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Gels, Volume 10, Issue 7 (July 2024) – 70 articles

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18 pages, 2433 KiB  
Article
Tuning Mechanical Properties, Swelling, and Enzymatic Degradation of Chitosan Cryogels Using Diglycidyl Ethers of Glycols with Different Chain Length as Cross-Linkers
by Yuliya Privar, Anna Skatova, Mariya Maiorova, Alexey Golikov, Andrey Boroda and Svetlana Bratskaya
Gels 2024, 10(7), 483; https://doi.org/10.3390/gels10070483 (registering DOI) - 21 Jul 2024
Abstract
Cross-linking chitosan at room and subzero temperature using a series of diglycidyl ethers of glycols (DEs)—ethylene glycol (EGDE), 1,4-butanediol (BDDE), and poly(ethylene glycol) (PEGDE) has been investigated to demonstrate that DEs can be a more powerful alternative to glutaraldehyde (GA) for fabrication of [...] Read more.
Cross-linking chitosan at room and subzero temperature using a series of diglycidyl ethers of glycols (DEs)—ethylene glycol (EGDE), 1,4-butanediol (BDDE), and poly(ethylene glycol) (PEGDE) has been investigated to demonstrate that DEs can be a more powerful alternative to glutaraldehyde (GA) for fabrication of biocompatible chitosan cryogels with tunable properties. Gelation of chitosan with DEs was significantly slower than with GA, allowing formation of cryogels with larger pores and higher permeability, more suitable for flow-through applications and cell culturing. Increased hydration of the cross-links with increased DE chain length weakened intermolecular hydrogen bonding in chitosan and improved cryogel elasticity. At high cross-linking ratios (DE:chitosan 1:4), the toughness and compressive strength of the cryogels decreased in the order EGDE > BDDE > PEGDE. By varying the DE chain length and concentration, permeable chitosan cryogels with elasticity moduli from 10.4 ± 0.8 to 41 ± 3 kPa, toughness from 2.68 ± 0.5 to 8.3 ± 0.1 kJ/m3, and compressive strength at 75% strain from 11 ± 2 to 33 ± 4 kPa were fabricated. Susceptibility of cryogels to enzymatic hydrolysis was identified as the parameter most sensitive to cross-linking conditions. Weight loss of cryogels increased with increased DE chain length, and degradation rate of PEGDE-cross-linked chitosan decreased 612-fold, when the cross-linker concentration increased 20-fold. Full article
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24 pages, 3479 KiB  
Article
A Meta-Analytical Way of Systematizing the Use of Hyaluronan Gels for the Relief of Osteoarthritis, Compared with New Treatment Alternatives
by Tudor Pinteala, Stelian Sergiu Maier, Norin Forna, Liliana Savin, Mihnea Theodor Sirbu, Dragos Cristian Popescu, Viorel Dan Cionca, Dan Constantin Putineanu and Paul Dan Sirbu
Gels 2024, 10(7), 481; https://doi.org/10.3390/gels10070481 (registering DOI) - 20 Jul 2024
Viewed by 73
Abstract
Hyaluronic acid, in the form of a gel or viscoelastic colloidal solution, is currently used for the viscosupplementation of joints affected by osteoarthritis, but its effectiveness is under debate in relation to newer alternatives. Based on meta-analytical arguments, the present article reinforces the [...] Read more.
Hyaluronic acid, in the form of a gel or viscoelastic colloidal solution, is currently used for the viscosupplementation of joints affected by osteoarthritis, but its effectiveness is under debate in relation to newer alternatives. Based on meta-analytical arguments, the present article reinforces the opinion that there are still no decisive arguments for its complete replacement but for its use adapted to the peculiarities of the disease manifestation and of the patients. A “broad” comparison is first made with almost all alternatives studied in the last decade, and then a meta-regression study is performed to compare and predict the effect size induced by viscosupplementation therapy and its main challenger of clinical interest, the platelet-rich plasma treatment. If they are computerized, the developed models can represent tools for clinicians in determining the appropriateness of the option or not for viscosupplementation in a manner adapted to the pain felt by the patients, to their age, or to other clinical circumstances. The models were generated using algorithms implemented in the R language and assembled in different R packages. All primary data and necessary R scripts are provided in accordance with the philosophy of reproducible research. Finally, we adhere in a documented way to the opinion that HA-based products, currently under circumspection, are still clinically useful. Full article
(This article belongs to the Special Issue Designing Hydrogels for Sustained Delivery of Therapeutic Agents)
16 pages, 4092 KiB  
Article
Development of Clindamycin-Releasing Polyvinyl Alcohol Hydrogel with Self-Healing Property for the Effective Treatment of Biofilm-Infected Wounds
by Nur Alifah, Juliana Palungan, Kadek Ardayanti, Muneeb Ullah, Andi Nokhaidah Nurkhasanah, Apon Zaenal Mustopa, Subehan Lallo, Rina Agustina, Jin-Wook Yoo and Nurhasni Hasan
Gels 2024, 10(7), 482; https://doi.org/10.3390/gels10070482 - 19 Jul 2024
Viewed by 369
Abstract
Self-healing hydrogels have good mechanical strength, can endure greater external force, and have the ability to heal independently, resulting in a strong bond between the wound and the material. Bacterial biofilm infections are life-threatening. Clindamycin (Cly) can be produced in the form of [...] Read more.
Self-healing hydrogels have good mechanical strength, can endure greater external force, and have the ability to heal independently, resulting in a strong bond between the wound and the material. Bacterial biofilm infections are life-threatening. Clindamycin (Cly) can be produced in the form of a self-healing hydrogel preparation. It is noteworthy that the antibacterial self-healing hydrogels show great promise as a wound dressing for bacterial biofilm infection. In this study, we developed a polyvinyl alcohol/borax (PVA/B) self-healing hydrogel wound dressing that releases Cly. Four ratios of PVA, B, and Cly were used to make self-healing hydrogels: F1 (4%:0.8%:1%), F2 (4%:1.2%:1%), F3 (1.6%:1%), and F4 (4%:1.6%:0). The results showed that F4 had the best physicochemical properties, including a self-healing duration of 11.81 ± 0.34 min, swelling ratio of 85.99 ± 0.12%, pH value of 7.63 ± 0.32, and drug loading of 98.34 ± 11.47%. The B–O–C cross-linking between PVA and borax caused self-healing, according to FTIR spectra. The F4 formula had a more equal pore structure in the SEM image. The PVA/B-Cly self-healing hydrogel remained stable at 6 ± 2 °C for 28 days throughout the stability test. The Korsmeyer–Peppas model released Cly by Fickian diffusion. In biofilm-infected mouse wounds, PVA/B-Cly enhanced wound healing and re-epithelialization. Our results indicate that the PVA/B-Cly produced in this work has reliable physicochemical properties for biofilm-infected wound therapy. Full article
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23 pages, 9760 KiB  
Article
Dual-Temperature/pH-Sensitive Hydrogels with Excellent Strength and Toughness Crosslinked Using Three Crosslinking Methods
by Jiaqi Wang, Wanying Yang, Yutong Li, Xuerong Ma, Yuxin Xie, Guangyan Zhou and Shouxin Liu
Gels 2024, 10(7), 480; https://doi.org/10.3390/gels10070480 - 19 Jul 2024
Viewed by 189
Abstract
Hydrogels are widely used as excellent drug carriers in the field of biomedicine. However, their application in medicine is limited by their poor mechanical properties and softness. To improve the mechanical properties of hydrogels, a novel triple-network amphiphilic hydrogel with three overlapping crosslinking [...] Read more.
Hydrogels are widely used as excellent drug carriers in the field of biomedicine. However, their application in medicine is limited by their poor mechanical properties and softness. To improve the mechanical properties of hydrogels, a novel triple-network amphiphilic hydrogel with three overlapping crosslinking methods using a one-pot free-radical polymerization was synthesized in this study. Temperature-sensitive and pH-sensitive monomers were incorporated into the hydrogel to confer stimulus responsiveness, making the hydrogel stimuli-responsive. The successful synthesis of the hydrogel was confirmed using techniques, such as proton nuclear magnetic resonance spectroscopy (1H NMR), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). In order to compare and analyze the properties of physically crosslinked hydrogels, physically–chemically double-crosslinked hydrogels, and physically–chemically clicked triple-crosslinked hydrogels, various tests were conducted on the gels’ morphology, swelling behavior, thermal stability, mechanical properties, and drug loading capacity. The results indicate that the triple-crosslinked hydrogel maintains low swelling, high mechanical strength, and good thermal stability while not significantly compromising its drug delivery capability. Full article
(This article belongs to the Special Issue Stimuli-Responsive Composite Gels)
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25 pages, 1275 KiB  
Review
Advanced Hydrogels in Breast Cancer Therapy
by Xiangyu Gao, Benjamin R. Caruso and Weimin Li
Gels 2024, 10(7), 479; https://doi.org/10.3390/gels10070479 - 19 Jul 2024
Viewed by 232
Abstract
Breast cancer is the most common malignancy among women and is the second leading cause of cancer-related death for women. Depending on the tumor grade and stage, breast cancer is primarily treated with surgery and antineoplastic therapy. Direct or indirect side effects, emotional [...] Read more.
Breast cancer is the most common malignancy among women and is the second leading cause of cancer-related death for women. Depending on the tumor grade and stage, breast cancer is primarily treated with surgery and antineoplastic therapy. Direct or indirect side effects, emotional trauma, and unpredictable outcomes accompany these traditional therapies, calling for therapies that could improve the overall treatment and recovery experiences of patients. Hydrogels, biomimetic materials with 3D network structures, have shown great promise for augmenting breast cancer therapy. Hydrogel implants can be made with adipogenic and angiogenic properties for tissue integration. 3D organoids of malignant breast tumors grown in hydrogels retain the physical and genetic characteristics of the native tumors, allowing for post-surgery recapitulation of the diseased tissues for precision medicine assessment of the responsiveness of patient-specific cancers to antineoplastic treatment. Hydrogels can also be used as carrier matrices for delivering chemotherapeutics and immunotherapeutics or as post-surgery prosthetic scaffolds. The hydrogel delivery systems could achieve localized and controlled medication release targeting the tumor site, enhancing efficacy and minimizing the adverse effects of therapeutic agents delivered by traditional procedures. This review aims to summarize the most recent advancements in hydrogel utilization for breast cancer post-surgery tissue reconstruction, tumor modeling, and therapy and discuss their limitations in clinical translation. Full article
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16 pages, 1693 KiB  
Review
Stimuli-Responsive Nanocomposite Hydrogels for Oral Diseases
by Raffaele Conte, Anna Valentino, Silvia Romano, Sabrina Margarucci, Orsolina Petillo and Anna Calarco
Gels 2024, 10(7), 478; https://doi.org/10.3390/gels10070478 - 18 Jul 2024
Viewed by 372
Abstract
Oral diseases encompassing conditions such as oral cancer, periodontitis, and endodontic infections pose significant challenges due to the oral cavity’s susceptibility to pathogenic bacteria and infectious agents. Saliva, a key component of the oral environment, can compromise drug efficacy during oral disease treatment [...] Read more.
Oral diseases encompassing conditions such as oral cancer, periodontitis, and endodontic infections pose significant challenges due to the oral cavity’s susceptibility to pathogenic bacteria and infectious agents. Saliva, a key component of the oral environment, can compromise drug efficacy during oral disease treatment by diluting drug formulations and reducing drug-site interactions. Thus, it is imperative to develop effective drug delivery methods. Stimuli-responsive nanocomposite hydrogels offer a promising solution by adapting to changes in environmental conditions during disease states, thereby enabling targeted drug delivery. These smart drug delivery systems have the potential to enhance drug efficacy, minimize adverse reactions, reduce administration frequency, and improve patient compliance, thus facilitating a faster recovery. This review explores various types of stimuli-responsive nanocomposite hydrogels tailored for smart drug delivery, with a specific focus on their applications in managing oral diseases. Full article
(This article belongs to the Special Issue Biopolymer-Based Gels for Drug Delivery and Tissue Engineering)
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38 pages, 15627 KiB  
Article
Comprehensive Biosafety Profile of Carbomer-Based Hydrogel Formulations Incorporating Phosphorus Derivatives
by Khaled Zakzak, Alexandra-Denisa Semenescu, Elena-Alina Moacă, Iasmina Predescu, George Drăghici, Lavinia Vlaia, Vicenţiu Vlaia, Florin Borcan and Cristina-Adriana Dehelean
Gels 2024, 10(7), 477; https://doi.org/10.3390/gels10070477 - 18 Jul 2024
Viewed by 262
Abstract
Determining the safety of a newly developed experimental product is a crucial condition for its medical use, especially for clinical trials. In this regard, four hydrogel-type formulations were manufactured, all of which were based on carbomer (Blank-CP940) and encapsulated with caffeine (CAF-CP940), phosphorus [...] Read more.
Determining the safety of a newly developed experimental product is a crucial condition for its medical use, especially for clinical trials. In this regard, four hydrogel-type formulations were manufactured, all of which were based on carbomer (Blank-CP940) and encapsulated with caffeine (CAF-CP940), phosphorus derivatives (phenyl phosphinic (CAF-S1-CP940) and 2-carboxyethyl phenyl phosphinic acids (CAF-S2-CP940)). The main aim of this research was to provide a comprehensive outline of the biosafety profile of the above-mentioned hydrogels. The complex in vitro screening (cell viability, cytotoxicity, morphological changes in response to exposure, and changes in nuclei morphology) on two types of healthy skin cell lines (HaCaT—human keratinocytes and JB6 Cl 41-5a—murine epidermal cells) exhibited a good biosafety profile when both cell lines were treated for 24 h with 150 μg/mL of each hydrogel. A comprehensive analysis of the hydrogel’s impact on the genetic profile of HaCaT cells sustains the in vitro experiments. The biosafety profile was completed with the in vivo and in ovo assays. The outcome revealed that the developed hydrogels exerted good biocompatibility after topical application on BALB/c nude mice’s skin. It also revealed a lack of toxicity after exposure to the hen’s chicken embryo. Further investigations are needed, regarding the in vitro and in vivo therapeutic efficacy and safety for long-term use and potential clinical translatability. Full article
(This article belongs to the Special Issue Synthetic, Natural and Hybrid Gels Intended for Various Applications)
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30 pages, 2858 KiB  
Review
Hydrogel-Based Therapies for Ischemic and Hemorrhagic Stroke: A Comprehensive Review
by Alexandra-Daniela Rotaru-Zăvăleanu, Venera Cristina Dinescu, Madalina Aldea and Andrei Gresita
Gels 2024, 10(7), 476; https://doi.org/10.3390/gels10070476 - 18 Jul 2024
Viewed by 215
Abstract
Stroke remains the second leading cause of death and a major cause of disability worldwide, significantly impacting individuals, families, and healthcare systems. This neurological emergency can be triggered by ischemic events, including small vessel arteriolosclerosis, cardioembolism, and large artery atherothromboembolism, as well as [...] Read more.
Stroke remains the second leading cause of death and a major cause of disability worldwide, significantly impacting individuals, families, and healthcare systems. This neurological emergency can be triggered by ischemic events, including small vessel arteriolosclerosis, cardioembolism, and large artery atherothromboembolism, as well as hemorrhagic incidents resulting from macrovascular lesions, venous sinus thrombosis, or vascular malformations, leading to significant neuronal damage. The resultant motor impairment, cognitive dysfunction, and emotional disturbances underscore the urgent need for effective therapeutic interventions. Recent advancements in biomaterials, particularly hydrogels, offer promising new avenues for stroke management. Hydrogels, composed of three-dimensional networks of hydrophilic polymers, are notable for their ability to absorb and retain substantial amounts of water. Commonly used polymers in hydrogel formulations include natural polymers like alginate, chitosan, and collagen, as well as synthetic polymers such as polyethylene glycol (PEG), polyvinyl alcohol (PVA), and polyacrylamide. Their customizable characteristics—such as their porosity, swelling behavior, mechanical strength, and degradation rates—make hydrogels ideal for biomedical applications, including drug delivery, cell delivery, tissue engineering, and the controlled release of therapeutic agents. This review comprehensively explores hydrogel-based approaches to both ischemic and hemorrhagic stroke therapy, elucidating the mechanisms by which hydrogels provide neuroprotection. It covers their application in drug delivery systems, their role in reducing inflammation and secondary injury, and their potential to support neurogenesis and angiogenesis. It also discusses current advancements in hydrogel technology and the significant challenges in translating these innovations from research into clinical practice. Additionally, it emphasizes the limited number of clinical trials utilizing hydrogel therapies for stroke and addresses the associated limitations and constraints, underscoring the need for further research in this field. Full article
(This article belongs to the Special Issue Recent Advances in Hydrogels for Biomedical Application)
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16 pages, 4415 KiB  
Article
Insights into the Injectivity and Propagation Behavior of Preformed Particle Gel (PPG) in a Low–Medium-Permeability Reservoir
by Hong He, Yuhang Tian, Lianfeng Zhang, Hongsheng Li, Yan Guo, Yu Liu and Yifei Liu
Gels 2024, 10(7), 475; https://doi.org/10.3390/gels10070475 - 18 Jul 2024
Viewed by 286
Abstract
Heterogeneous phase combined flooding (HPCF) has been a promising technology used for enhancing oil recovery in heterogeneous mature reservoirs. However, the injectivity and propagation behavior of preformed particle gel (PPG) in low–medium-permeability reservoir porous media is crucial for HPCF treatment in a low–medium-permeability [...] Read more.
Heterogeneous phase combined flooding (HPCF) has been a promising technology used for enhancing oil recovery in heterogeneous mature reservoirs. However, the injectivity and propagation behavior of preformed particle gel (PPG) in low–medium-permeability reservoir porous media is crucial for HPCF treatment in a low–medium-permeability reservoir. Thus, the injectivity and propagation behavior of preformed particle gel in a low–medium-permeability reservoir were systematically studied by conducting a series of sand pack flooding experiments. The matching factor (δ) was defined as the ratio of the average size of PPG particles to the mean size of pore throats and the pressure difference ratio (β) was proposed to characterize the injectivity and propagation ability of PPG. The results show that with the increase in particle size and the decrease in permeability, the resistance factor and residual resistance factor increase. With the increase in the matching factor, the resistance factor and residual resistance factor increase. The higher the resistance factor and residual resistance factor are, the worse the injectivity of particles is. By fitting the relationship curve, PPG injection and propagation standards were established: when the matching coefficient is less than 55 and β is less than 3.4, PPG can be injected; when the matching coefficient is 55–72 and β is 3.4–6.5, PPG injection is difficult; when the matching coefficient is greater than 72 and β is greater than 6.5, PPG cannot be injected Thus, the matching relationship between PPG particle size and reservoir permeability was obtained. This research will provide theoretical support for further EOR research and field application of heterogeneous phase combined flooding. Full article
(This article belongs to the Special Issue Advanced Gels for Oil Recovery)
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21 pages, 3732 KiB  
Review
Effect of Drying Methods on the Thermal and Mechanical Behavior of Bacterial Cellulose Aerogel
by Sebnem Sozcu, Jaroslava Frajova, Jakub Wiener, Mohanapriya Venkataraman, Blanka Tomkova and Jiri Militky
Gels 2024, 10(7), 474; https://doi.org/10.3390/gels10070474 - 18 Jul 2024
Viewed by 278
Abstract
Bacterial cellulose (BC) presents significant promise as a biomaterial, boasting unique qualities such as exceptional cellulose purity, robust mechanical strength, heightened crystalline structure, and biodegradability. Several studies have highlighted specific effects, such as the impact of dehydration/rehydration on BC tensile strength, the influence [...] Read more.
Bacterial cellulose (BC) presents significant promise as a biomaterial, boasting unique qualities such as exceptional cellulose purity, robust mechanical strength, heightened crystalline structure, and biodegradability. Several studies have highlighted specific effects, such as the impact of dehydration/rehydration on BC tensile strength, the influence of polymer treatment methods on mechanical properties, the correlation between microorganism type, drying method, and Young’s modulus value, and the relationship between culture medium composition, pH, and crystallinity. Drying methods are crucial to the structure, performance, and application of BC films. Research findings indicate that the method used for drying can influence the mechanical properties of BC films, including parameters such as tensile strength, Young’s modulus, and water absorption capacity, as well as the micromorphology, crystallinity, and thermal characteristics of the material. Their versatility makes them potential biomaterials applicable in various fields, including thermal and acoustic insulation, owing to their distinct thermal and mechanical attributes. This review delves into the thermal and mechanical behavior of bacterial cellulose aerogels, which are profoundly impacted by their drying mechanism. Full article
(This article belongs to the Special Issue Application of Aerogel into Textile Fabrics for Thermal Insulation)
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11 pages, 2656 KiB  
Article
Influence of a Solid Surface on PNIPAM Microgel Films
by Valentina Nigro, Roberta Angelini, Elena Buratti, Claudia Colantonio, Rosaria D’Amato, Franco Dinelli, Silvia Franco, Francesca Limosani, Rosa Maria Montereali, Enrico Nichelatti, Massimo Piccinini, Maria Aurora Vincenti and Barbara Ruzicka
Gels 2024, 10(7), 473; https://doi.org/10.3390/gels10070473 - 18 Jul 2024
Viewed by 219
Abstract
Stimuli-responsive microgels have attracted great interest in recent years as building blocks for fabricating smart surfaces with many technological applications. In particular, PNIPAM microgels are promising candidates for creating thermo-responsive scaffolds to control cell growth and detachment via temperature stimuli. In this framework, [...] Read more.
Stimuli-responsive microgels have attracted great interest in recent years as building blocks for fabricating smart surfaces with many technological applications. In particular, PNIPAM microgels are promising candidates for creating thermo-responsive scaffolds to control cell growth and detachment via temperature stimuli. In this framework, understanding the influence of the solid substrate is critical for tailoring microgel coatings to specific applications. The surface modification of the substrate is a winning strategy used to manage microgel–substrate interactions. To control the spreading of microgel particles on a solid surface, glass substrates are coated with a PEI or an APTES layer to improve surface hydrophobicity and add positive charges on the interface. A systematic investigation of PNIPAM microgels spin-coated through a double-step deposition protocol on pristine glass and on functionalised glasses was performed by combining wettability measurements and Atomic Force Microscopy. The greater flattening of microgel particles on less hydrophilic substrates can be explained as a consequence of the reduced shielding of the water–substrate interactions that favors electrostatic interactions between microgels and the substrate. This approach allows the yielding of effective control on microgel coatings that will help to unlock new possibilities for their application in biomedical devices, sensors, or responsive surfaces. Full article
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18 pages, 4403 KiB  
Article
Swelling, Protein Adsorption, and Biocompatibility of Pectin–Chitosan Hydrogels
by Sergey Popov, Nikita Paderin, Elizaveta Chistiakova, Alisa Sokolova, Ilya V. Konyshev, Vladislav S. Belozerov and Andrey A. Byvalov
Gels 2024, 10(7), 472; https://doi.org/10.3390/gels10070472 - 17 Jul 2024
Viewed by 250
Abstract
The study aims to determine how chitosan impacts pectin hydrogel’s ability to attach peritoneal leukocytes, activate complement, induce hemolysis, and adsorb blood proteins. The hydrogels PEC-Chi0, PEC-Chi25, PEC-Chi50, and PEC-Chi75 were prepared by placing a mixture solution of 4% pectin and 4% chitosan [...] Read more.
The study aims to determine how chitosan impacts pectin hydrogel’s ability to attach peritoneal leukocytes, activate complement, induce hemolysis, and adsorb blood proteins. The hydrogels PEC-Chi0, PEC-Chi25, PEC-Chi50, and PEC-Chi75 were prepared by placing a mixture solution of 4% pectin and 4% chitosan in a ratio of 4:0, 3:1, 2:2, and 1:3 in a solution of 1.0 M CaCl2. Chitosan was found to modify the mechanical properties of pectin–calcium hydrogels, such as hardness and cohesiveness-to-adhesiveness ratio. Chitosan in the pectin–calcium hydrogel caused pH-sensitive swelling in Hanks’ solution. The PEC-Chi75 hydrogel was shown to adsorb serum proteins at pH 7.4 to a greater extent than other hydrogels. PEC-Chi75’s strong adsorption capacity was related to lower peritoneal leukocyte adherence to its surface when compared to other hydrogels, showing improved biocompatibility. Using the optical tweezers approach, it was shown that the force of interaction between pectin–chitosan hydrogels and plasma proteins increased from 10 to 24 pN with increasing chitosan content from 0 to 75%. Thus, the properties of pectin–calcium hydrogel, which determine interactions with body tissues after implantation, are improved by the addition of chitosan, making pectin–chitosan hydrogel a promising candidate for smart biomaterial development. Full article
(This article belongs to the Special Issue Physically Cross-Linked Gels and Their Applications)
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14 pages, 2374 KiB  
Review
Micelle-Containing Hydrogels and Their Applications in Biomedical Research
by Jinghua Wu, Huapeng Li, Nan Zhang and Qingfei Zheng
Gels 2024, 10(7), 471; https://doi.org/10.3390/gels10070471 - 17 Jul 2024
Viewed by 349
Abstract
Hydrogels are one of the most commonly used materials in our daily lives, which possess crosslinked three-dimensional network structures and are capable of absorbing large amounts of fluid. Due to their outstanding properties, such as flexibility, tunability, and biocompatibility, hydrogels have been widely [...] Read more.
Hydrogels are one of the most commonly used materials in our daily lives, which possess crosslinked three-dimensional network structures and are capable of absorbing large amounts of fluid. Due to their outstanding properties, such as flexibility, tunability, and biocompatibility, hydrogels have been widely employed in biomedical research and clinics, especially in on-demand drug release. However, traditional hydrogels face various limitations, e.g., the delivery of hydrophobic drugs due to their highly hydrophilic interior environment. Therefore, micelle-containing hydrogels have been designed and developed, which possess both hydrophilic and hydrophobic microenvironments and enable the storage of diverse cargos. Based on the functionalities of micelles, these hydrogels can be classified into micelle-doped and chemically/physically crosslinked types, which were reported to be responsive to varied stimuli, including temperature, pH, irradiation, electrical signal, magnetic field, etc. Here, we summarize the research advances of micelle-containing hydrogels and provide perspectives on their applications in the biomedical field based on the recent studies from our own lab and others. Full article
(This article belongs to the Special Issue Designing Hydrogels for Sustained Delivery of Therapeutic Agents)
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14 pages, 7042 KiB  
Article
Sol–Gel Synthesis of TiO2 with Pectin and Their Efficiency in Solar Cells Sensitized by Quantum Dots
by Jean Flores-Gómez, Silvia Mota-Macías, Juan P. Guerrero-Jiménez, Victor Hugo Romero-Arellano and Juan Morales-Rivera
Gels 2024, 10(7), 470; https://doi.org/10.3390/gels10070470 - 17 Jul 2024
Viewed by 273
Abstract
In this study, titanium oxide TiO2 nanoparticles were produced using the sol–gel approach of green synthesis with pectin as the reducing agent. The synthetized TiO2 nanoparticles with pectin were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), visible light absorption [...] Read more.
In this study, titanium oxide TiO2 nanoparticles were produced using the sol–gel approach of green synthesis with pectin as the reducing agent. The synthetized TiO2 nanoparticles with pectin were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), visible light absorption (UV–Vis) and the BET method. The structure and morphology of the TiO2 powder were described with SEM, revealing uniform monodisperse grains with a distribution of 80% regarding sizes < 250 nm; the resulting crystal phase of synthetized TiO2 was identified as an anatase and rutile phase with a crystallinity size estimated between 27 and 40 nm. Also, the surface area was determined by nitrogen adsorption–desorption using the Brown–Emmet–Teller method, with a surface area calculated as 19.56 m2/g, typical of an IV type isotherm, indicating mesoporous NPs. UV–Vis spectra showed that sol–gel synthesis reduced the band gap from the 3.2 eV common value to 2.22 eV after estimating the optical band gap energy using the adsorption coefficient; this translates to a possible extended photo response to the visible region, improving photoactivity. In addition, the power conversion of the photoelectrode was compared based on similar assembly techniques of TiO2 electrode deposition. Quantum dot crystals were deposited ionically on the electrode surface, as two different paste formulations based on a pectin emulsifier were studied for layer deposition. The results confirm that the TiO2 paste with TiO2-synthesized powder maintained good connections between the nanocrystalline mesoporous grains and the deposited layers, with an efficiency of 1.23% with the transparent paste and 2.27% with the opaque paste. These results suggest that pectin could be used as a low-cost, functional sol–gel catalysis agent for the synthesis of controlled NPs of metal oxide. It demonstrates interesting optical properties, such as an increase in photo response, suggesting further applications to photocatalysts and biomedical features. Full article
(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)
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15 pages, 5522 KiB  
Article
Silk Fibroin-Enriched Bioink Promotes Cell Proliferation in 3D-Bioprinted Constructs
by Sara Lipari, Pasquale Sacco, Eleonora Marsich and Ivan Donati
Gels 2024, 10(7), 469; https://doi.org/10.3390/gels10070469 - 17 Jul 2024
Viewed by 244
Abstract
Three-dimensional (3D) bioprinting technology enables the controlled deposition of cells and biomaterials (i.e., bioink) to easily create complex 3D biological microenvironments. Silk fibroin (SF) has recently emerged as a compelling bioink component due to its advantageous mechanical and biological properties. This study reports [...] Read more.
Three-dimensional (3D) bioprinting technology enables the controlled deposition of cells and biomaterials (i.e., bioink) to easily create complex 3D biological microenvironments. Silk fibroin (SF) has recently emerged as a compelling bioink component due to its advantageous mechanical and biological properties. This study reports on the development and optimization of a novel bioink for extrusion-based 3D bioprinting and compares different bioink formulations based on mixtures of alginate methacrylate (ALMA), gelatin and SF. The rheological parameters of the bioink were investigated to predict printability and stability, and the optimal concentration of SF was selected. The bioink containing a low amount of SF (0.002% w/V) was found to be the best formulation. Light-assisted gelation of ALMA was exploited to obtain the final hydrogel matrix. Rheological analyses showed that SF-enriched hydrogels exhibited greater elasticity than SF-free hydrogels and were more tolerant to temperature fluctuations. Finally, MG-63 cells were successfully bioprinted and their viability and proliferation over time were analyzed. The SF-enriched bioink represents an excellent biomaterial in terms of printability and allows high cell proliferation over a period of up to 3 weeks. These data confirm the possibility of using the selected formulation for the successful bioprinting of cells into extracellular matrix-like microenvironments. Full article
(This article belongs to the Special Issue Feature Papers in Chemistry and Physics of Biological Gels)
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15 pages, 4651 KiB  
Article
Influence of Thermal Treatment on the Chemical and Structural Properties of Geopolymer Gels Doped with Nd2O3 and Sm2O3
by Miloš Nenadović, Sanja Knežević, Marija Ivanović, Snežana Nenadović, Danilo Kisić, Maja Popović and Jelena Potočnik
Gels 2024, 10(7), 468; https://doi.org/10.3390/gels10070468 - 17 Jul 2024
Viewed by 253
Abstract
In this research, the influence of the thermal treatment of geopolymer gels at 300 °C, 600 °C and 900 °C when incorporated with 5% rare earth elements (REEs) in the form of (GP-Sm) Sm2O3 and (GP-Nd) Nd2O3 [...] Read more.
In this research, the influence of the thermal treatment of geopolymer gels at 300 °C, 600 °C and 900 °C when incorporated with 5% rare earth elements (REEs) in the form of (GP-Sm) Sm2O3 and (GP-Nd) Nd2O3 was investigated. Changes in the chemical and structural properties of the geopolymer gels during thermal treatment for 1 h were monitored. Physico-chemical characterization was performed using the following methods: diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), scanning electron microscopy with energy dispersive spectrometry (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). Besides the characterization of the fundamental properties, some practical macroscopic properties were analyzed as well: sorptivity, open porosity, and Archimedean density. The stretching vibrations of Nd–O–Si and Sm–O–Si were confirmed at a value of around 680 cm−1and an Nd–O–Si absorption band at a higher value, together with the most dominant band of Si–O stretching vibration similar for all the samples. No significant chemical changes occurred. Structural analysis showed that for GP-Nd, the largest pore diameter was obtained at 900 °C, while for GP-Sm, the largest pore diameter was obtained at 600 °C. EDS confirmed the amount of dopant to be about 5%. X-ray photoelectron spectroscopy showed that for GP-Nd, the ratio of Si and Al changed the most, while for GP-Sm, the ratio of Si and Al decreased with increasing temperature. The contributions of both dopants in the GP-gel structure remained almost unchanged and stable at high temperatures. The atomic percentages obtained by XPS analysis were in accordance with the expected trend; the amount of Si increased with the temperature, while the amount of Al decreased with increasing temperature. The sorptivity and open porosity showed the highest values at 600 °C, while the density of both geopolymers decreased linearly with increasing temperature. Full article
(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)
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17 pages, 6718 KiB  
Article
Incorporation of Locust Bean Gum and Solid Lipid Microparticles as Strategies to Improve the Properties and Stability of Calcium-Rich Soy Protein Isolate Gels
by Thais C. Brito-Oliveira, Ana Clara M. Cavini, Leticia S. Ferreira, Izabel C. F. Moraes and Samantha C. Pinho
Gels 2024, 10(7), 467; https://doi.org/10.3390/gels10070467 - 17 Jul 2024
Viewed by 253
Abstract
The present study aimed to investigate the properties of calcium-rich soy protein isolate (SPI) gels (14% SPI; 100 mM CaCl2), the effects of incorporating different concentrations locust bean gum (LBG) (0.1–0.3%, w/v) to the systems and the stability [...] Read more.
The present study aimed to investigate the properties of calcium-rich soy protein isolate (SPI) gels (14% SPI; 100 mM CaCl2), the effects of incorporating different concentrations locust bean gum (LBG) (0.1–0.3%, w/v) to the systems and the stability of the obtained gels. Also, the incorporation of solid lipid microparticles (SLMs) was tested as an alternative strategy to improve the system’s stability and, therefore, potential to be applied as a product prototype. The gels were evaluated regarding their visual aspect, rheological properties, water-holding capacities (WHCs) and microstructural organizations. The CaCl2-induced gels were self-supported but presented low WHC (40.0% ± 2.2) which was improved by LBG incorporation. The obtained mixed system, however, presented low stability, with high syneresis after 10 days of storage, due to microstructural compaction. The gels’ stability was improved by SLM incorporation, which decreased the gelled matrices’ compaction and syneresis for more than 20 days. Even though the rheological properties of the emulsion-filled gels (EFGs) were very altered due to the ageing process (which may affect the sensory perception of a future food originated from this EFG), the incorporation of SLMs increased the systems potential to be applied as a calcium-rich product prototype. Full article
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25 pages, 5039 KiB  
Article
Functional Nanostructured Lipid Carrier-Enriched Hydrogels Tailored to Repair Damaged Epidermal Barrier
by Radwan Joukhadar, Laura Nižić Nodilo, Jasmina Lovrić, Anita Hafner, Ivan Pepić and Mario Jug
Gels 2024, 10(7), 466; https://doi.org/10.3390/gels10070466 - 16 Jul 2024
Viewed by 283
Abstract
In this study, a functional nanostructured lipid carriers (NLCs)-based hydrogel was developed to repair the damaged epidermal skin barrier. NLCs were prepared via a high-energy approach, using argan oil and beeswax as liquid and solid lipids, respectively, and were loaded with ceramides and [...] Read more.
In this study, a functional nanostructured lipid carriers (NLCs)-based hydrogel was developed to repair the damaged epidermal skin barrier. NLCs were prepared via a high-energy approach, using argan oil and beeswax as liquid and solid lipids, respectively, and were loaded with ceramides and cholesterol at a physiologically relevant ratio, acting as structural and functional compounds. Employing a series of surfactants and optimizing the preparation conditions, NLCs of 215.5 ± 0.9 nm in size and a negative zeta potential of −42.7 ± 0.9 were obtained, showing acceptable physical and microbial stability. Solid state characterization by differential scanning calorimetry and X-ray powder diffraction revealed the formation of imperfect crystal NLC-type. The optimized NLC dispersion was loaded into the gel based on sodium hyaluronate and xanthan gum. The gels obtained presented a shear thinning and thixotropic behavior, which is suitable for dermal application. Incorporating NLCs enhanced the rheological, viscoelastic, and textural properties of the gel formed while retaining the suitable spreadability required for comfortable application and patient compliance. The NLC-loaded gel presented a noticeable occlusion effect in vitro. It provided 2.8-fold higher skin hydration levels on the ex vivo porcine ear model than the NLC-free gel, showing a potential to repair the damaged epidermal barrier and nourish the skin actively. Full article
(This article belongs to the Special Issue Multifunctional Hydrogel for Wound Healing and Tissue Repair)
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17 pages, 9336 KiB  
Article
Enhancing Flame-Retardant Properties of Polyurethane Aerogels Doped with Silica-Based Particles
by Esther Pinilla-Peñalver, Óscar del Fresno, Darío Cantero, Adriana Moreira, Filipa Gomes, Francisca Miranda, Marcelo Oliveira, Mariana Ornelas, Luz Sánchez-Silva and Amaya Romero
Gels 2024, 10(7), 465; https://doi.org/10.3390/gels10070465 - 16 Jul 2024
Viewed by 315
Abstract
In this work, polyurethane (PUR) aerogels doped with different SiO2 particles, derived from a renewable source, were successfully synthesized, and the effects of SiO2 content on the properties of PUR aerogels were investigated. Specifically, three types of SiO2-based particles [...] Read more.
In this work, polyurethane (PUR) aerogels doped with different SiO2 particles, derived from a renewable source, were successfully synthesized, and the effects of SiO2 content on the properties of PUR aerogels were investigated. Specifically, three types of SiO2-based particles obtained from rice husk through different procedures were evaluated to enhance the thermal stability of the composites with special attention given to flame-retardant properties. With the optimal SiO2 particles, obtained through acid digestion, the influence of their content between 0.5 and 3 wt.% on the physicochemical characteristics of the synthesized aerogels was thoroughly examined. The results showed that increasing the doping agent content improved the lightness, thermal stability, and flame-retardant properties of the resulting PUR aerogels, with the best performance observed at a 2 wt.% doping level. The doped aerogel samples with non-modified SiO2 particles significantly enhanced the fire safety performance of the material, exhibiting up to an eightfold increase in flame retardancy. However, modification of the SiO2 particles with phytic acid did not slow down the combustion velocity when filling the aerogels. This research highlights the promising potential of doped PUR/SiO2 aerogels in advancing materials science and engineering applications for withstanding high temperatures and improving fire safety. Full article
(This article belongs to the Special Issue Advanced Aerogels: From Design to Application)
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14 pages, 3093 KiB  
Article
Microfluidic Rheology: An Innovative Method for Viscosity Measurement of Gels and Various Pharmaceuticals
by Zsófia Vilimi, Zsófia Edit Pápay, Bálint Basa, Xeniya Orekhova, Nikolett Kállai-Szabó and István Antal
Gels 2024, 10(7), 464; https://doi.org/10.3390/gels10070464 - 16 Jul 2024
Viewed by 189
Abstract
Measuring the viscosity of pharmaceutical dosage forms is a crucial process. Viscosity provides information about the stability of the composition, the release rate of the drug, bioavailability, and, in the case of injectable drug formulations, even the force required for injection. However, measuring [...] Read more.
Measuring the viscosity of pharmaceutical dosage forms is a crucial process. Viscosity provides information about the stability of the composition, the release rate of the drug, bioavailability, and, in the case of injectable drug formulations, even the force required for injection. However, measuring viscosity is a complex task with numerous challenges, especially for non-Newtonian materials, which include most pharmaceutical formulations, such as gels. Selecting the appropriate shear rate is critical. Since viscosity in many systems is highly temperature-dependent, stable temperature control is necessary during the measurement. Using microfluidics technology, it is now possible to perform rheological characterization and conduct fast and accurate measurements. Small sample volumes (even below 500 µL) are required, and viscosity determination can be carried out over a wide range of shear rates. Nevertheless, the pharmaceutical application of viscometers operating on the principle of microfluidics is not yet widespread. In our work, we compare the results of measurements taken with a microfluidic chip-based viscometer on different pharmaceutical forms (gels, solution) with those obtained using a traditional rotational viscometer, evaluating the relative advantages and disadvantages of the different methods. The microfluidics-based method enables time- and sample-efficient viscosity analysis of the examined pharmaceutical forms. Full article
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9 pages, 5045 KiB  
Article
When the Poisson Ratio of Polymer Networks and Gels Is Larger Than 0.5?
by Yuan Tian, Zilu Wang and Andrey V. Dobrynin
Gels 2024, 10(7), 463; https://doi.org/10.3390/gels10070463 - 16 Jul 2024
Viewed by 170
Abstract
We use coarse-grained molecular dynamics simulations to study deformation of networks and gels of linear and brush strands in both linear and nonlinear deformation regimes under constant pressure conditions. The simulations show that the Poisson ratio of networks and gels could exceed 0.5 [...] Read more.
We use coarse-grained molecular dynamics simulations to study deformation of networks and gels of linear and brush strands in both linear and nonlinear deformation regimes under constant pressure conditions. The simulations show that the Poisson ratio of networks and gels could exceed 0.5 in the nonlinear deformation regime. This behavior is due to the ability of the network and gel strands to sustain large reversible deformation, which, in combination with the finite strand extensibility results in strand alignment and monomer density, increases with increasing strand elongation. We developed a nonlinear network and gel deformation model which defines conditions for the Poisson ratio to exceed 0.5. The model predictions are in good agreement with the simulation results. Full article
(This article belongs to the Special Issue Recent Advances in Smart Gels)
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15 pages, 6046 KiB  
Article
High-Performance Supercapacitor Electrodes from Fully Biomass-Based Polybenzoxazine Aerogels with Porous Carbon Structure
by Thirukumaran Periyasamy, Shakila Parveen Asrafali and Jaewoong Lee
Gels 2024, 10(7), 462; https://doi.org/10.3390/gels10070462 - 15 Jul 2024
Viewed by 368
Abstract
In recent years, polybenzoxazine aerogels have emerged as promising materials for various applications. However, their full potential has been hindered by the prevalent use of hazardous solvents during the preparation process, which poses significant environmental and safety concerns. In light of this, there [...] Read more.
In recent years, polybenzoxazine aerogels have emerged as promising materials for various applications. However, their full potential has been hindered by the prevalent use of hazardous solvents during the preparation process, which poses significant environmental and safety concerns. In light of this, there is a pressing need to explore alternative methods that can mitigate these issues and propel the practical utilization of polybenzoxazine aerogels. To address this challenge, a novel approach involving the synthesis of heteroatom self-doped mesoporous carbon from polybenzoxazine has been devised. This process utilizes eugenol, stearyl amine, and formaldehyde to create the polybenzoxazine precursor, which is subsequently treated with ethanol as a safer solvent. Notably, the incorporation of boric acid in this method serves a dual purpose: it not only facilitates microstructural regulation but also reinforces the backbone strength of the material through the formation of intermolecular bridged structures between polybenzoxazine chains. Moreover, this approach allows ambient pressure drying, further enhancing its practicability and environmental friendliness. The resultant carbon materials, designated as ESC-N and ESC-G, exhibit distinct characteristics. ESC-N, derived from calcination, possesses a surface area of 289 m2 g−1, while ESC-G, derived from the aerogel, boasts a significantly higher surface area of 673 m2 g−1. Furthermore, ESC-G features a pore size distribution ranging from 5 to 25 nm, rendering it well suited for electrochemical applications such as supercapacitors. In terms of electrochemical performance, ESC-G demonstrates exceptional potential. With a specific capacitance of 151 F g−1 at a current density of 0.5 A g−1, it exhibits superior energy storage capabilities compared with ESC-N. Additionally, ESC-G displayed a more pronounced rectangular shape in its cyclic voltammogram at a low voltage scanning rate of 20 mV s−1, indicative of enhanced electrochemical reversibility. The impedance spectra of both carbon types corroborated these findings, further validating the superior performance of ESC-G. Furthermore, ESC-G exhibits excellent cycling stability, retaining its electrochemical properties even after 5000 continuous charge–discharge cycles. This robustness underscores its suitability for long-term applications in supercapacitors, reaffirming the viability of heteroatom-doped polybenzoxazine aerogels as a sustainable alternative to traditional carbon materials. Full article
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15 pages, 6253 KiB  
Article
Ballistic Gels in Experimental Fracture Setting
by Christoph Biehl, Ann-Cathrin Thiesse-Kraul, Sabine Stötzel, Salsabel Alzubi, Lotta Biehl, Matthias Mülke, Christian Heiss and Thaqif El Khassawna
Gels 2024, 10(7), 461; https://doi.org/10.3390/gels10070461 - 14 Jul 2024
Viewed by 262
Abstract
Biomechanical tests typically involve bending, compression, or shear stress, while fall tests are less common. The main challenge in performing fall tests is the non-reproducible directionality of bone when tested with soft tissue. Upon removal of the soft tissue, the explanted bone’s resistance [...] Read more.
Biomechanical tests typically involve bending, compression, or shear stress, while fall tests are less common. The main challenge in performing fall tests is the non-reproducible directionality of bone when tested with soft tissue. Upon removal of the soft tissue, the explanted bone’s resistance to impact diminishes. Therefore, ballistic gels can fix specimens in reproducible directions and simulate periosteal soft tissue. However, the use of ballistic gels in biomechanical studies is neither standardized nor widespread. This study aimed to optimize a ballistic gel consistency that mimics the upper thigh muscle in sheep. Our results suggest a standardized and flexible evaluation method by embedding samples in ballistic gel. Compression tests were conducted using cylindrical pieces of gluteal muscle from sheep. Various compositions of agarose and gelatin mixtures were tested to achieve a muscle-like consistency. The muscle-equivalent ballistic gel was found to consist of 29.5% gelatin and 0.35% agarose. Bones remained stable within the ballistic gel setup after freeze–thaw cycles between −20 °C and +20 °C. This method reduces the variability caused by muscle and improves storage quality, allowing for tests to be conducted under consistent conditionsBallistic gels of agarose and gelatin are suitable for bone fracture models. They have muscle-like strength, fix fractures simultaneously, are inexpensive to produce, and can be stored to allow repeated measurements of the same object with changing questions. Full article
(This article belongs to the Special Issue Engineering Hydrogel for Biomedical Applications (2nd Edition))
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14 pages, 3872 KiB  
Article
Analgesic Effect of Sulforaphane: A New Application for Poloxamer-Hyaluronic Acid Hydrogels
by Juliana Zampoli Boava Papini, Bruno de Assis Esteves, Vagner Gomes de Souza Oliveira, Henrique Ballassani Abdalla, Cintia Maria Saia Cereda, Daniele Ribeiro de Araújo and Giovana Radomille Tofoli
Gels 2024, 10(7), 460; https://doi.org/10.3390/gels10070460 - 13 Jul 2024
Viewed by 338
Abstract
Sulforaphane (SFN) has shown potential as an antioxidant and anti-inflammatory agent. To improve its druggability, we developed new analgesic formulations with sulforaphane-loaded hyaluronic acid (HA)-poloxamer (PL) hydrogel. This study evaluated the pre-clinical safety and effectiveness of these formulations. Effectiveness was tested on Wistar [...] Read more.
Sulforaphane (SFN) has shown potential as an antioxidant and anti-inflammatory agent. To improve its druggability, we developed new analgesic formulations with sulforaphane-loaded hyaluronic acid (HA)-poloxamer (PL) hydrogel. This study evaluated the pre-clinical safety and effectiveness of these formulations. Effectiveness was tested on Wistar rats divided into groups (n = 15) receiving (IM, 10 mg/kg) SFN formulations or control groups (without SFN). This study used a hind paw incision postoperative pain model to evaluate mechanical hypersensitivity with von Frey filaments. TNF-α, IL-1β, substance P, and CGRP levels verified anti-inflammatory activity in the hind paw tissue. Histopathology of tissues surrounding the injection site was assessed after 2 and 7 days post-treatment. To corroborate drug safety, cell viability of 3T3 and RAW 264.7 cultures was assessed. Additionally, RAW 264.7 cultures primed with carrageenan evaluated nitric oxide (NO) levels. All animals exhibited post-incisional hypersensitivity, and F2 (PL 407/338 (18/2%) + HA 1% + SFN 0.1%) showed a longer analgesic effect (p < 0.05). F2 reduced TNF-α, IL-1β, and CGRP levels (p < 0.05). Histopathological evaluation showed mild to moderate inflammatory reactions after the formulations’ injections. F2 produced no significant difference in cell viability (p > 0.05) but reduced NO production (p < 0.05). Thus, our results highlight the biocompatibility and effectiveness of F2. Full article
(This article belongs to the Special Issue Design and Optimization of Pharmaceutical Gels (2nd Edition))
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25 pages, 13480 KiB  
Review
Conductive Polymer-Based Hydrogels for Wearable Electrochemical Biosensors
by Dinakaran Thirumalai, Madhappan Santhamoorthy, Seong-Cheol Kim and Hyo-Ryoung Lim
Gels 2024, 10(7), 459; https://doi.org/10.3390/gels10070459 - 12 Jul 2024
Viewed by 365
Abstract
Hydrogels are gaining popularity for use in wearable electronics owing to their inherent biomimetic characteristics, flexible physicochemical properties, and excellent biocompatibility. Among various hydrogels, conductive polymer-based hydrogels (CP HGs) have emerged as excellent candidates for future wearable sensor designs. These hydrogels can attain [...] Read more.
Hydrogels are gaining popularity for use in wearable electronics owing to their inherent biomimetic characteristics, flexible physicochemical properties, and excellent biocompatibility. Among various hydrogels, conductive polymer-based hydrogels (CP HGs) have emerged as excellent candidates for future wearable sensor designs. These hydrogels can attain desired properties through various tuning strategies extending from molecular design to microstructural configuration. However, significant challenges remain, such as the limited strain-sensing range, significant hysteresis of sensing signals, dehydration-induced functional failure, and surface/interfacial malfunction during manufacturing/processing. This review summarizes the recent developments in polymer-hydrogel-based wearable electrochemical biosensors over the past five years. Initially serving as carriers for biomolecules, polymer-hydrogel-based sensors have advanced to encompass a wider range of applications, including the development of non-enzymatic sensors facilitated by the integration of nanomaterials such as metals, metal oxides, and carbon-based materials. Beyond the numerous existing reports that primarily focus on biomolecule detection, we extend the scope to include the fabrication of nanocomposite conductive polymer hydrogels and explore their varied conductivity mechanisms in electrochemical sensing applications. This comprehensive evaluation is instrumental in determining the readiness of these polymer hydrogels for point-of-care translation and state-of-the-art applications in wearable electrochemical sensing technology. Full article
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17 pages, 8476 KiB  
Article
Multi-Layer PVA-PANI Conductive Hydrogel for Symmetrical Supercapacitors: Preparation and Characterization
by Angelica Giovagnoli, Giada D’Altri, Lamyea Yeasmin, Valentina Di Matteo, Stefano Scurti, Maria Francesca Di Filippo, Isacco Gualandi, Maria Cristina Cassani, Daniele Caretti, Silvia Panzavolta, Maria Letizia Focarete, Mariangela Rea and Barbara Ballarin
Gels 2024, 10(7), 458; https://doi.org/10.3390/gels10070458 - 12 Jul 2024
Viewed by 625
Abstract
This work describes a simple, inexpensive, and robust method to prepare a flexible “all in one” integrated hydrogel supercapacitors (HySCs). Preparing smart hydrogels with high electrical conductivity, ability to stretch significantly, and excellent mechanical properties is the last challenge for tailored wearable devices. [...] Read more.
This work describes a simple, inexpensive, and robust method to prepare a flexible “all in one” integrated hydrogel supercapacitors (HySCs). Preparing smart hydrogels with high electrical conductivity, ability to stretch significantly, and excellent mechanical properties is the last challenge for tailored wearable devices. In this paper, we employed a physical crosslinking process that involves consecutive freezing and thawing cycles to prepare a polyvinyl alcohol (PVA)-based hydrogel. Exploiting the self-healing properties of these materials, the assembly of the different layers of the HySCs has been performed. The ionic conductivity within the electrolyte layer arises from the inclusion of an H2SO4 solution in the hydrogel network. Instead, the electronic conductivity is facilitated by the addition of the conductive polymer PANI-PAMPSA into the hydrogel layers. Electrochemical measures have highlighted newsworthy properties related to our HySCs, opening their use in wearable electronic applications. Full article
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17 pages, 5388 KiB  
Article
Development and Geometrical Considerations of Unique Conductive and Reversible Carbon-Nanotube Hydrogel without Need for Gelators
by Ryo Ogawa, Ryota Arakaki and Takahide Oya
Gels 2024, 10(7), 457; https://doi.org/10.3390/gels10070457 - 12 Jul 2024
Viewed by 349
Abstract
We propose a new type of CNT hydrogel that has unique conductive and reversible characteristics. We found in previous studies that CNT dispersions became gelatinous without any gelators when a specific CNT was combined with a specific dispersant. This hydrogel has conductive properties [...] Read more.
We propose a new type of CNT hydrogel that has unique conductive and reversible characteristics. We found in previous studies that CNT dispersions became gelatinous without any gelators when a specific CNT was combined with a specific dispersant. This hydrogel has conductive properties derived mainly from the CNTs it contains; and even after gelation, it can be returned to a liquid state by ultrasonic irradiation. Furthermore, the liquid is gelable again. In this study, we prepared several types of CNTs and several types of dispersants, experimentally verified the possibility of gelation by combining them, and geometrically investigated the gelation mechanism to determine how this unique hydrogel is formed. As a result, we found that the experimental results and the theory examined in this study were consistent with the combination of materials that actually become hydrogels. We expect that this study will allow us to anticipate whether or not an unknown combination of CNTs and dispersants will also become gelatinous. Full article
(This article belongs to the Special Issue Social Implementation of Advanced Gel Materials)
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14 pages, 2854 KiB  
Article
The Preparation and Evaluation of a Hydrochloride Hydrogel Patch with an Iontophoresis-Assisted Release of Terbinafine for Transdermal Delivery
by Mengfei Li, Xinghao Chen, Xiangxiang Su and Wenyan Gao
Gels 2024, 10(7), 456; https://doi.org/10.3390/gels10070456 - 12 Jul 2024
Viewed by 278
Abstract
Background: Terbinafine hydrochloride (TEB) is a broad-spectrum antifungal medication commonly used to treat fungal infections of the skin. This study designed a hydrogel patch assisted by an iontophoresis system to enhance the transdermal permeability of TEB, enabling deeper penetration into the skin layers. [...] Read more.
Background: Terbinafine hydrochloride (TEB) is a broad-spectrum antifungal medication commonly used to treat fungal infections of the skin. This study designed a hydrogel patch assisted by an iontophoresis system to enhance the transdermal permeability of TEB, enabling deeper penetration into the skin layers. Methods: The influences of current intensity, pH levels, and drug concentration on the TEB hydrogel patch’s permeability were explored using an adaptive ion electroosmosis system. The pharmacokinetic profile, facilitated by iontophoresis for transdermal permeation, was analyzed through the application of microdialysis technology. Scanning electron microscopy and transmission electron microscopy were employed to assess the impact of ion electroosmotic systems on skin integrity. Results: The cumulative drug accumulation within 8 h of the TEB hydrogel patches, assisted by iontophoresis, was 2.9 and 7.9 times higher than without iontophoresis assistance and TEB cream in the control group, respectively. TEB hydrogel patches assisted by iontophoresis can significantly increase the permeability of TEB, and the AUC(0–8 h) was 3.4 and 5.4 times higher, while the Cmax was 4.2 and 7.3 times higher than the TEB hydrogel patches without iontophoresis, respectively. This system has no significant impact on deep-layer cells. Conclusions: This system may offer a safe and effective clinical strategy for the local treatment of deep antifungal infections. Full article
(This article belongs to the Special Issue Novel Functional Gels for Biomedical Applications)
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24 pages, 12720 KiB  
Article
Multi-Technique Assessment of Chelators-Loaded PVA-Borax Gel-like Systems Performance in Cleaning of Stone Contaminated with Copper Corrosion Products
by Laura Giuliani, Chiara Genova, Valeria Stagno, Luca Paoletti, Andrea Louise Matulac, Alessandro Ciccola, Melania Di Fazio, Silvia Capuani and Gabriele Favero
Gels 2024, 10(7), 455; https://doi.org/10.3390/gels10070455 - 11 Jul 2024
Viewed by 335
Abstract
Currently, one of the most important challenges for the conservation of stone artworks is the removal of metal corrosion products on their surfaces. Traditional cleaning methods, which typically involve the application of aqueous solutions containing chelating agents capable of complexing these metal ions, [...] Read more.
Currently, one of the most important challenges for the conservation of stone artworks is the removal of metal corrosion products on their surfaces. Traditional cleaning methods, which typically involve the application of aqueous solutions containing chelating agents capable of complexing these metal ions, have shown some weaknesses. These weaknesses become apparent when such methods are applied to statues and other vertical surfaces or when aiming to limit the cleaning process to a specific area with controlled application times. Furthermore, the porosity of the stone surface plays a role concerning the cleaning efficiency. To address these issues, chelating agents can be incorporated into gel-like materials. This study is a proof of concept to evaluate the cleaning efficacy of various gel formulations composed of polyvinyl alcohol (PVA), borax (B), and agarose (AG), loaded with two chelators: ethylenediaminetetraacetic acid (EDTA) and potassium sodium tartrate (PST or Rochelle salt). Three types of carbonate stones (travertine, Lecce stone, and Carrara marble) characterized by different porosities were artificially stained with copper sulphates and treated with the different PVA-B-AG formulations. The effectiveness of the treatment was directly monitored on the stones using a multi-technique approach that included scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and non-invasive portable nuclear magnetic resonance (NMR). Additionally, the rheological properties of the gels were investigated, and the Fourier transform infrared attenuated total reflection spectroscopy (FTIR ATR) was used to analyse the chemical structure of the gel before and after treatment, aiming to understand the changes induced by the cleaning process. Full article
(This article belongs to the Special Issue Physical and Mechanical Properties of Polymer Gels (2nd Edition))
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12 pages, 2173 KiB  
Article
Comparative Analysis of Gracilaria chouae Polysaccharides Derived from Different Geographical Regions: Focusing on Their Chemical Composition, Rheological Properties, and Gel Characteristics
by Xiong Li, Wanzi Yao, Cebin Hu, Congyu Lin, Lijun You and Jian Mao
Gels 2024, 10(7), 454; https://doi.org/10.3390/gels10070454 - 11 Jul 2024
Viewed by 419
Abstract
Polysaccharides derived from diverse sources exhibit distinct rheological and gel properties, exerting a profound impact on their applicability in the food industry. In this study, we collected five Gracilaria chouae samples from distinct geographical regions, namely Rizhao (RZ), Lianyungang (LYG), Ningde (ND), Beihai [...] Read more.
Polysaccharides derived from diverse sources exhibit distinct rheological and gel properties, exerting a profound impact on their applicability in the food industry. In this study, we collected five Gracilaria chouae samples from distinct geographical regions, namely Rizhao (RZ), Lianyungang (LYG), Ningde (ND), Beihai (BH), and a wild source from Beihai (BHW). We conducted analyses on the chemical composition, viscosity, and rheological properties, as well as gel properties, to investigate the influence of chemical composition on variations in gel properties. The results revealed that the total sugar, sulfate content, and monosaccharide composition of G. chouae polysaccharides exhibit similarity; however, their anhydrogalactose content varies within a range of 15.31% to 18.98%. The molecular weight distribution of G. chouae polysaccharides ranged from 1.85 to 2.09 × 103 kDa. The apparent viscosity of the LYG and BHW polysaccharides was relatively high, whereas that of RZ and ND was comparatively low. The gel strength displayed a similar trend. BHW and LYG exhibited solid-like behavior, while ND, RZ, and BH demonstrated liquid-like characteristics at low frequencies. The redundancy analysis (RDA) analysis revealed a positive correlation between the texture profile analysis (TPA) characteristics and anhydrogalactose. The study could provide recommendations for the diverse applications of G. chouae polysaccharides derived from different geographical regions. Full article
(This article belongs to the Special Issue Food Gels: Structure and Function)
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