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Gels, Volume 9, Issue 12 (December 2023) – 72 articles

Cover Story (view full-size image): α-Form hydrated crystals form a lamellar gel in which the alkyl chains of the amphiphilic molecules are hexagonally arranged within bilayers below the gel-liquid crystal phase transition temperature. In practice, the lamellar gel network with excess water is called an "α-gel", particularly in the cosmetics industry. In this study, the hydration or water sorption of amphiphilic materials in water vapor was assessed using a humidity-controlled quartz crystal microbalance with dissipation monitoring technique. The key conclusion is that the significant hydration ability of hexadecyl phosphate salts neutralized with L-arginine and CsOH contributes to the formation of the corresponding α-form hydrated crystals. View this paper
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15 pages, 3806 KiB  
Article
Underused Marine Resources: Sudden Properties of Cod Skin Gelatin Gel
by Yuriy F. Zuev, Svetlana R. Derkach, Liliya R. Bogdanova, Nikolai G. Voron’ko, Yulia A. Kuchina, Aidar T. Gubaidullin, Ivan V. Lunev, Oleg I. Gnezdilov, Igor A. Sedov, Radik A. Larionov, Larisa Latypova and Olga S. Zueva
Gels 2023, 9(12), 990; https://doi.org/10.3390/gels9120990 - 18 Dec 2023
Cited by 1 | Viewed by 1291
Abstract
The main object of this work was to characterize the structure and properties of laboratory-made fish gelatin from cod skin in comparison with known commercial gelatins of fish and mammalian origin. This is one way we can contribute to the World Food Program [...] Read more.
The main object of this work was to characterize the structure and properties of laboratory-made fish gelatin from cod skin in comparison with known commercial gelatins of fish and mammalian origin. This is one way we can contribute to the World Food Program and characterize foodstuff resources from alternative natural sources. Our research was based on the combination of an expanded set of complementary physical–chemical methods to study the similarities and distinctions of hydrogels from traditional and novel gelatin sources from underused marine resources. In this work, we have compared the morphology, supramolecular structure and colloid properties of two commercial (mammalian and fish) gelatins with gelatin we extracted from cold-water cod skin in laboratory conditions. The obtained results are novel, showing that our laboratory-produced fish gelatin is much closer to the mammalian one in terms of such parameters as thermal stability and strength of structural network under temperature alterations. Especially interesting are our experimental observations comparing both fish gelatins: it was shown that the laboratory-extracted cod gelatin is essentially more thermally stable compared to its commercial analogue, being even closer in its rheological properties to the mammalian one. Full article
(This article belongs to the Special Issue Recent Advances in Food Gels)
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15 pages, 4860 KiB  
Article
Bidirectional Long Short-Term Memory Model of SoH Prediction for Gelled-Electrolyte Batteries under Charging Conditions
by Ting-Jung Kuo and Wei-Ting Chao
Gels 2023, 9(12), 989; https://doi.org/10.3390/gels9120989 - 17 Dec 2023
Viewed by 1004
Abstract
The impact of different charging currents and surrounding temperatures has always been an important aspect of battery lifetime for various electric vehicles and energy storage equipment. This paper proposes a bidirectional long short-term memory model to quantify these impacts on the aging of [...] Read more.
The impact of different charging currents and surrounding temperatures has always been an important aspect of battery lifetime for various electric vehicles and energy storage equipment. This paper proposes a bidirectional long short-term memory model to quantify these impacts on the aging of gel batteries and calculate their state of health. The training data set of the bidirectional long short-term memory model is collected by charging and discharging the gel battery for 300 cycles in a temperature-controlled box and an automated charge and discharge device under different operating conditions. The testing set is generated by a small energy storage device equipped with small solar panels. Data for 220 cycles at different temperatures and charging currents were collected during the experiment. The results show that the mean absolute error (MAE) and root-mean-square error (RMSE) between the training set and testing set are 0.0133 and 0.0251, respectively. In addition to the proposed model providing high accuracy, the gel battery proved to be stable and long-lasting, which makes the gel battery an ideal energy storage solution for renewable energy. Full article
(This article belongs to the Special Issue Research Progress and Application Prospects of Gel Electrolytes)
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18 pages, 3905 KiB  
Article
Enhancing Soil Resilience: Bacterial Alginate Hydrogel vs. Algal Alginate in Mitigating Agricultural Challenges
by Flavia Dorochesi, Cesar Barrientos-Sanhueza, Álvaro Díaz-Barrera and Italo F. Cuneo
Gels 2023, 9(12), 988; https://doi.org/10.3390/gels9120988 - 17 Dec 2023
Viewed by 995
Abstract
Erosion and tillage changes negatively the soil physical structure, which directly impacts agricultural systems and consequently food security. To mitigate these adverse modifications, different polymeric materials from synthetic and natural sources, have been used as soil conditioners to improve the hydro-mechanical behavior of [...] Read more.
Erosion and tillage changes negatively the soil physical structure, which directly impacts agricultural systems and consequently food security. To mitigate these adverse modifications, different polymeric materials from synthetic and natural sources, have been used as soil conditioners to improve the hydro-mechanical behavior of affected soils. One of the most interesting and used natural polymers is the alginate hydrogel. Although commercially available alginate hydrogels are primarily sourced from algal, they can also be sourced from bacteria. The gelation capacity of these hydrogels is determined by their molecular properties, which, in turn, are influenced by the production conditions. Bacterial alginate hydrogel production offers the advantage of precise control over environmental conditions during cultivation and extraction, thereby maintaining and enhancing their molecular properties. This, in turn, results in higher molecular weight and improved gelation capacity. In this study, we compared the effects of bacterial alginate (BH) and algal alginate (AH) hydrogels over the mechanical, hydraulic, and structural behavior of coarse quartz sand as a model soil. Mechanically, it was observed that the treatment with the lowest concentration of bacteria alginate hydrogel (BH1) reached higher values of yield strength, Young’s modulus (E), shear modulus (G) and strain energy (U) than those treatments with algal alginate hydrogel (AH). Furthermore, the increase in the aggregate stability could be associated with the improvement of mechanical parameters. On the other hand, a greater water retention capacity was observed in the BH treatments, as well as a greater decrease in hydraulic conductivity with respect to the AH and control treatments. All these changes could be explained by the formation of bridge-like structures between the sand particles and the hydrogel, and this alteration may result in a shift in the mechanical and wettability characteristics of the treated soils. Finally, our findings emphasize the superior impact of bacterial alginate hydrogel on enhancing the mechanical and hydraulic properties of coarse quartz sand compared to traditional algal alginate. Besides, the use of bacterial alginate hydrogel could be useful to counteract erosion and water scarcity scenarios in agricultural systems. Full article
(This article belongs to the Special Issue Advances in Functional Gel)
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14 pages, 7020 KiB  
Article
Wound Microenvironment Self-Adjusting Hydrogels with Thermo-Sensitivity for Promoting Diabetic Wound Healing
by Jia Li, Jing Guo, Bo-Xiang Wang, Yue Zhang, Qiang Yao, De-Hong Cheng and Yan-Hua Lu
Gels 2023, 9(12), 987; https://doi.org/10.3390/gels9120987 - 17 Dec 2023
Cited by 1 | Viewed by 1160
Abstract
The hard-healing chronic wounds of diabetics are still one of the most intractable problems in clinical skin injury repair. Wound microenvironments directly affect wound healing speed, but conventional dressings exhibit limited efficacy in regulating the wound microenvironment and facilitating healing. To address this [...] Read more.
The hard-healing chronic wounds of diabetics are still one of the most intractable problems in clinical skin injury repair. Wound microenvironments directly affect wound healing speed, but conventional dressings exhibit limited efficacy in regulating the wound microenvironment and facilitating healing. To address this serious issue, we designed a thermo-sensitive drug-controlled hydrogel with wound self-adjusting effects, consisting of a sodium alginate (SA), Antheraeapernyi silk gland protein (ASGP) and poly(N-isopropylacrylamide) (PNIPAM) for a self-adjusting microenvironment, resulting in an intelligent releasing drug which promotes skin regeneration. PNIPAM has a benign temperature-sensitive effect. The contraction, drugs and water molecules expulsion of hydrogel were generated upon surpassing lower critical solution temperatures, which made the hydrogel system have smart drug release properties. The addition of ASGP further improves the biocompatibility and endows the thermo-sensitive drug-controlled hydrogel with adhesion. Additionally, in vitro assays demonstrate that the thermo-sensitive drug-controlled hydrogels have good biocompatibility, including the ability to promote the adhesion and proliferation of human skin fibroblast cells. This work proposes an approach for smart drug-controlled hydrogels with a thermo response to promote wound healing by self-adjusting the wound microenvironment. Full article
(This article belongs to the Special Issue Advances in Functional Gel)
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32 pages, 3750 KiB  
Review
Rheology in Product Development: An Insight into 3D Printing of Hydrogels and Aerogels
by Raquel V. Barrulas and Marta C. Corvo
Gels 2023, 9(12), 986; https://doi.org/10.3390/gels9120986 - 17 Dec 2023
Cited by 3 | Viewed by 1930
Abstract
Rheological characterisation plays a crucial role in developing and optimising advanced materials in the form of hydrogels and aerogels, especially if 3D printing technologies are involved. Applications ranging from tissue engineering to environmental remediation require the fine-tuning of such properties. Nonetheless, their complex [...] Read more.
Rheological characterisation plays a crucial role in developing and optimising advanced materials in the form of hydrogels and aerogels, especially if 3D printing technologies are involved. Applications ranging from tissue engineering to environmental remediation require the fine-tuning of such properties. Nonetheless, their complex rheological behaviour presents unique challenges in additive manufacturing. This review outlines the vital rheological parameters that influence the printability of hydrogel and aerogel inks, emphasising the importance of viscosity, yield stress, and viscoelasticity. Furthermore, the article discusses the latest developments in rheological modifiers and printing techniques that enable precise control over material deposition and resolution in 3D printing. By understanding and manipulating the rheological properties of these materials, researchers can explore new possibilities for applications such as biomedicine or nanotechnology. An optimal 3D printing ink requires strong shear-thinning behaviour for smooth extrusion, forming continuous filaments. Favourable thixotropic properties aid viscosity recovery post-printing, and adequate yield stress and G′ are crucial for structural integrity, preventing deformation or collapse in printed objects, and ensuring high-fidelity preservation of shapes. This insight into rheology provides tools for the future of material design and manufacturing in the rapidly evolving field of 3D printing of hydrogels and aerogels. Full article
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19 pages, 9552 KiB  
Article
Non-Aqueous Poly(dimethylsiloxane) Organogel Sponges for Controlled Solvent Release: Synthesis, Characterization, and Application in the Cleaning of Artworks
by Francesca Porpora, Luigi Dei, Teresa T. Duncan, Fedora Olivadese, Shae London, Barbara H. Berrie, Richard G. Weiss and Emiliano Carretti
Gels 2023, 9(12), 985; https://doi.org/10.3390/gels9120985 - 15 Dec 2023
Viewed by 1094
Abstract
Polydimethylsiloxane (PDMS) organogel sponges were prepared and studied in order to understand the role of pore size in an elastomeric network on the ability to uptake and release organic solvents. PDMS organogel sponges have been produced according to sugar leaching techniques by adding [...] Read more.
Polydimethylsiloxane (PDMS) organogel sponges were prepared and studied in order to understand the role of pore size in an elastomeric network on the ability to uptake and release organic solvents. PDMS organogel sponges have been produced according to sugar leaching techniques by adding two sugar templates of different forms and grain sizes (a sugar cube template and a powdered sugar template), in order to obtain materials differing in porosity, pore size distribution, and solvent absorption and liquid retention capability. These materials were compared to PDMS organogel slabs that do not contain pores. The sponges were characterized by Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and compared with PDMS slabs that do not contain pores. Scanning electron microscopy (SEM) provided information about their morphology. X-ray micro-tomography (XMT) allowed us to ascertain how the form of the sugar templating agent influences the porosity of the systems: when templated with sugar cubes, the porosity was 77% and the mean size of the pores was ca. 300 μm; when templated with powdered sugar, the porosity decreased to ca. 10% and the mean pore size was reduced to ca. 75 μm. These materials, porous organic polymers (POPs), can absorb many solvents in different proportions as a function of their polarity. Absorption capacity, as measured by swelling with eight solvents covering a wide range of polarities, was investigated. Rheology data established that solvent absorption did not have an appreciable impact on the gel-like properties of the sponges, suggesting their potential for applications in cultural heritage conservation. Application tests were conducted on the surfaces of two different lab mock-ups that simulate real painted works of art. They demonstrated further that PDMS sponges are a potential innovative support for controlled and selective cleaning of works of art surfaces. Full article
(This article belongs to the Special Issue Gels for Removal and Adsorption (2nd Edition))
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18 pages, 6627 KiB  
Article
Thermoresponsive Alginate-Graft-pNIPAM/Methyl Cellulose 3D-Printed Scaffolds Promote Osteogenesis In Vitro
by Aikaterini Gialouri, Sofia Falia Saravanou, Konstantinos Loukelis, Maria Chatzinikolaidou, George Pasparakis and Nikolaos Bouropoulos
Gels 2023, 9(12), 984; https://doi.org/10.3390/gels9120984 - 15 Dec 2023
Cited by 3 | Viewed by 1685
Abstract
In this work, a sodium alginate-based copolymer grafted by thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) chains was used as gelator (Alg-g-PNIPAM) in combination with methylcellulose (MC). It was found that the mechanical properties of the resulting gel could be enhanced by the addition of [...] Read more.
In this work, a sodium alginate-based copolymer grafted by thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) chains was used as gelator (Alg-g-PNIPAM) in combination with methylcellulose (MC). It was found that the mechanical properties of the resulting gel could be enhanced by the addition of MC and calcium ions (Ca2+). The proposed network is formed via a dual crosslinking mechanism including ionic interactions among Ca2+ and carboxyl groups and secondary hydrophobic associations of PNIPAM chains. MC was found to further reinforce the dynamic moduli of the resulting gels (i.e., a storage modulus of ca. 1500 Pa at physiological body and post-printing temperature), rendering them suitable for 3D printing in biomedical applications. The polymer networks were stable and retained their printed fidelity with minimum erosion as low as 6% for up to seven days. Furthermore, adhered pre-osteoblastic cells on Alg-g-PNIPAM/MC printed scaffolds presented 80% viability compared to tissue culture polystyrene control, and more importantly, they promoted the osteogenic potential, as indicated by the increased alkaline phosphatase activity, calcium, and collagen production relative to the Alg-g-PNIPAM control scaffolds. Specifically, ALP activity and collagen secreted by cells were significantly enhanced in Alg-g-PNIPAM/MC scaffolds compared to the Alg-g-PNIPAM counterparts, demonstrating their potential in bone tissue engineering. Full article
(This article belongs to the Special Issue Design of Polymeric Hydrogels Biomaterials)
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17 pages, 4950 KiB  
Article
Electrochemical Performance of Symmetric Solid-State Supercapacitors Based on Carbon Xerogel Electrodes and Solid Polymer Electrolytes
by Boryana Karamanova, Emiliya Mladenova, Minju Thomas, Natalia Rey-Raap, Ana Arenillas, Francesco Lufrano and Antonia Stoyanova
Gels 2023, 9(12), 983; https://doi.org/10.3390/gels9120983 - 15 Dec 2023
Viewed by 1148
Abstract
For the development and optimization of solid-state symmetrical supercapacitors, herein, we propose using carbon-based electrodes and sodium- and lithium-form Aquivion electrolyte membranes, which serve as the separator and electrolyte. Carbon xerogels, synthesized using microwave-assisted sol-gel methodology, with designed and controlled properties were obtained [...] Read more.
For the development and optimization of solid-state symmetrical supercapacitors, herein, we propose using carbon-based electrodes and sodium- and lithium-form Aquivion electrolyte membranes, which serve as the separator and electrolyte. Carbon xerogels, synthesized using microwave-assisted sol-gel methodology, with designed and controlled properties were obtained as electrode materials. Commercial activated carbon (YP-50F, “Kuraray Europe” GmbH) was used as the active material for comparison. Notably, the developed solid-state symmetrical supercapacitors provide sufficiently high specific capacitances of 105–110 F g−1 at 0.2 A g−1, along with an energy density of 4.5 Wh kg−1 at 300 W kg−1, and a voltage window of 0–1.2 V in aqueous environments, also demonstrating an excellent cycling stability for up to 10,000 charge/discharge cycles. These results can demonstrate the potential applications of carbon xerogel as the active electrode material and cation exchange membrane as the electrolyte in the development of solid-state supercapacitor devices. Full article
(This article belongs to the Special Issue Gels for Flexible Electronics and Energy Devices)
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20 pages, 6360 KiB  
Article
Injectable Thermoresponsive Microparticle/Hydrogel System with Superparamagnetic Nanoparticles for Drug Release and Magnetic Hyperthermia Applications
by Henrique Carrelo, André R. Escoval, Tânia Vieira, Mercedes Jiménez-Rosado, Jorge Carvalho Silva, Alberto Romero, Paula Isabel P. Soares and João Paulo Borges
Gels 2023, 9(12), 982; https://doi.org/10.3390/gels9120982 - 15 Dec 2023
Viewed by 1133
Abstract
Cancer is a disease that continues to greatly impact our society. Developing new and more personalized treatment options is crucial to decreasing the cancer burden. In this study, we combined magnetic polysaccharide microparticles with a Pluronic thermoresponsive hydrogel to develop a multifunctional, injectable [...] Read more.
Cancer is a disease that continues to greatly impact our society. Developing new and more personalized treatment options is crucial to decreasing the cancer burden. In this study, we combined magnetic polysaccharide microparticles with a Pluronic thermoresponsive hydrogel to develop a multifunctional, injectable drug delivery system (DDS) for magnetic hyperthermia applications. Gellan gum and alginate microparticles were loaded with superparamagnetic iron oxide nanoparticles (SPIONs) with and without coating. The magnetic microparticles’ registered temperature increases up to 4 °C upon the application of an alternating magnetic field. These magnetic microparticles were mixed with drug-loaded microparticles, and, subsequently, this mixture was embedded within a Pluronic thermoresponsive hydrogel that is capable of being in the gel state at 37 °C. The proposed DDS was capable of slowly releasing methylene blue, used as a model drug, for up to 9 days. The developed hydrogel/microparticle system had a smaller rate of drug release compared with microparticles alone. This system proved to be a potential thermoresponsive DDS suitable for magnetic hyperthermia applications, thus enabling a synergistic treatment for cancer. Full article
(This article belongs to the Special Issue Recent Advances in Hydrogels for Biomedical Application)
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22 pages, 4644 KiB  
Article
Synergic Effect of Recycled Carbon Fibers and Microfibrillated Cellulose Gel for Enhancing the Mechanical Properties of Cement-Based Materials
by Matteo Sambucci, Seyed Mostafa Nouri, Sara Taherinezhad Tayebi and Marco Valente
Gels 2023, 9(12), 981; https://doi.org/10.3390/gels9120981 - 14 Dec 2023
Viewed by 1053
Abstract
A new hybrid fiber blend containing microfibrillated cellulose (MFC) gel and recycled carbon short fiber (RCSF) was implemented for designing fiber-reinforced cement mortars, to further improve the mechanical properties and enhance the sustainability of cement-based materials. The individual impact of single fibrous fillers [...] Read more.
A new hybrid fiber blend containing microfibrillated cellulose (MFC) gel and recycled carbon short fiber (RCSF) was implemented for designing fiber-reinforced cement mortars, to further improve the mechanical properties and enhance the sustainability of cement-based materials. The individual impact of single fibrous fillers as well as the synergistic effect of a hybrid fiber system (MFC + RCSF) were investigated in terms of the rheological properties, mechanical strength, and microstructure of the mortars. The results indicated that the workability of fresh mixtures slightly increased after fiber addition. The fibers incorporated alone improved the materials’ performance in different ways. The addition of RCSF led to improvements of up to 76% in flexural strength and 13% in compression strength for a fiber content of 0.75 wt.%. However, the addition of carbon fibers led to slight deteriorations in terms of porosity and water absorption. On the other hand, the use of MFC induced a less significant growth in terms of mechanical strength (+14% in flexural strength for 0.75 wt.% of cellulose) but greatly improved the microstructural quality of the mortar, significantly reducing its water permeability. Considering the optimum MFC dosage, MFC+RCSF hybrid mixtures showed positive effects on the mechanical properties and microstructure of the mortar, displaying further improvements in strength, while preserving a lower porosity and water absorption than the control mix. Full article
(This article belongs to the Special Issue Gel Formation and Processing Technologies for Material Applications)
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15 pages, 2454 KiB  
Article
Development of Efficient Sodium Alginate/Polysuccinimide-Based Hydrogels as Biodegradable Acetaminophen Delivery Systems
by Long Toan Trinh, Saebin Lim, Hyun Jong Lee and Il Tae Kim
Gels 2023, 9(12), 980; https://doi.org/10.3390/gels9120980 - 14 Dec 2023
Viewed by 1288
Abstract
Efficient drug delivery systems are essential for improving patient outcomes. Acetaminophen (AP), which is a kind of oral administration, is a commonly used pain reliever and fever reducer. However, oral administration carries various health risks, especially overdose and frequent use; for instance, AP [...] Read more.
Efficient drug delivery systems are essential for improving patient outcomes. Acetaminophen (AP), which is a kind of oral administration, is a commonly used pain reliever and fever reducer. However, oral administration carries various health risks, especially overdose and frequent use; for instance, AP is administered approximately 4 times per day. Therefore, the aim of this study is to develop an efficient delivery system for once-daily administration by combining sodium alginate and polysuccinimide (PSI) hydrogels to delay the release of analgesic AP. PSI is a biodegradable polymer that can be used safely and effectively in drug delivery systems because it is eliminated by hydrolysis in the intestine. The use of PSI also improves the mechanical properties of hydrogels and prolongs drug release. In this study, hydrogel characterizations such as mechanical properties, drug dissolution ability, and biodegradability were measured to evaluate the hydrolysis of PSI in the intestine. Based on the results, hydrogels could be designed to improve the structural mechanical properties and to allow the drug to be completely dissolved, and eliminated from the body through PSI hydrolysis in the intestines. In addition, the release profiles of AP in the hydrogels were evaluated, and the hydrogels provided continuous release of AP for 24 h. Our research suggests that sodium alginate/PSI hydrogels can potentially serve as biodegradable delivery systems for AP. These findings may have significant implications for developing efficient drug delivery systems for other classes of drugs. Full article
(This article belongs to the Special Issue Design and Optimization of Pharmaceutical Gels)
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28 pages, 3944 KiB  
Review
Cryogel Scaffolds for Tissue-Engineering: Advances and Challenges for Effective Bone and Cartilage Regeneration
by Vito Cosimo Carriero, Laura Di Muzio, Stefania Petralito, Maria Antonietta Casadei and Patrizia Paolicelli
Gels 2023, 9(12), 979; https://doi.org/10.3390/gels9120979 - 14 Dec 2023
Cited by 1 | Viewed by 1643
Abstract
Critical-sized bone defects and articular cartilage injuries resulting from trauma, osteonecrosis, or age-related degeneration can be often non-healed by physiological repairing mechanisms, thus representing a relevant clinical issue due to a high epidemiological incidence rate. Novel tissue-engineering approaches have been proposed as an [...] Read more.
Critical-sized bone defects and articular cartilage injuries resulting from trauma, osteonecrosis, or age-related degeneration can be often non-healed by physiological repairing mechanisms, thus representing a relevant clinical issue due to a high epidemiological incidence rate. Novel tissue-engineering approaches have been proposed as an alternative to common clinical practices. This cutting-edge technology is based on the combination of three fundamental components, generally referred to as the tissue-engineering triad: autologous or allogenic cells, growth-stimulating factors, and a scaffold. Three-dimensional polymer networks are frequently used as scaffolds to allow cell proliferation and tissue regeneration. In particular, cryogels give promising results for this purpose, thanks to their peculiar properties. Cryogels are indeed characterized by an interconnected porous structure and a typical sponge-like behavior, which facilitate cellular infiltration and ingrowth. Their composition and the fabrication procedure can be appropriately tuned to obtain scaffolds that match the requirements of a specific tissue or organ to be regenerated. These features make cryogels interesting and promising scaffolds for the regeneration of different tissues, including those characterized by very complex mechanical and physical properties, such as bones and joints. In this review, state-of-the-art fabrication and employment of cryogels for supporting effective osteogenic or chondrogenic differentiation to allow for the regeneration of functional tissues is reported. Current progress and challenges for the implementation of this technology in clinical practice are also highlighted. Full article
(This article belongs to the Special Issue Advanced Hydrogels for Tissue Engineering and Drug Delivery)
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14 pages, 8236 KiB  
Article
Eco-Friendly Method for Wood Aerogel Preparation with Efficient Catalytic Reduction of 4-Nitrophenol
by Qianqian Yu, Xiaohan Sun, Feng Liu, Zhaolin Yang, Shulei Wei, Chengyu Wang, Xin Li, Zechen He, Xiaodong Li and Yudong Li
Gels 2023, 9(12), 978; https://doi.org/10.3390/gels9120978 - 13 Dec 2023
Viewed by 1156
Abstract
The advancement of science and technology and the growth of industry have led to an escalating discharge of domestic sewage and industrial wastewater containing dyes. This surge in volume not only incurs higher costs but also exacerbates environmental burdens. However, the benefits of [...] Read more.
The advancement of science and technology and the growth of industry have led to an escalating discharge of domestic sewage and industrial wastewater containing dyes. This surge in volume not only incurs higher costs but also exacerbates environmental burdens. However, the benefits of green and reusable catalytic reduction materials within dye processes are still uncertain. Herein, this study utilized the eco-friendly deep eutectic solvent method (DESM) and the chlorite-alkali method (CAM) to prepare a cellulose-composed wood aerogel derived from natural wood for 4-nitrophenol (4-NP) reduction. The life cycle assessment of wood aerogel preparative process showed that the wood aerogel prepared by the one-step DESM method had fewer environmental impacts. The CAM method was used innovatively to make uniform the chemical functional groups of different wood species and various wood maturities. Subsequently, palladium nanoparticles (Pd NPs) were anchored in the skeleton structure of the wood aerogel with the native chemical groups used as a reducing agent to replace external reducing agents, which reduced secondary pollution and prevented the agglomeration of nanoparticles. Results showed that the catalytic reduction efficiency of 4-NP can reach 99.8%, which shows promises for applications in wastewater treatment containing dyes. Moreover, investigation of the advantages of preparation methods of wood aerogel has important implications for helping researchers and producers choose suitable preparation strategies according to demand. Full article
(This article belongs to the Special Issue International Perspectives on Aerogels)
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18 pages, 2602 KiB  
Article
Encapsulation of Leptadenia pyrotechnica (Khip) Extract in Carbomer Based Emulgel for Its Enhanced Antioxidant Effects and Its In Vitro Evaluation
by Shamaila Masood, Muhammad Sohail Arshad, Haji Muhammad Shoaib Khan, M. Yasmin Begum and Kashif ur Rehman Khan
Gels 2023, 9(12), 977; https://doi.org/10.3390/gels9120977 - 13 Dec 2023
Viewed by 1282
Abstract
Background: The use of natural products in skin care has been valued for their tremendous therapeutic benefits since ancient times. The current study was aimed at exploring the Leptadenia pyrotechnica plant extract and development of a stable emulgel loaded with the same extract [...] Read more.
Background: The use of natural products in skin care has been valued for their tremendous therapeutic benefits since ancient times. The current study was aimed at exploring the Leptadenia pyrotechnica plant extract and development of a stable emulgel loaded with the same extract to assess its cosmeceutical potentials. Methodology: A stable emulgel loaded with methanolic plant extract along with its control gel was prepared by homogenization. The antioxidant potential of extracts prepared in different solvents (methanol MLP, ethanol ELP, n-hexane nLP, ethyl acetate EALP, and petroleum ether PLP) was determined by DPPH scavenging activity. The presence of phytochemicals was confirmed by total phenolic and flavonoid content analysis (TPC/TFC). HPLC was used for quantification of bioactive components. FTIR analysis was performed for confirmation of functional groups. SPF was calculated via spectroscopic analysis for extract, control gel, and extract loaded emulgel. Stability studies included physical evaluation, pH, conductivity, spreadability, and rheological testing of both control and test emulgels at different temperatures, i.e., 8 °C ± 1, 25 °C ± 1, 40 °C ± 1, 40 °C ± 1 with RH of 75% for a period of 90 days. Results: DPPH radical scavenging activity showed the highest antioxidant activity of 85.5% ± 2.78 for MLP. TPC and TFC were also found to be highest for the methanolic fraction, i.e., 190.98 ± 0.40 mgGAE/g and 128.28 ± 2.64 mgQE/g, respectively. The SPF of methanolic extract, placebo gel, and LPEG was 13.43 ± 0.46, 2.37 ± 0.33, and 7.28 ± 0.56, respectively. HPLC assay confirmed the presence of catechin, vanillic acid, caffeic acid, and sinapinic acid. Rheological analysis showed that formulation has pseudo-plastic flow behavior. Other stability tests also revealed that prepared emulgel is a stable one. Conclusion: A stable emulgel loaded with Leptadenia pyrotechnica plant extract was successfully prepared and characterized for its cosmetic effects. Full article
(This article belongs to the Special Issue Beauty Gels: From Bench to Applications)
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24 pages, 2950 KiB  
Review
Enhancing Photocatalytic Properties of TiO2 Photocatalyst and Heterojunctions: A Comprehensive Review of the Impact of Biphasic Systems in Aerogels and Xerogels Synthesis, Methods, and Mechanisms for Environmental Applications
by Lizeth Katherine Tinoco Navarro and Cihlar Jaroslav
Gels 2023, 9(12), 976; https://doi.org/10.3390/gels9120976 - 13 Dec 2023
Cited by 5 | Viewed by 1541
Abstract
This review provides a detailed exploration of titanium dioxide (TiO2) photocatalysts, emphasizing structural phases, heterophase junctions, and their impact on efficiency. Key points include diverse synthesis methods, with a focus on the sol-gel route and variants like low-temperature hydrothermal synthesis (LTHT). [...] Read more.
This review provides a detailed exploration of titanium dioxide (TiO2) photocatalysts, emphasizing structural phases, heterophase junctions, and their impact on efficiency. Key points include diverse synthesis methods, with a focus on the sol-gel route and variants like low-temperature hydrothermal synthesis (LTHT). The review delves into the influence of acid-base donors on gelation, dissects crucial drying techniques for TiO2 aerogel or xerogel catalysts, and meticulously examines mechanisms underlying photocatalytic activity. It highlights the role of physicochemical properties in charge diffusion, carrier recombination, and the impact of scavengers in photo-oxidation/reduction. Additionally, TiO2 doping techniques and heterostructures and their potential for enhancing efficiency are briefly discussed, all within the context of environmental applications. Full article
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13 pages, 3049 KiB  
Article
Gel Polymer Electrolytes for Lithium-Ion Batteries Enabled by Photo Crosslinked Polymer Network
by Kyeongsik Kim, Wookil Chae, Jaehyeon Kim, Choongik Kim and Taeshik Earmme
Gels 2023, 9(12), 975; https://doi.org/10.3390/gels9120975 - 13 Dec 2023
Cited by 1 | Viewed by 1528
Abstract
We demonstrate a gel polymer electrolyte (GPE) featuring a crosslinked polymer matrix formed by poly(ethylene glycol) diacrylate (PEGDA) and dipentaerythritol hexaacrylate (DPHA) using the radical photo initiator via ultraviolet (UV) photopolymerization for lithium-ion batteries. The two monomers with acrylate functional groups undergo chemical [...] Read more.
We demonstrate a gel polymer electrolyte (GPE) featuring a crosslinked polymer matrix formed by poly(ethylene glycol) diacrylate (PEGDA) and dipentaerythritol hexaacrylate (DPHA) using the radical photo initiator via ultraviolet (UV) photopolymerization for lithium-ion batteries. The two monomers with acrylate functional groups undergo chemical crosslinking, resulting in a three-dimensional structure capable of absorbing liquid electrolytes to form a gel. The GPE system was strategically designed by varying the ratios between the main polymer backbone (PEGDA) and the crosslinker (DPHA) to achieve an optimal gel polymer electrolyte network. The resulting GPE exhibited enhanced thermal stability compared to conventional liquid electrolytes (LE) and demonstrated high ionic conductivity (1.40 mS/cm) with a high lithium transference number of 0.65. Moreover, the obtained GPE displayed exceptional cycle performance, maintaining a higher capacity retention (85.2%) comparable to the cell with LE (79.3%) after 200 cycles. Full article
(This article belongs to the Special Issue Synthetic, Natural and Hybrid Gels Intended for Various Applications)
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22 pages, 8010 KiB  
Article
Alkaline Hydrolysis of Waste Acrylic Fibers Using the Micro-Water Method and Its Application in Drilling Fluid Gel Systems
by Wenjun Long, Zhongjin Wei, Fengshan Zhou, Shaohua Li, Kang Yin, Yu Zhao, Siting Yu and Hang Qi
Gels 2023, 9(12), 974; https://doi.org/10.3390/gels9120974 - 13 Dec 2023
Cited by 1 | Viewed by 1376
Abstract
Filtrate reducer is a drilling fluid additive that can effectively control the filtration loss of drilling fluid to ensure the safe and efficient exploitation of oilfields. It is the most widely used treatment agent in oilfields. Due to its moderate conditions and controllable [...] Read more.
Filtrate reducer is a drilling fluid additive that can effectively control the filtration loss of drilling fluid to ensure the safe and efficient exploitation of oilfields. It is the most widely used treatment agent in oilfields. Due to its moderate conditions and controllable procedure, alkaline hydrolysis of high-purity waste polyacrylonitrile has been utilized for decades to produce filtrate reducer on a large scale in oilfields. However, the issues of long hydrolysis time, high viscosity of semi-finished products, high drying cost, and tail gas pollution have constrained the development of the industry. In this study, low-purity waste acrylic fiber was first separated and purified using high-temperature hydroplastization, and the hydrolyzed product was obtained using alkaline hydrolysis with the micro-water method, which was called MW−HPAN. The hydrolysis reaction was characterized using X-ray diffraction, scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis, and the elemental analysis showed a hydrolysis degree of 73.21%. The experimental results showed that after aging at 180 °C for 16 h, the filtration volume of the freshwater base slurry with 0.30% dosage and 4% brine base slurry with 1.20% dosage was 12.7 mL and 18.5 mL, respectively. The microstructure and particle size analysis of the drilling fluid gel system showed that MW−HPAN could prevent the agglomeration of clay and maintain a reasonable particle size distribution even under the combined deteriorating effect of high temperature and inorganic cations, thus forming a dense filter cake and achieving a low filtrate volume of the drilling fluid gel system. Compared with similar commercially available products, MW−HPAN has better resistance to temperature and salt in drilling fluid gel systems, and the novel preparation method is promising to be extended to practical production. Full article
(This article belongs to the Special Issue Gels for Oil and Gas Industry Applications (2nd Edition))
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15 pages, 3465 KiB  
Article
Enhancement of Curcumin’s Anti-Psoriatic Efficacy via Formulation into Tea Tree Oil-Based Emulgel
by Km Reena, Saurabh Mittal, Mohammad Faizan, Iram Jahan, Yasir Rahman, Rahmuddin Khan, Lalit Singh, Abdulsalam Alhalmi, Omar M. Noman and Ahmad Alahdab
Gels 2023, 9(12), 973; https://doi.org/10.3390/gels9120973 - 13 Dec 2023
Cited by 1 | Viewed by 1618
Abstract
Psoriasis is a chronic inflammatory skin disease characterized by the hyperproliferation and aberrant differentiation of epidermal keratinocytes. It is a debilitating condition that can cause significant physical and emotional distress. Natural anti-psoriatic agents have been investigated as alternatives to conventional allopathic medications, as [...] Read more.
Psoriasis is a chronic inflammatory skin disease characterized by the hyperproliferation and aberrant differentiation of epidermal keratinocytes. It is a debilitating condition that can cause significant physical and emotional distress. Natural anti-psoriatic agents have been investigated as alternatives to conventional allopathic medications, as they have notable limitations and drawbacks. Curcumin and tea tree oil are cost-efficient and effective anti-inflammatory medicines with less adverse effects compared to synthetic psoriasis medications. Our research endeavors to harness the therapeutic potential of these natural compounds by developing an herbal anti-psoriatic topical drug delivery system. This novel method uses curcumin and tea tree oil to create a bi-phasic emulgel drug delivery system. Formulations F1 (gel) and F2 (emulgel) have high drug content percentages of 84.2% and 96.7%, respectively. The emulgel showed better spreadability for cutaneous applications, with a viscosity of 92,200 ± 943 cp compared to the gel’s 56,200 ± 1725 cp. The emulgel released 94.48% of the drugs, compared to 87.58% for the gel. These formulations conform to the zero-order and Higuchi models, and their stability over a three-month period is crucial. In vivo, the emulgel healed psoriasis symptoms faster than the usual gel. The gathered results confirmed the emulgel’s potential as a drug delivery method, emphasizing the complementary benefits of tea tree oil and curcumin as an effective new therapy for psoriasis. Full article
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14 pages, 2131 KiB  
Article
Effects of Dextran on the Gel Properties of Faba Bean Protein Isolates Prepared Using Different Processes
by Huihua Tang, Xinyi Li, Junfei Chen, Biqin Liu, Rong Tang, Yuchun Chen, Hong Li, Ling Zou and Qiao Shi
Gels 2023, 9(12), 972; https://doi.org/10.3390/gels9120972 - 12 Dec 2023
Cited by 1 | Viewed by 1105
Abstract
The properties of faba bean (Vicia faba L.) protein isolate (FPI) gels depend on their starting protein material and can be modulated by the addition of polysaccharides. In order to investigate the interplay between these two factors, commercial FPI (FPI1) [...] Read more.
The properties of faba bean (Vicia faba L.) protein isolate (FPI) gels depend on their starting protein material and can be modulated by the addition of polysaccharides. In order to investigate the interplay between these two factors, commercial FPI (FPI1) and FPI prepared in-house (FPI2) were used to fabricate glucono-delta-lactone-induced gels, with or without dextran (DX) addition. FPI1 exhibited lower solubility in water and a larger mean particle size, likely because it experienced extensive degradation due to the intense conditions involved in its preparation. The FPI1 gel showed a similar water-holding capacity as the FPI2 gel; however, its hardness was lower and viscoelasticity was higher. After DX addition, the hardness of both FPI gels decreased, while their water-holding capacity increased. Interestingly, DX addition decreased the viscoelasticity of the FPI1 gel but enhanced the viscoelasticity of the FPI2 gel. The microstructural analysis demonstrated that the density of the aggregation network decreased in the FPI1 gel after DX addition but increased in the FPI2 gel. This was consistent with the changes observed in the dominant protein interaction forces in these gels after DX addition. Overall, these findings have the potential to guide ingredient selection for the tailored preparation of FPI gels. Full article
(This article belongs to the Section Gel Applications)
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19 pages, 4357 KiB  
Article
Evaluating the Efficacy of a Thermoresponsive Hydrogel for Delivering Anti-Collagen Antibodies to Reduce Posttraumatic Scarring in Orthopedic Tissues
by Andrzej Steplewski, Jolanta Fertala, Lan Cheng, Mark L. Wang, Michael Rivlin, Pedro Beredjiklian and Andrzej Fertala
Gels 2023, 9(12), 971; https://doi.org/10.3390/gels9120971 - 12 Dec 2023
Viewed by 1151
Abstract
Excessive posttraumatic scarring in orthopedic tissues, such as joint capsules, ligaments, tendons, muscles, and peripheral nerves, presents a significant medical problem, resulting in pain, restricted joint mobility, and impaired musculoskeletal function. Current treatments for excessive scarring are often ineffective and require the surgical [...] Read more.
Excessive posttraumatic scarring in orthopedic tissues, such as joint capsules, ligaments, tendons, muscles, and peripheral nerves, presents a significant medical problem, resulting in pain, restricted joint mobility, and impaired musculoskeletal function. Current treatments for excessive scarring are often ineffective and require the surgical removal of fibrotic tissue, which can aggravate the problem. The primary component of orthopedic scars is collagen I-rich fibrils. Our research team has developed a monoclonal anti-collagen antibody (ACA) that alleviates posttraumatic scarring by inhibiting collagen fibril formation. We previously established the safety and efficacy of ACA in a rabbit-based arthrofibrosis model. In this study, we evaluate the utility of a well-characterized thermoresponsive hydrogel (THG) as a delivery vehicle for ACA to injury sites. Crucial components of the hydrogel included N-isopropylacrylamide, poly(ethylene glycol) diacrylate, and hyaluronic acid. Our investigation focused on in vitro ACA release kinetics, stability, and activity. Additionally, we examined the antigen-binding characteristics of ACA post-release from the THG in an in vivo context. Our preliminary findings suggest that the THG construct exhibits promise as a delivery platform for antibody-based therapeutics to reduce excessive scarring in orthopedic tissues. Full article
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22 pages, 557 KiB  
Article
Efficacy of Chitosan, Pectin and Xanthan as Cold Gelling Agents in Emulsion Gels Stabilized with Legume Proteins to Be Used as Pork Backfat Replacers in Beef Burgers
by Nicoleta Cîrstea (Lazăr), Violeta Nour, Alexandru Radu Corbu and Georgiana Gabriela Codină
Gels 2023, 9(12), 970; https://doi.org/10.3390/gels9120970 - 11 Dec 2023
Viewed by 1494
Abstract
This study aimed to develop stable emulsion gels enriched in polyunsaturated fatty acids, formulated with a mixture of olive (75%) and linseed (25%) oils, by incorporating two different stabilizers—pea and soy protein isolates—and three different cold gelling agents—chitosan, pectin and xanthan—to be used [...] Read more.
This study aimed to develop stable emulsion gels enriched in polyunsaturated fatty acids, formulated with a mixture of olive (75%) and linseed (25%) oils, by incorporating two different stabilizers—pea and soy protein isolates—and three different cold gelling agents—chitosan, pectin and xanthan—to be used as pork backfat replacers in beef burgers. The color, pH, stability and textural properties of the emulsion gels were analyzed as affected by cold storage (4 °C, 7 days). Proximate composition, fatty acid content, technological and sensory properties were determined after burger processing. Meanwhile, color, pH, textural parameters and lipid oxidation were monitored in burgers at 0, 5 and 10 days of storage at 4 °C. A reduction of the fat content between 21.49% and 39.26% was achieved in the reformulated burgers as compared with the control, while the n-6/n-3 polyunsaturated fatty acid ratio decreased from 5.11 to 0.62. The highest moisture and fat retention were found in reformulated burgers made with xanthan, both with pea and soy proteins; however, their textural properties were negatively affected. The reformulated burgers made with chitosan were rated highest for sensory attributes and overall acceptability, not significantly different from the controls. Full article
(This article belongs to the Special Issue Food Gels: Properties and Applications)
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20 pages, 4124 KiB  
Review
Review of the Perspectives and Study of Thermo-Responsive Polymer Gels and Applications in Oil-Based Drilling Fluids
by Jintang Wang, Lei Liu, Siyang Zhang, Bo Liao, Ke Zhao, Yiyao Li, Jiaqi Xu and Longqiao Chen
Gels 2023, 9(12), 969; https://doi.org/10.3390/gels9120969 - 11 Dec 2023
Cited by 1 | Viewed by 1123
Abstract
Thermoresponsive polymer gels are a type of intelligent material that can react to changes in temperature. These materials possess excellent innovative properties and find use in various fields. This paper systematically analyzes the methods for testing and regulating phase transition temperatures of thermo-responsive [...] Read more.
Thermoresponsive polymer gels are a type of intelligent material that can react to changes in temperature. These materials possess excellent innovative properties and find use in various fields. This paper systematically analyzes the methods for testing and regulating phase transition temperatures of thermo-responsive polymer gels based on their response mechanism. The report thoroughly introduces the latest research on thermo-responsive polymer gels in oil and gas extraction, discussing their advantages and challenges across various environments. Additionally, it elucidates how the application limitations of high-temperature and high-salt conditions can be resolved through process optimization and material innovation, ultimately broadening the scope of application of thermo-responsive polymer gels in oil and gas extraction. The article discusses the technological development and potential applications of thermo-responsive polymer gels in oil-based drilling fluids. This analysis aims to offer researchers in the oil and gas industry detailed insights into future possibilities for thermo-responsive polymer gels and to provide helpful guidance for their practical use in oil-based drilling fluids. Full article
(This article belongs to the Special Issue Gel for Oil-Based Drilling Fluid)
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20 pages, 5926 KiB  
Article
Exploring Functionalized Magnetic Hydrogel Polyvinyl Alcohol and Chitosan Electrospun Nanofibers
by Mónica Guerra, Fábio F. F. Garrudo, Célia Faustino, Maria Emilia Rosa and Maria H. L. Ribeiro
Gels 2023, 9(12), 968; https://doi.org/10.3390/gels9120968 - 11 Dec 2023
Viewed by 1175
Abstract
Nanofibrous materials present interesting characteristics, such as higher area/mass ratio and reactivity. These properties have been exploited in different applications, such as drug-controlled release and site-specific targeting of biomolecules for several disease treatments, including cancer. The main goal of this study was to [...] Read more.
Nanofibrous materials present interesting characteristics, such as higher area/mass ratio and reactivity. These properties have been exploited in different applications, such as drug-controlled release and site-specific targeting of biomolecules for several disease treatments, including cancer. The main goal of this study was to develop magnetized nanofiber systems of lysozyme (Lys) for biological applications. The system envisaged electrospun polyvinyl alcohol (PVA) and PVA/chitosan (CS) nanofibers, loaded with Lys, crosslinked with boronic acids [phenylboronic acid (PBA), including 2-acetylphenylboronic acid (aPBA), 2-formylphenylboronic (fPBA), or bortezomib (BTZ)] and functionalized with magnetic nanobeads (IONPs), which was successfully built and tested using a microscale approach. Evaluation of the morphology of nanofibers, obtained by electrospinning, was carried out using SEM. The biological activities of the Lys-loaded PVA/CS (90:10 and 70:30) nanofibers were evaluated using the Micrococcus lysodeikticus method. To evaluate the success of the encapsulation process, the ratio of adsorbed Lys on the nanofibers, Lys activity, and in vitro Lys release were determined in buffer solution at pH values mimicking the environment of cancer cells. The viability of Caco-2 cancer cells was evaluated after being in contact with electrospun PVA + Lys and PVA/CS + Lys nanofibers, with or without boronic acid functionalation, and all were magnetized with IONPs. Full article
(This article belongs to the Special Issue Hydrogel-Based Novel Biomaterials: Achievements and Prospects)
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21 pages, 3368 KiB  
Review
Graphene-Based Aerogels for Biomedical Application
by Yeongsang Kim, Rajkumar Patel, Chandrashekhar V. Kulkarni and Madhumita Patel
Gels 2023, 9(12), 967; https://doi.org/10.3390/gels9120967 - 9 Dec 2023
Viewed by 1673
Abstract
Aerogels are three-dimensional solid networks with incredibly low densities, high porosity, and large specific surface areas. These aerogels have both nanoscale and macroscopic interior structures. Combined with graphene, the aerogels show improved mechanical strength, electrical conductivity, surface area, and adsorption capacity, making them [...] Read more.
Aerogels are three-dimensional solid networks with incredibly low densities, high porosity, and large specific surface areas. These aerogels have both nanoscale and macroscopic interior structures. Combined with graphene, the aerogels show improved mechanical strength, electrical conductivity, surface area, and adsorption capacity, making them ideal for various biomedical applications. The graphene aerogel has a high drug-loading capacity due to its large surface area, and the porous structure enables controlled drug release over time. The presence of graphene makes it a suitable material for wound dressings, blood coagulation, and bilirubin adsorption. Additionally, graphene’s conductivity can help in the electrical stimulation of cells for improved tissue regeneration, and it is also appropriate for biosensors. In this review, we discuss the preparation and advantages of graphene-based aerogels in wound dressings, drug delivery systems, bone regeneration, and biosensors. Full article
(This article belongs to the Special Issue Recent Advances in Aerogel-Based Composites)
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19 pages, 5261 KiB  
Article
An Amphiphilic Multiblock Polymer as a High-Temperature Gelling Agent for Oil-Based Drilling Fluids and Its Mechanism of Action
by Yinbo He, Mingliang Du, Jing He, Haiyang Liu, Yanhua Lv, Lei Guo, Peng Zhang and Yunhai Bai
Gels 2023, 9(12), 966; https://doi.org/10.3390/gels9120966 - 9 Dec 2023
Cited by 1 | Viewed by 1089
Abstract
Oil-based drilling fluids are widely used in challenging wells such as those with large displacements, deepwater and ultra-deepwater wells, deep wells, and ultra-deep wells due to their excellent temperature resistance, inhibition properties, and lubrication. However, there is a challenging issue of rheological deterioration [...] Read more.
Oil-based drilling fluids are widely used in challenging wells such as those with large displacements, deepwater and ultra-deepwater wells, deep wells, and ultra-deep wells due to their excellent temperature resistance, inhibition properties, and lubrication. However, there is a challenging issue of rheological deterioration of drilling fluids under high-temperature conditions. In this study, a dual-amphiphilic segmented high-temperature-resistant gelling agent (HTR-GA) was synthesized using poly fatty acids and polyether amines as raw materials. Experimental results showed that the initial decomposition temperature of HTR-GA was 374 °C, indicating good thermal stability. After adding HTR-GA, the emulsion coalescence voltage increased for emulsions with different oil-to-water ratios. HTR-GA could construct a weak gel structure in oil-based drilling fluids, significantly enhancing the shear-thinning and thixotropic properties of oil-based drilling fluids under high-temperature conditions. Using HTR-GA as the core, a set of oil-based drilling fluid systems with good rheological properties, a density of 2.2 g/cm3, and temperature resistance up to 220 °C were constructed. After aging for 24 h at 220 °C, the dynamic shear force exceeded 10 Pa, and G′ exceeded 7 Pa, while after aging for 96 h at 220 °C, the dynamic shear force exceeded 4 Pa, and G″ reached 7 Pa. The synthesized compound HTR-GA has been empirically validated to significantly augment the rheological properties of oil-based drilling fluids, particularly under high-temperature conditions, showcasing impressive thermal stability with a resistance threshold of up to 220 °C. This notable enhancement provides critical technical reinforcement for progressive exploration endeavors in deep and ultra-deep well formations, specifically employing oil-based drilling fluids. Full article
(This article belongs to the Special Issue Gel for Oil-Based Drilling Fluid)
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14 pages, 1340 KiB  
Article
Thermoreversible Gel-Dispersed Liquid Crystals
by Akihiko Matsuyama
Gels 2023, 9(12), 965; https://doi.org/10.3390/gels9120965 - 8 Dec 2023
Viewed by 1008
Abstract
A simple model is introduced to describe phase behaviours of binary mixtures of a thermoreversible gel and a low-molecular-weight liquid crystal (LC). We predict novel phase diagrams on the temperature–concentration plane, including sol–gel transition, nematic–isotropic phase transition, and phase separation. At high temperatures, [...] Read more.
A simple model is introduced to describe phase behaviours of binary mixtures of a thermoreversible gel and a low-molecular-weight liquid crystal (LC). We predict novel phase diagrams on the temperature–concentration plane, including sol–gel transition, nematic–isotropic phase transition, and phase separation. At high temperatures, the phase separation between the isotropic sol and gel phases appears. As the temperature decreases, we have the phase separation between nematic sol and isotropic gel phases, in which the nematic domains are dispersed in the isotropic gel phase. We suggest that thermoreversible gelation of reactive molecules mixed with LCs will become one of the new classes of polymer-dispersed liquid crystals. Full article
(This article belongs to the Special Issue Recent Advances in Thermoreversible Gelation)
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14 pages, 1733 KiB  
Article
Physico-Chemical, Textural and Sensory Evaluation of Emulsion Gel Formulated with By-Products from the Vegetable Oil Industry
by Ana Leahu, Sorina Ropciuc, Cristina Ghinea and Cristina Damian
Gels 2023, 9(12), 964; https://doi.org/10.3390/gels9120964 - 8 Dec 2023
Viewed by 1141
Abstract
The aim of this study was to obtain low fat mayonnaise-like emulsion gels using sesame cake and walnut cake by-products resulting from vegetable oil extraction. The ingredients used to formulate the mayonnaise like emulsion gel samples were corn starch, sesame seed cake (SSC), [...] Read more.
The aim of this study was to obtain low fat mayonnaise-like emulsion gels using sesame cake and walnut cake by-products resulting from vegetable oil extraction. The ingredients used to formulate the mayonnaise like emulsion gel samples were corn starch, sesame seed cake (SSC), walnuts seed cake (WSC), lemon juice, sunflower oil, mustard, sugar, salt, gelatin and water. Five different samples were prepared: one control lab sample (M) containing only corn starch and the other ingredients (without SSC and WSC), two samples (SO1 and SO2) with 2 and 4% of SSC (without corn starch and WSC) and two samples (WO1 and WO2) with 2 and 4% of WSC (without corn starch and SSC). Also, an egg-free commercial mayonnaise (CM) was purchased and used for comparison. Physicochemical (fat, protein, moisture, ash, carbohydrate, water activity, emulsion stability, viscosity, density and color), textural (hardness, adhesiveness, springiness, cohesiveness, gumminess and chewiness), and sensory (aspect, color, texture/firmness, flavor, taste and acceptability) attributes of all samples were investigated. The results showed that carbohydrate content decreased in all four seed cakes samples compared to the control sample, while protein and fat content increased in all seed cakes samples, with the largest increases observed in the sesame seed cake samples. It was observed that the CM sample has a carbohydrate content value close to that obtained for the M sample, while the protein content has the lowest value for the CM sample compared to all samples analyzed. The stability of the emulsion gels increased from 70.73% (control sample) to 83.64% for the sample with 2% addition sesame seed cake and to 84.09% for the 2% walnut cake added, due to the coagulation capacity of the added cakes. The type and concentration of oil seeds cake added in emulsion gels affected their textural properties such as hardness, adhesiveness, gumminess, and chewiness. The hardness and adhesiveness of low-fat mayonnaise-like emulsion gels samples decreased with the addition of oil seeds cake. However, the addition of by-products improved the sensory properties of emulsion gels. This study provided a theoretical basis for the food industry’s application of oilseed cakes, especially for the development of low-fat mayonnaise. Full article
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20 pages, 15454 KiB  
Article
Effect of Phytic Acid Addition on the Structure of Collagen-Hyaluronic Acid Composite Gel
by Yuliya Nashchekina, Evgeny Guryanov, Alexey Lihachev, Gleb Vaganov, Elena Popova, Natalya Mikhailova and Alexey Nashchekin
Gels 2023, 9(12), 963; https://doi.org/10.3390/gels9120963 - 8 Dec 2023
Viewed by 1327
Abstract
Composite collagen gels with hyaluronic acid are developed tissue-engineered structures for filling and regeneration of defects in various organs and tissues. For the first time, phytic acid was used to increase the stability and improve the mechanical properties of collagen gels with hyaluronic [...] Read more.
Composite collagen gels with hyaluronic acid are developed tissue-engineered structures for filling and regeneration of defects in various organs and tissues. For the first time, phytic acid was used to increase the stability and improve the mechanical properties of collagen gels with hyaluronic acid. Phytic acid is a promising cross-linker for collagen hydrogels and is a plant-derived antioxidant found in rich sources of beans, grains, and oilseeds. Phytic acid has several benefits due to its antioxidant, anticancer, and antitumor properties. In this work, studies were carried out on the kinetics of the self-assembly of collagen molecules in the presence of phytic and hyaluronic acids. It was shown that both of these acids do not lead to collagen self-assembly. Scanning electron microscopy showed that in the presence of phytic and hyaluronic acids, the collagen fibrils had a native structure, and the FTIR method confirmed the chemical cross-links between the collagen fibrils. DSC and rheological studies demonstrated that adding the phytic acid improved the stability and modulus of elasticity of the collagen gel. The presence of hyaluronic acid in the collagen gel slightly reduced the effect of phytic acid. The presence of phytic acid in the collagen gel improved the stability of the scaffold, but, after 1 week of cultivation, slightly reduced the viability of mesenchymal stromal cells cultured in the gel. The collagen type I gel with hyaluronic and phytic acids can be used to replace tissue defects, especially after the removal of cancerous tumors. Full article
(This article belongs to the Special Issue Physically Cross-Linked Gels and Their Applications)
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14 pages, 1224 KiB  
Article
Hard-to-Heal Wound Healing: Superiority of Hydrogel EHO-85 (Containing Olea europaea Leaf Extract) vs. a Standard Hydrogel. A Randomized Controlled Trial
by José Verdú-Soriano, Antonio Casado-Díaz, Marisol de Cristino-Espinar, Silvia Luna-Morales, Caridad Dios-Guerra, Paloma Moreno-Moreno, Gabriel Dorado, José Manuel Quesada-Gómez, Leocadio Rodríguez-Mañas and José Luis Lázaro-Martínez
Gels 2023, 9(12), 962; https://doi.org/10.3390/gels9120962 - 8 Dec 2023
Cited by 2 | Viewed by 1579
Abstract
Chronic wounds, especially those that are hard-to-heal, constitute a serious public-health problem. Although progress has been made in the development of wound dressings for healing, there is little high-quality evidence of their efficacy, with no evidence of superiority in the use of one [...] Read more.
Chronic wounds, especially those that are hard-to-heal, constitute a serious public-health problem. Although progress has been made in the development of wound dressings for healing, there is little high-quality evidence of their efficacy, with no evidence of superiority in the use of one hydrogel over another. To evaluate the superiority of a hydrogel (EHO-85), containing Olea europaea leaf extract (OELE), over a standard hydrogel (SH), the promotion and/or improvement of healing of difficult-to-heal wounds was compared in a prospective, parallel-group multicenter, randomized, observer-blinded, controlled trial (“MACAON”). Non-hospitalized patients with pressure, venous or diabetic foot-ulcers difficult-to-heal were recruited and treated with standard care, and EHO-85 (n = 35) or VariHesive (n = 34) as SH. Wound-area reduction (WAR; percentage) and healing rate (HR; mm2/day) were measured. EHO-85 showed a statistically significant superior effect over VariHesive. At the end of the follow-up period, the relative WAR decreased by 51.6% vs. 18.9% (p < 0.001), with a HR mean of 10.5 ± 5.7 vs. 1.0 ± 7.5 mm2/day (p = 0.036). EHO-85 superiority is probably based on its optimal ability to balance the ulcer bed, by modulating pH and oxidative stress. That complements the wetting and barrier functions, characteristics of conventional hydrogels. These results support the use of EHO-85 dressing, for treatment of hard-to-heal ulcers. Trial Registration AEMPS:PS/CR623/17/CE. Full article
(This article belongs to the Special Issue Advances in Hydrogels for Tissue Engineering)
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19 pages, 7234 KiB  
Article
Facile Fabrication of NIR-Responsive Alginate/CMC Hydrogels Derived through IEDDA Click Chemistry for Photothermal–Photodynamic Anti-Tumor Therapy
by Ali Rizwan, Israr Ali, Sung-Han Jo, Trung Thang Vu, Yeong-Soon Gal, Yong Hyun Kim, Sang-Hyug Park and Kwon Taek Lim
Gels 2023, 9(12), 961; https://doi.org/10.3390/gels9120961 - 7 Dec 2023
Cited by 1 | Viewed by 1447
Abstract
Novel chemically cross-linked hydrogels derived from carboxymethyl cellulose (CMC) and alginate (Alg) were prepared through the utilization of the norbornene (Nb)–methyl tetrazine (mTz) click reaction. The hydrogels were designed to generate reactive oxygen species (ROS) from an NIR dye, indocyanine green (ICG), for [...] Read more.
Novel chemically cross-linked hydrogels derived from carboxymethyl cellulose (CMC) and alginate (Alg) were prepared through the utilization of the norbornene (Nb)–methyl tetrazine (mTz) click reaction. The hydrogels were designed to generate reactive oxygen species (ROS) from an NIR dye, indocyanine green (ICG), for combined photothermal and photodynamic therapy (PTT/PDT). The cross-linking reaction between Nb and mTz moieties occurred via an inverse electron-demand Diels–Alder chemistry under physiological conditions avoiding the need for a catalyst. The resulting hydrogels exhibited viscoelastic properties (G′ ~ 492–270 Pa) and high porosity. The hydrogels were found to be injectable with tunable mechanical characteristics. The ROS production from the ICG-encapsulated hydrogels was confirmed by DPBF assays, indicating a photodynamic effect (with NIR irradiation at 1–2 W for 5–15 min). The temperature of the ICG-loaded hydrogels also increased upon the NIR irradiation to eradicate tumor cells photothermally. In vitro cytocompatibility assessments revealed the non-toxic nature of CMC–Nb and Alg–mTz towards HEK-293 cells. Furthermore, the ICG-loaded hydrogels effectively inhibited the metabolic activity of Hela cells after NIR exposure. Full article
(This article belongs to the Special Issue Advances in Cellulose-Based Hydrogels (2nd Edition))
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