nutraceuticals. Full article

(This article belongs to the Special Issue Advanced Gels in the Food System)

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21 pages, 11924 KiB

Open AccessArticle

Mechanisms of Covalent Bonds in Enhancing the Adsorption Stability of Clay–Polymer Gels in High-Temperature Environments

by Yu Wang, Fan Zhang, Liangbin Dou, Yutong Li, Kaiwen Wang, Zhengli Shi, Leyao Du, Wangyuan Zhang and Zonglun Wang

Gels 2025, 11(8), 623; https://doi.org/10.3390/gels11080623 - 9 Aug 2025

Abstract

To address the issue of drilling fluid performance drop and wellbore instability induced by desorption between treatment agents and clay in the high-temperature environment of ultra-deep drilling, this study synthesized three organosilicon polymers (ADE, ADM, ADD) with different substituents. The study confirmed that [...] Read more.

To address the issue of drilling fluid performance drop and wellbore instability induced by desorption between treatment agents and clay in the high-temperature environment of ultra-deep drilling, this study synthesized three organosilicon polymers (ADE, ADM, ADD) with different substituents. The study confirmed that the covalent bond significantly improved the high-temperature adsorption resistance of clay, which is closely related to the interface behavior of gels. Through rolling recovery, rheology, and filtration experiments for performance evaluation, these organic silicon polymers showed excellent high-temperature performance: the shale rolling recovery rate exceeded 80% at 210 °C, and the filtration loss was reduced to 14 mL, with a reduction rate of 53.3%. The adsorption capacity of the three polymers on clay remained unchanged from 150 °C to 210 °C, among which the adsorption amount of trimethoxy groups stabilized at 8–11 mg/g after 150 °C. The adsorption capacity of ethoxy groups increased by 7.9% at 150–210 °C. The adsorption capacity of dimethoxy groups with methyl steric hindrance increased by 28.1% at 150–210 °C. These results indicate that covalent bonds effectively enhance the high-temperature adsorption of clay, allowing for polymer molecules to firmly anchor on the clay surface at high temperatures. This breakthrough overcomes the limitations of traditional inhibitors in high-temperature desorption, and provides a valuable reference for the preparation of high-temperature adsorption resistant functional materials in water-based drilling fluid gel systems. Full article

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

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