Journal Description
Gels
Gels
is an international, peer-reviewed, open access journal on physical and chemical gels, published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High visibility: indexed within Scopus, SCIE (Web of Science), PubMed, PMC, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q1 (Polymer Science) / CiteScore - Q1 (Organic Chemistry)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 13 days after submission; acceptance to publication is undertaken in 2.8 days (median values for papers published in this journal in the first half of 2026).
- Recognition of Reviewers: Reviewers whose reports are timely and of high quality receive an APC discount voucher for a future publication in an MDPI journal. Become a reviewer.
- Journal Cluster of Polymer and Macromolecular Science: Polymers, Membranes, Gels, Polysaccharides, Textiles, Macromol, Microplastics and Adhesives.
Impact Factor:
6.4 (2025);
5-Year Impact Factor:
6.5 (2025)
Latest Articles
Physical-Field Engineering of Food Hydrogels: Multiscale Assembly, Processing Windows, and Functional Translation
Gels 2026, 12(10), 879; https://doi.org/10.3390/gels12100879 - 28 Sep 2026
Abstract
Food hydrogels are multiscale, water-rich networks whose functionality depends not only on composition but also on how processing energy is deposited and redistributed during network formation. Although acoustic, electric, magnetic, and pressure-based treatments have expanded the available strategies for hydrogel structuring, current evidence
[...] Read more.
Food hydrogels are multiscale, water-rich networks whose functionality depends not only on composition but also on how processing energy is deposited and redistributed during network formation. Although acoustic, electric, magnetic, and pressure-based treatments have expanded the available strategies for hydrogel structuring, current evidence remains fragmented by inconsistent dose reporting, thermal and electrochemical confounding, strong matrix dependence, limited validation in compositionally realistic foods, and insufficient scale-up and safety assessment. This review critically evaluates these technologies through a field–process–structure–function framework that links measurable field inputs and energy deposition to molecular and colloidal reconfiguration, network architecture, water mobility, and food functionality. Across the available literature, ultrasound has the broadest evidence base for precursor restructuring and gel network modification, while high-pressure processing shows comparatively strong support for direct gelation and composite network reinforcement. Electric-field approaches offer controllable electrothermal and directional effects but require more rigorous separation of field-specific contributions from thermal and electrochemical effects. Magnetic and conductive edible hydrogels remain comparatively early-stage, with much of the mechanistic evidence still derived from non-ingestible systems. Overall, beneficial responses occur within matrix-specific processing windows rather than increasing monotonically with treatment intensity. Future progress requires matched controls, quantitative dose reporting, realistic food matrices, food-grade safety validation, continuous-processing equipment, and energy-normalized assessment of technological feasibility.
Full article
(This article belongs to the Special Issue Advances and Prospects in the Food Applications of Hydrogels)
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Open AccessArticle
Composition-Dependent Viscosity and Properties of MCC/CNC Regenerated Cellulose Hydrogels Prepared Using TBAF/DMSO
by
Na Hyeon Kim, Maria Jose Silva Pincay, Yeongjun Kim, Hyosub Kim, Eunok Jang, Dong Hyun Kim, Sae-Byuk Lee, Mi-Kyung Park, Seockmo Ku, Eunsook Lee and Deokyeong Choe
Gels 2026, 12(10), 878; https://doi.org/10.3390/gels12100878 - 28 Sep 2026
Abstract
Although microcrystalline cellulose (MCC) and cellulose nanocrystals (CNCs) possess the same cellulose backbone, it remains unclear whether they have similar effects on solution viscosity behavior in tetrabutylammonium fluoride (TBAF)/dimethyl sulfoxide (DMSO) and the properties of the resulting regenerated hydrogels. This study investigated the
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Although microcrystalline cellulose (MCC) and cellulose nanocrystals (CNCs) possess the same cellulose backbone, it remains unclear whether they have similar effects on solution viscosity behavior in tetrabutylammonium fluoride (TBAF)/dimethyl sulfoxide (DMSO) and the properties of the resulting regenerated hydrogels. This study investigated the composition-dependent viscosity behavior of MCC/CNC solutions in TBAF/DMSO and the properties of the regenerated cellulose hydrogels. At 2.5% cellulose, the MCC solution achieved a maximum viscosity of 8.8 Pa·s at 2.5% TBAF, whereas the CNC solution reached 15.0 Pa·s at 5.5% TBAF. In mixed solutions, increasing the CNC content decelerated the viscosity increase, extending the time required for solution preparation and molding. After water-induced regeneration, the gel strength and cutting strength decreased from 70.8 to 33.6 N·mm and from 55.8 to 6.7 N·mm, respectively, as the formulation shifted from MCC-only to CNC-only. Conversely, the CNC-containing hydrogels exhibited higher optical transmittance than MCC-only hydrogels. Time-resolved photoluminescence measurements suggested composition-dependent local photophysical relaxation. Fourier-transform infrared spectroscopy revealed no formation of new covalent structures, while X-ray diffraction indicated that the regenerated hydrogels were predominantly amorphous. Thermogravimetric analysis revealed composition-dependent thermal degradation. These results demonstrate that controlling the MCC/CNC compositional ratio provides a means of balancing solution processability and regenerated hydrogel properties.
Full article
(This article belongs to the Section Gel Analysis and Characterization)
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Open AccessArticle
Physical Aging, Composition, and Carbon-Additive Identity as Separable Rheological Controls in Colloidal-Cellulose Nanofibril–Natural-Rubber-Latex Hydrogels
by
Branko Alič, Urška Šebenik and Matjaž Krajnc
Gels 2026, 12(10), 877; https://doi.org/10.3390/gels12100877 - 28 Sep 2026
Abstract
Hydrogels prepared from TEMPO-oxidized cellulose nanofibrils (TCNFs), natural rubber latex (NRL), and carbon additives change their rheological properties during storage, so formulation comparisons made at uncontrolled aging states can be misleading. Here, TCNF–NRL hydrogels containing graphene conductive additive (GCA), graphene nanoplatelets (GNP), multi-walled
[...] Read more.
Hydrogels prepared from TEMPO-oxidized cellulose nanofibrils (TCNFs), natural rubber latex (NRL), and carbon additives change their rheological properties during storage, so formulation comparisons made at uncontrolled aging states can be misleading. Here, TCNF–NRL hydrogels containing graphene conductive additive (GCA), graphene nanoplatelets (GNP), multi-walled carbon nanotubes (MWCNT), carboxylated multi-walled carbon nanotubes (MWCNT-COOH), or graphite were examined through four experimental sets that separate the effects of physical aging, total solids content, TCNF/carbon-additive ratio, carbon-additive loading, and additive identity. Oscillatory and steady-shear measurements were described with Cross and generalized Maxwell fits, and oscillatory-steady comparisons were quantified with a Cox–Merz deviation metric. Aging increased the storage modulus and the Cross low-shear viscosity by factors of 1.3 to 1.9 over about two weeks while the spectra remained elastic-dominated. At the late-storage comparison state, composition changed mainly the magnitude of the moduli and of the flow resistance: rankings by storage modulus and by low-shear viscosity agreed with Spearman rank coefficients of 0.89 to 1.00 across the four sets. At fixed base composition, the carbon additive changed the low-shear viscosity over a seven-fold range, from graphite and GCA at the low end to MWCNT at the high end, and the Cox–Merz deviation, expressed as the mean ratio of complex to steady-shear viscosity, ranged from 3.7 (GNP) to 7.3 (MWCNT). The late-storage states used for these comparisons are operational rather than equilibrated, and their ages differ between formulations, from 11 to 35 days, so the additive comparison was repeated at matched ages and the grouping was confirmed. No electrical or microstructural measurements were performed, so additive effects are reported as rheological observations, not as evidence of conductive-network formation.
Full article
(This article belongs to the Special Issue Advanced Functional Gels for Environmental and Energy Applications)
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Open AccessArticle
Dual-Drug Chitosan Hydrogel Loaded with Metformin and Cefazolin for Antibacterial, Anti-Inflammatory and Antioxidant Treatment of Drug-Resistant Bacteria-Infected Skin Wounds
by
Yilin Zhang, Jie Cao, Yong Yan, Zhaoyang Li, Haiqiang Ren, Chenxiong Xu, Chengfang Qiao and Wei Zhou
Gels 2026, 12(10), 876; https://doi.org/10.3390/gels12100876 - 28 Sep 2026
Abstract
Bacterial-infected skin wounds, especially those caused by drug-resistant pathogens accompanied by persistent inflammation, remain a major clinical therapeutic challenge. Rising antimicrobial resistance compromises the therapeutic effect of conventional single-agent antibiotics, creating an urgent demand for novel wound therapeutics that integrate bactericidal potency, immunomodulation
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Bacterial-infected skin wounds, especially those caused by drug-resistant pathogens accompanied by persistent inflammation, remain a major clinical therapeutic challenge. Rising antimicrobial resistance compromises the therapeutic effect of conventional single-agent antibiotics, creating an urgent demand for novel wound therapeutics that integrate bactericidal potency, immunomodulation and tissue regeneration capacity. In this work, an injectable multifunctional chitosan-based hydrogel (C@MC) was developed, which simultaneously incorporates metformin hydrochloride (as a potential antibiotic adjuvant) and cefazolin sodium (as a β-lactam class antibacterial drug). The optimized C@MC possesses interconnected three-dimensional pores with an initial storage modulus of ~0.83 kPa (C@MC360), featuring desirable mechanical strength, injectability, tissue adhesion and dual pH/glucose-responsive sustained drug release. In vitro evaluations revealed the dose-dependent bactericidal activity of C@MC against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and New Delhi metallo-β-lactamase-1-producing E. coli (NDM-1 E. coli, resistant bacteria). The highest drug-laden group nearly eliminated all wound bacteria in vitro. It scavenged reactive oxygen species (ROS) to lower cellular MDA levels and suppress pro-inflammatory TNF-α and IL-6 in LPS-stimulated RAW 264.7 macrophages. In full-thickness mouse wounds infected with NDM-1 E. coli, C@MC360 achieved nearly complete wound closure, with only a 4.2% residual wound area on day 14, accompanied by suppressed inflammatory infiltration and accelerated wound regeneration. This dual-drug hydrogel integrates antibiotic potentiation, anti-inflammation and antioxidation, providing an intervention regimen for skin wounds infected with drug-resistant bacteria.
Full article
(This article belongs to the Topic Advanced Biomaterials for Wound Healing: From Design to Application)
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Open AccessReview
Functional Hydrogels for Wearable and Implantable Neural Interfaces: Materials, Properties, and Applications
by
Joowan Kim, Jaewoo Park, Yeojin Lee, Goeun Kim, Yunsu Shin, Seoyun Eom and Jinmo Jeong
Gels 2026, 12(10), 875; https://doi.org/10.3390/gels12100875 - 28 Sep 2026
Abstract
Functional hydrogels are increasingly used in neural interfaces. As hydrophilic polymer networks that combine tissue-like softness with tunable conductivity and adhesion, they relieve two fundamental limitations of rigid conventional electrodes within a single material: the mechanical mismatch that drives the chronic foreign body
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Functional hydrogels are increasingly used in neural interfaces. As hydrophilic polymer networks that combine tissue-like softness with tunable conductivity and adhesion, they relieve two fundamental limitations of rigid conventional electrodes within a single material: the mechanical mismatch that drives the chronic foreign body response, and the electrical mismatch that raises interfacial impedance. This review discusses functional hydrogels through their core interfacial properties of biocompatibility, adhesion, and interfacial impedance/conductivity, and highlights how these requirements differ between skin-mounted wearable and implantable devices. Their applications in neural recording, electrical and ultrasound neuromodulation, and external and robotic device control are then covered in detail. Finally, the key challenges and future opportunities are summarized, including gelation control, long-term in vivo stability, integration with robotic hardware, and clinical translation. As the field advances, functional hydrogels are poised to become a core platform for next-generation neural interfaces.
Full article
(This article belongs to the Special Issue Advanced Functional Hydrogels for Wearable Medical Devices)
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Open AccessReview
Carboxymethylcellulose/Hyaluronic Acid Hybrid Nanoconjugates: Toward Multifunctional Platforms for Melanoma Skin Cancer Theranostics
by
Deborah V. Miranda, Alexandra A. P. Mansur, Herman S. Mansur and Isadora C. Carvalho
Gels 2026, 12(10), 874; https://doi.org/10.3390/gels12100874 - 28 Sep 2026
Abstract
Melanoma remains one of the most aggressive forms of skin cancer, characterized by high metastatic potential and risks of tissue trauma and post-surgical recurrence, with limited therapeutic options currently available. While conventional monotherapies often fail to provide comprehensive and efficient treatment, nanoparticle-functionalized hydrogel
[...] Read more.
Melanoma remains one of the most aggressive forms of skin cancer, characterized by high metastatic potential and risks of tissue trauma and post-surgical recurrence, with limited therapeutic options currently available. While conventional monotherapies often fail to provide comprehensive and efficient treatment, nanoparticle-functionalized hydrogel platforms have emerged as promising multifunctional systems for localized combination cancer therapy, capable of integrating multiple therapeutic modalities, such as chemodynamic therapy (CDT), photodynamic therapy (PDT), and photothermal therapy (PTT), tissue recovery support, antibacterial activity, and image-guided treatment into a single biomaterial. This review examines stimulus-responsive hydrogels based on the anionic polysaccharides carboxymethylcellulose (CMC) and hyaluronic acid (HA), conjugated with nanoparticles for melanoma theranostic applications. It evaluates their design, synergistic mechanisms, and therapeutic potential. It considers how combining CMC and HA overcomes the limitations of individual polymers, such as poor mechanical integrity and rapid degradation, and enhances key functionalities, particularly cell targeting and specificity. It also analyzes how incorporating functional nanoparticles can enable on-demand drug release, diagnostic imaging, immune microenvironment remodeling, and combined phototherapy (PTT/PDT). While HA-based nanotheranostic systems are widely documented, the potential of CMC in melanoma treatment remains largely untapped, despite its proven success in tissue engineering and wound management. Most significantly, the literature currently lacks any bio-nanohybrid platform that integrates CMC and HA, driven by functional hybrid nanoparticles, for targeted melanoma therapy. By identifying this critical gap, this review proposes new research avenues for designing these unified, multifunctional platforms as a highly promising strategy for cutaneous melanoma management.
Full article
(This article belongs to the Special Issue Cellulose-Based Gels: Synthesis, Properties, and Applications (2nd Edition))
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Open AccessArticle
Ambient-Dried Cellulose Nanofibril/H2TiO3 Composite Aerogel for Enhanced Lithium Capture at Seawater-Relevant pH
by
Xueqiao Wang, Jing Wang, Wenxuan Wang, Ruimeng Liu, Yimin Shi and Daxin Liang
Gels 2026, 12(10), 873; https://doi.org/10.3390/gels12100873 - 28 Sep 2026
Abstract
Efficient seawater lithium harvesting requires adsorbents combining high selectivity with scalable, low-energy fabrication. Although H2TiO3 lithium-ion sieves (HTO-LIS) exhibit exceptional Li+ selectivity, their deployment is hindered by strict alkaline requirements and reliance on energy-intensive shaping processes such as freeze-drying.
[...] Read more.
Efficient seawater lithium harvesting requires adsorbents combining high selectivity with scalable, low-energy fabrication. Although H2TiO3 lithium-ion sieves (HTO-LIS) exhibit exceptional Li+ selectivity, their deployment is hindered by strict alkaline requirements and reliance on energy-intensive shaping processes such as freeze-drying. Herein, we report a cellulose nanofibril (CNF) composite aerogel addressing both challenges simultaneously. Ammonium phytate (AP), a bio-derived polyphosphate, serves a dual function: as a green crosslinker for CNF and as an in situ alkalinity generator, creating a localized alkaline microenvironment around immobilized HTO nanoparticles that enables efficient topotactic H+/Li+ exchange at seawater-relevant pH 8 without requiring strongly alkaline bulk conditions. Crucially, the AP-crosslinked CNF skeleton withstands capillary forces during ambient-pressure drying, preserving a hierarchical macroporous network without freeze-drying. The resulting AP-CNF@HTO monolith achieves a Li+ capacity of 19.08 mg g−1 at pH 8, a 128.9% enhancement over pristine HTO, with excellent selectivity against competing ions in real seawater and 88.3% capacity retention after ten cycles. This work demonstrates that rational bio-based crosslinker selection can concurrently solve the alkaline microenvironment and ambient-drying challenges of HTO-LIS composites, offering an ambient-pressure-drying route with reduced reliance on energy-intensive freeze-drying for seawater lithium enrichment.
Full article
(This article belongs to the Special Issue Eco-Friendly Gels for Adsorption (2nd Edition))
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Open AccessEditorial
Functional Gels for Dental Applications: Current Advances and Future Perspectives
by
Pedro C. Lopes
Gels 2026, 12(10), 872; https://doi.org/10.3390/gels12100872 - 28 Sep 2026
Abstract
The continuous evolution of biomaterials has profoundly influenced modern dentistry by providing innovative solutions for disease prevention, minimally invasive treatment, tissue regeneration, and implant rehabilitation [...]
Full article
(This article belongs to the Special Issue Functional Gels for Dental Applications)
Open AccessArticle
In Vitro Modeling of Tendon with Type I Collagen Scaffolds
by
Katherine M. Arnold, Tannin Schmidt and Alix Deymier
Gels 2026, 12(10), 871; https://doi.org/10.3390/gels12100871 - 26 Sep 2026
Abstract
In vitro collagen scaffolds provide simplified systems for investigating tendon properties without the use of animal models. However, common scaffold processing approaches, including dehydration and chemical crosslinking, can alter scaffold water content, molecular structure, thermal, and mechanical properties in ways that are not
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In vitro collagen scaffolds provide simplified systems for investigating tendon properties without the use of animal models. However, common scaffold processing approaches, including dehydration and chemical crosslinking, can alter scaffold water content, molecular structure, thermal, and mechanical properties in ways that are not fully understood. In this study, we investigate the influence of ethanol-induced dehydration and genipin crosslinking on type I collagen scaffolds and compare their chemical and thermal properties with native murine Achilles tendons. Fourier Transform Infrared Spectroscopy (FTIR) demonstrated that ethanol treatment reduced molecularly bound water (from 127.3 to 48.0 a.u.) and caused shifts in amide bands (Amide I upshift, Amide II & III downshifts) commonly associated with dehydration, bringing values closer to those of native tendon. Genipin crosslinking further increased similarity to tendon, particularly in thermal behavior as measured by thermogravimetric analysis (TGA). Ten millimolar genipin-treated scaffolds pre-rehydration most closely approximated tendon but diverged post-rehydration. Crosslinking strongly restricted scaffold rehydration (final swelling factor 44.46 vs. 4.06) and altered mechanical properties. Together, these results demonstrate that dehydration and crosslinking influence collagen scaffolds across molecular, thermal, hydration, and mechanical properties. Careful control of these processing conditions, particularly hydration history, is therefore important for collagen-based in vitro models mimicking physicochemical features of native tendon.
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(This article belongs to the Special Issue Functional Hydrogels in Biomedicine)
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Open AccessArticle
HEC-Based Emulgels as Vehicles for NaDES Extracts: Safety, Efficacy, and Sensory Evaluation
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Milica Martinović, Vanja M. Tadić, Ana Žugić, Slavica Blagojević, Stevan Blagojević and Ivana Nešić
Gels 2026, 12(10), 870; https://doi.org/10.3390/gels12100870 - 25 Sep 2026
Abstract
Natural deep eutectic solvent (NaDES) extracts exhibit substantial bioactive potential, including antioxidant, UV-protective, and enzyme-inhibitory activities, owing to their rich phytochemical composition. However, their incorporation into appropriate dermal delivery systems is essential to maximize their efficacy. Our previous studies identified emulgels as innovative
[...] Read more.
Natural deep eutectic solvent (NaDES) extracts exhibit substantial bioactive potential, including antioxidant, UV-protective, and enzyme-inhibitory activities, owing to their rich phytochemical composition. However, their incorporation into appropriate dermal delivery systems is essential to maximize their efficacy. Our previous studies identified emulgels as innovative and effective vehicles for NaDES extracts of green tea and bilberry leaves. In the present study, the in vivo performance of hydroxyethyl cellulose (HEC)-based emulgels containing 12% (w/w) NaDES extracts was evaluated. Formulations stabilized with cetearyl olivate/sorbitan olivate (5%) were compared with those stabilized using cetearyl alcohol/cetearyl glucoside (6%) in a study involving 25 healthy volunteers. Over a 28-day application period, key biophysical skin parameters, including skin pH, transepidermal water loss (TEWL), erythema index (EI), skin capacitance (EC), melanin index (MI), and friction coefficient (F), were monitored. Additionally, a 24 h skin safety assessment and a sensory evaluation were conducted. Both formulations demonstrated excellent safety profiles, with no signs of irritation observed during the 24 h safety study. The emulgels stabilized with cetearyl olivate/sorbitan olivate produced significant improvements in skin biophysical parameters. Skin barrier recovery, indicated by a reduction in TEWL, was achieved within two weeks, while enhanced skin hydration was maintained throughout the study period. Sensory evaluation further demonstrated superior spreadability of the olivate-based formulations. Overall, these findings confirm that HEC-based emulgels are promising dermal delivery systems for NaDES extracts, combining excellent safety, efficacy, and favorable sensory properties.
Full article
(This article belongs to the Special Issue Recent Advances in Biopolymer Gels (3rd Edition))
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Open AccessArticle
Photothermal MOF–Alginate Hydrogel Beads for Solar-Driven Atmospheric Water Harvesting
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Roberto Di Pietro, Vincenza Brancato, Andrea Frazzica, Alessandro Sinopoli and Elpida Piperopoulos
Gels 2026, 12(10), 869; https://doi.org/10.3390/gels12100869 - 25 Sep 2026
Abstract
Atmospheric water harvesting (AWH) has emerged as a promising strategy for decentralised freshwater production in regions where conventional water infrastructure is limited. Among the various approaches, sorption-based systems employing metal–organic frameworks (MOFs) are particularly attractive due to their high surface area and tunable
[...] Read more.
Atmospheric water harvesting (AWH) has emerged as a promising strategy for decentralised freshwater production in regions where conventional water infrastructure is limited. Among the various approaches, sorption-based systems employing metal–organic frameworks (MOFs) are particularly attractive due to their high surface area and tunable pore chemistry. In this work, we report the development of structured photothermal composite beads based on Ca2+-crosslinked sodium alginate (SA) incorporating MIL-101(Cr) and MIL-100(Fe) MOFs together with graphene oxide (GO) as a solar absorber. The resulting MOF–alginate–GO beads combine high water adsorption capacity with efficient photothermal regeneration and good mechanical robustness. The Ca2+-crosslinked alginate network acts as a water-permeable hydrogel scaffold, enabling repeated swelling–drying cycles while integrating MOF sorption capacity and GO-mediated light-to-heat conversion. Dynamic vapour sorption measurements reveal characteristic cooperative adsorption behaviour, with MIL-101(Cr) beads exhibiting an earlier adsorption step at ~30–40% RH, while MIL-100(Fe) beads activate at ~45–55% RH. Under simulated solar irradiation (1 sun), the incorporation of GO enhances solar-to-thermal conversion, increasing the fraction of desorbed water by approximately 22%, 12%, and 8% relative to the corresponding GO-free SA, Fe/SA, and Cr/SA formulations, respectively. These results highlight the potential of MOF–alginate photothermal composites as scalable sorbents for solar-driven atmospheric water harvesting, particularly in moderate-humidity environments.
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(This article belongs to the Special Issue Stimuli-Responsive Functional Gels and Soft Materials)
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Open AccessArticle
Cyclodextrin-Containing Tannic Acid–Lipoic Acid Hydrogels for the Loading and Reduction-Responsive Release of Nile Red
by
Yuzheng Zhu, Kazuya U. Kobayashi, Akihiko Hatano, Manabu Suzuki and Kenichi Niikura
Gels 2026, 12(10), 868; https://doi.org/10.3390/gels12100868 - 25 Sep 2026
Abstract
Hydrophobic molecules are generally difficult to incorporate into aqueous hydrogels because of their poor water solubility. In this study, a cyclodextrin (CD)-containing tannic acid–lipoic acid (TA–LA) hydrogel was developed using lipoic acid-modified β-cyclodextrin (LACD). LACD retained the host–guest recognition ability of the cyclodextrin
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Hydrophobic molecules are generally difficult to incorporate into aqueous hydrogels because of their poor water solubility. In this study, a cyclodextrin (CD)-containing tannic acid–lipoic acid (TA–LA) hydrogel was developed using lipoic acid-modified β-cyclodextrin (LACD). LACD retained the host–guest recognition ability of the cyclodextrin cavity after lipoic acid modification and was successfully incorporated into the TA–LA hydrogel without interfering with gel formation. Using Nile Red (NR) as a model hydrophobic molecule, the LACD-containing hydrogel showed higher NR encapsulation efficiency and greater cyclodextrin retention than the hydrogel containing unmodified β-cyclodextrin. The LACD-containing hydrogel also exhibited reduction-responsive NR release in the presence of dithiothreitol (DTT). These results show that LACD can be incorporated into the TA–LA hydrogel while retaining the host–guest recognition ability of the cyclodextrin cavity and can be used for reduction-responsive release of NR.
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(This article belongs to the Section Gel Applications)
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Open AccessReview
Hyaluronan Hydrogels: Three Material States in Regenerative Orthopaedics
by
Fábio Ramos Costa, Maria Helena Andrade Santana, Rubens Martins de Andrade, João Protásio Netto, Luyddy Pires, Gabriel Azzini, André Kruel, Tomas Mosaner, Lucas Furtado da Fonseca and José Fábio Lana
Gels 2026, 12(10), 867; https://doi.org/10.3390/gels12100867 - 25 Sep 2026
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Hyaluronan-based materials are widely described as hydrogels, yet the term is applied without distinction to preparations that differ fundamentally in structure. This review addresses that imprecision by separating three material states of hyaluronan and by stating the criteria under which each may be
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Hyaluronan-based materials are widely described as hydrogels, yet the term is applied without distinction to preparations that differ fundamentally in structure. This review addresses that imprecision by separating three material states of hyaluronan and by stating the criteria under which each may be called a gel: native linear hyaluronan, which forms a viscoelastic solution; the hexadecylamide derivative (HYADD-4), which self-assembles into a transient physical network through hydrophobic interactions; and hyaluronan cross-linked with 1,4-butanediol diglycidyl ether (BDDE), which forms a covalent three-dimensional network. A material is treated as a gel here only where both a percolated network and a solid-like mechanical response are documented. On that basis the covalent network qualifies; the derivative is elastic-dominated across the walking-to-running frequency band of the knee but has not been subjected to a formal Winter–Chambon analysis and is therefore described as gel-like; and the linear solution does not qualify at the molecular weights and concentrations used in marketed viscosupplements. We review the chemistry of network formation, the comparative physicochemical and rheological behavior, including viscosity, the storage and loss moduli, boundary lubrication, and resistance to enzymatic and oxidative degradation, and the receptor-mediated and anti-inflammatory mechanisms of action involving CD44 and molecular-weight-dependent signaling. Clinical and regenerative applications in osteoarthritis viscosupplementation and in scaffolds and carriers for cells and growth factors are summarized for each state. The networked materials show higher viscoelasticity and greater resistance to degradation than the linear solution, which provides a rationale for longer residence; the evidence for a clinical advantage over conventional hyaluronan, however, rests largely on preclinical and rheological data. A three-state framework is proposed, pending validation, to support clearer interpretation of the literature and more rational material selection.
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Open AccessArticle
Super-Hydrophobic Macroporous TPU Gels for Oil–Water Separation and Organic Pollutant Adsorption
by
Jingjing An, Xianbo Zhou, Xuan Zhou, Yingying Wang, Zhihao Lin, Feng Xu and Zhenxing Fang
Gels 2026, 12(10), 866; https://doi.org/10.3390/gels12100866 - 24 Sep 2026
Abstract
Marine oil spills and plastic waste accumulation represent two critical environmental threats that urgently require integrated remediation strategies. In this work, we address both issues simultaneously by developing a facile, template-free, water-assisted thermally induced phase separation approach to fabricate superhydrophobic macroporous thermoplastic polyurethane
[...] Read more.
Marine oil spills and plastic waste accumulation represent two critical environmental threats that urgently require integrated remediation strategies. In this work, we address both issues simultaneously by developing a facile, template-free, water-assisted thermally induced phase separation approach to fabricate superhydrophobic macroporous thermoplastic polyurethane (TPU) gels from recycled TPU pellets. Under optimal conditions (8% TPU, 9:1 1,4-dioxane/water, 0 °C, 30 min), the gel exhibits an interconnected macroporous network with ~84% porosity and a BET surface area of 7.67 m2/g. Notably, it achieves intrinsic superhydrophobicity (150.3°) without any additives or surface modifications. The gel shows high absorption capacities (5.39–55.64 g/g), rapid kinetics (equilibrium within 15 s), and excellent recovery efficiency (>97%) in pump-assisted separation. Beyond oil/water mixtures, we systematically investigate trace organic pollutant adsorption from oil-in-water emulsions, achieving up to 97% removal efficiency. This work establishes a closed-loop “waste-to-resource” strategy, positioning recycled-TPU-derived macroporous gels as cost-effective candidates for oil spill remediation and wastewater treatment.
Full article
(This article belongs to the Special Issue Eco-Friendly Gels for Adsorption (2nd Edition))
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Open AccessArticle
Effect of a Fiber Raw Material Structure on the Properties of Cellulose/Polyacrylamide Double-Network Antifreezing Conductive Hydrogels Prepared in an AlCl3/ZnCl2 Aqueous System
by
Xiaowei Zhuang, Shuqi Guo, Yue Liu, Zhijun Wu, Yongshun Feng, Hui Qiao, Guoqiang Zhu and Xin Pan
Gels 2026, 12(10), 865; https://doi.org/10.3390/gels12100865 - 24 Sep 2026
Abstract
The trade-off between mechanical properties and ionic conductivity, together with low-temperature failure, restricts the practical application of ionically conductive hydrogels. In this work, four bleached pulp boards (eucalyptus, pine, bagasse and cotton) were dissolved in an AlCl3/ZnCl2 aqueous solution, followed
[...] Read more.
The trade-off between mechanical properties and ionic conductivity, together with low-temperature failure, restricts the practical application of ionically conductive hydrogels. In this work, four bleached pulp boards (eucalyptus, pine, bagasse and cotton) were dissolved in an AlCl3/ZnCl2 aqueous solution, followed by in situ polymerization of acrylamide to fabricate cellulose/polyacrylamide double-network conductive hydrogels. The cotton-based gel exhibited the best pristine tensile performance (105 kPa, 1566%) and the highest room temperature ionic conductivity (50.5 mS/cm). At −30 °C, except for pure PAM (which froze beyond the load cell limit), the other five gels remained soft (stress at 70% strain only 1.13–1.35 times that at room temperature). After freeze–thaw cycles, the tensile strengths of the bagasse and pine gels increased by 52% and 46%, respectively, whereas that of the cotton-based gel decreased by 37%. At −40 °C, the pine-based gel retained the best conductivity (0.83 mS/cm, 5.1% retention). In addition, the gels exhibited strain-dependent electrical resistance responses at the material level. The structure–property correlations indicate that the influence of the fiber source does not depend solely on the degree of polymerization, but arises from the combined effects of the aggregation state of regenerated cellulose, pore wall architecture, dynamic hydrogen bonding and water-binding capability on ion channel continuity, low-temperature ion transport and freeze–thaw-induced network reorganization. This study provides a material-level experimental basis for selecting fiber raw materials for antifreezing conductive hydrogels. Device-level performance remains to be validated.
Full article
(This article belongs to the Special Issue Cellulose Gels: Preparation, Properties and Applications)
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Open AccessArticle
Copper Peroxide-Loaded Dual-Responsive Hydrogel for Enhanced Diabetic Wound Healing Through Oxygen Release and Promotion of Angiogenesis
by
Lanqin Yu, Xiang Jia, Lejia Xu, Xiaojun Li, Na Li, Lihua Li, Yifan Zhang and Changren Zhou
Gels 2026, 12(10), 864; https://doi.org/10.3390/gels12100864 - 24 Sep 2026
Abstract
Diabetic foot ulcers (DFUs) present a major clinical challenge because of persistent hyperglycemia, hypoxia, impaired angiogenesis, and chronic inflammation. Conventional dressings have limited capacity to modulate these pathological processes. Here, we report a glucose/pH dual-responsive hydrogel, denoted CBOD, constructed through a dynamic covalent
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Diabetic foot ulcers (DFUs) present a major clinical challenge because of persistent hyperglycemia, hypoxia, impaired angiogenesis, and chronic inflammation. Conventional dressings have limited capacity to modulate these pathological processes. Here, we report a glucose/pH dual-responsive hydrogel, denoted CBOD, constructed through a dynamic covalent network comprising Schiff base and boronate ester bonds between phenylboronic acid-grafted chitosan (CS-BA) and dopamine-modified oxidized sodium alginate (OSA-DA). Copper peroxide (CuO2) nanoparticles are encapsulated within this network to form CuO2/CBOD. Under acidic (pH 5.5) and high-glucose conditions, competitive binding and bond hydrolysis promote network relaxation, facilitating the stimuli-dependent release of oxygen and copper ions. In vitro assessments demonstrate good cytocompatibility and enhanced migration and tube formation of human umbilical vein endothelial cells (HUVECs). In a diabetic rat model of full-thickness excisional wounds, the hydrogel accelerates wound closure, with closure approaching 100% by day 14. Treatment is associated with reduced expression of the M1-associated markers interleukin-1β (IL-1β) and cluster of differentiation 80 (CD80), increased expression of the M2-associated markers interleukin-10 (IL-10) and cluster of differentiation 163 (CD163), and enhanced expression of the vascular markers cluster of differentiation 31 (CD31) and alpha-smooth muscle actin (α-SMA). These findings support the potential of CuO2/CBOD as a multifunctional dressing for diabetic wound management.
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(This article belongs to the Special Issue Hydrogel for Sustained Delivery of Therapeutic Agents (3rd Edition))
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Open AccessReview
Working Hydration as a Design Variable in Hydrogel Fibers: Coupled Transport, Signal Fidelity, and Wearable Electronics
by
Yaqin Tian, Wanxue Sun, Liyin Hou, Shanshan Guo, Xiaojuan Wang, Caixia Ren and Zhe Cui
Gels 2026, 12(10), 863; https://doi.org/10.3390/gels12100863 - 24 Sep 2026
Abstract
Hydrogel fibers combine a hydrated medium resembling tissue with axial continuity, anisotropy, and textile processability. Yet performance is often evaluated at a nominal water content that cannot represent water redistribution during operation. Unlike previous reviews centered on composition, fabrication, or application, this Review
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Hydrogel fibers combine a hydrated medium resembling tissue with axial continuity, anisotropy, and textile processability. Yet performance is often evaluated at a nominal water content that cannot represent water redistribution during operation. Unlike previous reviews centered on composition, fabrication, or application, this Review uses the working hydration state to link network evolution, transport, signal generation, integration, and reliability. It refers to water distribution, physicochemical state, and exchange dynamics under operating conditions. Four themes are examined: network evolution induced by hydration, axial and radial transport, signal generation and decoupling, and preservation of function from fibers to textiles and biointerfaces. Comparative analysis indicates that reliable operation requires preserved axial pathways, controlled radial exchange, spatial separation of coupled signals, reference channels, and calibration after hydration and deformation histories. Direct fiber evidence is distinguished from transferable evidence from soft devices. Major gaps include inconsistent equilibration criteria, nonstandard hydration cycling, insufficient synchronized operando measurements, limited interlaboratory reproducibility and human validation over extended periods, and scarce manufacturing statistics. Future research should prioritize models that account for hydration, standardized service testing, scalable textile processing, and validation across devices and users. This framework establishes working hydration as a basis for material design, signal interpretation, and reliability assessment.
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(This article belongs to the Special Issue Advances in Hydrogels for Flexible Electronics)
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Open AccessArticle
Conetworks and Organogels of Poly(methyl acrylate) Crosslinked with Degradable, Disulfide and β-Thioester Containing Bisacrylate Macromonomer
by
Aiman Aitkazina, Ákos Szabó, László Trif, Klára Verebélyi, Dóra Fecske, Anna Petróczy and Béla Iván
Gels 2026, 12(10), 862; https://doi.org/10.3390/gels12100862 - 24 Sep 2026
Abstract
Here, we report, for the first time, on a new class of sulfur-containing double hydrophopbic conetworks, poly(methyl acrylate)-l-poly(3,6-dioxa-1,8-octane-dithiol-co-poly(ethylene glycol) diacrylate) (PMA-l-P(DODT-co-PEGDA). Direct one-pot synthesis of acrylate-telechelic P(DODT-co-PEGDA) macromonomer in a gram-scale for the
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Here, we report, for the first time, on a new class of sulfur-containing double hydrophopbic conetworks, poly(methyl acrylate)-l-poly(3,6-dioxa-1,8-octane-dithiol-co-poly(ethylene glycol) diacrylate) (PMA-l-P(DODT-co-PEGDA). Direct one-pot synthesis of acrylate-telechelic P(DODT-co-PEGDA) macromonomer in a gram-scale for the preparation of the conetworks was obtained by copolymerization of DODT with PEGDA via simultaneous oxidative disulfide formation and thiol–ene Michael addition click reactions. Conetworks with a broad composition range of 20–70 wt% sulfur-rich P(DODT-co-PEGDA) macrocrosslinker contents were obtained by radical copolymerization. High gel fractions and composition near to that of the feed ratios verified successful conetwork synthesis. DSC analysis indicates forced blending of the immiscible PMA and P(DODT-co-PEGDA) in the conetworks by one single Tg, which deviates from both the additive rule and the Fox equation for miscible blends. These novel conetworks exhibit high thermal stability up to ~300 °C and independent decomposition patterns of the components in two separate steps. The PMA-l-P(DODT-co-PEGDA) conetworks behave as organogels by swelling in organic solvents, such as THF, acetone, toluene, with composition dependent swelling degrees up to ~900%. Degradation by breaking the disulfide bonds with thiols followed by hydrolysis with NaOH led to complete disintegration of the PMA-l-P(DODT-co-PEGDA) conetworks. These findings enable establishing a new platform for the rational design of a variety of novel sulfur-containing functional and degradable macromolecular assemblies.
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(This article belongs to the Special Issue Women’s Special Issue Series: Gels (2nd Edition))
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Open AccessReview
Stimuli-Responsive Hydrogels for Oral Probiotic Delivery: Balancing Protection and Site-Specific Release
by
Sungwon Jung, Sookyung Noh, Hyeonseung Lee and Sohyeon Park
Gels 2026, 12(10), 861; https://doi.org/10.3390/gels12100861 - 24 Sep 2026
Abstract
Successful oral probiotic delivery requires protection of viable cells during gastrointestinal transit followed by efficient release at the target intestinal site. Stimuli-responsive hydrogels can provide both functions, although network properties that restrict acid, bile, and enzyme transport may also delay the structural changes
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Successful oral probiotic delivery requires protection of viable cells during gastrointestinal transit followed by efficient release at the target intestinal site. Stimuli-responsive hydrogels can provide both functions, although network properties that restrict acid, bile, and enzyme transport may also delay the structural changes required for release. This review discusses how crosslink density, particle geometry, the internal microenvironment, and interfacial layers shape this protection–release relationship. pH-, enzyme/microbiota-, redox-, and multi-stimuli-responsive systems are compared with emphasis on the structural changes that allow bacterial escape. Because probiotic cells are much larger than the molecular mesh of most hydrogels, release generally requires network opening through swelling, formation or enlargement of cell-scale pores or defects, erosion, fracture, de-crosslinking, or dissolution rather than ordinary molecular diffusion. Delivery performance should therefore be evaluated using release kinetics, viability of released cells, retained cells, and total viable recovery in sequential gastrointestinal models. Strain-specific testing, storage studies, and in vivo validation will also be important. The practical goal is a reproducible protection–release window that maintains cell viability without delaying release.
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(This article belongs to the Special Issue Engineering Advanced Gels for Biomedical Therapeutics and Sustainable Materials)
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Open AccessArticle
Bioinspired Suction-Cup Architecture Modulates Hydration and Pomegranate-Extract Release from NVP/HEMA/CMC Hydrogels
by
Nadda Chiaoprakobkij, Wasipim Chansiriwat, Wisanee Wisanwattana, Neti Waranuch, Thanyaporn Pinthong, Sukunya Ross, Jarupa Viyoch and Gareth Ross
Gels 2026, 12(10), 860; https://doi.org/10.3390/gels12100860 - 24 Sep 2026
Abstract
Surface architecture may tune hydrogel transport without changing formulation. Flat and suction-cup N-vinylpyrrolidone/2-hydroxyethyl methacrylate/carboxymethyl cellulose (NVP/HEMA/CMC) hydrogels prepared from the same nominal formulation were compared for hydration, equilibrium water content, pomegranate-extract uptake, and 60 min release. Suction-cup hydrogels showed greater short-term swelling (38.7
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Surface architecture may tune hydrogel transport without changing formulation. Flat and suction-cup N-vinylpyrrolidone/2-hydroxyethyl methacrylate/carboxymethyl cellulose (NVP/HEMA/CMC) hydrogels prepared from the same nominal formulation were compared for hydration, equilibrium water content, pomegranate-extract uptake, and 60 min release. Suction-cup hydrogels showed greater short-term swelling (38.7 ± 0.7%) than flat hydrogels (31.4 ± 0.6%), a 23.1% increase, while equilibrium water contents remained similar. Apparent extract uptake, estimated from loading-solution depletion, was 20.45 and 15.74 mg/g hydrated hydrogel for suction-cup and flat formats, respectively. After 60 min, cumulative apparent pomegranate-extract-equivalent release was 6.976 ± 0.681 and 4.208 ± 0.354 mg, respectively, representing a 65.8% increase. These values corresponded to approximately 17.6% and 15.2% of estimated initial loadings. Indirect-extract testing showed minimum viabilities of 86.24% for HaCaT cells and 71.01% for human dermal fibroblasts, exceeding the 70% ISO 10993-5 criterion. Overall, suction-cup architecture increased early swelling, estimated uptake, and cumulative release without altering formulation. Although the individual contributions of surface area, local thickness, liquid retention, and diffusion paths could not be separated, the results demonstrate that architectural modification can enhance early hydration and extract uptake and release while preserving the hydrogel formulation.
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(This article belongs to the Special Issue Polymeric Hydrogels for Biomedical Application (2nd Edition))
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