Gels

31 pages, 3432 KB

Open AccessArticle

Development of Pharmabiotic Gel-Serums with Lacticaseibacillus casei Postbiotics and Paraprobiotics Using Chitosan and Carbopol

by Pervin Soyer and A. Alper Öztürk

Gels 2026, 12(9), 838; https://doi.org/10.3390/gels12090838 (registering DOI) - 13 Sep 2026

Abstract

Postbiotic and paraprobiotic preparations are increasingly investigated as non-viable microbial-derived components for topical formulation development, offering an alternative to systems containing live microorganisms. However, their physicochemical and biological performance may depend strongly on the polymeric carrier, and direct comparisons of postbiotic and paraprobiotic [...] Read more.

Postbiotic and paraprobiotic preparations are increasingly investigated as non-viable microbial-derived components for topical formulation development, offering an alternative to systems containing live microorganisms. However, their physicochemical and biological performance may depend strongly on the polymeric carrier, and direct comparisons of postbiotic and paraprobiotic fractions derived from the same microbial source in different gel matrices remain limited. This study aimed to develop and comparatively evaluate Carbopol^®- and chitosan-based pharmabiotic gel-serums containing Lacticaseibacillus casei-derived postbiotic (PB) and paraprobiotic (PPB) fractions. The formulations were characterized in terms of macroscopic appearance, pH, spreadability, and rheological behavior, and their antimicrobial activity, effects on preformed biofilm biomass, and DPPH radical-scavenging activity were evaluated. Blank Carbopol^® and chitosan formulations and free PB and PPB fractions were included as controls to distinguish formulation-matrix-associated effects from those observed for the complete formulations. The developed gel-serums exhibited homogeneous initial macroscopic characteristics, pH values ranging from 4.22 to 5.66, and pseudoplastic shear-thinning behavior. Among the PB-containing systems, CA-CS-PB exhibited pronounced antimicrobial activity, with inhibition-zone diameters of 18.00 mm against Candida albicans and 19.93 mm against Candida krusei, and MIC values of 1156 μg/mL against both species. CA-CS-PB also reduced preformed Staphylococcus aureus and Pseudomonas aeruginosa biofilm biomass by 92.89% and 87.63%, respectively, and exhibited the highest DPPH radical-scavenging activity (73.50%). Among the PPB-containing systems, CA-C-PPB produced reductions of 94.63% and 93.71% in preformed S. aureus and P. aeruginosa biofilm biomass, respectively. Blank formulations also exhibited measurable biological responses, indicating that the activities of the complete formulations should be interpreted as formulation-level effects rather than being attributed exclusively to the incorporated PB or PPB fractions. Because PB and PPB were incorporated at different concentrations (5% and 1% w/w, respectively), these findings should not be interpreted as an equivalent-dose comparison of their intrinsic biological potency. Overall, the findings demonstrate the feasibility of incorporating L. casei-derived PB and PPB fractions into different polymeric gel-serum systems and highlight the influence of both the pharmabiotic fraction and carrier matrix on formulation performance. These results support further investigation of these systems as topical formulation platforms; however, storage stability, release behavior, compositional characterization, and skin-relevant safety and performance require further evaluation before dermocosmetic or dermatological applicability can be established. Full article

(This article belongs to the Special Issue Emerging Gel Technologies in Cosmetics and Pharmaceuticals)

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36 pages, 17574 KB

Open AccessReview

Cellulose Ionogels: Unraveling Structure–Property Relationships Through Multiscale In-Situ Characterization and Theoretical Modeling

by Jia Wei, Ziyan He, Jingtao Ruan, Junjie Ou, Wen Zhang, Bin Tan, Xiaoheng He, Zhen Wang and Yufei Tang

Gels 2026, 12(9), 837; https://doi.org/10.3390/gels12090837 (registering DOI) - 12 Sep 2026

Abstract

Cellulose ionogels have emerged as promising functional soft materials for flexible electronics, energy storage, and biosensing owing to their inherent biocompatibility and unique ionic conductivity. However, establishing precise structure–property relationships remains a fundamental challenge due to the complex, non-equilibrium dynamic processes—such as transient [...] Read more.

Cellulose ionogels have emerged as promising functional soft materials for flexible electronics, energy storage, and biosensing owing to their inherent biocompatibility and unique ionic conductivity. However, establishing precise structure–property relationships remains a fundamental challenge due to the complex, non-equilibrium dynamic processes—such as transient solvation, competing hydrogen-bonding networks, and mesoscopic phase separation—that occur during dissolution and gelation. Traditional static and post-mortem characterizations fail to capture these spatiotemporally dynamic behaviors, creating a critical knowledge gap. To overcome this bottleneck, the integration of real-time in situ/operando characterization techniques with multiscale computational simulations has established a novel, synergistic paradigm. This review comprehensively synthesizes recent advances in decoding the multiscale architectures of cellulose ionogels. We systematically analyze how molecular-scale calculations and time-resolved vibrational/electronic spectroscopies reveal interfacial solvation mechanisms and dynamic bond cleavage/reconstruction. We further evaluate how mesoscopic scattering, nanomechanical mapping, and rheological tools resolve network topology and structural heterogeneity. By bridging these multiscale diagnostics with macroscopic transport and mechanics, the dynamic coupling/decoupling mechanisms governing ionic conductivity, mechanical toughness, and thermal stability are critically decoded. Finally, key technical bottlenecks and future trajectories—including physics-informed machine learning, operando multi-field coupling probes, and AI-driven inverse material design—are outlined, providing theoretical guidelines and technical blueprints for next-generation sustainable ionogels. Full article

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

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21 pages, 2930 KB

Open AccessArticle

Effects of Hydrogel-Forming Composite Cryoprotectants on the Quality of Frozen Freshwater Crayfish (Procambarus clarkii)

by Diejun Jia, Haoran Zhuo, Yuxi Sun, Longwei Jiang, Lijuan Yang, Junhao Yang, Yuan Fu, Jiacheng Li, Lijie Shen, Ke Zhao, Yuxia Zhu, Shuibing Yang and Tao Huang

Gels 2026, 12(9), 836; https://doi.org/10.3390/gels12090836 (registering DOI) - 12 Sep 2026

Abstract

The use of a composite cryoprotectant to maintain the quality of freshwater crayfish (Procambarus clarkii) during frozen storage was investigated in this study. Chitosan (CTS) and carrageenan oligosaccharides (CG) are natural hydrogel-forming polysaccharides that serve as moisture barriers. The effects of [...] Read more.

The use of a composite cryoprotectant to maintain the quality of freshwater crayfish (Procambarus clarkii) during frozen storage was investigated in this study. Chitosan (CTS) and carrageenan oligosaccharides (CG) are natural hydrogel-forming polysaccharides that serve as moisture barriers. The effects of different concentrations of CTS (0–1.5%), CG (0–1.0%), antifreeze proteins (AFPs, 0–0.25%), and tea polyphenols (TP, 0–0.03%) on crayfish muscle tissue were evaluated by measuring water-holding capacity (WHC), total volatile basic nitrogen (TVB-N), and thiobarbituric acid reactive substances (TBARS). Based on single-factor experiments, a three-factor, three-level response surface methodology (RSM) was applied with WHC as the response variable. The results showed that a maximum WHC of 71.65 ± 0.46% was obtained under the optimal treatment, comprising 0.81% CG, 0.61% CTS, and 0.17% AFPs. This study provides a theoretical basis for developing composite cryoprotectants and frozen pre-cooled products from freshwater crayfish, as well as a reference for the application of polysaccharide-based hydrogels in aquatic product frozen preservation. Full article

(This article belongs to the Special Issue Food Gel-Based Systems: Gel-Forming and Food Applications (2nd Edition))

17 pages, 4562 KB

Open AccessArticle

Cooperative Repair for Laser-Induced Graphene via Modified Poly-phenylamine and Fe²⁺ for Thermal-Conductive Gels

by Nan Jiang, Guomin Ding, Bowen Yang, Shuai Liu, Luyao Wang, Zihan Li, Xu Han and Qilin Mei

Gels 2026, 12(9), 835; https://doi.org/10.3390/gels12090835 - 11 Sep 2026

Abstract

Laser-induced graphene (LIG) has great potential for multiple applications because of its large specific surface area, facile fabrication process, and tunable properties. However, abundant lattice defects severely degrade its conductivity. Herein, from an innovative perspective of precursor design, the poly-phenylamines (P-PAs) with improved [...] Read more.

Laser-induced graphene (LIG) has great potential for multiple applications because of its large specific surface area, facile fabrication process, and tunable properties. However, abundant lattice defects severely degrade its conductivity. Herein, from an innovative perspective of precursor design, the poly-phenylamines (P-PAs) with improved solubility and strong light absorption were synthesized, which act as an intercalated polymer for graphene oxide (GO) nanosheets. On this basis, the composite precursors show remarkably enhanced photothermal conversion capability and a compact stacked structure. These bring a 60% reduction in I_D/I_G in LIG after laser irradiation. To explain the above phenomenon, an isolation effect induced by the compact stacking precursor is proposed based on experimental results. Furthermore, the cooperative effect between P-PAs and Fe²⁺ is introduced, and a fluffy LIG aerogel with the lowest I_D/I_G ratio of 0.17 is prepared, which is barely achievable in conventional LIGs. When the obtained graphene aerogel is compounded with PDMS, the as-prepared thermal-conductive composite gel reaches a thermal conductivity of 1.05 W·m⁻¹·K⁻¹ and an ultralow interfacial thermal resistance of 37.2 mm²·K·W⁻¹ under a low graphene loading of 3.3 wt%. This intercalation strategy in GO precursor supplies a new route for preparing high-quality LIGs and thermal-conductive gels, which show great application prospects in thermal management devices. Full article

(This article belongs to the Special Issue Gel-Based Next-Generation Energy Storage)

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20 pages, 19365 KB

Open AccessArticle

Polyelectrolyte Complex/MMT Hybrid for SPI/WE Adhesives with Balanced Flame Retardancy and Shear Strength

by Han Yang, Yuxin Luo, Shiyi Ding, Chunchun Wu and Tao Zhang

Gels 2026, 12(9), 834; https://doi.org/10.3390/gels12090834 - 11 Sep 2026

Abstract

Soybean protein isolate (SPI) adhesives are eco-friendly but suffer from poor water resistance and bonding strength. Waterborne epoxy (WE) can effectively improve these properties; however, WE-modified SPI adhesives can hardly satisfy the growing stringent flame-retardant demands for plywood. Herein, we report a composite [...] Read more.

Soybean protein isolate (SPI) adhesives are eco-friendly but suffer from poor water resistance and bonding strength. Waterborne epoxy (WE) can effectively improve these properties; however, WE-modified SPI adhesives can hardly satisfy the growing stringent flame-retardant demands for plywood. Herein, we report a composite adhesive (SPI/20WE/THPS@CS/MMT) that simultaneously exhibits favorable flame retardancy and dry and wet shear strengths. In this system, a phosphorus-, nitrogen-, and sulfur-containing polyelectrolyte complex (THPS@CS) is fabricated by vacuum-drying an ionically crosslinked polyelectrolyte hydrogel derived from bis[tetrakis(hydroxymethyl)phosphonium] sulfate (THPS) and chitosan (CS) and subsequently incorporated into the SPI/WE matrix (SPI/20WE) together with montmorillonite (MMT). The plywood bonded with SPI/20WE/THPS@CS/MMT achieves a limiting oxygen index (LOI) of 28.0% and shows significantly reduced heat release in cone calorimeter tests. Meanwhile, the resultant plywood possesses high dry and wet shear strengths that fulfill the interior-use plywood criteria specified in GB/T 9846–2015. This work offers new insights into the design and fabrication of high-performance eco-friendly plywood adhesives. Full article

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

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16 pages, 2582 KB

Open AccessArticle

Siloxane-Reinforced GelMA/Methacrylated Chitosan Hydrogels for DLP Printing

by Yufan Zhang, Jing Wang, Bo Liu, Xueqin Zhang and Yunxuan Weng

Gels 2026, 12(9), 833; https://doi.org/10.3390/gels12090833 - 11 Sep 2026

Abstract

Photocrosslinked gelatin methacryloyl/methacrylated chitosan (GelMA/CSMA) hydrogels are attractive for biomedical applications but are limited by insufficient mechanical strength. Here, γ-methacryloxypropyltrimethoxysilane (MPTS) was prehydrolyzed and condensed to generate siloxane species retaining polymerizable methacrylate groups, which were subsequently incorporated into the GelMA/CSMA network as a [...] Read more.

Photocrosslinked gelatin methacryloyl/methacrylated chitosan (GelMA/CSMA) hydrogels are attractive for biomedical applications but are limited by insufficient mechanical strength. Here, γ-methacryloxypropyltrimethoxysilane (MPTS) was prehydrolyzed and condensed to generate siloxane species retaining polymerizable methacrylate groups, which were subsequently incorporated into the GelMA/CSMA network as a reinforcing phase. The effects of MPTS precursor concentration (2–5% w/v) and prehydrolysis time (12–48 h) on the morphology, viscoelasticity, compressive behavior, cytocompatibility, and DLP printability of the resulting GCM hydrogels were systematically investigated. FTIR confirmed methoxy-group consumption while retaining C=C functionality. SEM showed that increasing MPTS precursor concentration increased the apparent abundance of granular features, whereas prolonged prehydrolysis produced larger structures. XRD indicated a predominantly amorphous MPTS-derived phase. GCM-48 h-5% achieved a storage modulus of 23.5 kPa, compressive modulus of 0.682 MPa, and maximum compressive stress of 1.081 MPa, corresponding to 7.4-, 16.9-, and 4.0-fold increases over the GelMA/CSMA control, respectively. The hydrogels exhibited favorable L929 cytocompatibility and retained DLP printability under 405 nm irradiation. These findings demonstrate that regulating MPTS precursor concentration and prehydrolysis time provides a simple route to mechanically reinforce DLP-printable GelMA/CSMA hydrogels without directly incorporating preformed silica particles. Full article

(This article belongs to the Special Issue Biopolymer Hydrogels: Synthesis, Properties and Applications)

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24 pages, 6279 KB

Open AccessReview

Multifunctional Agarose-Based Biomaterials: From Tissue Engineering and Immunomodulation to Advanced Diagnostics and Translational Applications

by Zhenzhen Liu, Long Zhang, Jiayuan Xie, Jingyi Zhou, Yang Yang and Ling Wang

Gels 2026, 12(9), 832; https://doi.org/10.3390/gels12090832 - 11 Sep 2026

Abstract

Agarose, a naturally derived marine polysaccharide extracted from red algae, has evolved from a conventional electrophoretic matrix into a multifunctional biomaterial platform for biomedical engineering. Its thermoreversible gelation, tunable pore structure, optical transparency, generally low immunogenicity under tested conditions, and chemical modifiability enable [...] Read more.

Agarose, a naturally derived marine polysaccharide extracted from red algae, has evolved from a conventional electrophoretic matrix into a multifunctional biomaterial platform for biomedical engineering. Its thermoreversible gelation, tunable pore structure, optical transparency, generally low immunogenicity under tested conditions, and chemical modifiability enable applications in tissue engineering, drug delivery, molecular diagnostics, immunomodulation, and cell preservation. This review critically examines recent advances in agarose-based biomaterials, with emphasis on structure–property relationships, stimulus-responsive delivery systems, regenerative scaffolds, immune–material interactions, agarose-enabled diagnostic microdevices, and DMSO-free cryopreservation. Representative developments include proof-of-concept microfluidic detection of a cfDNA surrogate and histones in spiked plasma, agarose composite hydrogels for controlled release and osteochondral repair, agarose-containing composite hydrogels investigated for macrophage modulation, and agarose/trehalose systems that provide immediate post-thaw viability comparable to conventional DMSO-based preservation in the reported cell model, although post-thaw proliferation remained lower. Agarose is commercially established in electrophoresis and bioseparation, whereas therapeutic delivery and implantable regenerative systems remain predominantly preclinical. Remaining barriers include limited in vivo degradability, insufficient intrinsic cell adhesiveness and bioactivity, trade-offs among mechanical strength, injectability and printability, and incomplete manufacturing and regulatory standardization. Future work should prioritize well-defined degradation pathways, reproducible composition–property relationships, application-specific benchmarking, and clinically relevant validation. Full article

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

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31 pages, 6905 KB

Open AccessArticle

Composition-Dependent Performance of Hydrophobic Glass Wool Fiber Aerogels for Oil Absorption and Thermal Insulation

by Thi Thanh Hai Dam, Thanh Thanh Le, Nguyen Thi Hong Phuc, Nga H. N. Do, Quang M. N. Phan, Phan Minh Quoc Binh and Hai M. Duong

Gels 2026, 12(9), 831; https://doi.org/10.3390/gels12090831 - 11 Sep 2026

Abstract

Glass wool provides a lightweight fibrous framework with inherent thermal-insulation capability, yet its direct use in hydrophobic monolithic aerogels has received comparatively limited systematic investigation. Here, glass wool fiber (GWF)/poly(vinyl alcohol) (PVA) aerogels were fabricated by freeze-drying followed by vapor-phase methyltrimethoxysilane (MTMS) modification. [...] Read more.

Glass wool provides a lightweight fibrous framework with inherent thermal-insulation capability, yet its direct use in hydrophobic monolithic aerogels has received comparatively limited systematic investigation. Here, glass wool fiber (GWF)/poly(vinyl alcohol) (PVA) aerogels were fabricated by freeze-drying followed by vapor-phase methyltrimethoxysilane (MTMS) modification. A composition matrix of 1.0–3.0 wt.% GWF and 0.10–1.00 wt.% PVA was evaluated to determine composition-dependent changes in density, calculated porosity, wettability, compressive response, thermal conductivity, crude-oil absorption, uptake kinetics, and cyclic reusability. The aerogels exhibited densities of 0.014–0.046 g/cm³, calculated porosities of 97.68–99.39%, water contact angles of 131.0–141.3°, thermal conductivities of 32.1–38.5 mW/m·K, and compressive stress at 50% strain up to 146.20 kPa. Crude-oil absorption, defined here as predominantly physical uptake and retention within the porous fibrous network, ranged from 18.86 ± 1.50 to 55.12 ± 1.57 g/g. At 0.25 wt.% PVA, samples containing 1.0–3.0 wt.% GWF reached 81–91% of equilibrium uptake within 10 s. The pseudo-second-order model provided the better empirical fit without implying chemisorption. Overall, composition influenced the balance among oil uptake, mechanical resistance, cyclic reuse, and thermal insulation. Full article

(This article belongs to the Special Issue Synthesis and Application of Aerogel (2nd Edition))

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28 pages, 3559 KB

Open AccessArticle

pH-/Temperature-Triggered Gel Transition of Hyperbranched PEI-g-PDMAEMA as a Dual-Responsive Inhibitor for Clay Hydration Control

by Ming Zhong and Yang Xiong

Gels 2026, 12(9), 830; https://doi.org/10.3390/gels12090830 - 10 Sep 2026

Abstract

To mitigate clay hydration and wellbore instability during deepwater drilling, a pH/temperature dual-responsive graft copolymer, hyperbranched polyethylenimine-g-poly(2-(dimethylamino)ethyl methacrylate) (HPEI-g-PDMAEMA), was designed and synthesized via free radical polymerization. Optimized synthesis at an HPEI/DMAEMA mass ratio of 1:2 with 2.4% AIBN at 70 °C for [...] Read more.

To mitigate clay hydration and wellbore instability during deepwater drilling, a pH/temperature dual-responsive graft copolymer, hyperbranched polyethylenimine-g-poly(2-(dimethylamino)ethyl methacrylate) (HPEI-g-PDMAEMA), was designed and synthesized via free radical polymerization. Optimized synthesis at an HPEI/DMAEMA mass ratio of 1:2 with 2.4% AIBN at 70 °C for 10 h yielded a grafting ratio of 35.2% and a molecular weight of 84.3 kDa. The copolymer exhibits a tunable lower critical solution temperature (LCST) of approximately 48 °C at pH 8, decreasing with increasing pH due to tertiary amine deprotonation. Zeta potential measurements confirm that the polymer retains a positive charge (+5 mV at pH 8) under weakly alkaline conditions, enabling strong electrostatic anchoring onto negatively charged clay surfaces. Above the LCST, dynamic light scattering reveals a sharp increase in hydrodynamic diameter from ~30 nm to >200 nm, confirming a hydrophilic-to-hydrophobic transition of PDMAEMA segments that drives the formation of a hydrophobically associated gel barrier. This thermally triggered gelation is fully reversible, as evidenced by repeated heating–cooling cycles with almost complete transmittance recovery. The gel barrier drastically reduces water uptake, with inhibition performance against clay swelling at 60 °C being 18.5 percentage points higher than that at 25 °C. Hot-rolling tests demonstrate that with only 1.5 wt% inhibitor, shale recovery reaches 94.1% at 150 °C (8.8 percentage points higher than unmodified HPEI) and remains above 60% even in 20 wt% CaCl₂ or MgCl₂ brines, highlighting exceptional resistance to divalent cations. Water contact angle on treated clay surfaces increases from 18.5° to 52.6°, confirming effective surface hydrophobization. This work provides a molecular-level gel-engineering strategy where pH governs electrostatic anchoring and temperature triggers reversible hydrophobic gelation, enabling on-demand switching of clay wettability and hydration resistance under high-temperature, high-salinity conditions. Full article

(This article belongs to the Section Gel Applications)

18 pages, 3263 KB

Open AccessArticle

A Low-Polymer High-Temperature Water-Based Fracturing Gel Enabled by a Dual-Ligand Organic Zirconium Crosslinker: An Experimental Study

by Fei Liu, Xuewu Wang, Xiaqing Li, Peng Tao, Boyang Shen, Yuyu Zhang, Shaocan Dong and Yongfei Li

Gels 2026, 12(9), 829; https://doi.org/10.3390/gels12090829 - 10 Sep 2026

Abstract

This experimental study aimed to develop and evaluate a low-polymer, high-temperature water-based fracturing gel using a dual-ligand organic zirconium crosslinker regulated by sodium lactate and ethylene glycol. The crosslinker was selected by ligand screening and single-factor optimization using the apparent viscosity of LX641 [...] Read more.

This experimental study aimed to develop and evaluate a low-polymer, high-temperature water-based fracturing gel using a dual-ligand organic zirconium crosslinker regulated by sodium lactate and ethylene glycol. The crosslinker was selected by ligand screening and single-factor optimization using the apparent viscosity of LX641 gels as the primary response, and was characterized by FTIR and electron microscopy. Gelation, salt response, high-temperature shear rheology, oscillatory and steady-shear behavior, static fluid loss, gel breaking, proppant suspension, and core-permeability damage were then evaluated. The selected zirconium oxychloride octahydrate/sodium lactate/ethylene glycol/water/NaOH mass ratio was 10:6:4:15:1.2, with synthesis at 55 °C, pH 7, for 4 h. A 0.2 wt.% LX641 gel at a base-fluid/crosslinker-solution volume ratio of 100:0.5 retained an apparent viscosity of 246.84 mPa·s at 100 min after heating to 190 °C within 25 min and shearing at 190 °C for the remaining 75 min at 170 s⁻¹. The system also showed no visible settling of 10 wt.% 30-mesh ceramic proppant after 12 h, core-permeability damage of 11.98–13.65%, and visually clear broken fluid within 2 h using 0.01 wt.% ammonium persulfate at 70 °C. The results indicate that sodium-lactate/ethylene-glycol regulation can support substantial high-temperature viscosity retention at only 0.2 wt.% polymer loading, providing a low-polymer alternative for further development of high-temperature zirconium-crosslinked fracturing gels. Full article

(This article belongs to the Section Gel Applications)

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33 pages, 15017 KB

Open AccessArticle

Intrinsically Bioactive Tannic Acid-Grafted Succinoglycan for Self-Healing and Stimuli-Responsive Drug Delivery Hydrogels

by Sang-Il Park, Kyungho Kim, Sungmin Rhyu and Seunho Jung

Gels 2026, 12(9), 828; https://doi.org/10.3390/gels12090828 - 10 Sep 2026

Abstract

Tannic acid grafting provides a practical strategy for introducing bioactive phenolic functionality into microbial polysaccharides for multifunctional hydrogel design. Herein, tannic acid-modified succinoglycan (SG-TA) was prepared through an ascorbic acid/ H₂O₂-mediated free-radical process. Spectroscopic, thermal, and purification-control analyses were [...] Read more.

Tannic acid grafting provides a practical strategy for introducing bioactive phenolic functionality into microbial polysaccharides for multifunctional hydrogel design. Herein, tannic acid-modified succinoglycan (SG-TA) was prepared through an ascorbic acid/ H₂O₂-mediated free-radical process. Spectroscopic, thermal, and purification-control analyses were consistent with covalent incorporation of tannic acid-derived moieties into SG, while characteristic structural features of the SG framework remained evident after modification. SG-TA exhibited tannic acid-equivalent phenolic contents of up to 321.9 mg TAE/g and markedly enhanced antioxidant and antibacterial activities compared with native SG. SG-TA was subsequently incorporated into a poly(vinyl alcohol) (PVA)/borax network to form dynamic SG-TA/PVA/borax (STPB) hydrogels based on reversible interactions. The hydrogels exhibited composition-dependent viscoelasticity, rapid rheological recovery, macroscopic self-rejoining, enhanced deformability, antioxidant and antibacterial functionality, and preliminary cytocompatibility. Time-dependent phenolic release showed that SG-TA-derived phenolic species were partially released from the network, indicating contributions from both matrix-associated and releasable functionality. The reversible network also enabled pH- and glucose-responsive release of 5-fluorouracil as a model small-molecule drug. These findings demonstrate the potential of SG-TA as an intrinsically bioactive microbial polysaccharide for multifunctional, self-healing, and stimuli-responsive drug-delivery hydrogels. Full article

(This article belongs to the Special Issue Functional Gel-Based Biomaterials for Medical Applications)

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23 pages, 16388 KB

Open AccessArticle

Preparation and Rheological Behavior of Temperature-Resistant Hydroxypropyl Guar Gum Supramolecular Hydrogels Based on Dynamic Borate Ester Bonds

by Yikai Xing, Yongfei Li, Songwei Li, Bin Liu, Kai Gao, Chengjun Wang, Weiwei Han, Qian Wang and Yanling Wang

Gels 2026, 12(9), 827; https://doi.org/10.3390/gels12090827 - 10 Sep 2026

Abstract

The increasing depth of oil wells and associated elevated formation temperatures pose significant challenges to conventional crosslinked polymer gels used in hydraulic fracturing, as viscosity degradation severely impairs proppant transport and stimulation efficiency. In this study, a thermally stable organic boron crosslinker was [...] Read more.

The increasing depth of oil wells and associated elevated formation temperatures pose significant challenges to conventional crosslinked polymer gels used in hydraulic fracturing, as viscosity degradation severely impairs proppant transport and stimulation efficiency. In this study, a thermally stable organic boron crosslinker was developed and evaluated in combination with hydroxypropyl guar gum (HPG). The rheological performance of the crosslinked gel system was systematically investigated under high-temperature shearing conditions. At a guar gum concentration of 0.5 wt% and a crosslinker-to-gum ratio of 100:0.5, the system maintains a viscosity of 500 mPa·s at 120 °C and 170 s⁻¹, and the viscosity remains above 300 mPa·s after 60 min of continuous shearing, demonstrating outstanding thermal resistance. (For 0.3 wt% HPG, the optimal crosslinking ratio is 100:0.3; for 0.5 wt% HPG, the optimal ratio is 100:0.5). This gel formulation achieves efficient proppant transport with minimal additives. It maintains static proppant suspension for up to 48 h. After breaking, the fluid viscosity drops to approximately 5 mPa·s. With the addition of a flowback aid, surface tension can be reduced to as low as 16.29 mN/m, while the formation matrix permeability damage rate is limited to only 20.76%. Additionally, the gel features rapid breaking and low residue generation, making it highly suitable for high-temperature fracturing operations. Full article

(This article belongs to the Section Gel Applications)

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33 pages, 8063 KB

Open AccessArticle

Multifunctional Intelligent Hydrogels Based on MnO₂ Nanozymes and Ca²⁺ Signal Regulation for Diabetic Wound Repair

by Yanling Li, Yuhan Mao, Ji’e Zhang, Lele Li, Rongfeng Zhao, Qian Pang, Fang Yang and Ruixia Hou

Gels 2026, 12(9), 826; https://doi.org/10.3390/gels12090826 - 8 Sep 2026

Abstract

Diabetic refractory wounds are a prevalent and severe complication of diabetes, whose pathological progression is jointly mediated by multiple factors, including oxidative stress imbalance, chronic inflammation, impaired angiogenesis, bacterial infection, and biofilm formation. Current clinical hydrogel dressings generally suffer from drawbacks such as [...] Read more.

Diabetic refractory wounds are a prevalent and severe complication of diabetes, whose pathological progression is jointly mediated by multiple factors, including oxidative stress imbalance, chronic inflammation, impaired angiogenesis, bacterial infection, and biofilm formation. Current clinical hydrogel dressings generally suffer from drawbacks such as single-function performance, potential toxicity of nano-components, static networks incompatible with dynamic wound conditions, and the absence of bionic repair signals. Therefore, they cannot simultaneously satisfy the dual repair requirements of complex pathological microenvironments and dynamic mechanical properties for diabetic wounds. In this study, a multi-functional dynamically responsive composite hydrogel (MC group) with high-efficiency antioxidant, antibacterial, and pro-angiogenic capacities was fabricated. Using SDS-C₁₈ micelles as hydrophobic units, a rigid–flexible dual-network framework was constructed with polyvinyl alcohol (PVA) and methacrylated hyaluronic acid (HAMA). Manganese dioxide nanozymes were introduced to scavenge reactive oxygen species (ROS) and mitigate oxidative stress. Calcium-ion-mediated dynamic micelle reconstruction was adopted to regulate the hydrophilic–hydrophobic balance, while achieving antibacterial effects and facilitating tissue regeneration. In vitro experiments verified that the MC hydrogel possesses mechanical properties well-matched to human soft tissues (fracture stress: 25 kPa) and excellent biocompatibility (cell viability > 100%, hemolysis rate: only 0.13%). It also exhibits prominent antioxidant activity (DPPH radical-scavenging rate: 36.95%), antibacterial performance (>99.86% bactericidal rate against Staphylococcus aureus, survival rate of Escherichia coli reduced to 15.95%), and cell-migration-promoting activity (endothelial cell migration rate of 83.72% and mouse fibroblast migration rate of 90.88% within 24 h). In the full-thickness skin defect model of diabetic mice, the wound-healing rate reached 99% on day 16. Moreover, it promoted ordered collagen deposition, skin appendage regeneration, and functional microvascular reconstruction, thereby accomplishing high-quality tissue repair. This design synergistically intervenes in multiple pathological links of diabetic wounds, overcomes several key limitations of existing dressings, and provides an innovative strategy for developing smart dressings. Full article

(This article belongs to the Special Issue Polymeric Hydrogels for Biomedical Application (2nd Edition))

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22 pages, 13004 KB

Open AccessArticle

Variable-Amplitude Fatigue Life Prediction of SBS-Modified Asphalt Mixtures with Physical Gel Structures

by Chenze Fang, Jiahao Yang, Menghao Wang, Hongbin Zhu and Pingfan Hu

Gels 2026, 12(9), 825; https://doi.org/10.3390/gels12090825 - 8 Sep 2026

Abstract

The service life of SBS-modified asphalt mixtures with physical gel structures is strongly influenced by the loading sequence–interaction coupling effects. However, conventional linear models fail to accurately capture the influence of such coupling effects on fatigue life. This study, therefore, aims to develop [...] Read more.

The service life of SBS-modified asphalt mixtures with physical gel structures is strongly influenced by the loading sequence–interaction coupling effects. However, conventional linear models fail to accurately capture the influence of such coupling effects on fatigue life. This study, therefore, aims to develop a life prediction method for SBS-modified asphalt mixtures that explicitly accounts for the loading sequence–interaction coupling effects. First, indirect tensile monotonic loading tests, as well as constant-amplitude and variable-amplitude indirect tensile repeated loading tests were conducted to determine the fatigue life of SBS-modified asphalt mixtures under different loading modes. Subsequently, a viscoelastic fatigue damage model was developed to analyze the accumulation of fatigue damage in SBS-modified asphalt mixtures. Subsequently, the effects of loading sequence and loading interaction on the fatigue damage accumulation process in SBS-modified asphalt mixtures were investigated. Based on these analyses, a nonlinear fatigue damage accumulation model considering the loading sequence–interaction coupling effects was established. Finally, a nonlinear fatigue damage accumulation factor was introduced for developing a fatigue life prediction model for SBS-modified asphalt mixtures considering the loading sequence–interaction coupling effects. The results indicate that the low–high (σ_low–σ_high) and high–low (σ_high–σ_low) loading sequences, respectively, retard and accelerate the fatigue damage accumulation process of SBS-modified asphalt mixtures. Consequently, the corresponding cumulative fatigue life fractions are greater than 1 and less than 1, respectively. Furthermore, the resulting fatigue life is positively correlated with the first-level fatigue life fraction under the σ_low–σ_high sequence but negatively correlated under the σ_high–σ_low sequence. The developed nonlinear fatigue damage accumulation model can accurately track the nonlinear fatigue damage accumulation of SBS-modified asphalt mixtures. The established nonlinear fatigue life prediction model accurately predicts the fatigue life of SBS-modified asphalt mixtures with physical gel structures under cyclic loading with variable stress amplitudes. Full article

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

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59 pages, 10068 KB

Open AccessReview

Sustainable Polymer Aerogels: Multiscale Design from Biomass and Thermoset Networks to AI-Guided Materials Discovery

by Trung Chi Duong, Phan Minh Quoc Binh, Dam Thi Thanh Hai, Le Thanh Thanh, Truong Thanh Tuan, Nguyen Thi Phuong Nhung, Nguyen Van Kiet, Nga H. N. Do and Hai M. Duong

Gels 2026, 12(9), 824; https://doi.org/10.3390/gels12090824 - 8 Sep 2026

Abstract

Polymer aerogels have attracted increasing attention as lightweight porous materials for thermal insulation, separation, adsorption, remediation, and other environmental applications. Their low density and tunable surface chemistry also make them suitable for converting renewable, recycled, and waste-derived feedstocks into value-added materials. However, their [...] Read more.

Polymer aerogels have attracted increasing attention as lightweight porous materials for thermal insulation, separation, adsorption, remediation, and other environmental applications. Their low density and tunable surface chemistry also make them suitable for converting renewable, recycled, and waste-derived feedstocks into value-added materials. However, their overall sustainability remains difficult to assess because most studies focus on material properties, whereas solvent use, drying energy, processing yield, durability, regeneration, and end-of-life pathways are reported less consistently. This review examines sustainable polymer aerogels from the perspectives of cleaner production and waste valorization and focuses on two main features. First, a unified multiscale framework of structure, formation, and performance links network formation mechanisms, pore architecture, and macroscopic behavior across biomass-derived, thermoset, dynamic covalent, hybrid, and recycled polymer aerogels, which are compared in terms of feedstock origin, processing intensity, functional performance, durability, and circularity. Second, structure–property mapping is combined with sustainability-constrained, AI-guided design, with environmental descriptors treated as optimization objectives from the outset rather than as post hoc justifications. Particular attention is given to waste and secondary resources, including agricultural residues, textile waste, paper waste, recycled poly(ethylene terephthalate), and end-of-life tire fibers. The review also discusses how life-cycle assessment, service-based functional units, and minimum reporting standards can help assess whether sustainability claims are supported by measurable environmental benefits. Several recurring limitations emerge from the literature: sustainability is often discussed only qualitatively, processing data are insufficient to support robust life-cycle assessments, solvent exchange and drying remain major environmental hotspots, and circularity claims frequently conflate bio-based content, biodegradability, recyclability, and reusability. Finally, the review discusses how data-driven tools, including literature mining, machine learning, and multi-objective optimization, can support polymer-aerogel design when environmental descriptors are included from the beginning of materials development. The review also proposes a reporting and design roadmap for future work toward polymer aerogels that combine useful performance with lower resource intensity and credible end-of-life value retention. Full article

(This article belongs to the Special Issue Sustainable Advanced Materials in Aerogels and Hydrogels)

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20 pages, 13328 KB

Open AccessArticle

pH-Responsive Mixed Polymeric Micelles as Gel-Related Nanocarriers for Drug Delivery: A DPD Study on Block Ratio Modulation

by Wensheng Wu, Zhiwei Li, Xiang Li, Wenyuan Zeng, Zhimao Lin and Shasha Liu

Gels 2026, 12(9), 823; https://doi.org/10.3390/gels12090823 - 8 Sep 2026

Abstract

Polymeric micelles represent a fundamental self-assembled architecture of gel-based soft materials and have emerged as promising nanocarriers for anticancer drug delivery. Their performance is largely governed by the block composition of constituent copolymers, and understanding their self-assembly behavior provides critical insights into the [...] Read more.

Polymeric micelles represent a fundamental self-assembled architecture of gel-based soft materials and have emerged as promising nanocarriers for anticancer drug delivery. Their performance is largely governed by the block composition of constituent copolymers, and understanding their self-assembly behavior provides critical insights into the rational design of gel-related drug delivery systems. In this work, dissipative particle dynamics (DPD) simulations were performed to systematically investigate two types of mixed drug-loaded micellar systems self-assembled from a triblock copolymer mPEG-b-poly(2-(diethylamino)ethyl methacrylate)-b-PMMA (PDEAEMA, hereafter referred to as the DMA block for brevity) with either a diblock copolymer PDEAEMA-b-PMMA (polymer B) or PPEGMA-b-PDEAEMA (polymer C). By tailoring the ratios of hydrophobic (MMA, the constituent block of PMMA) and pH-sensitive (DMA) blocks, the protonation-responsive behavior, structural stability, drug loading capacity, and release kinetics of the micelles were comprehensively examined. The simulation results demonstrate that: (1) increasing the hydrophobic block ratio accelerates the protonation-triggered micellar swelling and drug release because the increased hydrophobic content enhances the core compactness which, upon protonation, generates a stronger driving force for chain extension, yet an optimal ratio (+16 MMA units) exists beyond which excessive hydrophobic blocks suppress release due to core densification; (2) increasing the pH-sensitive block ratio significantly enhances the maximum drug loading capacity (from 9.83% to 12.22% for the A/C system), but exerts only limited influence on the release rate; (3) the A/C mixed micelles with higher PEG content exhibit superior structural stability and drug loading capacity, while the A/B system with higher MMA content displays more sensitive pH-responsiveness. These findings reveal a competing mechanism between “protonation-driven force” and “structural resistance,” providing mesoscopic theoretical guidance for the rational design of pH-responsive polymeric nanocarriers and self-assembled soft materials via block ratio modulation. Full article

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

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17 pages, 30214 KB

Open AccessReview

Strain-Insensitive Conductive Hydrogel Materials for Motion-Artifact-Free Flexible Bioelectronics

by Yarong Ding, Yitong Dou, Lei Bai, Zhenyu Li, Jiayi Qi, Yufeng Li, Shaozhe Tan, Xuesi Zhang, Jiachun Sun, Yahui Song, Jingxuan Wu, Fei Han and Yingchun Li

Gels 2026, 12(9), 822; https://doi.org/10.3390/gels12090822 - 7 Sep 2026

Abstract

Flexible and stretchable electronics inevitably undergo stretching, compression, bending and torsion when conformally attached to skin, soft tissues and dynamic organs. While deformation-induced electrical variations act as target signals for motion sensors, they cause resistance/impedance drift, baseline shift and sensitivity degradation in physiological [...] Read more.

Flexible and stretchable electronics inevitably undergo stretching, compression, bending and torsion when conformally attached to skin, soft tissues and dynamic organs. While deformation-induced electrical variations act as target signals for motion sensors, they cause resistance/impedance drift, baseline shift and sensitivity degradation in physiological electrodes, temperature/chemical sensors, interconnects and stimulation devices, leading to motion artifacts and reduced long-term reliability. Hydrogels are pivotal materials for soft bioelectronic interfaces owing to their high water content, low modulus, tissue compatibility and ionic conductivity. However, their conductive networks are susceptible to structural reconstruction under deformation, dehydration, swelling and cyclic fatigue, meaning that stretchability is by no means equivalent to strain insensitivity. This review focuses on stable resistance/impedance and functional output within a specified strain window, this paper reviews three representative material systems, liquid metal (LM)-based composite hydrogels, conductive polymer/elastic network composite hydrogels, and hydrogen-bonded isotropic architectures. It further summarizes three design strategies—geometric and functional compensation, mechanical decoupling and strain isolation, and interfacial engineering for conductive network stabilization—and discusses their applications in wearable epidermal and implantable bioelectronics. Finally, unified evaluation metrics for strain insensitivity are proposed, with future directions covering high-conductivity–low-modulus synergy, long-term water/ionic stability, robust soft-hard interfaces, multiaxial deformation tolerance and scalable manufacturability. Full article

(This article belongs to the Special Issue Hydrogels with Appropriate/Tunable Properties for Biomedical Applications (3rd Edition))

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4 pages, 760 KB

Open AccessEditorial

Editorial for the Special Issue “Advances and Applications of Polymer Gels for Subsurface Energy and Storage”

by Baojun Bai and Jingyang Pu

Gels 2026, 12(9), 821; https://doi.org/10.3390/gels12090821 - 7 Sep 2026

Abstract

Polymer gels are essential functional materials for subsurface energy operations, playing a critical role in conformance control, fluid diversion, hydraulic fracturing, and leakage mitigation. As reservoirs become increasingly complex and the demand for sustainable energy grows, continued innovation in gel technologies is crucial. [...] Read more.

Polymer gels are essential functional materials for subsurface energy operations, playing a critical role in conformance control, fluid diversion, hydraulic fracturing, and leakage mitigation. As reservoirs become increasingly complex and the demand for sustainable energy grows, continued innovation in gel technologies is crucial. This editorial introduces a Special Issue titled “Advances and Applications of Polymer Gels for Subsurface Energy and Storage,” which compiles seven original research articles exploring recent developments in gel synthesis, characterization, and applications. The featured studies highlight the versatility of polymer gels, including nanoparticle-reinforced composites, foam–gel hybrids, recrosslinkable preformed particle gels, and advanced fracturing fluids. The contributions address key challenges across CO₂-enhanced oil recovery, heavy oil production, low-permeability reservoir fracturing, and combined enhanced oil recovery strategies. The findings demonstrate ongoing efforts to tailor gel systems for harsh reservoir conditions, improve sweep efficiency, and reduce formation damage, fostering more efficient and sustainable subsurface engineering practices. This Special Issue serves as a valuable resource for researchers and practitioners advancing polymer gel technologies for energy and storage applications. Full article

(This article belongs to the Special Issue Advances and Application of Polymer Gels for Subsurface Energy and Storage)

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20 pages, 17069 KB

Open AccessArticle

Feedstock-Dependent Water Sorption and Retention of Citric-Acid-Modified Lignocellulosic Biogels Under Simulated Climatic Conditions

by Tomáš Holeček, Michaela Filipi, Ivana Tomášková, Karolina Resnerová, Jan Macků and Kateřina Hájková

Gels 2026, 12(9), 820; https://doi.org/10.3390/gels12090820 - 7 Sep 2026

Abstract

Increasing drought frequency and irregular precipitation patterns highlight the need for sustainable soil water management. In this study, lignocellulosic biogels were prepared from Norway spruce and silver birch sawdust and from rapeseed and poppy straw using a 10 wt.% citric acid solution, with [...] Read more.

Increasing drought frequency and irregular precipitation patterns highlight the need for sustainable soil water management. In this study, lignocellulosic biogels were prepared from Norway spruce and silver birch sawdust and from rapeseed and poppy straw using a 10 wt.% citric acid solution, with a fixed addition of 5 mL of 80% lactic acid as a processing modifier. Two formulations differing in the volume of citric acid solution (180 or 250 mL per 12 g of dry feedstock), and consequently in both the liquid-to-solid ratio and absolute citric acid dose, were evaluated. Biomass chemical composition and density were determined, the amount of water absorbed by soil–biogel mixtures containing approximately 3.1% dry biogel relative to dry soil mass was measured gravimetrically after saturation and free drainage and water-loss kinetics of the separately saturated biogels were monitored under cyclic climatic conditions ranging from 12 to 35 °C and 25 to 75% relative humidity. FTIR spectroscopy was used to compare cellulose isolated from each feedstock with the corresponding biogels prepared using both the 180 and 250 mL formulations. Biogel performance depended on feedstock composition and physical characteristics. Among the tested formulations, the poppy-derived 180 mL biogel produced the highest water absorption in the soil–biogel system, whereas spruce-derived biogels exhibited more stable residual water content during prolonged desorption. The poppy-derived 180 mL formulation increased water absorption in the soil–biogel system from 88.46 g in untreated soil to 122.86 g, corresponding to an increase of 38.9%. FTIR analysis indicated an increased contribution of carbonyl-containing structures consistent with incorporation of the acid modifiers and possible ester formation; however, the spectra did not provide direct evidence of crosslinking density. Increasing the citric acid solution volume did not consistently improve water absorption by the soil–biogel system or water-loss behavior of the isolated biogels. These laboratory results demonstrate a feedstock-dependent interaction with formulation and provide a basis for further evaluation of lignocellulosic residues as renewable water-retaining soil amendments under soil–plant and field conditions. Full article

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

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