Gels | August 2025 - Browse Articles

33 pages, 6314 KB

Open AccessReview

Gel-Type Electrofluorochromic Devices for Advanced Optoelectronic Applications

by Xuecheng Wang, Lijing Wen, Jinxia Ren, Yonghen Wen, Yonghua Li, Yizhou Zhang and Kenneth Yin Zhang

Gels 2025, 11(8), 673; https://doi.org/10.3390/gels11080673 - 21 Aug 2025

Viewed by 679

Abstract

Gel-type electrofluorochromic (EFC) devices, which reversibly modulate photoluminescence under electrical stimuli, have emerged as versatile platforms for advanced optoelectronic applications. By integrating redox-active luminophores with soft, ion-conductive gel matrices, these systems combine the structural robustness of solids with the ionic mobility of liquids, [...] Read more.

Gel-type electrofluorochromic (EFC) devices, which reversibly modulate photoluminescence under electrical stimuli, have emerged as versatile platforms for advanced optoelectronic applications. By integrating redox-active luminophores with soft, ion-conductive gel matrices, these systems combine the structural robustness of solids with the ionic mobility of liquids, enabling a high-contrast, flexible, and multifunctional operation. This review provides a comprehensive overview of gel-based EFC technologies, outlining fundamental working principles, device architectures, and key performance metrics such as contrast ratio, switching time, and cycling stability. Gel matrices are categorized into ionogels, organogels, and hydrogels, and their physicochemical properties are discussed in relation to EFC device performance. Recent advances are highlighted across applications ranging from flexible displays and rewritable electronic paper to strain and biosensors, data encryption, smart windows, and hybrid energy-interactive systems. Finally, current challenges and emerging strategies are analyzed to guide the design of next-generation adaptive, intelligent, and energy-efficient optoelectronic platforms. Full article

(This article belongs to the Special Issue Sustainable Functional Hydrogels in Flexible Electronics, Energy and Thermoelectrics)

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18 pages, 3623 KB

Open AccessArticle

A Succinoglycan-Riclin-Zinc-Phthalocyanine-Based Composite Hydrogel with Enhanced Photosensitive and Antibacterial Activity Targeting Biofilms

by Yunxia Yang, Hongmei Zhang, Xueqing Zhang, Shuyan Shen, Baojuan Wu, Dexin Peng, Jie Yin and Yanqing Wang

Gels 2025, 11(8), 672; https://doi.org/10.3390/gels11080672 - 21 Aug 2025

Viewed by 548

Abstract

Bacterial infections cause serious problems associated with wound treatment and serious complications, leading to serious threats to the global public. Bacterial resistance was mainly attributed to the formation of biofilms and their protective properties. Hydrogels suitable for irregular surfaces with effective antibacterial activity [...] Read more.

Bacterial infections cause serious problems associated with wound treatment and serious complications, leading to serious threats to the global public. Bacterial resistance was mainly attributed to the formation of biofilms and their protective properties. Hydrogels suitable for irregular surfaces with effective antibacterial activity have attracted extensive attention as potential materials. In this study, a succinoglycan-riclin-zinc-phthalocyanine-based composite (RL-Zc) hydrogel was synthesized through an amine reaction within an hour. The hydrogel was characterized via FT-IR, SEM, and rheology analysis, exhibiting an elastic solid gel state stably. The hydrogel showed large inhibition circles on E. coli as well as S. aureus under near-infrared irradiation (NIR). RL-Zc hydrogel exhibited positively charged surfaces and possessed a superior penetrability toward bacterial biofilm. Furthermore, RL-Zc hydrogel generated abundant single oxygen and mild heat rapidly, resulting in disrupted bacterial biofilm as well as amplified antibacterial effectiveness. A metabolomics analysis confirmed that RL-Zc hydrogel induced a metabolic disorder in bacteria, which resulted from phospholipid metabolism and oxidative stress metabolism related to biofilm disruption. Hence, this study provided a potential phototherapy for biofilm-induced bacterial resistance. Full article

(This article belongs to the Section Gel Analysis and Characterization)

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22 pages, 4366 KB

Open AccessArticle

Controlled Fabrication of pH-Visualised Silk Fibroin–Sericin Dual-Network Hydrogels for Urine Detection in Diapers

by Yuxi Liu, Kejing Zhan, Jiacheng Chen, Yu Dong, Tao Yan, Xin Zhang and Zhijuan Pan

Gels 2025, 11(8), 671; https://doi.org/10.3390/gels11080671 - 21 Aug 2025

Viewed by 673

Abstract

Urine pH serves as an indicator of systemic acid–base balance and helps detect early-stage urinary and renal disorders. However, conventional monitoring methods rely on instruments or manual procedures, limiting their use among vulnerable groups such as infants and bedridden elderly individuals. In this [...] Read more.

Urine pH serves as an indicator of systemic acid–base balance and helps detect early-stage urinary and renal disorders. However, conventional monitoring methods rely on instruments or manual procedures, limiting their use among vulnerable groups such as infants and bedridden elderly individuals. In this study, a pH-responsive smart hydrogel was developed and integrated into diapers to enable real-time, equipment-free, and visually interpretable urine pH monitoring. An optimised degumming process enabled one-step preparation of a silk fibroin–sericin aqueous solution. We employed a visible light-induced photo-crosslinking strategy to fabricate a dual-network hydrogel with enhanced strength and stability. Increasing sericin content accelerated gelation (≤15 min) and improved performance, achieving a maximum stress of 54 kPa, strain of 168%, and water absorption of 566%. We incorporated natural anthocyanins and fine-tuned them to produce four distinct colour changes in response to urine pH, with significantly improved colour differentiation (ΔE). Upon contact with urine, the hydrogel displays green within the normal pH range, indicating a healthy state. At the same time, a reddish-purple or blue colour serves as a visual warning of abnormal acidity or alkalinity. This intelligent hydrogel system combines rapid gelation, excellent mechanical properties, and a sensitive visual response, offering a promising platform for body fluid monitoring. Full article

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15 pages, 6475 KB

Open AccessArticle

Catalytic Interface of rGO-VO₂/W₅O₁₄ Hydrogel for High-Performance Electrochemical Water Oxidation

by Mrunal Bhosale, Rutuja U. Amate, Pritam J. Morankar and Chan-Wook Jeon

Gels 2025, 11(8), 670; https://doi.org/10.3390/gels11080670 - 21 Aug 2025

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Abstract

The continuous increase in global energy demand necessitates the development of sustainable, clean, and highly efficient methods of energy generation. Electrochemical water splitting, comprising hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), represents a promising strategy but remains hindered by sluggish reaction [...] Read more.

The continuous increase in global energy demand necessitates the development of sustainable, clean, and highly efficient methods of energy generation. Electrochemical water splitting, comprising hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), represents a promising strategy but remains hindered by sluggish reaction kinetics and limited availability of highly active electrocatalysts especially under alkaline conditions. Addressing this challenge, we successfully synthesized a rGO-VO₂/W₅O₁₄ (rG-VO₂/W₅O₁₄) hydrogel electrocatalyst through a facile hydrothermal approach. The prepared composite distinctly reveals an advantageous hierarchical microstructure characterized by VO₂ nanoflakes uniformly distributed on the surface of rGO nanosheets, intricately integrated with W₅O₁₄ nanorods. Evaluated in a 1.0 M KOH electrolyte, the optimized rG-VO₂/W₅O₁₄-2 catalyst demonstrates remarkable electrocatalytic performance towards OER, achieving a low overpotential of 265.8 mV and a reduced Tafel slope of 81.9 mV dec⁻¹. Furthermore, the catalyst maintains robust stability with minimal performance degradation, exhibiting an overpotential of only 273.0 mV after 5000 cyclic stability tests. The superior catalytic activity and durability are attributed to the synergistic combination of enriched chemical composition, effective electron transfer, and abundant catalytic active sites inherent in the well-optimized rG-VO₂/W₅O₁₄-2 composite. Full article

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

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22 pages, 6464 KB

Open AccessArticle

Evaluation and Experiment of High-Strength Temperature- and Salt-Resistant Gel System

by Changhua Yang, Di Xiao, Jun Wang and Tuo Liang

Gels 2025, 11(8), 669; https://doi.org/10.3390/gels11080669 - 21 Aug 2025

Viewed by 514

Abstract

To address the issues of poor thermal stability, inadequate salt tolerance, and environmental risks in conventional gel systems for the development of high-temperature, high-salinity heterogeneous reservoirs, a triple-synergy gel system comprising anionic polyacrylamide (APAM), polyethyleneimine (PEI), and phenolic resin (SMP) was developed in [...] Read more.

To address the issues of poor thermal stability, inadequate salt tolerance, and environmental risks in conventional gel systems for the development of high-temperature, high-salinity heterogeneous reservoirs, a triple-synergy gel system comprising anionic polyacrylamide (APAM), polyethyleneimine (PEI), and phenolic resin (SMP) was developed in this study. The optimal synthesis parameters—APAM of 180 mg/L, PEI:SMP = 3:1, salinity of 150,000 ppm, and temperature of 110 °C—were determined via response surface methodology, and a time–viscosity model was established. Compared with existing binary systems, the proposed gel exhibited a mass retention rate of 93.48% at 110 °C, a uniform porous structure (pore size of 2–8 μm), and structural stability under high salinity (150,000 ppm). Nuclear magnetic resonance displacement tests showed that the utilization efficiency of crude oil in 0.1–1 μm micropores increased to 21.32%. Parallel dual-core flooding experiments further confirmed the selective plugging capability in heterogeneous systems with a permeability contrast of 10:1: The high-permeability layer (500 mD) achieved a plugging rate of 98.7%, while the recovery factor of the low-permeability layer increased by 13.6%. This gel system provides a green and efficient profile control solution for deep, high-temperature, high-salinity reservoirs. Full article

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

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14 pages, 1801 KB

Open AccessArticle

Constructive Neuroengineering of Axon Polarization Control Using Modifiable Agarose Gel Platforms for Neuronal Circuit Construction

by Soya Hagiwara, Kazuhiro Tsuneishi, Naoya Takada and Kenji Yasuda

Gels 2025, 11(8), 668; https://doi.org/10.3390/gels11080668 - 21 Aug 2025

Viewed by 410

Abstract

Axon polarization is a fundamental process in neuronal development, providing the structural basis for directional signaling in neural circuits. Precise control of axon specification is, thus, essential for the bottom-up construction of neuronal networks with defined architecture and connectivity. Although neurite length and [...] Read more.

Axon polarization is a fundamental process in neuronal development, providing the structural basis for directional signaling in neural circuits. Precise control of axon specification is, thus, essential for the bottom-up construction of neuronal networks with defined architecture and connectivity. Although neurite length and elongation timing have both been implicated as determinants of axonal fate, their relative contributions have remained unresolved due to technical limitations in manipulating these factors independently in conventional culture systems. Here, we developed a constructive neuroengineering platform based on modifiable agarose gel microstructures that enables dynamic, in situ control of neurite outgrowth length and timing during neuronal cultivation. This approach allowed us to directly address whether axon polarization depends primarily on neurite length or the order of neurite extension. Using a single-neurite elongation paradigm, we quantitatively defined two length thresholds for axon specification: a critical length of 43.3 μm, corresponding to a 50% probability of axonal differentiation, and a definitive length of 95.4 μm, beyond which axonal fate was reliably established. In experiments involving simultaneous or sequential elongation of two neurites, we observed that neurite length—not elongation order—consistently predicted axonal identity, even when a second neurite was introduced after the first had already begun to grow. The presence of a competing neurite modestly elevated the effective critical length, suggesting inhibitory interactions that modulate length thresholds. These findings provide the first direct experimental confirmation that neurite length is the primary determinant of axon polarization and demonstrate the utility of constructive microfabrication approaches for dissecting fundamental principles of neuronal polarity. Our platform establishes a powerful experimental foundation for future efforts to achieve complete control over axon and dendrite orientation during the engineered construction of functional neuronal circuits. Full article

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

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24 pages, 1061 KB

Open AccessReview

Soft Gels in Food Systems: Recent Advances, Applications, and Technological Innovations

by Manuela Machado, Eduardo Manuel Aguiar da Costa and Sara Silva

Gels 2025, 11(8), 667; https://doi.org/10.3390/gels11080667 - 21 Aug 2025

Viewed by 1240

Abstract

Soft gels, such as hydrogels, organogels, aerogels, and bigels, represent versatile materials that are increasingly utilized within food systems to modify texture, regulate nutrient delivery, serve as fat substitutes, and enhance product shelf life. Their structural diversity and tunable properties enable targeted solutions [...] Read more.

Soft gels, such as hydrogels, organogels, aerogels, and bigels, represent versatile materials that are increasingly utilized within food systems to modify texture, regulate nutrient delivery, serve as fat substitutes, and enhance product shelf life. Their structural diversity and tunable properties enable targeted solutions for healthier, more sustainable, and consumer-centric products. This review provides a critical overview of recent advances in soft gel science, emphasizing industrial feasibility, regulatory compliance, and strategies to overcome commercialization barriers such as cost, scalability, and consumer acceptance. For each gel type, we compare functional performance with conventional structuring and encapsulation systems, highlighting cases where soft gels offer superior stability, bioactive protection, or caloric reduction. We also examine emerging applications, including gel-based frying media, 3D printing, and nano-enabled formulations, alongside potential risks related to long-term exposure and bioaccumulation. Regulatory frameworks across major jurisdictions are summarized, and sustainability considerations, from sourcing to life cycle impact, are discussed. By integrating technological innovation with safety, regulatory, and market perspectives, this review identifies key research priorities and practical pathways for translating soft gel technologies from laboratory concepts into commercially viable, health-driven food solutions. Full article

(This article belongs to the Special Issue Recent Advances in Soft Gels in the Food Industry and Technology)

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17 pages, 2566 KB

Open AccessArticle

Synergistic Epichlorohydrin-Crosslinked Carboxymethyl Xylan for Enhanced Thermal Stability and Filtration Control in Water-Based Drilling Fluids

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

Gels 2025, 11(8), 666; https://doi.org/10.3390/gels11080666 - 20 Aug 2025

Viewed by 454

Abstract

Polymers derived from renewable polysaccharides offer promising avenues for the development of high-temperature, environmentally friendly drilling fluids. However, their industrial application remains limited by inadequate thermal stability and poor colloidal compatibility in complex mud systems. In this study, we report the rational design [...] Read more.

Polymers derived from renewable polysaccharides offer promising avenues for the development of high-temperature, environmentally friendly drilling fluids. However, their industrial application remains limited by inadequate thermal stability and poor colloidal compatibility in complex mud systems. In this study, we report the rational design and synthesis of epichlorohydrin-crosslinked carboxymethyl xylan (ECX), developed through a synergistic strategy combining covalent crosslinking with hydrophilic functionalization. When incorporated into water-based drilling fluid base slurries, ECX facilitates the formation of a robust gel suspension. Comprehensive structural analyses (FT-IR, XRD, TGA/DSC) reveal that dual carboxymethylation and ether crosslinking impart a 10 °C increase in glass transition temperature and a 15% boost in crystallinity, forming a rigid–flexible three-dimensional network. ECX-modified drilling fluids demonstrate excellent colloidal stability, as evidenced by an enhancement in zeta potential from −25 mV to −52 mV, which significantly improves dispersion and interparticle electrostatic repulsion. In practical formulation (1.0 wt%), ECX achieves a 620% rise in yield point and a 71.6% reduction in fluid loss at room temperature, maintaining 70% of rheological performance and 57.5% of filtration control following dynamic aging at 150 °C. Tribological tests show friction reduction up to 68.2%, efficiently retained after thermal treatment. SEM analysis further confirms the formation of dense and uniform polymer–clay composite filter cakes, elucidating the mechanism behind its high-temperature resilience and effective sealing performance. Furthermore, ECX demonstrates high biodegradability (BOD₅/COD = 21.3%) and low aquatic toxicity (EC₅₀ = 14 mg/L), aligning with sustainable development goals. This work elucidates the correlation between molecular engineering, gel microstructure, and macroscopic function, underscoring the great potential of eco-friendly polysaccharide-based crosslinked polymers for industrial gel-based fluid design in harsh environments. Full article

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

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33 pages, 15465 KB

Open AccessArticle

Effect of Phosphate Phase Incorporation on 3D-Printed Hydrogel Scaffolds: Towards Customizable Bone Graft Materials

by Andreea Trifan, Eduard Liciu, Andrei-Silviu Nedelcu, Mihai Dragomir, Doru-Daniel Cristea, Ciprian-Ștefan Mateescu, David-Andrei Nițulescu, Cătălina-Ana-Maria Cîrstea, Adela Banciu, Gabriela Toader, Aurel Diacon and Cristina Busuioc

Gels 2025, 11(8), 665; https://doi.org/10.3390/gels11080665 - 20 Aug 2025

Cited by 1 | Viewed by 528

Abstract

Bone defects remain a significant clinical challenge, creating a severe need for advanced biomaterials for tissue regeneration. This study addresses this issue by developing 3D-printed composite hydrogels containing alginate, gelatine, and resorbable calcium phosphates (monetite and brushite) for bone tissue engineering. The scaffolds [...] Read more.

Bone defects remain a significant clinical challenge, creating a severe need for advanced biomaterials for tissue regeneration. This study addresses this issue by developing 3D-printed composite hydrogels containing alginate, gelatine, and resorbable calcium phosphates (monetite and brushite) for bone tissue engineering. The scaffolds were fabricated using extrusion-based 3D printing and evaluated for their morphology, porosity, mechanical strength, swelling, degradation, and in vitro mineralization, while their cytocompatibility was assessed using LIVE/DEAD cell viability assays. The key findings demonstrate that calcium phosphate incorporation enhanced the mechanical stability by 15–25% compared to the controls, and mineral deposition increased significantly in the composite scaffolds. The developed hydrogels are bioactive and represent promising, customizable scaffolds for bone regeneration. These results support their further investigation as viable alternatives to traditional bone grafts for clinical bone tissue engineering applications. Full article

(This article belongs to the Special Issue Novel Gels for 3D Bioprinting in Tissue Engineering)

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14 pages, 1557 KB

Open AccessArticle

Modulating CT Attenuation of Polyvinyl Alcohol Cryogels for Individualized Training Phantoms in Interventional Radiology: A Proof-of-Concept Study

by Martin Volk, Ivan Vogt, Marilena Georgiades, Johanna Menhorn, Mathias Becker, Georg Rose, Maciej Pech and Oliver S. Grosser

Gels 2025, 11(8), 664; https://doi.org/10.3390/gels11080664 - 20 Aug 2025

Viewed by 565

Abstract

Anthropomorphic CT phantoms are essential training tools for interventional radiology. Given the high technical demands and stringent safety requirements in this field, realistic CT phantoms are vital simulation tools that support effective hands-on training, procedural planning, and risk mitigation. However, commercially available phantom [...] Read more.

Anthropomorphic CT phantoms are essential training tools for interventional radiology. Given the high technical demands and stringent safety requirements in this field, realistic CT phantoms are vital simulation tools that support effective hands-on training, procedural planning, and risk mitigation. However, commercially available phantom geometries are limited in their scope. This study investigates the use of polyvinyl alcohol (PVA) to fabricate customizable training phantoms. PVA, a non-toxic material, can be processed into PVA cryogels (PVA-C) with tissue-like mechanical properties. We modified PVA-C (10 wt.% PVA) by incorporating various additives to adjust X-ray attenuation and achieve Hounsfield units (HUs) similar to different soft tissues. HU values were measured at X-ray tube voltages of 70, 120, and 150 kV. The inclusion of barium sulfate (e.g., U = 120 kV; 0.1–2 wt.%: 33.29 ± 5.45–323.72 ± 12.64 HU) and iohexol (e.g., U = 120 kV; 0.1–2 wt.%: 26.05 ± 4.74–161.99 ± 5.69 HU) significantly increased HU values. Iohexol produced more homogeneous HU distributions than barium sulfate and cellulose derivatives, with the latter having air gaps and inconsistencies. The tested formulations encompassed a wide range of soft tissue densities, with HU values varying significantly across the energy range (p < 0.001). While cellulose derivatives showed variable HU modulation, their primary role appears to be in modifying phantom texture and morphology rather than precise attenuation control. In conclusion, PVA-C demonstrates strong potential for use in interventional radiology training phantoms. Further studies may enhance phantom realism by replicating tissue textures, for example, through the incorporation of cellulose-based substances. Full article

(This article belongs to the Special Issue Gel-Related Materials: Challenges and Opportunities (2nd Edition))

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20 pages, 1921 KB

Open AccessArticle

Photoactive Hydrogels as Materials for Biological Applications: Preparation of Thermally Stable Photoactive Films

by Oscar G. Marambio, Lidia Álvarez, Héctor Díaz-Chamorro, Julio Sánchez, Rudy Martin-Trasancos, Christian Erick Palavecino and Guadalupe del C. Pizarro

Gels 2025, 11(8), 663; https://doi.org/10.3390/gels11080663 - 20 Aug 2025

Viewed by 638

Abstract

Hydrogel materials have become an efficient, bioactive, and multifunctional alternative with great potential for biomedical applications. In this work, photoactive films were successfully designed for optical processing, and their photoactivity was tested in photodynamic therapy (PDT), such as antimicrobial patches. The stimulus-response hydrogel [...] Read more.

Hydrogel materials have become an efficient, bioactive, and multifunctional alternative with great potential for biomedical applications. In this work, photoactive films were successfully designed for optical processing, and their photoactivity was tested in photodynamic therapy (PDT), such as antimicrobial patches. The stimulus-response hydrogel films are made of a hydrophilic polymer based on vinyl monomers, specifically 2-hydroxyethyl methacrylate (HEMA) and acrylamide (AAm), in a 1:1 molar ratio, along with the photochromic agent, 3,3-dimethylindolin-6′-nitrobenzoespiropirano (BSP), and a crosslinking agent, N,N’-methylenebisacrylamide (MBA). These hydrogel films were successfully created using the photoinitiator 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (IRGACURE 2959), MBA, and BSP in different concentrations (0.1, 0.3, and 0.5 mol%), which were later tested in photodynamic therapy (PDT) with the photosensitizer Ru(bpy)₂²⁺ against Staphylococcus aureus. The results showed that, while free Ru(bpy)₂²⁺ needed concentrations of 4–8 µg/mL to eliminate methicillin-sensitive (MSSA) strains, only partial inactivation was achieved for methicillin-resistant (MRSA) strains. The addition of the hydrogel films with BSP improved their effectiveness, lowering the minimum inhibitory concentration (MIC) to 2 µg/mL to fully inactivate MSSA and MRSA strains. These findings demonstrate that the combined use of hydrogel films containing BSP and Ru(bpy)₂²⁺ within a hydrogel matrix not only boosts antimicrobial activity but also highlights the potential of these photoactive films as innovative photosensitive antimicrobial coatings. This synergistic effect of BSP and Ru(bpy)₂²⁺ indicates that these materials are promising candidates for next-generation antimicrobial coatings and creative photosensitive materials. Full article

(This article belongs to the Special Issue Hydrogels, Microgels, and Nanogels: From Fundamentals to Applications (3rd Edition))

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26 pages, 1955 KB

Open AccessArticle

A Bioactive Emulgel Formulation of Equisetum telmateia Ehrh. Methanol Extract: Integrating Antioxidant Activity, Skin Enzyme Inhibition, and Permeation Kinetics

by Tuğba Buse Şentürk, Timur Hakan Barak, Emre Şefik Çağlar, Emine Saldamlı, Ebru Özdemir Nath and Zafer Ömer Özdemir

Gels 2025, 11(8), 662; https://doi.org/10.3390/gels11080662 - 20 Aug 2025

Viewed by 1010

Abstract

Equisetum telmateia Ehrh. (great horsetail) belongs to the Equisetaceae family and its aerial parts have been traditionally used for skin conditions and to achieve healthy and resilient skin, nails, and hair. This study aimed to evaluate the inhibition of skin-related enzymes by, the [...] Read more.

Equisetum telmateia Ehrh. (great horsetail) belongs to the Equisetaceae family and its aerial parts have been traditionally used for skin conditions and to achieve healthy and resilient skin, nails, and hair. This study aimed to evaluate the inhibition of skin-related enzymes by, the antioxidant capacity of, and the phytochemical composition of E. telmateia. Additionally, a novel emulgel was formulated from the main methanolic extract and characterized in terms of pH, viscosity, determination of content quantification, textural profile analysis, and spreadability. After the characterization studies, in vitro release and ex vivo permeation and penetration studies were performed. Firstly, the dried aerial parts of E. telmateia were macerated in methanol, followed by partitioning with solvents of increasing polarity: n-hexane, chloroform, ethyl acetate, and n-butanol. Antioxidant activity was assessed using DPPH, FRAP, CUPRAC, and TOAC assays, while enzyme inhibition was analyzed for collagenase, elastase, hyaluronidase, and tyrosinase. LC-MS/MS analysis identified 53 phytochemical compounds. Protocatechuic acid, the main phenolic compound, was quantitatively analyzed in each subfraction by HPTLC. The in vitro release studies showed sustained release of the reference substance (protocatechuic acid) and the kinetic modeling of the release was fitted to the Higuchi model. The ex vivo permeation and penetration studies showed that the formulation exhibited a retention of 3.06 ± 0.21 µg.cm⁻² after 24 h, whereas the suspended extract demonstrated a skin retention of 1.28 ± 0.47 µg.cm⁻². Both the extracts and the formulated emulgel exhibited inhibitory effects on skin-related enzymes. Our finding suggested that E. telmateia might be a valuable ingredient for wrinkle care and skin-regenerating cosmetics. Full article

(This article belongs to the Special Issue Properties and Structure of Plant-Based Emulsion Gels)

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35 pages, 3721 KB

Open AccessReview

Research Progress of Supramolecular Gels in the Field of Petroleum Engineering

by Liyao Dai, Jinsheng Sun, Kaihe Lv, Yingrui Bai, Jianlong Wang, Chaozheng Liu and Mei-Chun Li

Gels 2025, 11(8), 661; https://doi.org/10.3390/gels11080661 - 19 Aug 2025

Viewed by 814

Abstract

Traditional petroleum engineering materials have problems such as single functionality and poor environmental adaptability in terms of lost circulation control and enhanced oil recovery. Supramolecular gels, with their dynamic reversible non-covalent network structure, demonstrate unique advantages in this regard. This paper classifies supramolecular [...] Read more.

Traditional petroleum engineering materials have problems such as single functionality and poor environmental adaptability in terms of lost circulation control and enhanced oil recovery. Supramolecular gels, with their dynamic reversible non-covalent network structure, demonstrate unique advantages in this regard. This paper classifies supramolecular gels into hydrogen bond type, metal coordination type, host–guest type, and electrostatic interaction type based on differences in crosslinking structures. It explains the construction principles and characteristics of each type of gel and analyses their application progress in petroleum engineering fields, such as lost circulation control in drilling, temporary plugging in fracturing, and profile control in enhanced oil recovery. It also discusses the advantages and disadvantages of different systems and future development directions. Research has shown that the molecular design strategy of supramolecular gels can effectively address technical challenges under complex conditions, offering new insights for oil and gas field development. Further optimization of their long-term stability and large-scale production technology is needed to advance their practical application. Full article

(This article belongs to the Special Issue Polymer Gels for the Oil and Gas Industry)

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38 pages, 9897 KB

Open AccessArticle

Experimental Investigation of Synergistic Enhanced Oil Recovery by Infill Well Pattern and Chemical Flooding After Polymer Flooding

by Xianmin Zhang, Junzhi Yu, Lijie Liu, Xilei Liu, Xuan Lu and Qihong Feng

Gels 2025, 11(8), 660; https://doi.org/10.3390/gels11080660 - 19 Aug 2025

Viewed by 604

Abstract

Well pattern infill adjustment combined with chemical flooding is an important technical approach for significantly improving oil recovery in high-water-cut reservoirs after polymer flooding. Current research predominantly focuses on the evaluation of oil displacement potential through either well pattern infilling or chemical flooding [...] Read more.

Well pattern infill adjustment combined with chemical flooding is an important technical approach for significantly improving oil recovery in high-water-cut reservoirs after polymer flooding. Current research predominantly focuses on the evaluation of oil displacement potential through either well pattern infilling or chemical flooding alone, while systematic experimental investigations and mechanism studies on the synergistic effect of well pattern infilling and chemical flooding remain insufficient. To overcome the limitations of single adjustment measures, this study proposes a synergistic improved oil recovery (IOR) strategy integrating branched preformed particle gel (B-PPG) heterogeneous phase composite flooding (HPCF) with well pattern infill adjustment. Two-dimensional visual physical simulation experiments are conducted to evaluate the synergistic oil displacement effects of different displacement systems and well pattern adjustment strategies after polymer flooding and to elucidate the synergistic IOR mechanisms under the coupling of dense well patterns and chemical flooding. The experimental results demonstrate that, under well pattern infill conditions, the HPCF system exhibits significant water control and oil enhancement effects during the chemical flooding stage, achieving a 29.95% increase in stage recovery compared to the water flooding stage. The system effectively blocks high-permeability channels while enhancing displacement in low-permeability zones through a coupling effect, thereby significantly expanding the displacement sweep volume, improving displacement uniformity, and efficiently mobilizing the remaining oil in low-permeability and residual oil-rich areas. Meanwhile, well pattern infill adjustment optimizes the injection–production well pattern layout, shortens the inter-well spacing, and effectively increases the displacement pressure differential between injection and production wells. This induces disturbances and reconfiguration of the streamline field, disrupts the original high-permeability channel-dominated flow regime, further expands the sweep range of the remaining oil, and substantially improves overall oil recovery. The findings of this study enrich and advance the theoretical framework of water control and potential tapping, as well as synergistic IOR mechanisms, in high-water-cut and strongly heterogeneous reservoirs, providing a reliable theoretical and technical basis for the efficient development and remaining oil recovery in such reservoirs during the late production stage. Full article

(This article belongs to the Special Issue Polymer Gels for the Oil and Gas Industry)

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31 pages, 7032 KB

Open AccessReview

Rheological, Structural, and Biological Trade-Offs in Bioink Design for 3D Bioprinting

by Jeevithan Elango and Camilo Zamora-Ledezma

Gels 2025, 11(8), 659; https://doi.org/10.3390/gels11080659 - 19 Aug 2025

Cited by 2 | Viewed by 1532

Abstract

Bioinks represent the core of 3D bioprinting, as they are the carrier responsible for enabling the fabrication of anatomically precise, cell-laden constructs that replicate native tissue architecture. Indeed, their role goes beyond structural support, as they must also sustain cellular viability, proliferation, and [...] Read more.

Bioinks represent the core of 3D bioprinting, as they are the carrier responsible for enabling the fabrication of anatomically precise, cell-laden constructs that replicate native tissue architecture. Indeed, their role goes beyond structural support, as they must also sustain cellular viability, proliferation, and differentiation functions, which are critical for applications in the field of regenerative medicine and personalized therapies. However, at present, a persistent challenge lies in reconciling the conflicting demands of rheological properties, which are essential for printability and biological functionality. This trade-off limits the clinical translation of bioprinted tissues, particularly for vascularized or mechanically dynamic organs. Despite huge progress during the last decade, challenges persist in standardizing bioink characterization, scaling production, and ensuring long-term biomimetic performance. Based on these challenges, this review explores the inherent trade-off faced by bioink research optimizing rheology to ensure printability, shape fidelity, and structural integrity, while simultaneously maintaining high cell viability, proliferation, and tissue maturation offering insights into designing next-generation bioinks for functional tissue engineering. Full article

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

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16 pages, 1177 KB

Open AccessReview

Beyond Biomaterials: Engineering Bioactive Hydrogels as Immuno-Mechanobiological Niches for Osteochondral Regeneration

by Francesca Semeraro, Valentina Rafaela Herrera Millar, Lucia Aidos, Mirko Sergio, Lorenzo Impieri, Giuseppe Michele Peretti, Laura Mangiavini, Alessia Di Giancamillo and Nicolò Rossi

Gels 2025, 11(8), 658; https://doi.org/10.3390/gels11080658 - 19 Aug 2025

Viewed by 926

Abstract

Osteochondral regeneration remains a major clinical challenge due to the complex architecture and biomechanical demands of the osteochondral unit. Bioactive hydrogels have emerged as promising materials capable of supporting repair through their capacity to mimic the extracellular matrix (ECM), enable cell encapsulation, and [...] Read more.

Osteochondral regeneration remains a major clinical challenge due to the complex architecture and biomechanical demands of the osteochondral unit. Bioactive hydrogels have emerged as promising materials capable of supporting repair through their capacity to mimic the extracellular matrix (ECM), enable cell encapsulation, and deliver bioactive cues. However, recent insights reveal that simply engineering hydrogels for structural and cellular support is insufficient. A new paradigm is emerging—one that embraces the complexity of the osteochondral niche by integrating immunomodulatory and mechanobiological cues into biomaterial design. In particular, the hydrogel’s capacity to modulate macrophage polarization and support the immunoregulatory function of mesenchymal stem cells (MSCs) is critical to orchestrate regenerative outcomes. Simultaneously, the mechanical properties of hydrogels—such as stiffness, porosity, and viscoelasticity—can profoundly influence stem cell fate and local tissue morphogenesis. This review discusses recent advances in hydrogel-based strategies for osteochondral repair, highlighting the interplay between immunological signals and the mechanical microenvironment, and calls for a shift from reductionist tissue-engineering approaches to systems-level design of tunable, immuno-mechanobiological microenvironments. Full article

(This article belongs to the Special Issue Hydrogels for Tissue Engineering)

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33 pages, 5982 KB

Open AccessReview

Sol–Gel-Synthesized Metal Oxide Nanostructures: Advancements and Prospects for Spintronic Applications—A Comprehensive Review

by Kais Iben Nassar, Sílvia Soreto Teixeira and Manuel P. F. Graça

Gels 2025, 11(8), 657; https://doi.org/10.3390/gels11080657 - 19 Aug 2025

Cited by 3 | Viewed by 2086

Abstract

Spintronics, an interdisciplinary field merging magnetism and electronics, has attracted considerable interest due to its potential to transform data storage, logic devices, and emerging quantum technologies. Among the materials explored for spintronic applications, metal oxide nanostructures synthesized via sol–gel methods offer a unique [...] Read more.

Spintronics, an interdisciplinary field merging magnetism and electronics, has attracted considerable interest due to its potential to transform data storage, logic devices, and emerging quantum technologies. Among the materials explored for spintronic applications, metal oxide nanostructures synthesized via sol–gel methods offer a unique combination of low-cost processing, structural tunability, and defect-mediated magnetic control. This comprehensive review presents a critical overview of recent advances in sol–gel-derived magnetic oxides, such as Co-doped ZnO, La_1−xSr_xMnO₃, Fe₃O₄, NiFe₂O₄, and transition-metal-doped TiO₂, with emphasis on synthesis strategies, the dopant distribution, and room-temperature ferromagnetic behavior. Key spintronic functionalities, including magnetoresistance, spin polarization, and magnetodielectric effects, are systematically examined. Importantly, this review differentiates itself from the prior literature by explicitly connecting sol–gel chemistry parameters to spin-dependent properties and by offering a comparative analysis of multiple oxide systems. Critical challenges such as phase purity, reproducibility, and defect control are also addressed. This paper concludes by outlining future research directions, including green synthesis, the integration with 2D materials, and machine-learning-assisted optimization. Overall, this work bridges sol–gel synthesis and spintronic material design, offering a roadmap for advancing next-generation oxide-based spintronic devices. Full article

(This article belongs to the Special Issue Novel Polymer Gels: Synthesis, Properties, and Applications (2nd Edition))

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40 pages, 1205 KB

Open AccessReview

Natural Waxes as Gelators in Edible Structured Oil Systems: A Review

by Dafni Dimakopoulou-Papazoglou, Konstantina Zampouni and Eugenios Katsanidis

Gels 2025, 11(8), 656; https://doi.org/10.3390/gels11080656 - 18 Aug 2025

Viewed by 1220

Abstract

The use of natural waxes to create edible structured oil systems, namely oleogels and bigels, represents an innovative approach to replacing trans and saturated fats in food products, offering healthier alternatives for the food industry. This review aims to provide a detailed overview [...] Read more.

The use of natural waxes to create edible structured oil systems, namely oleogels and bigels, represents an innovative approach to replacing trans and saturated fats in food products, offering healthier alternatives for the food industry. This review aims to provide a detailed overview of the utilization of natural waxes in the formulation of oleogels and bigels, their interactions with other ingredients, and the methods employed to assess their physicochemical properties. A comprehensive analysis is also presented on the impact of processing parameters on the physicochemical and structural characteristics of these systems, as well as their oxidative stability. Additionally, the application of structured oil systems in various food products, including spreads, dairy, and meat products, is explored, along with a discussion of the attributes of the final products. Full article

(This article belongs to the Special Issue Gels: 10th Anniversary)

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15 pages, 2515 KB

Open AccessArticle

Carbon Dot Integrated Cellulose-Based Green-Fluorescent Aerogel for Detection and Removal of Copper Ions in Water

by Guanyan Fu, Chenzhan Peng, Jiangrong Yu, Jiafeng Cao, Shilin Peng, Tian Zhao and Dong Xu

Gels 2025, 11(8), 655; https://doi.org/10.3390/gels11080655 - 18 Aug 2025

Viewed by 471

Abstract

Industrial pollution caused by Cu(II) ions remains one of the most critical environmental challenges worldwide. A novel green-fluorescent aerogel has been successfully developed for simultaneous sensing and adsorption of Cu(II) through the cross-linking of carboxymethyl nanocellulose and carbon dots (C dots) using epichlorohydrin [...] Read more.

Industrial pollution caused by Cu(II) ions remains one of the most critical environmental challenges worldwide. A novel green-fluorescent aerogel has been successfully developed for simultaneous sensing and adsorption of Cu(II) through the cross-linking of carboxymethyl nanocellulose and carbon dots (C dots) using epichlorohydrin as a linker. The C dots were synthesized by heating glucose and aspartate mixed solutions at 150 °C. Under UV illumination, the aerogel exhibited intense homogeneous green fluorescence originating from the uniformly dispersed C dots, whose emission can be efficiently quenched by Cu(II) ions. By leveraging smartphone-based imaging, the concentration of Cu(II) was quantified within the range of 5–200 µg/L, with a detection limit of 3.7 µg/L. The adsorption isotherm of Cu(II) onto the aerogel strictly conformed to the Freundlich isotherm model (fitting coefficient R² = 0.9992), indicating a hybrid adsorption mechanism involving both physical adsorption and chemical complexation. The maximum adsorption capacity reached 149.62 mg/g, a value surpassing many reported adsorbents. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy analyses confirmed that the interactions between the aerogel and Cu(II) involved chelation and redox reactions, mediated by functional groups such as hydroxyl, amino, and carboxyl moieties. The straightforward fabrication process of the aerogel, coupled with its low cost, abundant raw materials, facile synthesis, and superior Cu(II) removal efficiency, positions this bifunctional fluorescent material as a promising candidate for large-scale environmental remediation applications. Full article

(This article belongs to the Section Gel Applications)

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18 pages, 5866 KB

Open AccessArticle

Enzyme-Triggered Formation of Tensegrity Structures for Mechanospatial Manipulation of Hydrogels

by Juan Wang, Xu Han, Qingtai Li, Meng Qin, Bin Xue, Wenxu Sun, Yi Cao and Wei Sun

Gels 2025, 11(8), 654; https://doi.org/10.3390/gels11080654 - 18 Aug 2025

Viewed by 478

Abstract

Hydrogels with spatially programmable mechanical properties hold great potential for use in biomedical applications. Inspired by the architecture of the cytoskeleton, we present a strategy for constructing tensegrity-structured hydrogels (TS-Gels) through enzyme-triggered crystal growth to enable precise mechanospatial manipulation. Specifically, alkaline phosphatase (ALP) [...] Read more.

Hydrogels with spatially programmable mechanical properties hold great potential for use in biomedical applications. Inspired by the architecture of the cytoskeleton, we present a strategy for constructing tensegrity-structured hydrogels (TS-Gels) through enzyme-triggered crystal growth to enable precise mechanospatial manipulation. Specifically, alkaline phosphatase (ALP) was covalently anchored to a polyacrylamide (PAAm) hydrogel matrix to catalyze the in situ dephosphorylation of phosphotyrosine precursors, leading to the formation of rigid tyrosine crystals. These crystals functioned as compressive sticks, establishing tensegrity structures within the hydrogel network. By tuning the crystallization kinetics, both the structural morphology and mechanical reinforcement could be precisely controlled. The resulting TS-Gels exhibited significantly enhanced local tensile strength and stiffness, allowing for spatial–mechanical patterning via photo-initiated printing, mold-assisted shaping, and laser engraving. Furthermore, the unique mechanospatial tunability of TS-Gels was demonstrated in tribological surface engineering, underscoring their potential for use in tissue engineering and responsive biomaterials. Full article

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

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25 pages, 4527 KB

Open AccessArticle

New Antimicrobial Gels Based on Clove Essential Oil–Cyclodextrin Complex and Plant Extracts for Topical Use

by Alina Ionela Stancu, Lia Mara Dițu, Eliza Oprea, Anton Ficai, Irinel Adriana Badea, Mihaela Buleandră, Oana Brîncoveanu, Anca Gabriela Mirea, Sorina Nicoleta Voicu, Adina Magdalena Musuc, Ludmila Aricov, Daniela Cristina Culita and Magdalena Mititelu

Gels 2025, 11(8), 653; https://doi.org/10.3390/gels11080653 - 18 Aug 2025

Viewed by 817

Abstract

This study aimed to develop and characterise novel hydrogels based on natural bioactive compounds for topical antimicrobial applications. Four gel systems were formulated using different polymers, namely polyacrylic acid (Carbopol 940, CBP-G), chitosan with high and medium molecular weights (CTH-G and CTM-G), and [...] Read more.

This study aimed to develop and characterise novel hydrogels based on natural bioactive compounds for topical antimicrobial applications. Four gel systems were formulated using different polymers, namely polyacrylic acid (Carbopol 940, CBP-G), chitosan with high and medium molecular weights (CTH-G and CTM-G), and sodium alginate (ALG-G), incorporating tinctures of Verbena officinalis and Aloysia triphylla, Laurus nobilis essential oil, and a β-cyclodextrin–clove essential oil complex. All gels displayed a homogeneous macroscopic appearance and maintained stability for over 90 days. Rheological studies demonstrated gel-like behaviour for CBP-G and ALG-G, with well-defined linear viscoelastic regions and distinct yield points, while CTM-G exhibited viscoelastic liquid-like properties. SEM imaging confirmed uniform and continuous matrices, supporting controlled active compound distribution. Thermogravimetric analysis (TG-DTA) revealed a two-step degradation profile for all gels, characterised by high thermal stability up to 230 °C and near-total decomposition by 500 °C. FTIR spectra confirmed the incorporation of bioactive compounds and products and highlighted varying interaction strengths with polymer matrices, which were stronger in CBP-G and CTH-G. Antimicrobial evaluation demonstrated that chitosan-based gels exhibited the most potent inhibitory and antibiofilm effects (MIC = 2.34 mg/mL) and a cytocompatibility assessment on HaCaT keratinocytes showed enhanced cell viability for chitosan gels and dose-dependent cytotoxicity for alginate formulations at high concentrations. Overall, chitosan-based gels displayed the most favourable combination of stability, antimicrobial activity, and biocompatibility, suggesting their potential for topical pharmaceutical use. Full article

(This article belongs to the Special Issue Hydrogels, Microgels, and Nanogels: From Fundamentals to Applications (3rd Edition))

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17 pages, 1362 KB

Open AccessReview

Advanced Hydrogels in Fibrocartilage Regeneration of the Glenoid Labrum

by Benjamin R. Caruso, Jihun Cha and Tammam Hanna

Gels 2025, 11(8), 652; https://doi.org/10.3390/gels11080652 - 18 Aug 2025

Viewed by 1038

Abstract

Glenoid labral tears are relatively common orthopedic injuries in adults. Anatomically, the glenoid labrum is a fibrocartilaginous structure that contributes to shoulder stability and function. The treatment for labral injury may be conservative, such as activity modification and rest, or operative, depending on [...] Read more.

Glenoid labral tears are relatively common orthopedic injuries in adults. Anatomically, the glenoid labrum is a fibrocartilaginous structure that contributes to shoulder stability and function. The treatment for labral injury may be conservative, such as activity modification and rest, or operative, depending on the extent of tissue damage. Hydrogels are polymeric networks with great potential in treating glenoid labral tears and other cartilage-related injuries. Hydrogels are highly biocompatible, hydrophilic, and non-immunogenic, with tunable mechanical properties that support nutrient diffusion, cell viability, and angiogenesis, making them well suited for cartilage regeneration. Hydrogels can deliver growth factors like TGF-β or PDGF and may be combined with peptides or adhesion molecules to enhance tissue integration, repair, and even physical support. This article introduces current treatment options for glenoid labral injuries, reviews the role of hydrogels in cartilage regeneration, and summarizes recent translational research focused on hydrogel-based labral repair. Full article

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

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15 pages, 2998 KB

Open AccessArticle

CMCSMA-Citric Acid Hydrogel-Coated Pancreatic Duct Stent Used for Pancreatic Calculi

by Jing Li, Jiahao Yang and Shige Wang

Gels 2025, 11(8), 651; https://doi.org/10.3390/gels11080651 - 16 Aug 2025

Viewed by 446 | Correction

Abstract

Pancreatic calculi, a common complication of chronic pancreatitis, significantly contribute to ductal obstruction, increased intraductal pressure, and debilitating abdominal pain. Although endoscopic pancreatic duct stenting alleviates ductal stenosis, conventional stents lack litholytic functionality, limiting their therapeutic efficacy. To address this challenge, we developed [...] Read more.

Pancreatic calculi, a common complication of chronic pancreatitis, significantly contribute to ductal obstruction, increased intraductal pressure, and debilitating abdominal pain. Although endoscopic pancreatic duct stenting alleviates ductal stenosis, conventional stents lack litholytic functionality, limiting their therapeutic efficacy. To address this challenge, we developed a drug-eluting pancreatic duct stent coated with a carboxymethyl chitosan methacrylate (CMCSMA)-based hydrogel utilizing 50% w/v citric acid (CA) as a litholytic agent. Polydopamine (PDA) interlayer was employed to enhance interfacial adhesion between the hydrogel and the stent surface. The CMCSMA hydrogel exhibited favorable physicochemical properties, including rapid gelation, excellent compressive strength (229.2 ± 14.8 kPa), hemocompatibility, and cytocompatibility. In vitro release studies revealed sustained CA release, achieving 66.3% cumulative release within 72 h. The hydrogel-coated stent demonstrated superior litholytic activity, dissolving over 90% of pancreatic calculi within 24 h. These results underscore the potential of CMCSMA-CA hydrogel-coated stents as a biocompatible and effective local drug delivery platform for targeted pancreatic duct litholysis. Full article

(This article belongs to the Special Issue Properties and Applications of Biomaterials Related to Gels (3rd Edition))

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19 pages, 7889 KB

Open AccessArticle

Tannic Acid-Enhanced Gelatin-Based Composite Hydrogel as a Candidate for Canine Periodontal Regeneration

by Laura C. Pinho, Marta Ferreira, Angélica Graça, Joana Marto, Bruno Colaço, Maria Helena Fernandes and Catarina Santos

Gels 2025, 11(8), 650; https://doi.org/10.3390/gels11080650 - 15 Aug 2025

Viewed by 978

Abstract

Periodontal disease in dogs leads to progressive bone loss and adversely impacts overall health. However, cost-effective regenerative strategies are still limited in veterinary practice. This study aimed to develop and evaluate a novel tannic acid (TA)–gelatin-based hydrogel (Gel), incorporating graphene oxide (GO) and [...] Read more.

Periodontal disease in dogs leads to progressive bone loss and adversely impacts overall health. However, cost-effective regenerative strategies are still limited in veterinary practice. This study aimed to develop and evaluate a novel tannic acid (TA)–gelatin-based hydrogel (Gel), incorporating graphene oxide (GO) and hydroxyapatite nanoparticles (HA), as a potential barrier material for guided tissue regeneration (GTR) applications. The hydrogels—Gel, Gel-GO, Gel-HA, and Gel-GO-HA—were characterized for chemical structure, molecular interactions, surface morphology, nanoparticle dispersion, and tensile strength. Cytotoxicity was assessed using L929 fibroblasts (ISO 10993-5), while cell viability/proliferation, morphology, and alkaline phosphatase (ALP) production were evaluated using canine periodontal ligament-derived cells. Results show that crosslinking with tannic acid enhanced the incorporation of graphene oxide and hydroxyapatite nanoparticles via hydrogen bonding into TA–gelatin-based hydrogels. This combination increased surface roughness, reduced degradation rate, and enabled shape memory behavior, critical for guided tissue regeneration (GTR) membranes. The extracts from Gel-HA-GO showed that cytotoxicity was both time- and concentration-dependent in L929 fibroblasts, whereas enhanced cell proliferation and increased ALP production were observed in cultures derived from canine periodontal ligament cells. These findings suggest that TA–gelatin-based hydrogels incorporating GO and HA demonstrated favorable mechanical and physicochemical properties, biocompatibility, and osteogenic potential. These attributes suggest their viability as a promising composite for the development of innovative GTR strategies to address periodontal tissue loss in veterinary medicine. Full article

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

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13 pages, 9916 KB

Open AccessArticle

Near-Infrared Dye-Loaded Thermosensitive Hydrogels as Novel Fluorescence Tissue Markers

by Seon Sook Lee and Yongdoo Choi

Gels 2025, 11(8), 649; https://doi.org/10.3390/gels11080649 - 15 Aug 2025

Viewed by 670

Abstract

Accurate intraoperative localization of deep-seated lesions remains a major challenge in minimally invasive procedures such as laparoscopic and robotic surgeries. Current marking strategies—including ink tattooing and metallic clips—are limited by dye diffusion, or poor intraoperative visibility. To address these issues, we developed and [...] Read more.

Accurate intraoperative localization of deep-seated lesions remains a major challenge in minimally invasive procedures such as laparoscopic and robotic surgeries. Current marking strategies—including ink tattooing and metallic clips—are limited by dye diffusion, or poor intraoperative visibility. To address these issues, we developed and evaluated four thermosensitive injectable hydrogel systems incorporating indocyanine green-human serum albumin (ICG-HSA) complexes: (1) hexanoyl glycol chitosan (HGC), (2) Pluronic F-127, (3) PCL–PEG–PCL, and (4) PLA–PEG–PLA. All hydrogel formulations exhibited sol–gel transitions at physiological temperatures, facilitating in situ dye entrapment and prolonged fluorescence retention. In vivo fluorescence imaging revealed that HGC and Pluronic F-127 hydrogels retained signals for up to five and two days, respectively. In contrast, polyester-based hydrogels (PCL–PEG–PCL and PLA–PEG–PLA) preserved fluorescence for up to 21–30 days. PLA–PEG–PLA showed the highest signal-to-background ratios and sustained intensity, while PCL–PEG–PCL also achieved long-term retention. These findings suggest that thermosensitive hydrogels incorporating ICG-HSA complexes represent promising tissue marker platforms for real-time, minimally invasive, and long-term fluorescence-guided lesion tracking. Full article

(This article belongs to the Special Issue Innovative Applications of Gelated Matrices in Biomedical and Environmental Engineering)

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19 pages, 5599 KB

Open AccessArticle

GelMA@ginsenoside Rb3 Targets Inflammatory Microenvironment in Periodontitis via MAPK Pathway

by Jinmeng Sun, Minmin Sun, Zekun Li, Luyun Liu, Xinjuan Liu, Yuhui Sun and Gang Ding

Gels 2025, 11(8), 648; https://doi.org/10.3390/gels11080648 - 15 Aug 2025

Viewed by 661

Abstract

This study aims to develop a gelatin methacryloyl (GelMA)-based ginsenoside Rb3 (G-Rb3) drug delivery system and investigate its application in the treatment of periodontitis and the underlying mechanisms. Periodontal ligament stem cells (PDLSCs) were obtained and identified. The appropriate concentration ranges of G-Rb3 [...] Read more.

This study aims to develop a gelatin methacryloyl (GelMA)-based ginsenoside Rb3 (G-Rb3) drug delivery system and investigate its application in the treatment of periodontitis and the underlying mechanisms. Periodontal ligament stem cells (PDLSCs) were obtained and identified. The appropriate concentration ranges of G-Rb3 and lipopolysaccharide (LPS) were investigated by the CCK-8 experiments. Quantitative RT-PCR, ELISA, and Western blot were performed to assess the effects of GelMA@G-Rb3 on LPS-treated PDLSCs. The possible mechanisms were determined through network pharmacology analysis and Western blot. The therapeutic effects of GelMA@G-Rb3 in rat periodontitis animal models were systematically evaluated using Micro-CT, H&E staining, Masson staining, and immunofluorescence staining. PDLSCs were successfully isolated and characterized. The in vitro results indicated that GelMA@G-Rb3 significantly alleviated LPS-induced inflammation in PDLSCs by inhibiting the p38/ERK signaling pathway and activating the PI3K/AKT signaling pathway. In vivo experiments confirmed that GelMA@G-Rb3 significantly reduced alveolar bone resorption, and promoted periodontal tissue regeneration, while simultaneously demonstrating significant regulatory effects on the MAPK signaling pathway. This study demonstrated the efficacy of the GelMA@G-Rb3 system in modulating the inflammatory responses of periodontitis and improving the periodontal tissue regeneration, which establish a solid foundation and proposed innovative therapeutic approaches for the treatment of periodontitis. Full article

(This article belongs to the Special Issue Biopolymer Gel-Assisted Synthesis of Particles for Biomedical Applications (2nd Edition))

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35 pages, 6417 KB

Open AccessReview

Hydrogel-Based Treatment of Diabetic Wounds: From Smart Responsive to Smart Monitoring

by Xinghan He, Yongyi Wei and Ke Xu

Gels 2025, 11(8), 647; https://doi.org/10.3390/gels11080647 - 15 Aug 2025

Cited by 1 | Viewed by 2546

Abstract

Diabetic wounds are characterized by a refractory healing cycle resulting from the synergistic effects of hyperglycemic microenvironment, oxidative stress, bacterial infection, and impaired angiogenesis. Conventional hydrogel dressings, with limited functionality, struggle to address the complexities of chronic diabetic ulcers. Smart hydrogels, possessing biocompatibility, [...] Read more.

Diabetic wounds are characterized by a refractory healing cycle resulting from the synergistic effects of hyperglycemic microenvironment, oxidative stress, bacterial infection, and impaired angiogenesis. Conventional hydrogel dressings, with limited functionality, struggle to address the complexities of chronic diabetic ulcers. Smart hydrogels, possessing biocompatibility, porous architectures mimicking extracellular matrix, and environmental responsiveness, have emerged as promising biomaterials for diabetic wound management. This review systematically elucidates the specific response mechanisms of smart hydrogels to wound microenvironmental stimuli, including pH, matrix metalloproteinase-9 (MMP-9), reactive oxygen species (ROS), and glucose levels, enabling on-demand release of antimicrobial agents and growth factors through dynamic bond modulation or structural transformations. Subsequently, the review highlights recent advances in novel hydrogel-based sensors fabricated via optical (photonic crystal, fluorescence) and electrochemical principles for real-time monitoring of glucose levels and wound pH. Finally, critical challenges in material development and scalable manufacturing of multifunctional hydrogel components are discussed, alongside prospects for precision diagnostics and therapeutics in diabetic wound care. Full article

(This article belongs to the Special Issue Hydrogel for Sustained Delivery of Therapeutic Agents (3rd Edition))

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16 pages, 2534 KB

Open AccessArticle

Sodium Alginate/Carboxymethyl Chitosan Hydrogel Microbeads for Antibiotic Adsorption in Single and Binary Systems

by Zhisong Qian, Xinpeng Li, Gege Yan, Xiaoyong Chen, Mohd Shaiful Sajab, Gongtao Ding and Wan Nazihah Liyana Wan Jusoh

Gels 2025, 11(8), 646; https://doi.org/10.3390/gels11080646 - 14 Aug 2025

Viewed by 665

Abstract

The use of pharmaceuticals to treat human and animal diseases has resulted in the increase of antibiotic traces in the water system and soil, thus raising concerns about the environmental aspect. In this study, sodium alginate (SA) and carboxymethyl chitosan (CMCS) hydrogel microbeads [...] Read more.

The use of pharmaceuticals to treat human and animal diseases has resulted in the increase of antibiotic traces in the water system and soil, thus raising concerns about the environmental aspect. In this study, sodium alginate (SA) and carboxymethyl chitosan (CMCS) hydrogel microbeads were developed to enhance the adsorption of antibiotics by applying electrostatic spray in the fabrication of microbeads. Two hydrogel microbead sizes, SC-400 (~400 µm) and SC-2000 (~2000 µm), were used for the adsorption of tetracycline (TC) and ciprofloxacin (CIP) antibiotics in single and binary systems. The microbeads exhibited a good adsorption capacity and were able to achieve a maximum adsorption at pH 7 and 25 °C. Adsorption kinetics expressed suitability in the pseudo-second-order kinetic model for TC and CIP antibiotics. These results demonstrate that both single and binary systems align well with the Freundlich and Temkin isotherm models, indicating their suitability in explaining the adsorption mechanisms. These mechanisms predominantly involve electrostatic interactions between the SA/CMCS hydrogel microbeads and the antibiotics TC and CIP. This study highlights the capability of using SA/CMCS hydrogel microbeads for antibiotic removal and other environmental applications. Full article

(This article belongs to the Special Issue Properties and Applications of Biomaterials Related to Gels (3rd Edition))

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16 pages, 2324 KB

Open AccessArticle

A Stability Study of [Cu(I)(dmby)₂]TFSI in Biopolymer-Based Aqueous Quasi-Solid Electrolytes

by Giulia Adriana Bracchini, Elvira Maria Bauer, Claudia Mazzuca and Marilena Carbone

Gels 2025, 11(8), 645; https://doi.org/10.3390/gels11080645 - 14 Aug 2025

Viewed by 479

Abstract

In the field of advanced electrical energy conversion and storage, remarkable attention has been given to the development of new, more sustainable electrolytes. In this regard, the combination of redox shuttles with aqueous bio-polymer gels seems to be a valid alternative via which [...] Read more.

In the field of advanced electrical energy conversion and storage, remarkable attention has been given to the development of new, more sustainable electrolytes. In this regard, the combination of redox shuttles with aqueous bio-polymer gels seems to be a valid alternative via which to overcome the typical drawbacks of common liquid electrolytes such as corrosion, volatility or leakage. Despite the promising results obtained so far, redox-active species such as bis(6,6′-dimethyl-2,2′-bipyridine)copper(I) trifluoromethanesulfonylimide, ([Cu(I)(dmby)₂]TFSI), still present inherent challenges associated with their poor water solubility and oxidative lability, which prevents their employment in cheap and sustainable aqueous electrolytes. The present study investigates the stabilization of the Cu(I) complex ([Cu(I)(dmby)₂]TFSI) within two natural hydrogels based on the biopolymers κ-carrageenan and galactomannan, using ZnO nanoparticles as gelling agents. These eco-friendly and biocompatible systems are proposed as potential matrices for quasi-solid electrolytes (QSEs), offering a promising platform for advanced electrolyte design in electrochemical applications. Both hydrogels effectively stabilized and retained the redox species within their networks. In order to shed light on distinct stabilization mechanisms, complementary FTIR and SEM analyses were relevant to reveal the structural rearrangements, specific to each matrix, upon complex incorporation. Furthermore, thermogravimetric analysis confirmed notable thermal resilience in both systems, with the galactomannan-based gel demonstrating enhanced performance. Altogether, this work introduces a novel strategy for embedding copper-based redox couples into gelled electrolytes, paving the way toward their integration in real electrochemical devices, where long-term stability, redox retention, and energy conversion efficiency are critical evaluation criteria. Full article

(This article belongs to the Special Issue Electroactive Hydrogels: Application in Soft Actuators and Flexible Devices)

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15 pages, 3160 KB

Open AccessArticle

Annealed Polyvinyl Alcohol Hydrogels for Cartilage Replacement: Effects of Synthesis Parameters on Mechanical Properties

by Hassan Mahmoud, Christian M. Puttlitz, Benjamin C. Gadomski and Kevin M. Labus

Gels 2025, 11(8), 644; https://doi.org/10.3390/gels11080644 - 14 Aug 2025

Viewed by 755

Abstract

The objective of this paper was to determine the interactive effects of multiple synthesis parameters on annealed PVA hydrogel properties and assess these hydrogels for the application of cartilage replacement. PVA hydrogels were synthesized at two different molecular weight ranges (89–98 kDa and [...] Read more.

The objective of this paper was to determine the interactive effects of multiple synthesis parameters on annealed PVA hydrogel properties and assess these hydrogels for the application of cartilage replacement. PVA hydrogels were synthesized at two different molecular weight ranges (89–98 kDa and 146–186 kDa), two polymer concentrations (10% PVA and 20% PVA), and four different annealing temperatures (120 °C, 135 °C, 150 °C, and 165 °C). The compressive, tensile, and wear mechanical properties were measured, and the crystalline structure of these hydrogels was assessed via differential scanning calorimetry. Hydrogels showed increasing polymer weight percent, tensile modulus, and compressive modulus with increasing annealing temperature. Depending on synthesis parameters, the hydrogels matched or exceeded the previously published compressive and tensile properties of native cartilage. Higher molecular weight PVA hydrogels (146–186 kDa) exhibited less wear, but greater friction, compared to lower molecular weight PVA (89–98 kDa). The PVA hydrogels exhibited crystallinity in the range of 53–78%, but no consistent differences in crystallinity were detected between hydrogel variants. It was concluded that the (10% PVA, 146 kDa, 165 °C) annealed PVA hydrogel demonstrated the most appropriate balance of high tensile strength and compressive compliance comparable to cartilage. Full article

(This article belongs to the Special Issue Hydrogels for Cartilage Tissue Engineering and Mechanobiology)

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