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Gels
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Functional Gel Materials and Applications
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Functional Gel Materials and Applications

A special issue of Gels (ISSN 2310-2861). This special issue belongs to the section "Gel Applications".

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 20895

Special Issue Editors

Dr. Di Chen

E-Mail Website
Guest Editor
Ningbo Innovation Center, Zhejiang University, Hangzhou 310027, China
Interests: polymer gels; photo patterning; dynamic covalent networks; shape-shifting materials
Dr. Zizheng Fang

E-Mail Website
Guest Editor
ZJU-Hangzhou Global Scientific and Technological Innovation Center, No. 733, Jianshe San Road, Xiaoshan District, Hangzhou 311200, China
Interests: 3D/4D printing; gel manufacturing; shape memory polymers; dynamic covalent chemistry
Dr. Hua Ren

E-Mail Website
Guest Editor
Ningbo Innovation Center, Zhejiang University, Hangzhou 310027, China
Interests: polymer gels; dynamic covalent networks; epoxy resin

Special Issue Information

Dear Colleagues,

Gels are liquid swollen networks with fascinating functionalities. Sometimes, they also represent a physical state for materials between liquid and solid. Recent years have witnessed rapid growth in gels and their applications. With the rational molecular design, gels can respond to many environmental stimulations. A typical example is a smart hydrogel, which is sensitive to changing temperatures, pH values, chemical components, etc. The multi-responsive features of gels, consequently, inspire various unique applications. In addition, mechanical properties have a big impact. Owing to the soft textures, gels are usually employed in biological fields for wound healing and tissue engineering. Through the diverse approaches to strengthening gels, they can tolerate large external forces for long-term services, thus being applied to flexible electronics and soft machines. In addition, some unique functions of gels are achieved by mimicking biological intelligence.

Despite huge progress, new questions and challenges continuously emerge. Future works demand interdisciplinary cooperation between material science, chemistry, biology, and engineering. This Special Issue, “Functional gel materials and applications”, aims to provide a platform to present the latest innovative progress on gels, including different network designs and unique usages. In addition, works that report the deep structure information of a gel and present correlations between the molecular structures and functions are also welcome.

Dr. Di Chen
Dr. Zizheng Fang
Dr. Hua Ren
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Gels is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • network design of gels
  • gel applications
  • structure characterizations related to gel functions
  • novel manufacturing of gel materials

Published Papers (16 papers)

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Research

13 pages, 2949 KiB  
Article
Anti-UV Microgel Based on Interfacial Polymerization to Decrease Skin Irritation of High Permeability UV Absorber Ethylhexyl Methoxycinnamate
by Wei Wang, Qi-Tong He, Yin-Feng Chen, Bai-Hui Wang, Wen-Ying Xu, Qing-Lei Liu and Hui-Min Liu
Gels 2024, 10(3), 177; https://doi.org/10.3390/gels10030177 - 02 Mar 2024
Viewed by 806
Abstract
Ethylhexyl methoxycinnamate (EHMC) is frequently employed as a photoprotective agent in sunscreen formulations. EHMC has been found to potentially contribute to health complications as a result of its propensity to produce irritation and permeate the skin. A microgel carrier, consisting of poly(ethylene glycol [...] Read more.
Ethylhexyl methoxycinnamate (EHMC) is frequently employed as a photoprotective agent in sunscreen formulations. EHMC has been found to potentially contribute to health complications as a result of its propensity to produce irritation and permeate the skin. A microgel carrier, consisting of poly(ethylene glycol dimethacrylate) (pEDGMA), was synthesized using interfacial polymerization with the aim of reducing the irritation and penetration of EHMC. The thermogravimetric analysis (TGA) indicated that the EHMC content accounted for 75.72% of the total composition. Additionally, the scanning electron microscopy (SEM) images depicted the microgel as exhibiting a spherical morphology. In this study, the loading of EHMC was demonstrated through FTIR and contact angle tests. The UV resistance, penetration, and skin irritation of the EHMC-pEDGMA microgel were additionally assessed. The investigation revealed that the novel sunscreen compound, characterized by limited dermal absorption, had no irritant effects and offered sufficient protection against ultraviolet radiation. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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17 pages, 10793 KiB  
Article
The Advantages of Non-Adhesive Gel-like Embolic Materials in the Endovascular Treatment of Benign Hypervascularized Lesions of the Head and Neck
by Andrey Petrov, Arkady Ivanov, Egor Kolomin, Nikita Tukanov, Anna Petrova, Larisa Rozhchenko and Julia Suvorova
Gels 2023, 9(12), 954; https://doi.org/10.3390/gels9120954 - 04 Dec 2023
Viewed by 1073
Abstract
Objectives: The use of non-adhesive gel-like embolic materials (NAGLEMs) in the endovascular treatment of hypervascularized formations in the head and neck is gaining in popularity because of a number of important characteristics involved. Their primary benefits are their capacity to penetrate diseased vasculature, [...] Read more.
Objectives: The use of non-adhesive gel-like embolic materials (NAGLEMs) in the endovascular treatment of hypervascularized formations in the head and neck is gaining in popularity because of a number of important characteristics involved. Their primary benefits are their capacity to penetrate diseased vasculature, effectively distribute, and, most importantly, remain controllable during the process. We reviewed the literature and evaluated the results of using NAGLEMs in comparison to other embolizing substances (namely, coils, glue, and particles) as alternative embolizing agents for patients receiving care at our clinic. The process comprised evaluating the safety, effectiveness, and technological elements of endovascular therapy used to treat two categories of hypervascular pathological abnormalities that were surgically corrected between 2015 and 2023. Arteriovenous malformations (AVMs) located in the head, neck, and paragangliomas with jugular/carotid body localization are combined by intense shunting blood flow and shared requirements for the embolic agent used in endovascular treatment (such as penetration, distribution, delayed polymerization, and controllability). An analysis of the literature was also conducted. Results showed 18 patients diagnosed with neck paragangliomas of the carotid body and jugular type. Five patients with arteriovenous malformation (AVM) of the face and neck were included, consisting of sixteen females and seven males with an average age of 55 ± 13 years. Endovascular procedures were performed using NAGLEMs (ONYX (Medtronic, Irvine, CA, USA), SQUID (Balt, Montmorency, France), and PHIL (Microvention, Tustin, CA, USA)) and dimethyl sulfoxide (DMSO)-compatible balloon catheters. All patients achieved complete or partial embolization of hypervascularized formations using one or more stages of endovascular treatment. Additionally, three AVMs of the face and two paragangliomas of the neck were surgically excised following embolization. In other instances, formations were not deemed necessary to be removed. The patients’ condition upon discharge was assessed by the modified Rankin Scale (mRs) and rated between 0 and 2. Conclusion: Currently, NAGLEMs are predominantly used to treat hypervascularized formations in the neck and head due to their fundamental properties. These properties include a lack of adhesion and a delay in predictable polymerization (after 30–40 min). NAGLEMs also exhibit excellent distribution and penetration throughout the vascular bed of the formation. Adequate controllability of the process is largely achieved through the presence of embolism forms of different viscosity, as well as excellent X-ray visualization. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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17 pages, 5037 KiB  
Article
Injectable Decellularized Extracellular Matrix-Based Bio-Ink with Excellent Biocompatibility for Scarless Urethra Repair
by Wenzhuo Fang, Ming Yang, Yangwang Jin, Kaile Zhang, Ying Wang, Meng Liu, Yuhui Wang, Ranxing Yang and Qiang Fu
Gels 2023, 9(11), 913; https://doi.org/10.3390/gels9110913 - 17 Nov 2023
Viewed by 1035
Abstract
In recent years, decellularized extracellular matrices (dECM) derived from organs have attracted much attention from researchers due to their excellent biocompatibility, capacity to promote cell proliferation and migration, as well as pro-vascularization. However, their inferior mechanical properties, slow cross-linking, weak strengths, and poor [...] Read more.
In recent years, decellularized extracellular matrices (dECM) derived from organs have attracted much attention from researchers due to their excellent biocompatibility, capacity to promote cell proliferation and migration, as well as pro-vascularization. However, their inferior mechanical properties, slow cross-linking, weak strengths, and poor supporting properties remain their inevitable challenges. In our study, we fabricated a novel dECM hydrogel with better crosslinking strength and speed, stronger support properties, and better mechanical properties. The hydrogel, which we named gelatin-based dECM powder hydrogel (gelatin-dECM hydrogel), was prepared by mixing dECM microparticles in gelatin solution and adding certain amount of 1-Ethyl-3-(3-dimethyl-aminopropyl-1-carbodiimide) (EDC) and N-hydroxysuccinimide (NHS). We evaluated the utility of this hydrogel by assessing the degradation rate, mechanical properties, and biocompatibility. The results showed that the gelatin-dECM hydrogel has high mechanical properties and biocompatibility and also has the ability to promote cell proliferation and migration. After injection of this hydrogel around the surgical sites of urethras in rabbits, the incorporation of dECM powder was demonstrated to promote angiogenesis as well as scarless repair by histological sections after surgery. The application of this novel hydrogel provides a new perspective for the treatment of post-traumatic urethral stricture. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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18 pages, 3422 KiB  
Article
Evaluation of Mitigation Role of L-Phenylalanine-Based Low-Molecular-Weight Gelator against Oil Pollution-Induced Nile Tilapia Toxicity
by Mohamed Mehawed Abdellatif, Noha M. Sabry, Saber Ibrahim, Samah M. Bassem, Wagdy K. B. Khalil and Fagr Kh. Abdel-Gawad
Gels 2023, 9(11), 848; https://doi.org/10.3390/gels9110848 - 26 Oct 2023
Viewed by 2065
Abstract
A lot of oil is leaked into aquatic environments, significantly impacting fish health and, consequently, human populations. This study aimed to introduce an L-phenylalanine-based low-molecular-weight gelator (expressed as Z-Phe-C18) as a smart remediation tool for oil spills. Several groups of Nile [...] Read more.
A lot of oil is leaked into aquatic environments, significantly impacting fish health and, consequently, human populations. This study aimed to introduce an L-phenylalanine-based low-molecular-weight gelator (expressed as Z-Phe-C18) as a smart remediation tool for oil spills. Several groups of Nile tilapia were allocated in aquaria exposed to different doses of crude engine oil with/without the organogelator for 4 weeks. The results revealed a significant increase in biochemical oxygen demand, chemical oxygen demand, electrical conductivity, and total dissolved solids in water samples of fish aquaria exposed to oil pollution. The antioxidant activity levels, micronucleus formation, and expression patterns of stress-related genes were significantly higher in the livers of fish exposed to crude oil than in those of control fish. On the contrary, fish groups exposed to oil pollution and treated with the organogelator indicated that antioxidant enzymes, micronucleus incidence, and gene expression alteration of stress-related genes declined compared with those exposed to oil pollution only. The results suggest that oil pollution can induce oxidative stress via the enhancement of oxygen free radical formation. On the contrary, oil removal by the organogelator decreases oxidative stress and consequently strengthens fish immunity. So, we can conclude that organogelator treatment is promoting oxidative resistance development by increasing the activities of antioxidant enzymes, which are important in protection against oil pollution and preventing peroxidation of fish tissues. Promisingly, the organogelator could be used as a tool for the remediation of oil pollution in aquatic environments. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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17 pages, 5427 KiB  
Article
Removal of Arsenate by Fixed-Bed Columns Using Chitosan-Magnetite Hydrogel Beads and Chitosan Hydrogel Beads: Effect of the Operating Conditions on Column Efficiency
by Eduardo Mendizabal, Nely Ríos-Donato, Carlos Federico Jasso-Gastinel and Ilse Paulina Verduzco-Navarro
Gels 2023, 9(10), 825; https://doi.org/10.3390/gels9100825 - 19 Oct 2023
Cited by 2 | Viewed by 1184
Abstract
Fixed-bed columns packed with chitosan-magnetite (ChM) hydrogel and chitosan (Ch) hydrogel were used for the removal of arsenate ions from aqueous solutions at a pH of 7.0. The effect of flow rate (13, 20, and 25 mL/h), height of the columns (13 and [...] Read more.
Fixed-bed columns packed with chitosan-magnetite (ChM) hydrogel and chitosan (Ch) hydrogel were used for the removal of arsenate ions from aqueous solutions at a pH of 7.0. The effect of flow rate (13, 20, and 25 mL/h), height of the columns (13 and 33 cm), and initial arsenate concentration (2, 5 and 10 mg/L) on the column’s efficiency for the removal of As(V) is reported. The maximum adsorption capacity (qb), obtained before the allowed concentration of contaminant is exceeded, the adsorption capacity (qe) when the column is exhausted, and the mass transfer zone were determined. With this information, the efficiency of the column was calculated, which is given by the HL/HLUB ratio. The higher this ratio, the higher the efficiency of the column. The highest efficiency and the highest uptake capacity value at breakthrough point were obtained when using the lower flow rate, lower initial arsenate concentration, and longer bed length. When 33 cm-high columns were fed with a 10 mg As(V)/L solution at 13 mL/h, the maximum uptake capacity values at exhaustion obtained for Ch and ChM were 1.24 and 3.84 mg/g, respectively. A pH increase of the solution at the column’s exit was observed and is attributed to the proton transfer from the aqueous solution to the amino and hydroxyl groups of chitosan. The incorporation of magnetite into Ch hydrogels significantly increases their capacity to remove As(V) due to the formation of complexes between arsenic and the magnetite surface. Experimental data were fitted to the Thomas model, the Yoon–Nelson model and the Bohart–Adams model using non-linear regression analysis. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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17 pages, 16693 KiB  
Article
Self-Standing 3D-Printed PEGDA–PANIs Electroconductive Hydrogel Composites for pH Monitoring
by Rocco Carcione, Francesca Pescosolido, Luca Montaina, Francesco Toschi, Silvia Orlanducci, Emanuela Tamburri and Silvia Battistoni
Gels 2023, 9(10), 784; https://doi.org/10.3390/gels9100784 - 26 Sep 2023
Cited by 2 | Viewed by 987
Abstract
Additive manufacturing (AM), or 3D printing processes, is introducing new possibilities in electronic, biomedical, sensor-designing, and wearable technologies. In this context, the present work focuses on the development of flexible 3D-printed polyethylene glycol diacrylate (PEGDA)- sulfonated polyaniline (PANIs) electrically conductive hydrogels (ECHs) for [...] Read more.
Additive manufacturing (AM), or 3D printing processes, is introducing new possibilities in electronic, biomedical, sensor-designing, and wearable technologies. In this context, the present work focuses on the development of flexible 3D-printed polyethylene glycol diacrylate (PEGDA)- sulfonated polyaniline (PANIs) electrically conductive hydrogels (ECHs) for pH-monitoring applications. PEGDA platforms are 3D printed by a stereolithography (SLA) approach. Here, we report the successful realization of PEGDA–PANIs electroconductive hydrogel (ECH) composites produced by an in situ chemical oxidative co-polymerization of aniline (ANI) and aniline 2-sulfonic acid (ANIs) monomers at a 1:1 equimolar ratio in acidic medium. The morphological and functional properties of PEGDA–PANIs are compared to those of PEGDA–PANI composites by coupling SEM, swelling degree, I–V, and electro–chemo–mechanical analyses. The differences are discussed as a function of morphological, structural, and charge transfer/transport properties of the respective PANIs and PANI filler. Our investigation showed that the electrochemical activity of PANIs allows for the exploitation of the PEGDA–PANIs composite as an electrode material for pH monitoring in a linear range compatible with that of most biofluids. This feature, combined with the superior electromechanical behavior, swelling capacity, and water retention properties, makes PEGDA–PANIs hydrogel a promising active material for developing advanced biomedical, soft tissue, and biocompatible electronic applications. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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23 pages, 6854 KiB  
Article
Tioconazole-Loaded Transethosomal Gel Using Box–Behnken Design for Topical Applications: In Vitro, In Vivo, and Molecular Docking Approaches
by Muhammad Imran Qureshi, Qazi Adnan Jamil, Faisal Usman, Tanveer A. Wani, Mudassir Farooq, Hamid Saeed Shah, Hassan Ahmad, Ruqaiya Khalil, Muhammad Sajjad, Seema Zargar and Safina Kausar
Gels 2023, 9(9), 767; https://doi.org/10.3390/gels9090767 - 21 Sep 2023
Viewed by 1656
Abstract
Tioconazole (TCZ) is a broad-spectrum fungicidal BCS class II drug with reported activity against Candida albicans, dermatophytes, and certain Staphylococci bacteria. We report the use of TCZ-loaded transethosomes (TEs) to overcome the skin’s barrier function. TCZ-loaded TEs were fabricated by using [...] Read more.
Tioconazole (TCZ) is a broad-spectrum fungicidal BCS class II drug with reported activity against Candida albicans, dermatophytes, and certain Staphylococci bacteria. We report the use of TCZ-loaded transethosomes (TEs) to overcome the skin’s barrier function. TCZ-loaded TEs were fabricated by using a cold method with slight modification. Box–Behnken composite design was utilized to investigate the effect of independent variables. The fabricated TEs were assessed with various physicochemical characterizations. The optimized formulation of TCZ-loaded TEs was incorporated into gel and evaluated for pH, conductivity, drug content, spreadability, rheology, in vitro permeation, ex vivo permeation, and in vitro and in vivo antifungal activity. The fabricated TCZ-loaded TEs had a % EE of 60.56 to 86.13, with particle sizes ranging from 219.1 to 757.1 nm. The SEM images showed spherically shaped vesicles. The % drug permeation was between 77.01 and 92.03. The kinetic analysis of all release profiles followed Higuchi’s diffusion model. The FTIR, DSC, and XRD analysis showed no significant chemical interactions between the drug and excipients. A significantly higher antifungal activity was observed for TCZ-loaded transethosomal gel in comparison to the control. The in vivo antifungal study on albino rats indicated that TCZ-loaded transethosomal gel showed a comparable therapeutic effect in comparison to the market brand Canesten®. Molecular docking demonstrated that the TCZ in the TE composition was surrounded by hydrophobic excipients with increased overall hydrophobicity and better permeation. Therefore, TCZ in the form of transethosomal gel can serve as an effective drug delivery system, having the ability to penetrate the skin and overcome the stratum corneum barrier with improved efficacy. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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18 pages, 6751 KiB  
Article
Water Consolidation Performance of Acrylic-Polymer-Modified Materials and Their Concrete Impermeability Repair Characteristics
by Dong Yan, Lipeng Lai, Xuedang Xiao, Lei Zhang, Zilong Zhao and Jun Zhao
Gels 2023, 9(9), 764; https://doi.org/10.3390/gels9090764 - 19 Sep 2023
Viewed by 824
Abstract
Acrylic materials exhibit favorable grouting repair performance. However, their curing products are easily inclined to drying shrinkage, and their concrete impermeability repair characteristics have seldom been investigated. To improve material properties, reveal the impermeability repair mechanism, and address drying shrinkage, this study proposed [...] Read more.
Acrylic materials exhibit favorable grouting repair performance. However, their curing products are easily inclined to drying shrinkage, and their concrete impermeability repair characteristics have seldom been investigated. To improve material properties, reveal the impermeability repair mechanism, and address drying shrinkage, this study proposed the addition of styrene–acrylate copolymer emulsion (styrene–acrylic emulsion) to the grouting material to prepare two-component acrylate grouting materials. Using orthogonal and single-factor tests combined with physical and mechanical properties, the mechanical properties and impermeability repair performance (physical and mechanical properties combined) of grouting materials were analyzed and studied, and the optimal ratio of each component of acrylate grouting materials was determined. Results show that (1) the hydrogel produced by the reaction of sodium methacrylate with hydroxyethyl acrylate has good physical and mechanical properties. (2) With the increase in the accelerator dosage, the setting time of slurry initially decreases and then increases; as the initiator dosage increases, the setting time of slurry decreases, which is negatively correlated with the initiator dosage. (3) Talcum powder can improve the physical and chemical properties of gel and enhance the reliability and durability of acrylate grouting materials, and the comprehensive performance is the best at a dosage of 3%. (4) Styrene–acrylic emulsion can increase the solid content and reduce the volume drying shrinkage when added to grouting materials. The fractured impermeable specimens were repaired by grouting with prepared acrylate grouting materials and cured for 24 h for the impermeability test, and the water pressure for the 24 h impermeability repair was 1.0 MPa. This study’s results provide important reference and basis for revealing the impermeability principle of acrylate grouting materials and evaluating their impermeability. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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12 pages, 3097 KiB  
Article
Using the Water Absorption Ability of Dried Hydrogels to Form Hydrogel-Supported Lipid Bilayers
by Che-Lun Chin, Lu-Jan Huang, Zheng-Xian Lu, Wei-Chun Weng and Ling Chao
Gels 2023, 9(9), 751; https://doi.org/10.3390/gels9090751 - 15 Sep 2023
Viewed by 1056
Abstract
The formation of supported lipid bilayers (SLBs) on hydrogels can act as a biocompatible anti-fouling interface. However, generating continuous and mobile SLBs on materials other than conventional glass or mica remains a significant challenge. The interaction between lipid membrane vesicles and a typical [...] Read more.
The formation of supported lipid bilayers (SLBs) on hydrogels can act as a biocompatible anti-fouling interface. However, generating continuous and mobile SLBs on materials other than conventional glass or mica remains a significant challenge. The interaction between lipid membrane vesicles and a typical hydrogel is usually insufficient to induce membrane vesicle rupture and form a planar lipid membrane. In this study, we demonstrate that the water absorption ability of a dried polyacrylamide (PAAm) hydrogel could serve as a driving force to facilitate the formation of the hydrogel–SLBs. The absorption driving force vanishes after the hydrogels are fully hydrated, leaving no extra interaction hindering lipid lateral mobility in the formed SLBs. Our fluorescence recovery after photobleaching (FRAP) results show that SLBs only form on hydrogels with adequate absorption abilities. Moreover, we discovered that exposure to oxygen during drying could lead to the formation of an oxidized crust on the PAAm hydrogel surface, impeding SLB formation. Therefore, minimizing oxygen exposure during drying is crucial to achieving high-quality hydrogel surfaces for SLB formation. This water absorption method enables the straightforward fabrication of hydrogel–SLBs without the need for additional substrates or charges, thereby expanding their potential applications. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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12 pages, 2839 KiB  
Article
Creation of Molecular Gel Materials Using Polyrotaxane-Derived Polymeric Organogelator
by Yutaka Ohsedo and Tomoka Shinoda
Gels 2023, 9(9), 730; https://doi.org/10.3390/gels9090730 - 08 Sep 2023
Viewed by 800
Abstract
Molecular gels, which are soft and flexible materials, are candidates for healthcare, cosmetic base, and electronic applications as new materials. In this study, a new polymeric organogelator bearing a polyrotaxane (PR) structure was developed and could induce the gelation of N [...] Read more.
Molecular gels, which are soft and flexible materials, are candidates for healthcare, cosmetic base, and electronic applications as new materials. In this study, a new polymeric organogelator bearing a polyrotaxane (PR) structure was developed and could induce the gelation of N′,N″-dimethylformamide (DMF), a known solvent for dissolving polymeric materials and salts. Furthermore, the resulting DMF molecular gels exhibited thixotropic properties, observed by the inversion method using vials, which are essential for gel spreading. The scanning electron microscopy of the xerogels suggested that the gel-forming ability and thixotropic property of gels were imparted by the network of the laminated aggregates of thin layer material similar to those of other gels made of clay materials. This thin layer material would be formed by the aggregation of polymeric organogelators. The dynamic viscoelasticity measurements of the obtained gels revealed the stability and pseudo-thixotropic behaviors of the obtained gels, as well as a specific concentration effect on the mechanical behavior of the gels attributed to the introduction of the PR structure. Additionally, the preparation of the polymer organogelator/polymer composites was investigated to improve the mechanical properties via the filler effect induced by the agglomerates of organogelator. Moreover, the tensile tests confirmed that the introduction of the gelator enhanced the mechanical properties of the composites. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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16 pages, 3088 KiB  
Article
Imiquimod-Loaded Chitosan-Decorated Di-Block and Tri-Block Polymeric Nanoparticles Loaded In Situ Gel for the Management of Cervical Cancer
by Aliyah Almomen, Mohamed Badran, Adel Ali Alhowyan, Musaed Alkholief and Aws Alshamsan
Gels 2023, 9(9), 713; https://doi.org/10.3390/gels9090713 - 03 Sep 2023
Viewed by 1030
Abstract
Background: Cervical intraepithelial neoplasia, the predisposing factor for cervical cancer (CC), is caused by human papillomavirus (HPV) infection and can be treated with imiquimod (IMQ). However, poor water solubility and side effects such as local inflammation can render IMQ ineffective. The aim of [...] Read more.
Background: Cervical intraepithelial neoplasia, the predisposing factor for cervical cancer (CC), is caused by human papillomavirus (HPV) infection and can be treated with imiquimod (IMQ). However, poor water solubility and side effects such as local inflammation can render IMQ ineffective. The aim of this study is to design a prolonged release nano system in combination with mucoadhesive–thermosensitive properties for an effective vaginal drug delivery. Methods: Polylactic-co-glycolic acid (PLGA), polycaprolactone (PCL), poly lactide-co-caprolactone (PLA-PCL), and poly L-lactide-co-caprolactone-co-glycolide (PLGA-PCL) were used to create IMQ nanoparticles. Chitosan (CS) was then added to the surfaces of the IMQ NPs for its mucoadhesive properties. The NPs were then incorporated into poloxamer hydrogels. The NPs’ size and morphology, encapsulation efficiency (EE), in vitro drug release, gel characterization, ex vivo drug permeation, and in vitro safety and efficacy were characterized. Results: Two batches of NPs were prepared, IMQ NPs and CS-coated NPs (CS-IMQ NPs). In general, both types of NPs were uniformly spherical in shape with average particle sizes of 237.3 ± 4.7 and 278.2 ± 5.4 nm and EE% of 61.48 ± 5.19% and 37.73 ± 2.88 for IMQ NPs and CS-IMQ NPs, respectively. Both systems showed prolonged drug release of about 80 and 70% for IMQ NPs and CS-IMQ NPs, respectively, within 48 h. The gelation temperatures for the IMQ NPs and CS-IMQ NPs were 30 and 32 °C, respectively; thus, suitable for vaginal application. Although ex vivo permeability showed that CS-IMQ NPs showed superior penetration compared to IMQ NPs, both systems enhanced drug penetration (283 and 462 µg/cm2 for IMQ NPs and CS-IMQ NPs, respectively) relative to the control (60 µg/cm2). Both systems reduced the viability of cervical cancer cells, with a minimal effect of the normal vaginal epithelium. However, IMQ NPs exhibited a more pronounced cytotoxic effect. Both systems were able to reduce the production of inflammatory cytokines by at least 25% in comparison to free IMQ. Conclusion: IMQ and CS-IMQ NP in situ gels enhanced stability and drug release, and improved IMQ penetration through the vaginal tissues. Additionally, the new systems were able to increase the cytotoxic effect of IMQ against CC cells with a reduction in inflammatory responses. Thus, we believe that these systems could be a good alternative to commercial IMQ systems for the management of CC. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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12 pages, 2748 KiB  
Article
Comparative Studies on the Organogel Formation of a Polyester in Three Different Base Oils by X-ray Analysis, Rheology and Infrared Spectroscopy
by Max Jopen, Michael Paulus, Christian Sternemann, Patrick Degen and Ralf Weberskirch
Gels 2023, 9(9), 696; https://doi.org/10.3390/gels9090696 - 29 Aug 2023
Cited by 1 | Viewed by 858
Abstract
High-performance greases typically consist of a base oil and polyurea as a thickener material. To date, few alternatives to polyureas have been investigated. Polyesters could be one such alternative; however, little is known about the gelation of such polyesters because, unlike polyureas, they [...] Read more.
High-performance greases typically consist of a base oil and polyurea as a thickener material. To date, few alternatives to polyureas have been investigated. Polyesters could be one such alternative; however, little is known about the gelation of such polyesters because, unlike polyureas, they cannot form hydrogen bonds between the polymer chains. Here, we present studies on the gel formation of a polyester based thickener poly(hexane dodecanoate) with 1-octanol endgroups in three different base oils, i.e., a mineral oil (Brightstock 150), a synthetic Polyalphaolefin (Spectrasyn 40) and castor oil (85 to 90 wt.% ricinoleic acid triglyceride). Small- and wide-angle X-ray scattering measurements indicate a strong interaction of the polyester with castor oil and an increase in the crystalline fraction, with an increasing polymer amount from 5 to 40 wt.%. Moreover, infrared analysis of the polyester in castor oil showed gel formation at a minimum concentration of 20 wt.%. The strong interaction of the polyester with castor oil compared to the other two base oils led to an increase in the yield point γF as a measure of the mechanical stability of the gel, which was determined to be 5.9% compared to 0.8% and 1.0% in Brightstock and Spectrasyn, respectively. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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17 pages, 3712 KiB  
Article
Development and Characterization of Gel-Based Buccoadhesive Bilayer Formulation of Nifedipine
by M. Alagusundaram, Nem Kumar Jain, M. Yasmin Begum, S. Angala Parameswari, Vinod Kumar Nelson, Mohammad F. Bayan and Balakumar Chandrasekaran
Gels 2023, 9(9), 688; https://doi.org/10.3390/gels9090688 - 26 Aug 2023
Viewed by 1170
Abstract
A promising controlled drug delivery system has been developed based on polymeric buccoadhesive bilayered formulation that uses a drug-free backing layer and a polymeric hydrophilic gel buccoadhesive core layer containing nifedipine. The DSC thermogravimetric analysis confirms the drug’s entrapment in the gel layer [...] Read more.
A promising controlled drug delivery system has been developed based on polymeric buccoadhesive bilayered formulation that uses a drug-free backing layer and a polymeric hydrophilic gel buccoadhesive core layer containing nifedipine. The DSC thermogravimetric analysis confirms the drug’s entrapment in the gel layer and reveals no evidence of a potential interaction. Various ratios of bioadhesive polymers, including HPMC K100, PVP K30, SCMC, and CP 934, were combined with EC as an impermeable backing layer to ensure unidirectional drug release towards the buccal mucosa. The polymeric compositions of hydrophilic gel-natured HPMC, SCMC, and CP formed a matrix layer by surrounding the core nifedipine during compression. Preformulation studies were performed for all of the ingredients in order to evaluate their physical and flow characteristics. Ex vivo buccoadhesive strength, surface pH, swelling index, in vitro and in vivo drug release, and ex vivo permeation investigations were performed to evaluate the produced gel-based system. Rapid temperature variations had no appreciable impact on the substance’s physical properties, pharmacological content, or buccoadhesive strength during stability testing using actual human saliva. It was clear from a histological examination of the ex vivo mucosa that the developed system did not cause any irritation or inflammation at the site of administration. The formulation NT5 was the best one, with a correlation coefficient of 0.9966. The in vitro and in vivo drug release profiles were well correlated, and they mimic the in vitro drug release pattern via the biological membrane. Thus, the developed gel-based formulation was found to be novel, stable, and useful for the targeted delivery of nifedipine. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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14 pages, 3008 KiB  
Article
Evaluation of Propolis Hydrogel for the Treatment of Dentinal Sensitivity: A Clinical Study
by Saad Mohammed AlQahtani, Raghavendra Reddy Nagate, Manae Musa Musleh Al-Ahmari, Mohammad Al. Magbol, Shankar T. Gokhale, Shreyas Tikare and Saurabh Chaturvedi
Gels 2023, 9(6), 483; https://doi.org/10.3390/gels9060483 - 12 Jun 2023
Cited by 1 | Viewed by 1397
Abstract
Background: Propolis is a natural resinous substance collected by honeybees, chiefly from buds and the leaves, branches, and bark of trees. Its role as a wound-healing gel has been studied, but the use of a propolis hydrogel in the treatment of dentinal hypersensitivity [...] Read more.
Background: Propolis is a natural resinous substance collected by honeybees, chiefly from buds and the leaves, branches, and bark of trees. Its role as a wound-healing gel has been studied, but the use of a propolis hydrogel in the treatment of dentinal hypersensitivity has not been evaluated. Dentin hypersensitivity (DH) is commonly treated via iontophoresis using fluoridated desensitizers. The aim of the present study was to compare and evaluate the effects of a 10% propolis hydrogel, 2% sodium fluoride (NaF), and 1.23% acidulated phosphate fluoride (APF) when used in conjunction with iontophoresis for the treatment of cervical dentin hypersensitivity (DH). Methods: Systemically healthy patients complaining of DH were selected for this single-centre, parallel, double-blind randomized clinical trial. Three substances were selected as desensitizers for study in the present trial: a 10% propolis hydrogel, 2% sodium fluoride, and 1.23% acidulated phosphate fluoride, all in conjunction with iontophoresis. Any decrease in DH following the application of specific stimuli was assessed at baseline, before and after application, on the 14th day following use, and on the 28th day following the intervention. Results: Intra-group comparisons show diminished values of DH at maximum post-op follow-up intervals which were significantly trimmed down from the baseline (p < 0.05). The 2% NaF demonstrated a significant reduction in DH over 1.23% APF and the 10% propolis hydrogel (p < 0.05). However, there was no statistically significant difference in the mean difference between the APF and propolis hydrogel groups assessed via tactile, cold, and air tests (p > 0.05). Conclusion: All three desensitizers have proved to be useful when used in conjugation with iontophoresis. Within the limitations of this study, a 10% propolis hydrogel can be used as a naturally occurring alternative to commercially available fluoridated desensitizers. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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14 pages, 3362 KiB  
Article
pH Modulated Formation of Complexes with Various Stoichiometry between Polymer Network and Fe(III) in Thermosensitive Gels Modified with Gallic Acid
by Klaudia Kaniewska, Patrycja Kościelniak and Marcin Karbarz
Gels 2023, 9(6), 447; https://doi.org/10.3390/gels9060447 - 29 May 2023
Cited by 1 | Viewed by 1688
Abstract
Thermoresponsive gels based on N-isopropylacrylamide functionalized with amino groups were modified with gallic acid, with gallate (3,4,5-trihydroxybenzoic) groups being introduced into the polymer network. We investigated how the properties of these gels were affected at varying pH, by the formation of complexes [...] Read more.
Thermoresponsive gels based on N-isopropylacrylamide functionalized with amino groups were modified with gallic acid, with gallate (3,4,5-trihydroxybenzoic) groups being introduced into the polymer network. We investigated how the properties of these gels were affected at varying pH, by the formation of complexes between the polymer network of the gels and Fe3+ ions (which form stable complexes with gallic acid, exhibiting 1:1, 1:2, or 1:3 stoichiometry, depending on pH). The formation of complexes with varying stoichiometry within the gel was confirmed using UV-Vis spectroscopy, and the influence of such complexes on swelling behavior and volume phase transition temperature were investigated. In the appropriate temperature range, complex stoichiometry was found to strongly affect the swelling state. Changes in the pore structure and mechanical properties of the gel caused by the formation of complexes with varying stoichiometry were investigated using scanning electron microscopy and rheological measurements, respectively. The volume changes exhibited by p(NIPA-5%APMA)-Gal-Fe gel were found to be greatest at close to human body temperature (~38 °C). Modification of thermoresponsive pNIPA gel with gallic acid opens new opportunities for the development of pH- and thermosensitive gel materials. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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17 pages, 4817 KiB  
Article
Polyurethane Shape Memory Polymer/pH-Responsive Hydrogel Hybrid for Bi-Function Synergistic Actuations
by Shuyi Peng, Xingyu Cao, Ye Sun, Lin Chen, Chao Ma, Lang Yang, Hongliang Zhao, Qijie Liu, Zhenzhong Liu and Chunxin Ma
Gels 2023, 9(5), 428; https://doi.org/10.3390/gels9050428 - 21 May 2023
Cited by 1 | Viewed by 1788
Abstract
Stimuli-responsive actuating hydrogels response to the external stimulus with complex deformation behaviors based on the programmable anisotropic structure design are one of the most important smart soft materials, which have great potential applications in artificial muscles, smart values, and mini-robots. However, the anisotropic [...] Read more.
Stimuli-responsive actuating hydrogels response to the external stimulus with complex deformation behaviors based on the programmable anisotropic structure design are one of the most important smart soft materials, which have great potential applications in artificial muscles, smart values, and mini-robots. However, the anisotropic structure of one actuating hydrogel can only be programmed one time, which can only provide single actuating performance, and subsequently, has severely limited their further applications. Herein, we have explored a novel SMP/hydrogel hybrid actuator through combining polyurethane shape memory polymer (PU SMP) layer and pH-responsive polyacrylic-acid (PAA) hydrogel layer by a napkin with UV-adhesive. Owing to both the super-hydrophilicity and super-lipophilicity of the cellulose-fiber based napkin, the SMP and the hydrogel can be bonded firmly by the UV-adhesive in the napkin. More importantly, this bilayer hybrid 2D sheet can be programmed by designing a different temporary shape in heat water which can be fixed easily in cool water to achieve various fixed shapes. This hybrid with a fixed temporary shape can achieve complex actuating performance based on the bi-functional synergy of temperature-triggered SMP and pH-responsive hydrogel. The relatively high modulus PU SMP achieved high to 87.19% and 88.92% shape-fixing ratio, respectively, correspond to bending and folding shapes. The hybrid actuator can actuate with the 25.71 °/min actuating speed. Most importantly, one SMP/hydrogel bi-layer hybrid sheet was repeatedly programmed at least nine times in our research to fix various temporary 1D, 2D and 3D shapes, including bending, folding and spiraling shapes. As a result, only one SMP/hydrogel hybrid can provide various complex stimuli-responsive actuations, including the reversable bending-straightening, spiraling-unspiraling. A few of the intelligent devices have been designed to simulate the movement of the natural organisms, such as bio-mimetic “paw”, “pangolin” and “octopus”. This work has developed a new SMP/hydrogel hybrid with excellent multi-repeatable (≥9 times) programmability for high-level complex actuations, including the 1D to 2D bending and the 2D to 3D spiraling actuations, which also provides a new strategy to design other new soft intelligent materials and systems. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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