Gels | August 2026 - Browse Articles

29 pages, 10395 KB

Open AccessArticle

Visualized Experimental Investigation of Flow-Field Reconstruction and Enhanced Oil Recovery by Heterogeneous-Phase Composite Flooding in Complex Narrow-Channel Reservoirs

by Xianmin Zhang, Junzhi Yu, Kuiqian Ma, Lei Zhang, Yue Wang and Fei Shi

Gels 2026, 12(8), 752; https://doi.org/10.3390/gels12080752 - 21 Aug 2026

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Abstract

Complex narrow-channel reservoirs are strongly constrained by depositional architecture, resulting in highly nonuniform areal waterflood sweep, and pronounced water-cut variations among different channel types. These characteristics pose substantial challenges to stabilizing oil production and controlling water cut at high water-cut stages. To elucidate [...] Read more.

Complex narrow-channel reservoirs are strongly constrained by depositional architecture, resulting in highly nonuniform areal waterflood sweep, and pronounced water-cut variations among different channel types. These characteristics pose substantial challenges to stabilizing oil production and controlling water cut at high water-cut stages. To elucidate how narrow-channel planform architecture controls waterflood sweep, gel-assisted flow-field regulation by heterogeneous-phase composite flooding (HPCF), and remaining-oil mobilization, three representative configurations were reproduced in two-dimensional visual physical models. Sequential waterflood–HPCF–post-waterflood experiments were conducted, and time-lapse images and dynamic production data were integrated to characterize sweep evolution and remaining-oil mobilization across displacement stages. The results demonstrate that narrow-channel architecture exerts primary control on preferential flow-path development, gel migration and retention, spatial fluid redistribution, and displacement performance. During waterflooding, injected water preferentially migrated through high-permeability zones along channel centerlines, leaving channel margins, branch termini, and poorly connected regions insufficiently swept. After HPCF injection, the gel-containing composite system preferentially entered the established dominant flow paths. Gel retention and accumulation selectively increased flow resistance in these pathways, while mobility control induced subsequent fluids to divert toward bypassed regions, thereby enlarging the macroscopic swept volume and improving local displacement efficiency. A low injection rate promoted sustained gel-assisted flow diversion within bifurcated channels, whereas a high injection rate facilitated gel-slug propagation against the geometric constraints of highly sinuous channels and expanded its spatial coverage. Compared with waterflooding alone, HPCF increased the ultimate oil recovery of the three channel models by 19.23–26.47 percentage points. These findings clarify the coupled effects of narrow-channel architecture, gel transport and injection parameters on the profile-control and oil-recovery performance of HPCF, providing a mechanistic basis for water control and development optimization in high-water-cut narrow-channel reservoirs. Full article

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

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58 pages, 19121 KB

Open AccessSystematic Review

N-Acetylcysteine Applied to Hydrogels: A Comprehensive Systematic Review

by Ermelinda Silvana Junckes, Pâmela Elise Munzlinger, Carla Dalmolin, Marco Fosca, Marcia Margarete Meier and Julietta V. Rau

Gels 2026, 12(8), 751; https://doi.org/10.3390/gels12080751 - 21 Aug 2026

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Abstract

N-acetylcysteine (NAC) is a thiol-containing molecule with antioxidant, anti-inflammatory, antimicrobial, and cytoprotective properties that has increasingly been incorporated into hydrogel-based biomaterials. This systematic review evaluates the strategies used to integrate NAC into hydrogels and examines their effects on material properties, controlled release, biocompatibility, [...] Read more.

N-acetylcysteine (NAC) is a thiol-containing molecule with antioxidant, anti-inflammatory, antimicrobial, and cytoprotective properties that has increasingly been incorporated into hydrogel-based biomaterials. This systematic review evaluates the strategies used to integrate NAC into hydrogels and examines their effects on material properties, controlled release, biocompatibility, and therapeutic activity. The review was conducted according to the PRISMA guidelines using Scopus, PubMed, Web of Science, and SciFinder to identify English-language articles published between 2000 and 2025. Seventy-three studies met the eligibility criteria of this review. NAC has been employed as a physically loaded therapeutic agent, covalently conjugated polymer modifier, contributor to hydrogel crosslinking, metal-coordination ligand, and compound incorporated into nano- and microparticulate carriers dispersed in hydrogel. These approaches enable the modulation of gelation, swelling, adhesion, degradation, and drug-release kinetics. NAC-containing hydrogels have demonstrated robust antioxidant, antimicrobial, antibiofilm, anti-inflammatory, angiogenic, and tissue-regenerative properties in various in vitro and in vivo models, underscoring their potential for advanced biomaterial applications. Release profiles varied from rapid stimulus-responsive delivery to sustained release over several days, depending on the network architecture and the NAC–matrix interactions. However, comparisons among studies were limited by the heterogeneous formulations, release conditions, biological models, and outcome measures. Standardized physicochemical characterization, NAC stability assessment, dose–response evaluation, and rigorous preclinical validation are required to support the translation of NAC-based hydrogels into biomedical applications. We hope that this review will help scientists and innovation centers understand the potential of the NAC-containing hydrogel biomaterials discussed in this study, as well as the opportunities and demands for additional research in this field. Full article

(This article belongs to the Special Issue Properties and Structure of Hydrogel-Related Materials (3rd Edition))

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15 pages, 1270 KB

Open AccessArticle

Soft Polymeric Matrix-Mediated Stabilization of Bulk Heterojunction Morphology for Thermally Robust Organic Photovoltaics

by Unyong Lee, Junpyo Seo and Minwoo Nam

Gels 2026, 12(8), 750; https://doi.org/10.3390/gels12080750 - 21 Aug 2026

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Abstract

Suppressing thermally driven morphological evolution while preserving efficient charge transport pathways remains a critical challenge for improving the long-term stability of organic photovoltaics (OPVs). Herein, a soft polymeric matrix strategy based on gel-related soft material concepts is demonstrated for stabilizing bulk heterojunction (BHJ) [...] Read more.

Suppressing thermally driven morphological evolution while preserving efficient charge transport pathways remains a critical challenge for improving the long-term stability of organic photovoltaics (OPVs). Herein, a soft polymeric matrix strategy based on gel-related soft material concepts is demonstrated for stabilizing bulk heterojunction (BHJ) morphology and simultaneously improving the efficiency and thermal durability of OPVs. The incorporation of an optimal 5 wt% polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) as a soft polymeric matrix component into a PM6:Y6 blend modulates the nanoscale morphology and local packing characteristics of the acceptor phase. These changes improve charge-transport balance and charge collection, increasing the power conversion efficiency (PCE) from 14.27% to 15.22%, corresponding to a 6.7% relative enhancement over the control device. More importantly, after 10 days of thermal aging at 85 °C, the SEBS device retains 87.1% of its initial PCE, compared with 72.5% for the control device. Complementary morphological and spectroscopic analyses reveal suppressed thermally induced structural evolution and aggregation in the SEBS-containing films. These findings demonstrate that a gel-related soft polymeric matrix can regulate BHJ organization and mitigate thermally driven morphological evolution, providing a simple strategy for addressing the efficiency–stability trade-off and realizing thermally robust OPVs. Full article

(This article belongs to the Special Issue Applications of Gels in Energy Materials and Devices (2nd Edition))

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19 pages, 36653 KB

Open AccessArticle

Engineering Parameter Window for Filament Formation and Early-Stage Evolution in Embedded Printing of Gelatin/Alginate Hydrogels Within Carbomer Support Baths

by Jinwei Li, Wang Tang, Zihang Yan, Huansi Mo, Jinhu Wang, Lin Lin, Yong Wang, Hui You and Yuanfen Chen

Gels 2026, 12(8), 749; https://doi.org/10.3390/gels12080749 - 21 Aug 2026

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Abstract

Embedded 3D printing of hydrophilic hydrogels in aqueous support baths often suffers from filament deformation, positional deviation, and diffusion before complete cross-linking, while practical parameter-selection guidelines for specific material systems remain limited. In this work, an integrated engineering evaluation method was developed to [...] Read more.

Embedded 3D printing of hydrophilic hydrogels in aqueous support baths often suffers from filament deformation, positional deviation, and diffusion before complete cross-linking, while practical parameter-selection guidelines for specific material systems remain limited. In this work, an integrated engineering evaluation method was developed to characterize filament formation and early-stage evolution during embedded printing of gelatin/sodium alginate inks in Carbomer support baths. Filament quality was assessed using cross-sectional geometry, contour irregularity, deposition position, and early-stage diffusion ratio. The effects of printing kinematics and material rheology are systematically examined to establish a practical process window for this hydrophilic ink–bath system. The results show that the speed ratio between substrate and ink is a primary factor controlling filament geometry and deposition position, and a ratio close to 1 yields the most balanced cross-sectional morphology without position shift from the printed nozzle. Ink with high viscosity maintains contour irregularity within a narrow range of 0.005–0.009 and suppresses early diffusion, whereas a support bath with high viscosity and ink with high viscosity combination further slows diffusional evolution by about 70%. Based on the identified process window, several three-dimensional hydrogel structures were fabricated successfully. The proposed workflow provides a practical route for process evaluation and parameter selection in hydrophilic embedded printing, especially for continuous filament and tubular structures, and offers engineering guidance for bio-soft material fabrication in applications. Full article

(This article belongs to the Special Issue Advanced Functional Hydrogels and 3D Scaffolds for Biomedical Applications)

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16 pages, 1728 KB

Open AccessArticle

Adhesive Bonding to Hydraulic Gel-Forming Calcium Silicate-Based Cements: Effects of Cement Type, Adhesive Strategy, and Restoration Timing

by Gizem Akın Tartuk, Merve Yeniçeri Özata and Sadullah Kaya

Gels 2026, 12(8), 748; https://doi.org/10.3390/gels12080748 - 20 Aug 2026

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Abstract

Calcium silicate-based cements are hydraulic biomaterials that form a calcium silicate hydrate (C-S-H) gel during hydration, a process fundamental to their setting and progressive physicochemical development. Although these materials are widely used in vital pulp therapy, evidence regarding the effects of adhesive strategy [...] Read more.

Calcium silicate-based cements are hydraulic biomaterials that form a calcium silicate hydrate (C-S-H) gel during hydration, a process fundamental to their setting and progressive physicochemical development. Although these materials are widely used in vital pulp therapy, evidence regarding the effects of adhesive strategy and restoration timing on bonding performance, particularly for newer premixed formulations, remains limited. This study evaluated the effects of cement type, adhesive strategy, and restoration timing on the shear bond strength (SBS) of resin composite bonded to MTA Angelus and Well-Root PT. A total of 270 specimens were distributed across two cement types, three adhesive strategies, and three restoration intervals (45 min, 24 h, and 7 days). After thermocycling, SBS and failure modes were assessed. SBS data were analyzed using three-way ANOVA, whereas failure-mode distributions were evaluated using chi-square or Fisher’s exact tests (α = 0.05). Cement type, adhesive strategy, restoration timing, and their interactions significantly influenced SBS (p < 0.001). Well-Root PT exhibited higher early bond strength than MTA Angelus. The two-step etch-and-rinse adhesive produced the highest SBS values, whereas the universal adhesive produced the lowest. Restoration after 24 h significantly increased SBS compared with restoration after 45 min, with no additional improvement observed at 7 days. Within the limitations of this in vitro study, bonding performance was influenced by cement type, adhesive strategy, and restoration timing. The time-dependent increase in SBS is consistent with continued hydration and development of the C-S-H gel-based cement matrix, although the specific microstructural changes underlying this behavior were not directly characterized. Full article

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

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15 pages, 2301 KB

Open AccessArticle

Rheological Characterization of Yeast Protein–Sanxan Composite Hydrogels via SAOS, LAOS and Thermal Analysis

by Xuesong Cao, Yujie Qu and Zhiping Fan

Gels 2026, 12(8), 747; https://doi.org/10.3390/gels12080747 - 20 Aug 2026

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Abstract

Future foods are driving an urgent need for sustainable and functional protein resources, and synthetic biology is emerging as a powerful platform to produce such proteins efficiently. Here, we designed a yeast protein (YP)–sanxan composite hydrogel obtained. The introduction of YP significantly improved [...] Read more.

Future foods are driving an urgent need for sustainable and functional protein resources, and synthetic biology is emerging as a powerful platform to produce such proteins efficiently. Here, we designed a yeast protein (YP)–sanxan composite hydrogel obtained. The introduction of YP significantly improved thermal stability (by 5–15 °C) and ensured polymer compatibility. Rheological analysis indicated a frequency-dependent weak gel (tan δ = 0.1–0.3), making it suitable for safe swallowing. The material exhibited Type III nonlinear viscoelastic behavior, characterized by inter-cycle strain softening and a weak overshoot in G″, with Lissajous curves revealing a strain-induced transition from solid-like to fluid-like behavior. Crucially, YP-reinforced gels (5–20%) exhibited higher elastic moduli, indicating that the incorporation of YP strengthened the gel network and increased its structural rigidity, as further confirmed by Strain Sweep. With its tunable rheology and superior thermal stability, this hydrogel holds great potential for functional foods, 3D food printing, delivery systems, and biomedical scaffolds. Full article

(This article belongs to the Special Issue Food Gels: Structure and Properties (3rd Edition))

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29 pages, 41563 KB

Open AccessArticle

Paeonol-Loaded Cyclodextrin/Composite Hydrogel for Enhanced Transdermal Delivery and Skin Photoaging Repair

by Xinrui Chen, Yong Liu, Ruofei Zu, Wenwen Li, Xueer Wang, Xinyi Yang, Chuanji Zhu, Yuling Xu, Ziwen Xie and Hongmei Xia

Gels 2026, 12(8), 746; https://doi.org/10.3390/gels12080746 - 20 Aug 2026

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Abstract

Skin photoaging is closely associated with oxidative stress, inflammatory responses, and dysregulated collagen metabolism. Paeonol (Pae) possesses antioxidant and anti-inflammatory activities; however, its poor water solubility and short skin retention time limit its topical application. In this study, a transdermal delivery system based [...] Read more.

Skin photoaging is closely associated with oxidative stress, inflammatory responses, and dysregulated collagen metabolism. Paeonol (Pae) possesses antioxidant and anti-inflammatory activities; however, its poor water solubility and short skin retention time limit its topical application. In this study, a transdermal delivery system based on a carboxymethyl chitosan (CMCS)/Carbomer 940 (Carb940) composite gel loaded with hydroxypropyl-β-cyclodextrin inclusion complexes of paeonol (Pae-CD) was developed. Pae-CD was prepared using an ultrasound-assisted saturated aqueous solution method, and the physicochemical properties, sustained-release behavior, transdermal permeation, antioxidant activity, and safety of Pae-CD/gel were evaluated. Furthermore, a mouse model of skin photoaging induced by combined ultraviolet A (UVA)/ultraviolet B (UVB) irradiation was established to investigate its reparative effects in vivo. The results showed that Pae-CD/gel exhibited a homogeneous three-dimensional porous structure, favorable sustained-release characteristics, enhanced skin retention capacity, and good cellular compatibility. In vivo experiments demonstrated that Pae-CD/gel markedly ameliorated ultraviolet-induced skin dryness, abnormal epidermal thickening, and dermal collagen loss. It also reduced oxidative stress and inflammatory factor levels, down-regulated matrix metalloproteinase-1 (MMP-1) and matrix metalloproteinase-3 (MMP-3) expression, and promoted the restoration of collagen type I (COL-1) and hydroxyproline (HYP) levels. Systemic safety evaluation revealed no obvious toxicity. In summary, Pae-CD/gel exerts antioxidant and anti-inflammatory effects and regulates collagen metabolism by enhancing transdermal delivery and local retention, thereby providing a safe and effective topical delivery strategy for the repair of skin photoaging. Full article

(This article belongs to the Special Issue Preparation, Properties and Applications of Functional Hydrogels: New Insights)

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14 pages, 1225 KB

Open AccessArticle

Dosimetric Characterization Using Quantitative Magnetic Resonance Imaging of PAGAT and Gd-PAGAT Polymer Gel Dosimeters at High Gd Concentration

by Melani Fuentealba, Gerardo Belmar and Mauricio Santibáñez

Gels 2026, 12(8), 745; https://doi.org/10.3390/gels12080745 - 20 Aug 2026

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Abstract

Gadolinium-doped polymer gel dosimeters enable experimental evaluation of dose enhancement in low-energy radiotherapy, although the high Gd concentrations required substantially alter their magnetic relaxation properties, making the optimal Magnetic Resonance Imaging (MRI) readout uncertain. This study characterized the dosimetric response of PAGAT and [...] Read more.

Gadolinium-doped polymer gel dosimeters enable experimental evaluation of dose enhancement in low-energy radiotherapy, although the high Gd concentrations required substantially alter their magnetic relaxation properties, making the optimal Magnetic Resonance Imaging (MRI) readout uncertain. This study characterized the dosimetric response of PAGAT and Gd-PAGAT (9 mg/mL Gd) irradiated with a 150 kVp X-ray beam from 1 to 10 Gy using quantitative 1.5 T MRI. Quantitative R₁ and R₂ maps were obtained from variable flip-angle spoiled gradient echo (SPGR) and multi-echo spin echo (MSE) sequences, respectively, and validated by UV-Vis spectrophotometry. R₁ showed no significant dose dependence in Gd-PAGAT because of severe T₁ shortening. In contrast, R₂ exhibited a robust response, with second-order polynomial fits (R² = 0.9984 for PAGAT and 0.9969 for Gd-PAGAT) and linear behavior between 1 and 7 Gy. The dose sensitivity of Gd-PAGAT was 2.84 ± 0.19 times higher than that of PAGAT (0.5328 vs. 0.1949 s⁻¹·Gy⁻¹). Spectrophotometry confirmed the PAGAT calibration but showed markedly lower sensitivity for Gd-PAGAT, particularly at low doses. These findings demonstrate that R₂ mapping overcomes the limitations imposed by extreme T₁ shortening, extending the applicability of Gd-PAGAT dosimeters for three-dimensional dose enhancement studies in low-energy radiotherapy. Full article

(This article belongs to the Special Issue Gel-Based Materials for Sensors, Self-Powered Nanogenerators, and Artificial Intelligence Prospects)

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36 pages, 11454 KB

Open AccessReview

Bioactive Hydrogel–MOF Composites as Resistance-Modulating Wound Interfaces: Molecular Mechanisms and Rational Design for Chronic Wound Management

by Nallely G. Hernández-Hernández, Irving A. González-Lara, Lesly Katleya Usme-Duque, Lía A. Martínez-Berlanga, Grecia D. Ortíz-Hernández, María I. León-Campos, Bertha Puente-Urbina, Miguel A. Medina-Morales, Elan I. Loredo-Alcalá, Leopoldo J. Ríos-González, Thelma K. Morales-Martínez, Roberto Arredondo-Valdés, Adolfo Romero-Galarza, Lucía F. Cano-Salazar, Rebeca Betancourt-Galindo, María O. González-Díaz, Nayeli Rodríguez-Fuentes, Javier Enríquez-Medrano, Florentino Soriano-Corral, Raul Rosales-Ibáñez, Amairany Rodríguez-Navarrete, Denis A. Cabrera-Munguía and Jesús A. Claudio-Rizo Show full author list Hide full author list

Gels 2026, 12(8), 744; https://doi.org/10.3390/gels12080744 - 20 Aug 2026

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Abstract

Chronic wounds are complex environments marked by persistent inflammation, oxidative stress, hypoxia, and conditions that favor antimicrobial resistance (AMR). Conventional antibiotics often fail due to bacterial persistence and the physicochemical barriers of the wound milieu. Biofilm-associated extracellular polymeric substances (EPS), efflux pump activity, [...] Read more.

Chronic wounds are complex environments marked by persistent inflammation, oxidative stress, hypoxia, and conditions that favor antimicrobial resistance (AMR). Conventional antibiotics often fail due to bacterial persistence and the physicochemical barriers of the wound milieu. Biofilm-associated extracellular polymeric substances (EPS), efflux pump activity, quorum sensing (QS), and horizontal gene transfer (HGT) collectively drive antimicrobial tolerance and resistance dissemination, turning chronic wounds into reservoirs of multidrug-resistant pathogens. Consequently, emerging wound therapies demand multifunctional strategies that modulate the wound microenvironment while interfering with resistance-associated phenotypes. Hydrogel–metal–organic framework (MOF) composites have been explored as multifunctional interfaces that combine extracellular matrix-mimetic properties, tunable porosity, stimuli-responsiveness, and controlled therapeutic delivery with the bioactive functions of MOFs. Depending on their composition and architecture, these systems may exert antimicrobial and antibiofilm effects through ionic, electrostatic, osmotic, catalytic, and oxidative mechanisms, while also influencing ROS levels, inflammation, angiogenesis, and local drug transport. However, antimicrobial activity alone does not equate to resistance modulation. Evidence for direct effects on efflux systems, resistance phenotypes, or HGT remains inconsistent across reported platforms. This review critically examines representative hydrogel–MOF systems for chronic wound applications, comparing their composition, physicochemical properties, biological functions, proposed resistance-related mechanisms, advantages, limitations, and current level of evidence. We emphasize distinguishing experimentally demonstrated resistance-modulating effects from mechanistically proposed functions, and identifying design trade-offs and evidence gaps that must be addressed to develop wound interfaces capable of both supporting tissue regeneration and improving infection control. Full article

(This article belongs to the Special Issue Biopolymer-Based Gels for Drug Delivery and Tissue Engineering (3rd Edition))

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20 pages, 3775 KB

Open AccessArticle

Polyelectrolyte Microcapsules: An Efficient and Rapid Adsorbent for Uranine

by Aleksandr L. Kim, Egor V. Musin and Sergey A. Tikhonenko

Gels 2026, 12(8), 743; https://doi.org/10.3390/gels12080743 - 19 Aug 2026

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Abstract

Fluorescein-based tracers like uranine are extensively used in hydrogeology, textile marking, and cosmetics, yet their discharge generates dilute wastewater streams that challenge conventional treatment due to low removal efficiency and high operational costs. This study evaluates the sorption potential of polyelectrolyte microcapsules (PMCs) [...] Read more.

Fluorescein-based tracers like uranine are extensively used in hydrogeology, textile marking, and cosmetics, yet their discharge generates dilute wastewater streams that challenge conventional treatment due to low removal efficiency and high operational costs. This study evaluates the sorption potential of polyelectrolyte microcapsules (PMCs) fabricated via a green, aqueous layer-by-layer (LbL) assembly on sacrificial CaCO₃ templates for uranine decontamination. The PMCs achieve rapid equilibrium within ≤5 min, with kinetics governed by the pseudo-second-order model and equilibrium data described by the Langmuir isotherm, yielding a maximum capacity of 12.1 mg/g. Sorption is highly efficient at neutral to mildly acidic pH (3.0–7.0) and low ionic strength (≤0.15 M NaCl), providing 98–100% removal from dilute streams (C₀ ≤ 10 mg/L) and consistently reducing effluent concentrations to <0.05 mg/L. Saturated capsules exhibit low spontaneous dye release (≤10%) in deionized water under the tested conditions. Although limited regenerability precludes multi-cycle industrial use, the rapid sorption kinetics and high uranine removal efficiency make PMCs well suited for single-use polishing applications. By offering a scalable, solvent-free synthesis and targeted removal of emerging fluorescent pollutants from low-concentration effluents, this work presents a sustainable, low-energy alternative for advanced wastewater treatment, aligning with green chemical engineering and circular water management principles. Full article

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36 pages, 1713 KB

Open AccessReview

After the Nozzle: Post-Printing Maturation, Failure Modes, and Use-Point Assessment of Cell-Laden Extrusion-Bioprinted Hydrogel Constructs

by Yifan Li, Xiuyu Wen, Linken Li, Li Li and Jianghong He

Gels 2026, 12(8), 742; https://doi.org/10.3390/gels12080742 - 19 Aug 2026

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Abstract

Cell-laden hydrogel bioinks for extrusion bioprinting are commonly evaluated by precursor rheology, extrusion behavior, and immediate shape fidelity, yet these measures do not establish whether printed constructs remain stable and functional during culture or tissue maturation. This review examines the post-printing evolution of [...] Read more.

Cell-laden hydrogel bioinks for extrusion bioprinting are commonly evaluated by precursor rheology, extrusion behavior, and immediate shape fidelity, yet these measures do not establish whether printed constructs remain stable and functional during culture or tissue maturation. This review examines the post-printing evolution of cell-laden extrusion-printed hydrogel constructs, prioritizing direct evidence from cell-laden prints and using acellular prints and bulk hydrogels only to clarify mechanisms. Maturation is organized into immediate stabilization, network evolution and environmental equilibration, and long-term remodeling. Crosslinking, hydration, ion exchange, stress relaxation, degradation, cellular contraction, and matrix deposition may support maturation or cause structural, mechanical, interfacial, transport, and biofunctional failure. We propose a conceptual, research-oriented use-point assessment framework that compares each construct with relevant reference states and application-specific requirements after stabilization, during culture, and before intended use. The framework links the earliest observed critical deviation to relevant measurements, targeted redesign, and reassessment under the same conditions. A cartilage construct illustrates sequential evaluation of geometry, wet-state mechanics, cell distribution, and matrix formation. Current evidence is limited by inconsistent assessment times, incomplete reporting, and few integrated longitudinal studies. Future work should standardize maturation histories, model construct trajectories, and prospectively validate product-specific criteria. Evaluation should focus on the complete cell-laden extrusion-printed construct at its intended use point rather than on the freshly printed filament. Full article

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18 pages, 7990 KB

Open AccessArticle

Rose Bengal Immobilization in and Release from Calcium Alginate Gels for Singlet-Oxygen-Generating Photosensitizing Systems

by Alexander Kopylov, Anastasiya Cherkasova, Ilya Shershnev, Valentin Bekeshev, Nadezhda Aksenova, Victoriya Timofeeva, Anastasiya Akovantseva, Tatyana Zarkhina, Valeriya Kardumyan, Peter Timashev and Anna Solovieva

Gels 2026, 12(8), 741; https://doi.org/10.3390/gels12080741 - 19 Aug 2026

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Abstract

Calcium alginate (CaA) xerogels and aerogels were evaluated as carriers for Rose Bengal (RB) in singlet-oxygen-generating systems intended for photodynamic applications. Hybrid CaA/polyvinylpyrrolidone (PVP) matrices were also prepared. Nitrogen sorption showed that the CaA xerogels(A) were mesoporous, with a specific surface area of [...] Read more.

Calcium alginate (CaA) xerogels and aerogels were evaluated as carriers for Rose Bengal (RB) in singlet-oxygen-generating systems intended for photodynamic applications. Hybrid CaA/polyvinylpyrrolidone (PVP) matrices were also prepared. Nitrogen sorption showed that the CaA xerogels(A) were mesoporous, with a specific surface area of S_BET ~225 m²/g and a mean pore diameter of approximately 9.3 nm; the corresponding S_BET values were approximately 300 m²/g for the aerogels and below 1 m²/g for the xerogels. RB introduced during xerogel formation from water was retained in the matrix and was not released into phosphate-buffered saline (PBS, pH 7.2). By contrast, RB loaded from isopropanol was released from the xerogels(A) and aerogels, with the fastest release observed for CaA aerogels. RB incorporated into xerogels(A) and aerogels retained singlet-oxygen-generating activity. In air, the highest luminescence response was observed for RB immobilized in hybrid CaA/PVP aerogel films containing approximately 10 wt% PVP. These findings suggest that such systems hold promise for applications in photodynamic therapy of superficial skin injuries. Xerogels(A) are also attractive carrier candidates because they avoid supercritical drying and, for the CaA xerogel(A) studied here, released 50% of the loaded RB within approximately 5 min. Full article

(This article belongs to the Special Issue Alginate-Based Gels: Preparation, Characterization and Application (3rd Edition))

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18 pages, 2168 KB

Open AccessArticle

Understanding the Effect of Zein–Resveratrol Interactions on the Mechanical and Functional Properties of Zein Gels

by Iulia Matei, Alexandra Busuioc, Ludmila Aricov, Anca Ruxandra Leonties, Vlad Tudor Popa and Aurica Precupas

Gels 2026, 12(8), 740; https://doi.org/10.3390/gels12080740 - 18 Aug 2026

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Abstract

The potential of zein gels as functional delivery platforms for resveratrol (RESV), a natural polyphenol with antiamyloidogenic action but low systemic bioavailability, is explored by a combination of spectroscopic (circular dichroism, infrared, fluorescence, UV–Vis), calorimetric (differential scanning microcalorimetry) and rheological methods. Molecular docking [...] Read more.

The potential of zein gels as functional delivery platforms for resveratrol (RESV), a natural polyphenol with antiamyloidogenic action but low systemic bioavailability, is explored by a combination of spectroscopic (circular dichroism, infrared, fluorescence, UV–Vis), calorimetric (differential scanning microcalorimetry) and rheological methods. Molecular docking is also applied for mapping the interaction sites and forces between native zein and RESV. Zein–RESV interactions in solution are systematically evaluated to understand the structural changes from a soluble protein–polyphenol system to a gel network. The concentration-dependent effect of RESV on the structural and thermal stability of zein is investigated in relation to the mechanical and functional properties of zein–RESV gels. It is shown that RESV acts as a promoter of zein aggregation, with a more pronounced effect obtained at a RESV:zein 1:1 molar ratio. By increasing the α-helix content, RESV induces a more ordered zein secondary structure in solution. In gel, the three-dimensional zein network is disrupted by hydrophobic and hydrogen-bonding interactions with RESV. Fluorescence spectra of zein gels point to conformational changes upon interaction that are confirmed by infrared spectroscopy. A significant viscoelastic deformation of the gel occurs when the RESV:zein molar ratio increases to 4:1. The RESV:zein 1:1 gel network demonstrates optimal viscoelastic properties for the release of RESV, following a biphasic transition from diffusion to matrix-controlled release. The findings of this study contribute to the structural design of zein-based systems for encapsulating and delivering bioactive compounds. Full article

(This article belongs to the Special Issue Protein Gels: Advances and Prospects)

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22 pages, 3462 KB

Open AccessArticle

Maleic Acid-Grafted Poly(vinylpyrrolidone) Hydrogels Synthesized by Gamma Radiation for pH-Responsive Drug Delivery

by Miguel S. Pérez-Garibay and Emilio Bucio

Gels 2026, 12(8), 739; https://doi.org/10.3390/gels12080739 - 18 Aug 2026

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Abstract

Poly(vinylpyrrolidone) hydrogels net(PVP) were synthesized by gamma radiation at a dose rate of 11.8 kGy h⁻¹ and subsequently functionalized with maleic acid (MA) via radiation-induced grafting using the direct method to obtain pH-responsive hydrogels for the loading and controlled release of bioactive [...] Read more.

Poly(vinylpyrrolidone) hydrogels net(PVP) were synthesized by gamma radiation at a dose rate of 11.8 kGy h⁻¹ and subsequently functionalized with maleic acid (MA) via radiation-induced grafting using the direct method to obtain pH-responsive hydrogels for the loading and controlled release of bioactive compounds. Under the selected conditions, MA grafting reached approximately 18%. The obtained hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR-ATR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and swelling studies. The results confirmed the successful incorporation of MA into the hydrogel network and demonstrated that grafting imparted pH-responsive behavior due to the ionization of carboxylic acid groups, yielding two critical pH values at 4.4 and 6.0. Loading and release studies using naringin and benzalkonium chloride showed that the grafted hydrogels exhibited enhanced loading capacity and sustained release profiles governed by the hydrogel network and by interactions between the loaded compounds and the carboxylic groups from MA. Furthermore, hydrogels loaded with antimicrobial agents effectively inhibited the growth of Escherichia coli and Staphylococcus aureus. These findings demonstrate that gamma radiation-induced MA grafting is an effective strategy for developing pH-responsive PVP hydrogels with potential applications as multifunctional wound dressing materials. Full article

(This article belongs to the Special Issue Advanced Functional Gels: Design, Properties, and Applications)

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19 pages, 9770 KB

Open AccessArticle

Synergistic Removal of Pb(II), Cd(II) and Cr(VI) by Chitosan-Encapsulated Phosphorus-Modified Biochar: Multi-Site Sorption and Immobilization

by Yang Feng, Min Zhou, Jiangyan Wu, Lingli Li, Haoming Chen and Lingyi Tang

Gels 2026, 12(8), 738; https://doi.org/10.3390/gels12080738 - 18 Aug 2026

Viewed by 323

Abstract

Heavy metal pollution has become a global environmental problem. Achieving efficient, stable, and sustainable immobilization of heavy metals by phosphorus (P)-modified biochar remains challenging because of the potential risk of P release. In this study, chitosan-embedded P-modified biochar (CPBC) was produced for the [...] Read more.

Heavy metal pollution has become a global environmental problem. Achieving efficient, stable, and sustainable immobilization of heavy metals by phosphorus (P)-modified biochar remains challenging because of the potential risk of P release. In this study, chitosan-embedded P-modified biochar (CPBC) was produced for the remediation of Pb(II), Cd(II), and Cr(VI). The specific surface area of CPBC was 5.5 times higher than that of the pristine biochar (BC), and the surface was enriched with functional groups such as -OH and -NH₃. P-modification facilitated the precipitation of the heavy metals, and chitosan blocked the precipitates inside the biochar. The nature of BC safeguarded the ability to transfer electrons and reduce Cr(VI) to Cr(III), which was further enhanced by the chitosan. Hence, the maximum sorption capacities of CPBC for Pb(II), Cd(II), and Cr(VI) were 29.23%, 129.13%, and 122.12% greater than those of BC. The sequential extraction confirmed that the immobilized Pb(II), Cd(II), and Cr(VI) on CPBC were highly stable, with the sum of acid-soluble and nonbioavailable fractions accounting for 89.14%, 83.73%, and 93.53%, respectively. In addition, chitosan effectively suppressed P release from the P-modified biochar, thereby improving its environmental safety while maintaining excellent heavy metal immobilization performance. The present study demonstrates that CPBC is an effective, environmentally friendly, and universal sorbent to remediate heavy metal pollution in water. Full article

(This article belongs to the Special Issue Gels in Agriculture and Environment: Prospects and Challenges)

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6 pages, 224 KB

Open AccessEditorial

Application of Composite Gels in Food Processing and Engineering

by Lei Zhou and Xiaoyan Hu

Gels 2026, 12(8), 737; https://doi.org/10.3390/gels12080737 - 18 Aug 2026

Viewed by 226

Abstract

Foods are complex structures typically composed of proteins, polysaccharides, and fats [...] Full article

(This article belongs to the Special Issue Application of Composite Gels in Food Processing and Engineering)

22 pages, 4450 KB

Open AccessArticle

Bifunctional Aloe-Birch Extracts for Green Silver Nanoparticle Synthesis and Synergistic Antimicrobial Microneedles Toward Infected Wound Healing

by Shun Zhang, Xu Liu, Yiyun Wei, Kun Bao, Xiaojuan Zhang and Chenlu Zhang

Gels 2026, 12(8), 736; https://doi.org/10.3390/gels12080736 - 17 Aug 2026

Viewed by 344

Abstract

Plant-mediated green synthesis of silver nanoparticles (AgNPs) predominantly relies on single botanical sources, constraining reduction efficiency and forfeiting the therapeutic potential of residual biomass. This study employed aloe vera and birch bark extracts as reducing agents. A combination of single-factor analysis and response [...] Read more.

Plant-mediated green synthesis of silver nanoparticles (AgNPs) predominantly relies on single botanical sources, constraining reduction efficiency and forfeiting the therapeutic potential of residual biomass. This study employed aloe vera and birch bark extracts as reducing agents. A combination of single-factor analysis and response surface methodology was employed to prepare monodisperse 30 nm AgNPs (with a Zeta potential of −35.3 mV and confirmed by XPS as metallic Ag⁰). It was loaded into carboxymethyl chitosan-vanillin-polyvinyl alcohol (CVP) gel microneedles using the vacuum casting method. The mechanical strength of these microneedles reaches 0.302 N/needle, exceeding the skin penetration threshold. Throughout the entire preparation process, both its Ag⁰ chemical state and crystal structure were maintained (by FT-IR and XRD). The MIC values of AgNPs@CVP against four pathogens ranged from 0.977 to 7.813 μg/mL, with a biofilm disruption rate exceeding 70%, and demonstrated excellent biocompatibility (hemolytic rate < 1.6%, cell survival rate > 80%). In a rat wound infection model, high-dose microneedle therapy reduced the residual wound area to 10.9% by day 9. This strategy inhibited the secretion of TNF-α and IL-6 while promoting epithelial regeneration, angiogenesis, and collagen deposition. This bifunctional Aloe-Birch strategy converges green nanomaterial synthesis with therapeutic delivery within a single bio-based platform, advancing sustainable nanomedicine paradigms and providing a resource-efficient blueprint for clinical infectious wound management. Full article

(This article belongs to the Topic Advanced Biomaterials for Drug Delivery)

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19 pages, 12825 KB

Open AccessArticle

Development and Stability Evaluation of Oleogel-in-Water Emulsions Using Whey Protein Isolate–Ferulic Acid Nanoparticles for Ganoderma Lucidum Spore Oil Encapsulation

by Wenjia Yan, Yuting Bao, Hao Wang, Shanshan Xu, Chengfang He, Zhuochen Wang and Jian Jiang

Gels 2026, 12(8), 735; https://doi.org/10.3390/gels12080735 - 17 Aug 2026

Viewed by 305

Abstract

This work evaluated how ferulic acid (FA) impacted the conformational properties of whey protein isolate (WPI) and altered the environmental tolerance of oleogel/water (Og/W) emulsions formulated with Ganoderma lucidum spore oil (GLSO). Molecular dynamics simulation analyses revealed that FA interacted with α-lactalbumin via [...] Read more.

This work evaluated how ferulic acid (FA) impacted the conformational properties of whey protein isolate (WPI) and altered the environmental tolerance of oleogel/water (Og/W) emulsions formulated with Ganoderma lucidum spore oil (GLSO). Molecular dynamics simulation analyses revealed that FA interacted with α-lactalbumin via hydrogen bonding and hydrophobic interactions, whereas it bound into the hydrophobic cavity of β-lactoglobulin through a “lock-and-key” mode driven primarily by hydrophobic forces. Fourier transform infrared spectroscopy analysis verified that such non-covalent forces triggered the dissociation and structural extension of WPI, which was manifested as a significant loss of α-helix and β-sheet architectures along with a corresponding rise in random coils. FA addition increased the positive charge, mean droplet size, interfacial contact angle and antioxidant stability of WPI-FA nanoparticles when the WPI-to-FA ratio exceeded 1:2 (i.e., WPI was in excess relative to FA). The GLSO-based Og/W emulsions exhibited a weak gel structure with predominantly elastic characteristics. Furthermore, WPI-FA nanoparticles fabricated at a 2:1 ratio minimized emulsion droplet size and imparted optimal stability to the Og/W emulsions, demonstrating superior freeze–thaw and salt resistance, alongside suppressed GLSO flavor release. This work provides critical insights into tailoring protein-polyphenol interactions to stabilize GLSO-based Og/W emulsion delivery systems for food applications. Full article

(This article belongs to the Special Issue Next-Generation Food Colloids: Protein-Based to Emulsion-Based Gel Systems)

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19 pages, 28226 KB

Open AccessArticle

Synthesizing a Calcium Lignosulfonate Composite Water Retention Agent and Evaluating Its Regulatory Effect on Water Evaporation and Crack Evolution in Saline–Alkali Soil

by Xiaojing Chen, Baichuan Li, Zhiping Yang, Ke Wang, Xiaodi Guo and Hua Li

Gels 2026, 12(8), 734; https://doi.org/10.3390/gels12080734 - 17 Aug 2026

Viewed by 289

Abstract

In this study, we synthesized a lignin-based superabsorbent hydrogel (LWR) to relieve severe evaporation and structural degradation in inland saline–alkali soils. The LWR was prepared via free-radical graft copolymerization of calcium lignosulfonate (CL) and acrylic acid (AA), with its swelling performance optimized systematically. [...] Read more.

In this study, we synthesized a lignin-based superabsorbent hydrogel (LWR) to relieve severe evaporation and structural degradation in inland saline–alkali soils. The LWR was prepared via free-radical graft copolymerization of calcium lignosulfonate (CL) and acrylic acid (AA), with its swelling performance optimized systematically. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize its chemical and microscopic structure, and the soil column was exposed to three drying–wetting cycles to explore the effects of hydrogel dosage on soil evaporation and crack evolution. CL may graft into polyacrylic acid under optimal conditions (60% AA neutralization, 4% CL, 1% initiator, and 0.03% crosslinker) to form a porous hydrophilic 3D network. Consequently, the optimized LWR achieved swelling capacities of 1480 g/g and 122 g/g in deionized water and a 0.9% NaCl solution, respectively, showing high water absorbency and salt resistance. During cyclic drying and wetting, soil evaporation was first dominated by the hydrogel’s water retention capabilities; then, it was controlled physically by soil surface cracks. A moderate LWR dosage of 0.3% was used to maintain stable water retention in soil and the intact soil structure, which likely occurred due to its strong water absorption and hypothesized calcium ion bridging anti-cracking interactions. This work overturns the traditional view that a higher hydrogel dosage yields better water retention. Instead, it highlights the importance of conducting a long-term joint evaluation of the hydrogel’s water retention capacity and its resistance to soil dry–wet deformation stress, thereby offering theoretical support for eco-friendly water retention agent design and saline–alkali land remediation. Full article

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

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26 pages, 17196 KB

Open AccessArticle

Organic–Inorganic Hybrid Gel Microspheres as a Plugging Agent for Ultra-High Temperature and High-Salinity Water-Based Drilling Fluids

by Yuanwei Sun, Jinsheng Sun, Kaihe Lv, Xianbin Huang and Jingping Liu

Gels 2026, 12(8), 733; https://doi.org/10.3390/gels12080733 - 17 Aug 2026

Viewed by 339

Abstract

With the continuous expansion of ultra-deep and deep well drilling toward complex geological formations, the performance stability of water-based drilling fluids and wellbore stability under ultra-high temperature and high-salinity conditions have become critical challenges. High temperature and salt contamination can induce the degradation [...] Read more.

With the continuous expansion of ultra-deep and deep well drilling toward complex geological formations, the performance stability of water-based drilling fluids and wellbore stability under ultra-high temperature and high-salinity conditions have become critical challenges. High temperature and salt contamination can induce the degradation or failure of drilling fluid additives, while the development of pores and fractures in complex formations further increases the risk of filtrate invasion. Conventional polymer and inorganic plugging agents often suffer from insufficient thermal stability, poor salt tolerance, or limited adaptability to complex pore structures. In this study, an organic–inorganic hybrid gel microsphere plugging agent (HGP) with a core–shell structure was developed by in situ polymerization of AMPS, styrene (St), and sodium styrene sulfonate (SSS) on KH570-modified nano-SiO₂. The hybrid microspheres consisted of a rigid SiO₂ core and a flexible polymer shell, providing synergistic thermal stability, mechanical strength, and deformation capability. Structural characterization confirmed the successful formation of the designed organic–inorganic hybrid structure. After aging at 240 °C, HGP maintained stable morphology and dispersion characteristics, while exerting minimal influence on drilling fluid rheological properties. The addition of 3 wt% HGP reduced API fluid loss by approximately 30% and decreased sand bed invasion by approximately 50% after high-temperature aging. Under 35 wt% NaCl and 5 wt% CaCl₂ contamination, HGP maintained effective filtration control, reducing fluid loss by more than 50% compared with the base fluid. Furthermore, HGP achieved core plugging efficiencies above 94% and reduced mud cake permeability by over 70%, demonstrating superior plugging performance compared with polymer microspheres NF-1 and SiO₂ particles. The enhanced performance was considered to arise from the synergistic effects of stable dispersion, pore-throat bridging, deformation filling, and structural stabilization. This study provides a rigid–flexible hybrid strategy for designing high-performance plugging agents for ultra-high temperature and high-salinity water-based drilling fluids. Full article

(This article belongs to the Topic Polymer Gels for Oil Drilling and Enhanced Recovery)

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27 pages, 17420 KB

Open AccessArticle

Foam-Templated Polymer Gels for Mitigating Sediment Entrainment in Salt Caverns: A Robust Strategy for Safe CCUS Operations

by Erdong Yao and Kun Zhang

Gels 2026, 12(8), 732; https://doi.org/10.3390/gels12080732 - 17 Aug 2026

Viewed by 254

Abstract

As critical infrastructure for carbon capture, utilization, and storage (CCUS) and large-scale energy storage, subsurface salt caverns are seriously challenged by fluid-induced sediment mobilization during the supplementary debrining. Conventional bulk resin consolidation often causes severe viscous fingering, uneven consolidation, and pore clogging under [...] Read more.

As critical infrastructure for carbon capture, utilization, and storage (CCUS) and large-scale energy storage, subsurface salt caverns are seriously challenged by fluid-induced sediment mobilization during the supplementary debrining. Conventional bulk resin consolidation often causes severe viscous fingering, uneven consolidation, and pore clogging under hypersaline conditions. Here, we develop a foam-templated hybrid polymer gel co-stabilized by silica nanoparticles, polyvinyl alcohol, and the zwitterionic surfactant. The key novelty is the use of foam as a transient transport template that redistributes the resin phase and promotes selective cementation at grain-contact points instead of indiscriminate pore filling. This nano-reinforced gel system remained stable under hypersaline conditions (24% NaCl), and temperatures ranging from 20–80 °C. Micro-CT analysis showed that this selective templating preserved an interconnected pore network with a porosity above 45% and a CT-derived permeability of approximately 1.18 D, while reducing binder consumption by 55.6% relative to bulk resin injection. Crucially, a 1:200 geometrically scaled, velocity-matched pilot model demonstrated that this gel strategy limited sediment entrainment below 0.5% and reduced fluid discharge by 45.9%. These results establish a material-efficient consolidation strategy that combines sediment stabilization with permeability preservation, providing a promising solution for safer supplementary debrining in salt-cavern CCUS and energy-storage operations. Full article

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

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24 pages, 5869 KB

Open AccessArticle

Silica Nanoparticle-Reinforced Wormlike Micellar Gels for High-Temperature Flow Redistribution in Heterogeneous Porous Media

by Kun Zhang and Xiongfei Liu

Gels 2026, 12(8), 731; https://doi.org/10.3390/gels12080731 - 17 Aug 2026

Viewed by 304

Abstract

Maintaining the rheological performance of wormlike micellar fluids at elevated temperatures remains challenging. Conventional viscoelastic surfactant (VES) systems may undergo thermally induced micellar scission and loss of gel-like viscoelasticity at elevated temperatures. In this study, we investigate the size-dependent reinforcement of long-chain C22 [...] Read more.

Maintaining the rheological performance of wormlike micellar fluids at elevated temperatures remains challenging. Conventional viscoelastic surfactant (VES) systems may undergo thermally induced micellar scission and loss of gel-like viscoelasticity at elevated temperatures. In this study, we investigate the size-dependent reinforcement of long-chain C22⁺ wormlike micellar systems by silica nanoparticles under a temperature-ramp protocol reaching 160 °C. Under the applied temperature-ramp protocol, the formulation containing 0.10 wt% of 15 nm SiO₂ nanoparticles exhibited the highest measured rheological response among the tested formulations, retaining an apparent viscosity of approximately 210 mPa·s and a plateau storage modulus of approximately 18.5 Pa during the 20 min isothermal holding period at 160 °C, compared with a plateau storage modulus of approximately 11 Pa for the corresponding VES system. At equal nanoparticle mass loading, the 15 nm particles produced approximately 18% and 6% higher G′ and G″, respectively, than the 500 nm particles. The rheological results, together with qualitative electrokinetic measurements after dilution, are consistent with nanoparticle-surfactant association that may promote micellar entanglement and network reinforcement. The nanoparticle-enhanced viscoelastic surfactant (N-EVES) formulation reduced the acid-rock reaction rate to approximately 25% of that measured for conventional HCl while showing an apparent effective H⁺ diffusion coefficient of the same order. Scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDS) detected Si- and N-containing species on the treated carbonate surface, suggesting that surface adsorption or deposition may contribute to reaction retardation. Parallel dual-core flooding under a permeability contrast of approximately 13 showed fluid redistribution toward the low-permeability core. Based on the axial wormhole penetration length obtained from the CT reconstruction, the normalized axial wormhole penetration fraction of the low-permeability core was approximately 70% for the 0.10 wt% formulation. These results provide experimental evidence of nanoparticle-size-dependent rheological reinforcement, acid-rock reaction retardation, and core-scale flow redistribution under strongly acidic and high-temperature conditions. Full article

(This article belongs to the Section Gel Applications)

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18 pages, 7884 KB

Open AccessArticle

Dual−Network PVA/PAM Hydrogel Strain Sensor for Machine−Learning−Assisted Rehabilitation−Oriented Hand Motion Monitoring

by Wendi Liu, Jintao Wang, Yuanduo Wang, Zhangqi Xia, Ruixin Liu, Yixuan Li, Xinyang He and Hailou Wang

Gels 2026, 12(8), 730; https://doi.org/10.3390/gels12080730 - 17 Aug 2026

Viewed by 368

Abstract

Wearable rehabilitation monitoring requires soft strain sensors with mechanical robustness, stable electromechanical responses, and intelligent motion recognition capability. Here, we report a poly(vinyl alcohol)/polyacrylamide (PVA/PAM) double−network hydrogel strain sensor for rehabilitation−oriented wearable monitoring. The hydrogel was prepared by ultraviolet ray (UV)−initiated acrylamide polymerization [...] Read more.

Wearable rehabilitation monitoring requires soft strain sensors with mechanical robustness, stable electromechanical responses, and intelligent motion recognition capability. Here, we report a poly(vinyl alcohol)/polyacrylamide (PVA/PAM) double−network hydrogel strain sensor for rehabilitation−oriented wearable monitoring. The hydrogel was prepared by ultraviolet ray (UV)−initiated acrylamide polymerization followed by freeze−thaw−induced PVA crystallization, forming a covalent PAM network interpenetrated with a physically crosslinked PVA network. The resulting hydrogel possessed a compact porous structure, improved stretchability, and stable deformation recovery. The optimized sensor exhibited a tensile strength of approximately 0.52 MPa, an elongation at break of approximately 480%, a response time of 0.12 s, and a recovery time of 0.17 s. It generated repeatable resistance signals under cyclic strain, finger bending, wrist motion, and grip training. Furthermore, the sensor enabled morse−code information transmission and support vector machine (SVM)−based recognition of rehabilitation−related hand states, including straight, bend, and clench. This work provides a soft hydrogel sensing platform for real−time rehabilitation−oriented hand motion, while morse−code encoding provides auxiliary assistance and an emergency communication function. Full article

(This article belongs to the Special Issue Advances in Hydrogels for Flexible Electronics)

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22 pages, 1967 KB

Open AccessArticle

Phytochemical Profiling, Biological Activities, and Development of Hydrogel Sheets Containing Phanera sirindhorniae Leaf Extract

by Chuda Chittasupho, Piyapong Pumival, Weerasak Samee, Sudarshan Singh, Julalak Chorachoo Ontong, Siriporn Okonogi, Nophadon Luangpirom, Marlyn Dian Laksitorini and Sirivan Athikomkulchai

Gels 2026, 12(8), 729; https://doi.org/10.3390/gels12080729 - 16 Aug 2026

Viewed by 334

Abstract

Phanera sirindhorniae (formerly known as Bauhinia sirindhorniae) is a Thai medicinal plant with reported traditional use for the treatment of inflammation; however, its comprehensive phytochemical, biological, and formulation potential remains underexplored. This study aimed to evaluate the phytochemical composition, antioxidant, anti-inflammatory, and [...] Read more.

Phanera sirindhorniae (formerly known as Bauhinia sirindhorniae) is a Thai medicinal plant with reported traditional use for the treatment of inflammation; however, its comprehensive phytochemical, biological, and formulation potential remains underexplored. This study aimed to evaluate the phytochemical composition, antioxidant, anti-inflammatory, and antimicrobial activities of extracts from the flower (BSFE), stem (BSSE), and leaf (BSLE), and to develop a BSLE-loaded hydrogel sheet for topical application. Among the extracts, BSSE exhibited the highest total phenolic content (503.71 ± 7.56 mg GAE/g) and total flavonoid content (4778.67 ± 255.47 mg EGCG/g), along with strong antioxidant activity, as demonstrated by DPPH (IC₅₀ = 17.05 µg/mL) and FRAP assays. BSLE showed superior anti-inflammatory activity by significantly suppressing nitric oxide and pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) in LPS-stimulated RAW264.7 macrophages, whereas BSSE displayed moderate effects. In antimicrobial evaluation, BSSE exhibited the strongest activity among the extracts, particularly against Escherichia coli and Staphylococcus species, although its potency remained lower than that of standard antibiotics. HPLC analysis identified 3,4-dihydroxybenzoic acid and luteolin as characteristic anti-inflammatory markers in BSLE. Based on its promising anti-inflammatory activity, BSLE was incorporated into hydrogel sheets (BSLE-F1 and BSLE-F2) using HPMC/PVA matrices with varying PEG 600 content. Both formulations demonstrated suitable physicochemical properties and skin-compatible pH. BSLE-F2 showed improved water retention and dimensional stability, whereas BSLE-F1 exhibited superior peelability, swelling capacity, and tensile strength. In conclusion, BSLE-F1 demonstrated a more favorable balance of mechanical and functional properties, suggesting its suitability as a topical anti-inflammatory hydrogel sheet. This study highlights the potential of P. sirindhorniae extracts for developing multifunctional, natural-based topical delivery systems. Full article

(This article belongs to the Special Issue Biobased Gels for Drugs and Cells (2nd Edition))

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23 pages, 6199 KB

Open AccessArticle

Effects of Aloe Vera and Guava Leaf Extract on Threadfin Bream Surimi Gel: Physicochemical, Textural and Rheological Properties

by Staphny Snowy Dsouza, Umesh Patil, Avtar Singh, Natchaphol Buamard, Mallikarjun Chanchi Prashanthkumar, Hui Hong, Bin Zhang, Yadong Zhao and Soottawat Benjakul

Gels 2026, 12(8), 728; https://doi.org/10.3390/gels12080728 - 16 Aug 2026

Viewed by 474

Abstract

Polyphenol-mediated protein interactions offer a promising approach for improving surimi gel networks. Nevertheless, the comparative and combined effects of polyphenol-rich plant extract and polysaccharide-based additives on gel properties remain insufficiently explored. Therefore, individual and combined effects of dechlorophyllized guava leaf extract (DGLE), a [...] Read more.

Polyphenol-mediated protein interactions offer a promising approach for improving surimi gel networks. Nevertheless, the comparative and combined effects of polyphenol-rich plant extract and polysaccharide-based additives on gel properties remain insufficiently explored. Therefore, individual and combined effects of dechlorophyllized guava leaf extract (DGLE), a source of polyphenols and aloe vera powder (AVP), an acemannan-rich polysaccharide, on the physicochemical, textural and rheological properties of threadfin bream (Nemipterus spp.) surimi gel were investigated. DGLE obtained by ultrasonication followed by dechlorophyllization exhibited high total phenolic content (439.35 ± 4.72 mg GAE/g dry extract) and total flavonoid content (666.66 ± 60.52 mg QE/g dry extract). LCMS/MS-QTOF profiling tentatively identified 12 phenolic compounds, including ellagic acid, catechins, quercetin glycosides, EGCG, etc. Surimi gel incorporated with 0.2% AVP and 0.05% DGLE individually achieved the highest breaking force and deformation with minimum expressible moisture content, though whiteness decreased with increasing concentrations. SDS-PAGE and FTIR analyses confirmed polyphenol-protein interaction and acemannan-gel network association. Gel with 0.2% AVP alone showed the highest hardness, gumminess, chewiness and elevated G′, while 0.05% DGLE alone yielded the highest springiness and cohesiveness, consistent with dense cross-linking observed in SEM (p < 0.05). AVP combined with DGLE exhibited a reduced gel-strengthening effect, especially at increasing DGLE concentrations. Thus, DGLE alone at 0.05% improved surimi gel properties. This finding could provide insight into the use of DGLE as a natural additive to improve surimi gel. Full article

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70 pages, 30761 KB

Open AccessReview

Innovative Hydroxyapatite–Hydrogel Composites for Cartilage Regeneration

by Anita Ioana Visan, Liviu Duta and Irina Negut

Gels 2026, 12(8), 727; https://doi.org/10.3390/gels12080727 - 15 Aug 2026

Viewed by 435

Abstract

Articular cartilage defects remain a significant clinical challenge due to the limited intrinsic regenerative capacity of cartilage and the inability of many current therapeutic approaches to restore the structure and function of native hyaline tissue. As a result, considerable research efforts have been [...] Read more.

Articular cartilage defects remain a significant clinical challenge due to the limited intrinsic regenerative capacity of cartilage and the inability of many current therapeutic approaches to restore the structure and function of native hyaline tissue. As a result, considerable research efforts have been directed toward the development of tissue-engineering and biomaterial-based strategies capable of promoting more effective regeneration. Among these, hydroxyapatite–hydrogel (HAp–hydrogel) composites have emerged as particularly promising candidates because they combine the biological functionality of HAp with the structural versatility of hydrogel networks. Hydrogels provide a highly hydrated, extracellular matrix-like environment that supports cell survival, facilitates matrix deposition, and enables the localized delivery of therapeutic agents. At the same time, their physicochemical properties can be tailored through a variety of crosslinking approaches and advanced responsive design strategies. The incorporation of HAp, either in nano- or microscale form, contributes to mechanical reinforcement, supports subchondral bone regeneration, and influences cellular behavior through both biochemical and mechanotransductive mechanisms. Beyond promoting chondrogenic differentiation, HAp–hydrogel composites have also been investigated for their capacity to modulate inflammation, stimulate angiogenesis within the subchondral region, provide antibacterial protection, and maintain a microenvironment conducive to tissue repair. This review critically examines recent advances in the development and application of HAp–hydrogel composites for cartilage regeneration, highlighting material design principles, fabrication strategies, healing mechanisms, and the key challenges that continue to influence their clinical translation. Full article

(This article belongs to the Special Issue Innovative Gels: Structure, Properties, and Emerging Applications)

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28 pages, 16438 KB

Open AccessArticle

Gel-Dominated Microstructural Evolution and Strength Development in Phosphogypsum-Based PRBA Systems for Road Base Applications

by Ruiyuan Li, Guangdong An, Yuwen Deng, Yonglan Zong, Kai Li, Xiaofeng Huang, Ping Ning, Xin Sun and Quxiu Dai

Gels 2026, 12(8), 726; https://doi.org/10.3390/gels12080726 - 15 Aug 2026

Viewed by 326

Abstract

A significant pile-up of phosphogypsum, with utilization under 30% in some areas, has caused serious environmental problems. This study presents a powdered recycled binder-aggregate (PRBA), prepared by activating a phosphogypsum-fly ash-steel slag ternary system via a sodium silicate-calcium hydroxide activator. The optimal L3 [...] Read more.

A significant pile-up of phosphogypsum, with utilization under 30% in some areas, has caused serious environmental problems. This study presents a powdered recycled binder-aggregate (PRBA), prepared by activating a phosphogypsum-fly ash-steel slag ternary system via a sodium silicate-calcium hydroxide activator. The optimal L3 at 55% PRBA with PG:FA:SS of 4:3:4 achieved 28-day compressive strength of 9.33 MPa, 22.0% higher than control L0 at 7.65 MPa, reaching 12.47 MPa at 56 days. The C-S-H gel network evolved from 100–200 nm tubular to under 10 nm lamellar structures, reducing average pore diameter from 82 nm to 52.5 nm. Non-isothermal kinetic modeling revealed that C-S-H/AFt dehydration follows Jander three-dimensional diffusion with R² = 0.998 and activation energy decreasing from 161.3 to 99.3 kJ/mol at 14 days. A relay-race mechanism was identified: steel slag provides early Ca²⁺, phosphogypsum supplies SO₄²⁻ forming AFt skeletons, and fly ash densifies the matrix via pozzolanic reactions. Environmental assessment showed P and F solidification rates of 66.7% and 88.3%, plus 10.77 g CO₂/kg carbonation. Converting inert industrial wastes into a reactive cementitious system enables 55% natural aggregate replacement and pollutant immobilization, offering scalable pathways for phosphogypsum valorization in road base applications. Full article

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

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23 pages, 10066 KB

Open AccessArticle

Delayed Crosslinking and Plugging Performance of Polyacrylamide Gel Using CaCl₂-Tolerant Delayed-Release Crosslinker in High-Calcium Medium

by Huajie Liu, Zhiwei Tao, Theis I. Solling, Sergei E. Chernyshov, Huanan Zhang, Liming Zhang and Dmitriy A. Martyushev

Gels 2026, 12(8), 725; https://doi.org/10.3390/gels12080725 - 14 Aug 2026

Viewed by 295

Abstract

Lost circulation is a major technical bottleneck restricting safe and efficient while-drilling plugging operations. Polyacrylamide gel has become a widely used plugging material in drilling engineering. Unlike rigid, cement-like plugging materials, the gel system formed in this study does not develop a hardened, [...] Read more.

Lost circulation is a major technical bottleneck restricting safe and efficient while-drilling plugging operations. Polyacrylamide gel has become a widely used plugging material in drilling engineering. Unlike rigid, cement-like plugging materials, the gel system formed in this study does not develop a hardened, consolidated structure capable of anchoring or binding the drill bit during subsequent drilling operations, thereby eliminating the risk of bit-sticking. Nevertheless, the gel possesses sufficient elastic (viscoelastic) structural strength—reflected in its storage modulus (G′)—to effectively resist deformation and displacement under differential pressure, thereby providing reliable fracture-sealing performance, which effectively prevents pipe-sticking risks. However, high-concentration PAM molecular chains easily stretch and entangle in aqueous solution, triggering an abnormal increase in initial viscosity and poor pumpability. Although Ca²⁺ can inhibit the premature water absorption and thickening of PAM to maintain system fluidity, an excessively high Ca²⁺ concentration will suppress the hydrolysis of Al³⁺ and hinder the formation of hydroxyaluminum—the key crosslinking component of the gel system. To solve the above contradiction, a CaCl₂-tolerant delayed-release crosslinker was synthesized. ZnO was selected as a carrier to adsorb and immobilize polynuclear hydroxyaluminum complexes hydrolyzed from an inorganic aluminum crosslinker at 70 °C, realizing the controlled delayed release of the crosslinker. The microstructures and chemical bonding were characterized by SEM elemental mapping, FT-IR and ²⁷Al MAS NMR. The results confirm that abundant aluminum species are uniformly loaded on the ZnO surface to form stable Zn–O–Al covalent bonds, and the loaded aluminum exists mainly in the form of hydroxyaluminum. With increasing temperature, the Zn–O–Al bonds gradually break and slowly release hydroxyaluminum species. A novel delayed crosslinking gel system was ultimately optimized, composed of 6% CaCl₂, 10.4% PAM and 3% ZnO loaded with polynuclear hydroxyaluminum. The system exhibits excellent delayed gelation behavior, with a fluidity loss time longer than 120 min and a gelation time over 200 min. It maintains favorable fluidity within 30–90 °C, and the formed gel shows a stable elastic modulus (G′) and viscous modulus (G″). Moreover, the system achieves a plugging rate of more than 90% and a breakthrough pressure above 5 MPa, demonstrating superior comprehensive plugging performance for while-drilling plugging applications. Full article

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

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22 pages, 11770 KB

Open AccessArticle

Welan Gum, a Bacterial Polysaccharide, Promotes Maize Seedling Growth Through TOR and MAPK Signaling Pathways

by Yulin Fu, Haoran Chen, Shuwen Wang, Wenhui Han, Lin Shen, Wenhui Ma, Xiaoxiao Gao, Wudeng Wang and Fang Yu

Gels 2026, 12(8), 724; https://doi.org/10.3390/gels12080724 - 14 Aug 2026

Viewed by 288

Abstract

Welan gum, a high-molecular-weight exopolysaccharide from Sphingomonas sp., exhibits exceptional rheological stability and robust hydrogel properties, emerging as a highly promising agricultural biomaterial. In this study, we show that the application of welan gum promotes maize seedling growth by enhancing nitrogen use efficiency [...] Read more.

Welan gum, a high-molecular-weight exopolysaccharide from Sphingomonas sp., exhibits exceptional rheological stability and robust hydrogel properties, emerging as a highly promising agricultural biomaterial. In this study, we show that the application of welan gum promotes maize seedling growth by enhancing nitrogen use efficiency via the coordinated transcriptional reprogramming of nitrogen regulators and transporters. Mechanistically, welan gum activates the TOR pathway and the MAPK cascade, leading to the phosphorylation of ZmS6K and the terminal MAPK ZmMPK3-1. Notably, TOR inhibition reduces ZmMPK3-1 phosphorylation, demonstrating that TOR activity is indispensable for MAPK activation. Furthermore, the TOR components ZmTOR and ZmLST8 physically interact with ZmMPK3-1, and ZmLST8 independently enhances ZmMPK3-1 kinase activity, revealing a multilayered regulatory mechanism triggered by welan gum. In addition, welan gum upregulates MPK3-targeted defense genes, effectively reconciling the plant growth–defense trade-off. Elucidating this TOR–MAPK crosstalk provides the mechanistic basis for translating welan gum into sustainable gel-based biofertilizers. Collectively, this study uncovers a cooperative signaling network that underpins welan gum-mediated growth promotion, establishing the strong potential of PGPR-derived polysaccharide hydrogels as sustainable, functional biofertilizers for modern agriculture. Full article

(This article belongs to the Special Issue Gels in Agriculture and Environment: Prospects and Challenges)

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Open AccessArticle

Garlic-Extract-Functionalized Fe₃O₄ Magnetic Colloids as Building Blocks for Gel-like Emulsified-Oil Capture

by Wanxin Hao, Yan Wu, Mengting Zhang, Yunpeng Fan, Gang Yan and Shouyu Zhao

Gels 2026, 12(8), 723; https://doi.org/10.3390/gels12080723 - 14 Aug 2026

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Abstract

Stable emulsified oil droplets are difficult to separate because of persistent interfacial films and colloidal stability. Garlic-extract-functionalized Fe₃O₄ magnetic colloids, operationally denoted Allicin@Fe₃O₄, were prepared by in situ coprecipitation as organic–inorganic building blocks for gel-like interfacial [...] Read more.

Stable emulsified oil droplets are difficult to separate because of persistent interfacial films and colloidal stability. Garlic-extract-functionalized Fe₃O₄ magnetic colloids, operationally denoted Allicin@Fe₃O₄, were prepared by in situ coprecipitation as organic–inorganic building blocks for gel-like interfacial capture. The sample name identifies the allicin-containing garlic-extract route and does not imply that allicin was proven to be the predominant surface species. SEM, FTIR, and XRD supported deposition of an organic, sulfur/oxygen-containing surface layer and retention of crystalline Fe₃O₄, but these methods are not species-specific. The colloids removed more than 95% of emulsified oil within 20 min and reached an experimental equilibrium apparent uptake of approximately 380 mg·g⁻¹. Tests across pH 3–11, 0–50 g·L⁻¹ NaCl, 15–55 °C, and representative coexisting ions showed robust but condition-dependent removal. Removal remained above 90% after five reuse cycles and was approximately 84% after ten cycles. Calculations using allicin as a representative garlic organosulfur molecule suggest how polar sulfur/oxygen regions and allyl segments could favor oil–droplet anchoring and association; they do not establish the surface composition of the extract-derived coating. The capture behavior is consistent with transient, gel-like particle–droplet association coupled to magnetic recovery. These results connect bio-derived surface functionalization, gel-related colloidal structuring, and magnetic separation under the tested batch conditions. Full article

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

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Gels, Volume 12, Issue 8 (August 2026) – 96 articles

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