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Volume 11
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Gels, Volume 11, Issue 2 (February 2025) – 30 articles

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28 pages, 4115 KiB  
Review
Bioprinting-By-Design of Hydrogel-Based Biomaterials for In Situ Skin Tissue Engineering
by Alisa Douglas, Yufei Chen, Margarita Elloso, Adam Levschuk and Marc G. Jeschke
Gels 2025, 11(2), 110; https://doi.org/10.3390/gels11020110 - 3 Feb 2025
Abstract
Burns are one of the most common trauma injuries worldwide and have detrimental effects on the entire body. However, the current standard of care is autologous split thickness skin grafts (STSGs), which induces additional injuries to the patient. Therefore, the development of alternative [...] Read more.
Burns are one of the most common trauma injuries worldwide and have detrimental effects on the entire body. However, the current standard of care is autologous split thickness skin grafts (STSGs), which induces additional injuries to the patient. Therefore, the development of alternative treatments to replace traditional STSGs is critical, and bioprinting could be the future of burn care. Specifically, in situ bioprinting offers several advantages in clinical applications compared to conventional in vitro bioprinting, primarily due to its ability to deposit bioink directly onto the wound. This review provides an in-depth discussion of the aspects involved in in situ bioprinting for skin regeneration, including crosslinking mechanisms, properties of natural and synthetic hydrogel-based bioinks, various in situ bioprinting methods, and the clinical translation of in situ bioprinting. The current limitations of in situ bioprinting is the ideal combination of bioink and printing mechanism to allow multi-material dispensing or to produce well-orchestrated constructs in a timely manner in clinical settings. However, extensive ongoing research is focused on addressing these challenges, and they do not diminish the significant potential of in situ bioprinting for skin regeneration. Full article
(This article belongs to the Special Issue Hydrogel-Based Scaffolds with a Focus on Medical Use (2nd Edition))
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13 pages, 1746 KiB  
Article
Physical and Structural Properties of Chitosan–Squid Gelatin Hydrogels
by Uriel Ramírez-Campas, Santiago P. Aubourg, Wilfrido Torres-Arreola, Maribel Plascencia-Jatomea and Josafat Marina Ezquerra-Brauer
Gels 2025, 11(2), 109; https://doi.org/10.3390/gels11020109 - 3 Feb 2025
Viewed by 128
Abstract
The development of functional hydrogels is currently receiving great attention. In this study, a squid by-product, gelatin (SG)–acetic acid solution, was added to a commercial chitosan (CH)–acetic acid solution to develop an antioxidant hydrogel. The CH–SG mass ratios evaluated were 1:0, 2:1, and [...] Read more.
The development of functional hydrogels is currently receiving great attention. In this study, a squid by-product, gelatin (SG)–acetic acid solution, was added to a commercial chitosan (CH)–acetic acid solution to develop an antioxidant hydrogel. The CH–SG mass ratios evaluated were 1:0, 2:1, and 1:2. Glutaraldehyde was used as cross linker. The effects of the SG addition to the hydrogel on different properties (physical in general, stability in aqueous media at pH 7.2, swelling, textural profile, and antioxidant) were evaluated. The interaction of CH and SG was established by scanning electron microscope microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). As a result, the addition of SG decreased the resistance to flow, hardness, chewiness, and stability, but increased the springiness, resilience, and antioxidant properties of CH hydrogels. The SEM analysis revealed that the CH-GS hydrogel showed a relatively more porous structure. FTIR and NMR analyses suggested a good compatibility of the components due mainly to an increased hydrogen bond formation. The present results suggest that CH could establish a valuable interaction with SG, so that a new hydrogel with enhanced textural and antioxidant properties would be produced, which would enable its potential application in biomedical and food industries. Full article
(This article belongs to the Special Issue Modification of Gels in Creating New Food Products)
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12 pages, 3505 KiB  
Article
Stomatitis Healing via Hydrogels Comprising Proline, Carboxyvinyl Polymer, and Water
by Raichi Hanaki, Koji Harada, Yoshihiro Sasaki, Michiaki Matsumoto and Yoshiro Tahara
Gels 2025, 11(2), 108; https://doi.org/10.3390/gels11020108 - 3 Feb 2025
Viewed by 231
Abstract
Chemotherapy using anticancer agents and radiotherapy of cancers frequently induce the development of stomatitis as a side effect. In the present study, hydrogels for effective stomatitis healing under anticancer drug administration were developed using three components, namely proline, carboxyvinyl polymer, and water (denoted [...] Read more.
Chemotherapy using anticancer agents and radiotherapy of cancers frequently induce the development of stomatitis as a side effect. In the present study, hydrogels for effective stomatitis healing under anticancer drug administration were developed using three components, namely proline, carboxyvinyl polymer, and water (denoted proline gels). Characterization including tilting, Fourier transform infrared spectra, and viscoelasticity measurements indicated that proline gels with proline concentrations over 300 μmol/g could retain water on the tongue of mice. The degradation and release behavior of proline gels in serological environments were evaluated, revealing that proline gels were degraded by serological salt concentrations, and the cumulative amount of proline released from proline gels depended on the concentration of proline in the gel. Proline gels were applied to the stomatitis area on the tongue of mice under anticancer drug administration, with subsequent reduction in the stomatitis area and regeneration of the mucosal epithelium layer, demonstrating effective stomatitis healing by proline gels with proline concentrations over 500 μmol/g. Other control samples including the carboxyvinyl polymer or proline alone did not reduce the stomatitis area in model mice. These results suggested that the proline gel is promising for the mucosa regeneration of anticancer drug-induced stomatitis. Full article
(This article belongs to the Special Issue Hydrogel for Tissue Regeneration (2nd Edition))
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14 pages, 12024 KiB  
Article
Evaluation of Bacterial Cellulose/Alginate-Based Hydrogel and Frog Skin Dressings in Equine Skin Wound Healing
by Rita C. Campebell, Andressa B. Oliveira, Jéssyca L. A. Fagundes, Beatriz N. A. Fortes, Henrique C. Veado, Isabel L. Macedo, Bruno S. L. Dallago, Hernane S. Barud, José Adorno, Pablo A. V. Salvador, Paulo S. Santos and Márcio B. Castro
Gels 2025, 11(2), 107; https://doi.org/10.3390/gels11020107 - 3 Feb 2025
Viewed by 230
Abstract
This study evaluates the wound-healing process in horses following the application of two treatment modalities: bacterial cellulose hydrogel with alginate (BCAW) and frog skin (FSW) dressings on experimentally induced skin wounds. Throughout the experiment, no clinical abnormalities were noted in the horses, although [...] Read more.
This study evaluates the wound-healing process in horses following the application of two treatment modalities: bacterial cellulose hydrogel with alginate (BCAW) and frog skin (FSW) dressings on experimentally induced skin wounds. Throughout the experiment, no clinical abnormalities were noted in the horses, although initial wound assessments indicated edema and sensitivity. Local hemorrhage was observed in some cases on Day 0, with granulation tissue formation evident by Day 14. Epithelialization began around Day 14 but did not reach complete healing in any group by Day 28. The analysis showed no significant differences in skin wound area or wound contraction rates among the treatment groups compared to control wounds (CWs) over the evaluation periods. Histopathological evaluations also indicated no significant differences in inflammatory responses or healing markers, such as fibroblast proliferation and neovascularization in skin wounds across groups. Despite expectations based on prior research in other species, the treatments with BCAW and FSW did not demonstrate substantial pro-healing effects in horses with induced skin wounds. These findings underscore the complexity of equine wound healing and suggest further investigation is needed to optimize treatment strategies in this species and enhance the translational potential for human clinical applications. Full article
(This article belongs to the Special Issue Alginate-Based Gels: Preparation, Characterization and Application (2nd Edition))
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26 pages, 2822 KiB  
Article
Investigation of a Thermoresponsive In Situ Hydrogel Loaded with Nanotriphala: Implications for Antioxidant, Anti-Inflammatory, and Antimicrobial Therapy in Nasal Disorders
by Rungsinee Phongpradist, Chuda Chittasupho, Sudarshan Singh, Julalak Chorachoo Ontong, Sarin Tadtong, Puriputt Akachaipaibul, Charatda Punvittayagul, Kriangkrai Thongkorn, Pornngarm Dejkriengkraikul, Jutamas Jiaranaikulwanitch, Sunee Chansakaow and Darunee Hongwiset
Gels 2025, 11(2), 106; https://doi.org/10.3390/gels11020106 - 2 Feb 2025
Viewed by 417
Abstract
Oxidative stress plays a crucial role in chronic nasal disorders, contributing to inflammation, tissue damage, and impaired mucosal function, highlighting the need for targeted therapies. Recent advancements in nasal drug delivery systems have expanded their applications for treating respiratory and inflammatory conditions. Among [...] Read more.
Oxidative stress plays a crucial role in chronic nasal disorders, contributing to inflammation, tissue damage, and impaired mucosal function, highlighting the need for targeted therapies. Recent advancements in nasal drug delivery systems have expanded their applications for treating respiratory and inflammatory conditions. Among these, hydrogel-based systems offer prolonged release of active pharmaceutical ingredients (APIs), enhancing therapeutic efficacy and reducing dosing frequency. This study initially evaluates the antioxidant, anti-inflammatory, antimicrobial, and cytotoxic properties of Nanotriphala, followed by its incorporation into a thermoresponsive in situ hydrogel system, which was subsequently developed and characterized as a novel formulation. Nanotriphala exhibited >90% cell viability and significantly reduced nitric oxide (NO) levels by 40.55 µg/mL at 250 µg/mL. The hydrogel was characterized by key parameters, including viscosity, gelling time, pH, gelling temperature, texture analysis, and ex vivo spreadability. Stability was assessed under various conditions, and mutagenicity and antimutagenicity were evaluated using the Ames test. Results showed that the hydrogel gelled at 34 °C, exhibited good spreadability (10.25 ± 0.28 cm), a viscosity of 227 ± 22 cP, and maintained a pH of 5.75 ± 0.01, with optimal hardness and adhesiveness suitable for nasal application. It demonstrated antimicrobial activity against E. coli, P. aeruginosa, S. aureus, and S. epidermidis at minimal bactericidal concentrations (MBCs) of 32, 2, 4, and 8 µg/mL, respectively, with low mutagenicity (mutagenic index < 2) and strong antimutagenic activity (>60%). The gallic acid content was 0.5796 ± 0.0218 µg/100 mL. Stability studies confirmed optimal storage at 4 °C. These findings suggest that in situ hydrogel loaded with Nanotriphala is a promising nasal drug delivery system for managing oxidative stress and related inflammatory conditions. Full article
(This article belongs to the Special Issue Hydrogel for Sustained Delivery of Therapeutic Agents (2nd Edition))
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21 pages, 4941 KiB  
Article
Ophthalmic In Situ Nanocomposite Gel for Delivery of a Hydrophobic Antioxidant
by Marta Slavkova, Christina Voycheva, Teodora Popova, Borislav Tzankov, Diana Tzankova, Ivanka Spassova, Daniela Kovacheva, Denitsa Stefanova, Virginia Tzankova and Krassimira Yoncheva
Gels 2025, 11(2), 105; https://doi.org/10.3390/gels11020105 - 2 Feb 2025
Viewed by 413
Abstract
The topical administration of in situ hydrogels for ocular pathologies is a promising application strategy for providing high effectiveness and patient compliance. Curcumin, a natural polyphenol, possesses all the prerequisites for successful therapy of ophthalmic diseases, but unfortunately its physicochemical properties hurdle the [...] Read more.
The topical administration of in situ hydrogels for ocular pathologies is a promising application strategy for providing high effectiveness and patient compliance. Curcumin, a natural polyphenol, possesses all the prerequisites for successful therapy of ophthalmic diseases, but unfortunately its physicochemical properties hurdle the practical use. Applying a composite in situ thermoresponsive hydrogel formulation embedded with polymer nanoparticles is a potent strategy to overcome all the identified drawbacks. In the present work we prepared uniform spherical nanoparticles (296.4 ± 3.1 nm) efficiently loaded with curcumin (EE% 82.5 ± 2.3%) based on the biocompatible and biodegradable poly-(lactic-co-glycolic acid). They were thoroughly physicochemically characterized in terms of FTIR, SEM, TGA, and DLS, in vitro release following Fickian diffusion (45.62 ± 2.37%), and stability over 6 months. Their lack of cytotoxicity was demonstrated in vitro on HaCaT cell lines, and the potential for antioxidant protection was also outlined, starting from concentrations as low as 0.1 µM and reaching 41% protection at 5 µM. An in situ thermoresponsive hydrogel (17% w/v poloxamer 407 and 0.1% Carbopol) with suitable properties for ophthalmic application was optimized with respect to gelation temperature (31.40 ± 0.36 °C), gelling time (8.99 ± 0.28 s) upon tears dilution, and gel erosion (90.75 ± 4.06%). Upon curcumin-loaded nanoparticle embedding, the in situ hydrogels demonstrated appropriate pseudoplastic behavior and viscosity at 35 °C (2129 ± 24 Pa∙s), 6-fold increase in the permeation, and prolonged release over 6 h. Full article
(This article belongs to the Special Issue Composite Hydrogels for Biomedical Applications)
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31 pages, 3323 KiB  
Article
Plant-Derived B-CGT Hydrogel Accelerates Diabetic Wound Healing Through Multitarget Modulation of Inflammation, Angiogenesis, and Tissue Remodeling
by Fei Ran, Kailang Mu, Lingli Zhou, Leqiang Peng, Gang Liu, Yuchen Liu, Yuxin Pang, Guo Feng, Changmao Guo, Tianjian Wang and Qiumei Luo
Gels 2025, 11(2), 104; https://doi.org/10.3390/gels11020104 - 2 Feb 2025
Viewed by 185
Abstract
Diabetic wound healing presents significant challenges due to impaired angiogenesis, chronic inflammation, and cellular dysfunction. Building on previous research, this study further explores the potential of a plant-derived glucosyloxybenzyl 2-isobutylmalates (B-CGT) hydrogel in promoting diabetic wound healing. Network pharmacology and molecular docking analyses [...] Read more.
Diabetic wound healing presents significant challenges due to impaired angiogenesis, chronic inflammation, and cellular dysfunction. Building on previous research, this study further explores the potential of a plant-derived glucosyloxybenzyl 2-isobutylmalates (B-CGT) hydrogel in promoting diabetic wound healing. Network pharmacology and molecular docking analyses suggest that B-CGT may regulate key mechanisms, such as apoptosis, inflammation, and matrix remodeling, through core targets including SIRT1, CASP8, and MMP8. In vivo studies further demonstrated that B-CGT hydrogel significantly accelerated wound closure in diabetic mice, enhanced angiogenesis, promoted collagen deposition, and achieved immune balance by modulating macrophage polarization, thereby shifting the inflammatory environment toward a repair state. Moreover, B-CGT hydrogel significantly improved the wound microenvironment by upregulating VEGF expression and exerting antioxidant effects. By combining theoretical predictions with experimental validation, this study elucidates the multi-target synergistic regulatory mechanisms of B-CGT hydrogel. These findings provide new research directions for addressing immune imbalance and angiogenesis defects in diabetic wound healing and lay a scientific foundation for the optimization and application of chronic wound treatment strategies. Full article
(This article belongs to the Special Issue Advances in Gels for Wound Treatment)
17 pages, 2887 KiB  
Article
Preparation and Properties of Glycerohydrogels Based on Silicon Tetraglycerolate, Chitosan Hydrochloride and Glucomannan
by Sergei L. Shmakov, Olga S. Ushakova, Marina A. Kalinicheva and Anna B. Shipovskaya
Gels 2025, 11(2), 103; https://doi.org/10.3390/gels11020103 - 2 Feb 2025
Viewed by 248
Abstract
Glycerohydrogels based on silicon glycerolate, chitosan (CS) and polyvinyl alcohol (PVA) are widely studied for use in biomedical applications. In line with the general trend of replacing synthetic polymers with natural ones in such compositions, it would be of interest to replace PVA [...] Read more.
Glycerohydrogels based on silicon glycerolate, chitosan (CS) and polyvinyl alcohol (PVA) are widely studied for use in biomedical applications. In line with the general trend of replacing synthetic polymers with natural ones in such compositions, it would be of interest to replace PVA with the polysaccharide glucomannan (GM), as well as to introduce functional additives to impart the desired properties, including gelation time, to the final hydrogel. In this work, a comprehensive study of the preparation conditions and properties of glycerohydrogels based on silicon tetraglycerolate, chitosan hydrochloride (CS·HCl) and GM was carried out. Viscometry was used to assess the conformational state of CS·HCl and GM macromolecules, and their associates in solution before gelation. Gelation was studied using the vessel inversion method. The mucoadhesive and the dermoadhesive properties of the glycerohydrogels obtained were assessed using the tearing off method from the model substrates simulating mucous and dermal tissues. The conformational state of the individual polymers and their mixed associates in solution before gelation was estimated; the intrinsic viscosity and the hydrodynamic radius of the macromolecular coils were calculated. The influence of various factors (addition of ε-aminocaproic and hydrochloric acids, sodium chloride, hydroxide and tetraborate to vary the acidity and ionic strength of the medium, as well as temperature) and the molecular weight of chitosan on the gelation time was studied. The gelation time achieved was less than 2 min, which is promising in practical terms, i.e., for creating liquid plasters. Our best samples are not inferior to the commercial preparation “Metrogyl Denta”® in terms of tearing force during mucoadhesion and dermoadhesion at short gelation times. Thus, the glycerohydrogels synthesized by us and based on silicon tetraglycerolate, CS·HCl and GM could find usage in new biopharmaceutical and biomedical applications. Full article
(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)
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24 pages, 1484 KiB  
Article
Flocculation Mechanism and Microscopic Statics Analysis of Polyacrylamide Gel in Underwater Cement Slurry
by Hao Lu, Bo Dai, Chunhe Li, Hua Wei and Jinhui Wang
Gels 2025, 11(2), 99; https://doi.org/10.3390/gels11020099 (registering DOI) - 1 Feb 2025
Viewed by 162
Abstract
Zeta potential testing, Fourier infrared spectroscopy, and total organic carbon analysis were employed in this manuscript to explore the flocculation mechanism of polyacrylamide (PAM) on slurry with a high content of polycarboxylate ether (PCE). Through the combination of assessments of chemical bond shifts, [...] Read more.
Zeta potential testing, Fourier infrared spectroscopy, and total organic carbon analysis were employed in this manuscript to explore the flocculation mechanism of polyacrylamide (PAM) on slurry with a high content of polycarboxylate ether (PCE). Through the combination of assessments of chemical bond shifts, adsorption indicators, and intrinsic viscosity of high-molecular-weight polymer systems, the microscale flocculation mechanisms of different PAM dosages in cement suspensions were elucidated, showcasing stages of “adsorption–lubrication–entanglement”. Initially (PAM < 0.3%), with PAM introduction, the polymer primarily underwent adsorption interactions, including hydrogen bonding between the ester group, amine group, and water molecules; chelation between the ester group and Ca2+ and Al3+ on the cement surface; and bridging between PAM’s long-chain structure and cement particles. As the PAM content increased, the cement particles’ adsorption capacity saturated (PAM < 0.67%). The entropy loss of polymer conformation could not be offset by adsorption energy, leading to its exclusion from the interface and depletion attractive forces. Slurry movement shifted from inter-particle motion to high-molecular-weight polymer sliding in interstitial fluid, forming a lubrication effect. With further PAM content no less than 0.67%, the polymer solution reached a critical entanglement concentration, and the contact of the rotation radius of the long-chain molecules led to entanglement domination. By introducing bridging adsorption, depletion attraction, and entanglement forces, the cohesion of cement-based polymer suspensions was subsequently determined. The results showed a linear correlation between cohesion and PAM concentration raised to powers of 0.30, 1.0, and 0.75 at different interaction stages, and a multiscale validation from microscopic flocculation mechanisms to macroscopic performance was finally completed through a comparative analysis with macroscopic anti-washout performance. Full article
(This article belongs to the Special Issue Gels for Removal and Adsorption (3rd Edition))
18 pages, 5530 KiB  
Article
Comparative Analysis of Tunicate vs. Plant-Based Cellulose in Chitosan Hydrogels for Bone Regeneration
by Laura Furlan, Annj Zamuner, Andrea Riccioni, Giacomo Sabbadin, Teresa Russo, Vito Gallicchio, Gabriella D’Auria, Lucia Falcigno, Lucia Manni, Loriano Ballarin, Elisabetta Schievano, Paola Brun and Monica Dettin
Gels 2025, 11(2), 102; https://doi.org/10.3390/gels11020102 - 1 Feb 2025
Viewed by 201
Abstract
A novel hydrogel scaffold for bone regeneration based on chitosan, selected for its biocompatibility, biodegradability, and antimicrobial properties, was covalently functionalized with a bioactive peptide from bone morphogenetic protein-2 (BMP-2) to guide osteoblast growth and proliferation. This study evaluates the impact of incorporating [...] Read more.
A novel hydrogel scaffold for bone regeneration based on chitosan, selected for its biocompatibility, biodegradability, and antimicrobial properties, was covalently functionalized with a bioactive peptide from bone morphogenetic protein-2 (BMP-2) to guide osteoblast growth and proliferation. This study evaluates the impact of incorporating different concentrations (8, 16, or 24% wt/wt) of plant-based micro-fibrillated cellulose or tunicate nanocellulose to improve the mechanical and biological properties of peptide-grafted chitosan hydrogel matrices. While the mechanical properties of the matrices increase with increasing cellulose content, regardless of its source, the behavior of human osteoblasts used in biological tests discriminates between the two types of cellulose and shows better results (proliferation at 2 and 7 days, and mineralization) for the enrichment with tunicate cellulose. Full article
(This article belongs to the Special Issue Properties and Applications of Biomaterials Related to Gels (2nd Edition))
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19 pages, 5230 KiB  
Article
Development and Characterization of Niaprazine-Loaded Xanthan Gum-Based Gel for Oral Administration
by Elena Giuliano, Emanuela Longo, Agnese Gagliardi, Silvia Costa, Federica Squillace, Silvia Voci, Mario Verdiglione and Donato Cosco
Gels 2025, 11(2), 101; https://doi.org/10.3390/gels11020101 - 1 Feb 2025
Viewed by 217
Abstract
Niaprazine is a sedative-hypnotic drug initially developed as an antihistamine and used for its notable sedative effects, particularly in children. Following its withdrawal from the market by the producer, the drug has been administered as magistral formulations available in syrup form, but there [...] Read more.
Niaprazine is a sedative-hypnotic drug initially developed as an antihistamine and used for its notable sedative effects, particularly in children. Following its withdrawal from the market by the producer, the drug has been administered as magistral formulations available in syrup form, but there are several important disadvantages to this, including instability, taste issues, lack of controlled release, and the potential for unreliable dosing due to incomplete swallowing. There is also an increased risk of dental caries, as well as the fact that these formulations are not suitable for children who suffer from diabetes. The purpose of the current investigation is to prepare and characterize xanthan gum-based gels for the oral administration of niaprazine. Niaprazine gels appear as transparent-whiteish, non-sticky substances, with the drug uniformly dispersed throughout the systems. They are also stable over time. Dynamic rheology revealed their advantageous shear-thinning properties, which enable the formulation to be flexibly dosed orally through administration via syringe. During experimentation, the evaluation of the mucoadhesion features and the in vitro drug release profile were also performed. The results demonstrate that the formulation may represent an alternative to niaprazine syrup, allowing easy preparation, administration, and increased compliance in various categories of patients, including pediatric. Full article
(This article belongs to the Special Issue Advanced Gel Materials for Bioengineering)
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16 pages, 5868 KiB  
Article
Whitening Efficiency of Papain and Bromelain Gels in Removing Dental Stains
by Stanca Cuc, Codruta Sarosi, Ioan Petean, Amalia Moldovan, Cecilia Bacali and Sorin Claudiu Man
Gels 2025, 11(2), 100; https://doi.org/10.3390/gels11020100 - 1 Feb 2025
Viewed by 273
Abstract
This study aimed to evaluate the micro-nanostructure and color changes of dental enamel after treatment with new gel formulations containing papain or bromelain. Eighty caries-free, extracted human teeth were randomly divided into two groups (n = 40) and stained by immersion in either [...] Read more.
This study aimed to evaluate the micro-nanostructure and color changes of dental enamel after treatment with new gel formulations containing papain or bromelain. Eighty caries-free, extracted human teeth were randomly divided into two groups (n = 40) and stained by immersion in either coffee or Tedi juice for 4 h daily over five consecutive days. After staining, the samples were washed and stored in artificial saliva at 37 °C. The stained samples were then treated with four different whitening gels (GC, G1, G2, and Opalescence 15%) for 4 h daily. Following each treatment, the samples were rinsed and stored in artificial saliva. Color changes were measured using a digital spectrophotometer to assess CIEL*a*b* ΔE* and the Whiteness index (WI). The enamel micro-nanostructure was analyzed using SEM and AFM. Data were statistically analyzed using one-way ANOVA followed by Tukey’s HSD test. The results showed that gels containing papain and bromelain were more effective than the commercial gel in removing stains. SEM and AFM analysis indicated that papain was particularly effective for removing coffee stains, while bromelain was better for stains from natural juices. Healthy enamel has a Ra value of approximately 10 nm, which increases to about 40 nm after staining. Papain restored enamel roughness to approximately 8 nm for coffee stains and bromelain restored it to 11 nm for juice stains, delivering optimal results, while commercial gel ensures a roughness of about 15 nm after stain removal. CIELAB reveals notable changes in ΔE and WI after bleaching, revealing that papain gel is optimal for coffee stain removal and bromelain gel is optimal for natural juice stains. In conclusion, dental stains should be assessed by a dentist to determine the most suitable gel for achieving optimal results. Full article
(This article belongs to the Special Issue Global Excellence in Bioactive Gels)
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19 pages, 3975 KiB  
Article
Optimization of the Preparation Process of Crosslinked Polyvinyl Alcohol and Its Thermal Stability in Cementing Slurry
by Junhao Li, Haochen Ai, Qingchen Wang, Huifeng He, Xiaofeng Chang, Gang Chen, Alena Golian-Struhárová, Michal Slaný and Fangling Qin
Gels 2025, 11(2), 98; https://doi.org/10.3390/gels11020098 - 30 Jan 2025
Viewed by 371
Abstract
This study focuses on addressing the limitations of fluid loss additive in cement slurry under higher temperatures. The synthesis process of glutaraldehyde-crosslinked polyvinyl alcohol (PVA) was optimized to develop an efficient fluid loss additive for oil well cement slurries. Using one-factor experiments and [...] Read more.
This study focuses on addressing the limitations of fluid loss additive in cement slurry under higher temperatures. The synthesis process of glutaraldehyde-crosslinked polyvinyl alcohol (PVA) was optimized to develop an efficient fluid loss additive for oil well cement slurries. Using one-factor experiments and the uniform design method, the optimal synthesis parameters were established: a reaction temperature of 50 °C; an acid concentration of 1 mol/L; a PVA mass concentration of 8%; a molar ratio of glutaraldehyde to PVA hydroxyl group of 1.47; and a crosslinking degree of 1.49%. The optimized crosslinked PVA demonstrated the ability to control API fluid loss within 50 mL when applied at 1% concentration in cement slurry under conditions of 30–110 °C and 6.9 MPa. Rheological analysis at medium and high temperatures revealed improved slurry properties, including smooth thickening curves and unaffected compressive strength. Further analyses, including thermogravimetric analysis (TGA), Zeta potential testing, and scanning electron microscopy (SEM), revealed that the crosslinked PVA hydrogel remained thermally stable up to 260 °C. Chemical crosslinking transformed the linear PVA into a network structure, enhancing its molecular weight, viscoelasticity, and thermal stability. This thermal resistance mechanism is attributed to the hydrogel’s high-strength reticular structure which forms a uniform, dense, and highly stable adsorption layer, thereby improving both the additive’s efficiency and the hydrogel’s temperature resistance. Full article
(This article belongs to the Special Issue Advances in Functional Hydrogels and Their Applications)
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16 pages, 56818 KiB  
Article
An Amide-Carboxylic Acid Compound as Gel Structure Breaker to Improve the Rheology of Oil-Based Drilling Fluids
by Yu Zhang, Kaihe Lv, Xianbin Huang, Zhe Li, Yang Zhang and Zhenhang Yuan
Gels 2025, 11(2), 97; https://doi.org/10.3390/gels11020097 - 30 Jan 2025
Viewed by 362
Abstract
High-density oil-based drilling fluids (OBDFs) are widely used in drilling operations, but during their application, the viscosity of the fluid typically increases due to the enhancement of the solid-phase gel network structure. This can lead to issues such as impaired fluid circulation, increased [...] Read more.
High-density oil-based drilling fluids (OBDFs) are widely used in drilling operations, but during their application, the viscosity of the fluid typically increases due to the enhancement of the solid-phase gel network structure. This can lead to issues such as impaired fluid circulation, increased blowout risks, and accelerated drill bit wear. In this study, a compound (OCD), synthesized from tall oil fatty acids, diethylene triamine, and maleic anhydride, was developed to disrupt the strong gel structure in high-density OBDFs, thereby reducing the viscosity of the OBDFs. Rheological properties, including viscosity, yield point, and gel strength, were tested to evaluate the viscosity-reducing effect of OCD on both laboratory-prepared and field high-density OBDFs. Additionally, the effects of OCD on electrical stability (ES), high-temperature high-pressure (HTHP) filtration loss, and solid-phase settling stability were also tested. Finally, the mechanism of OCD was analyzed through contact angle tests, particle size analysis, and microstructural observations. The experimental results demonstrated that OCD could effectively reduce the viscosity of various high-density OBDFs. Adding 2 wt% of OCD reduced the apparent viscosity of laboratory-prepared OBDFs by 20.4%, and reduced the apparent viscosity of field OBDFs with a density of 1.7 g/cm3 by 29.2%. Furthermore, OCD showed good compatibility with OBDFs, having negligible effects on HTHP filtration loss and ES, and maintained good viscosity-reducing performance even at 180 °C. Mechanistic studies revealed that OCD enhanced the hydrophobicity of the solid phase, reduced the particle size of solids, and prevented the formation of excessive network structures in the oil. Therefore, this study provides significant practical value for controlling the rheological performance of the gel system in OBDFs. Full article
(This article belongs to the Special Issue Gels in the Oil Field)
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42 pages, 4303 KiB  
Review
Hydrogels from Protein–Polymer Conjugates: A Pathway to Next-Generation Biomaterials
by Oubadah Alayoubi, Yağmur Poyraz, Gana Hassan, Sümeyye Berfin Gül, Nergiz Çalhan, Naz Mina Mert Şahin, Megha Gautam, Aylin Kutlu, Bengü Özuğur Uysal, Ebru Demet Akten and Önder Pekcan
Gels 2025, 11(2), 96; https://doi.org/10.3390/gels11020096 - 29 Jan 2025
Viewed by 388
Abstract
Hybrid hydrogels from protein–polymer conjugates are biomaterials formed via the chemical bonding of a protein molecule with a polymer molecule. Protein–polymer conjugates offer a variety of biological properties by combining the mechanical strength of polymers and the bioactive functionality of proteins. These properties [...] Read more.
Hybrid hydrogels from protein–polymer conjugates are biomaterials formed via the chemical bonding of a protein molecule with a polymer molecule. Protein–polymer conjugates offer a variety of biological properties by combining the mechanical strength of polymers and the bioactive functionality of proteins. These properties allow these conjugates to be used as biocompatible components in biomedical applications. Protein–polymer conjugation is a vital bioengineering strategy in many fields, such as drug delivery, tissue engineering, and cancer therapy. Protein–polymer conjugations aim to create materials with new and unique properties by combining the properties of different molecular components. There are various ways of creating protein–polymer conjugates. PEGylation is one of the most common conjugation techniques where a protein is conjugated with Polyethylene Glycol. However, some limitations of PEGylation (like polydispersity and low biodegradability) have prompted researchers to devise novel synthesis techniques like PEGylation, where synthetic polypeptides are used as the polymer component. This review will illustrate the properties of protein–polymer conjugates, their synthesis methods, and their various biomedical applications. Full article
(This article belongs to the Special Issue Gel-Related Papers from the 9th Asian Conference on Colloid and Interface Science 2023 (ACCIS 2023))
21 pages, 8997 KiB  
Article
Cellulose Nanofiber Aerogel from Banana Peduncle Modified with Graphene Oxide as Bio-Adsorbent for Lead and Chromium Ions
by Anjar Priyatmojo, Riza Wirawan, Husaini Ardy, Dita Puspitasari, Putri P. P. Asri and Lia A. T. W. Asri
Gels 2025, 11(2), 95; https://doi.org/10.3390/gels11020095 - 28 Jan 2025
Viewed by 377
Abstract
Textile industry waste contains high concentrations of heavy metals such as Pb(II) and Cr(VI) that must be reduced before they are released to the environment. The adsorption method is one way to reduce the heavy metal content. In this work, we develop a [...] Read more.
Textile industry waste contains high concentrations of heavy metals such as Pb(II) and Cr(VI) that must be reduced before they are released to the environment. The adsorption method is one way to reduce the heavy metal content. In this work, we develop a porous cellulose nanofiber (CNF) aerogel modified with graphene oxide (GO) as an alternative aerogel adsorbent for Pb(II) and Cr(VI). Cellulose was extracted from banana peduncle, a biomass waste that remains largely underutilized. The addition of GO aims to increase the adsorption properties. The aerogel adsorbents were synthesized by varying the ultrasonication time to 45 min for CNF 45 and 60 min for CNF 60, and the amount of GO added to 1 mL and 2 mL. The aerogel adsorbents were successfully prepared using the freeze-drying method with CNF45, CNF60, CNF45/GO1, CNF45/GO2, CNF60/GO1, and CNF60/GO2 variations. CNF was successfully isolated from a banana peduncle with an average diameter of 44.16 nm for 45 min (CNF 45) and an average diameter of 14.6 nm for 60 min (CNF 60) of ultrasonication. Chemical treatment and ultrasonication reduced the crystallinity index value of cellulose by 73% and 61% for CNF 45 and CNF 60, respectively. CNF aerogel has a very low shrinkage rate (<7%), resulting in a larger surface area. CNF60/GO2 obtained the optimum adsorption ability for Pb(II) metal at a concentration of 100 ppm and 27.27 mg/g at 30 min. On the other hand, the adsorption ability of Cr(VI) metal was obtained by CNF60/GO2 at a concentration of 100 ppm and 13.48 mg/g at 30 min. SEM images show that all aerogel adsorbents are porous, with a porosity value range of 96–98%. In conclusion, CNF60/GO2 proved to be the most effective aerogel adsorbent, offering the potential for heavy metal removal from industrial wastewater. Full article
(This article belongs to the Special Issue Advanced Hydrogel for Water Treatment (2nd Edition))
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22 pages, 30132 KiB  
Review
Advances in 3D and 4D Printing of Gel-Based Foods: Mechanisms, Applications, and Future Directions
by Zhou Qin, Zhihua Li, Xiaowei Huang, Liuzi Du, Wenlong Li, Peipei Gao, Zhiyang Chen, Junjun Zhang, Ziang Guo, Zexiang Li, Baoze Liu and Tingting Shen
Gels 2025, 11(2), 94; https://doi.org/10.3390/gels11020094 - 27 Jan 2025
Viewed by 603
Abstract
This review examines recent advancements in gel-based 3D and 4D food-printing technologies, with a focus on their applications in personalized nutrition and functional foods. It emphasizes the critical role of tunable rheological and mechanical properties in gels such as starch, protein, and Pickering [...] Read more.
This review examines recent advancements in gel-based 3D and 4D food-printing technologies, with a focus on their applications in personalized nutrition and functional foods. It emphasizes the critical role of tunable rheological and mechanical properties in gels such as starch, protein, and Pickering emulsions, which are essential for successful printing. The review further explores 4D food printing, highlighting stimuli-responsive mechanisms, including color changes and deformation induced by external factors like temperature and pH. These innovations enhance both the sensory and functional properties of printed foods, advancing opportunities for personalization. Key findings from recent studies are presented, demonstrating the potential of various gels to address dietary challenges, such as dysphagia, and to enable precise nutritional customization. The review integrates cutting-edge research, identifies emerging trends and challenges, and underscores the pivotal role of gel-based materials in producing high-quality 3D-printed foods. Additionally, it highlights the potential of Pickering emulsions and lipid gels for expanding functionality and structural diversity. Overall, this work provides a comprehensive foundation for advancing future research and practical applications in gel-based 3D and 4D food printing. Full article
(This article belongs to the Special Issue Recent Advance in Food Gels (2nd Edition))
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16 pages, 5386 KiB  
Article
Enzymatically Cross-Linked Hydrogel Beads Based on a Novel Poly(aspartamide) Derivative
by Wenzhuo Hou, Hui Yi and Guangyan Zhang
Gels 2025, 11(2), 93; https://doi.org/10.3390/gels11020093 - 26 Jan 2025
Viewed by 316
Abstract
In recent years, hydrogel beads and in situ hydrogels have gained wide attention in various fields such as biomedicine. In this study, 3-(4-hydroxyphenyl) propionic acid (HP) was introduced into the side chain of poly(α,β-[N-(2-hydroxyethyl)-D,L-aspartamide]) (PHEA) to synthesize phenolic hydroxyl-functionalized [...] Read more.
In recent years, hydrogel beads and in situ hydrogels have gained wide attention in various fields such as biomedicine. In this study, 3-(4-hydroxyphenyl) propionic acid (HP) was introduced into the side chain of poly(α,β-[N-(2-hydroxyethyl)-D,L-aspartamide]) (PHEA) to synthesize phenolic hydroxyl-functionalized poly(aspartamide) derivative PHEA-HP with enzyme-catalyzed cross-linking potential. First, the chemical structure of PHEA-HP was characterized by FT-IR, UV and 1H NMR, and the results of in vitro cytotoxicity against L929 cell line and hemolysis experiment showed that PHEA-HP did not have toxicity to cells (viability > 90%) and had good blood compatibility. Then, rheological measurement confirmed the formation of PHEA-HP-based in situ hydrogel with a high storage modulus (G′) around 104 Pa, and the vial-tilting method revealed that the gelation time of PHEA-HP aqueous solution could be tuned in the wide range of 5–260 s by varying the concentrations of hydrogen peroxide (H2O2) and horseradish peroxidase (HRP). Finally, hydrogel beads of different diameters containing methylene blue (for easy observation) were prepared using a coaxial needle and syringe pumps, and the effect of the flow rate of the outer phase on the diameters of the hydrogel beads was also investigated. Therefore, PHEA-HP may be a promising and safe poly(aspartamide) derivative that can be used to prepare in situ hydrogels and hydrogel beads for applications closely related to the human body. Full article
(This article belongs to the Special Issue Advances in Responsive Hydrogels (2nd Edition))
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15 pages, 4234 KiB  
Article
The Synthesis and Spectroscopic Characterization of Structural Changes in Hydrophobic Silica Aerogels upon Encapsulation of the LCC ICCG Enzyme
by Tatiana Alpízar-Rojas, Juan Diego Barboza-Carmona, Erik Butenschön, Guzel Musabirova, Erick Castellón, Jörg Matysik and Isaac F. Céspedes-Camacho
Gels 2025, 11(2), 92; https://doi.org/10.3390/gels11020092 - 25 Jan 2025
Viewed by 962
Abstract
Silica aerogels are highly porous materials known for their low density and extensive surface area, making them ideal for applications in thermal insulation, catalysis, and environmental remediation. This study investigates the structural changes of functionalized hydrophobic silica aerogels used as carriers of the [...] Read more.
Silica aerogels are highly porous materials known for their low density and extensive surface area, making them ideal for applications in thermal insulation, catalysis, and environmental remediation. This study investigates the structural changes of functionalized hydrophobic silica aerogels used as carriers of the LCC ICCG enzyme. The aerogels were synthesized using the sol-gel method, with trimethylethoxysilane (TMES) as a functionalizing agent to enhance hydrophobicity. The enzyme-encapsulated aerogels were characterized using hyperpolarized 129Xe NMR, 29Si NMR, nitrogen sorption analysis, TEM, contact angle measurements, and FT-IR spectroscopy to evaluate their structural and chemical properties. The results confirmed successful encapsulation of the enzyme, as indicated by changes in the pore structure and network morphology. These findings demonstrate that functionalized silica aerogels can effectively support LCC ICCG immobilization, offering a promising approach for plastic degradation applications. Full article
(This article belongs to the Special Issue Synthesis and Application of Aerogel)
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13 pages, 2932 KiB  
Article
Encapsulation of Fatty Acids Using Linear Dextrin from Waxy Potato Starch: Effect of Debranching Time and Degree of Unsaturation
by Huifang Xie, Qingfei Duan, Guohua Hu, Xinyi Dong, Litao Ma, Jun Fu, Yiwen Yang, Huaran Zhang, Jiahui Song, Qunyu Gao and Long Yu
Gels 2025, 11(2), 91; https://doi.org/10.3390/gels11020091 - 24 Jan 2025
Viewed by 440
Abstract
This study investigates the effects of the debranching time of waxy potato starch using pullulanase and recrystallization on particle morphology, debranching degree, and crystal structure. The results demonstrated that after gelatinization and debranching, the surface of the starch crystals became rough and uneven [...] Read more.
This study investigates the effects of the debranching time of waxy potato starch using pullulanase and recrystallization on particle morphology, debranching degree, and crystal structure. The results demonstrated that after gelatinization and debranching, the surface of the starch crystals became rough and uneven due to hydrolysis, with most particles showing a fragmented surface. The crystalline state was not significantly changed with debranching time. X-ray diffraction analysis revealed no significant differences in the patterns of recrystallized linear dextrin (LD) after various debranching times. Notably, the short-range ordered structure of LD after debranching and recrystallization was more organized than that of the original or gelatinized starch. Additionally, polarized light microscopy showed that the birefringent pattern disappeared as a result of debranching and recrystallization, indicating the breakdown of particle structure, although the overall particle morphology did not change significantly with varying debranching times. Furthermore, linear dextrin derived from starch debranched for 6 h (with pullulanase at 15 μg/g) successfully embedded stearic acid, oleic acid, and linoleic acid, forming a VI-type starch–fatty acid complex. Full article
(This article belongs to the Special Issue Recent Advances in Food Gels (2nd Edition))
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17 pages, 3279 KiB  
Article
Fabrication of Functional Polymers with Gradual Release of a Bioactive Precursor for Agricultural Applications
by Oscar G. Marambio, Rudy Martin-Trasancos, Julio Sánchez, Felipe A. Ramos and Guadalupe del C. Pizarro
Gels 2025, 11(2), 90; https://doi.org/10.3390/gels11020090 - 24 Jan 2025
Viewed by 440
Abstract
Biodegradable and biocompatible polymeric materials and stimulus-responsive hydrogels are widely used in the pharmaceutical, agricultural, biomedical, and consumer sectors. The effectiveness of these formulations depends significantly on the appropriate selection of polymer support. Through chemical or enzymatic hydrolysis, these materials can gradually release [...] Read more.
Biodegradable and biocompatible polymeric materials and stimulus-responsive hydrogels are widely used in the pharmaceutical, agricultural, biomedical, and consumer sectors. The effectiveness of these formulations depends significantly on the appropriate selection of polymer support. Through chemical or enzymatic hydrolysis, these materials can gradually release bioactive agents, enabling controlled drug release. The objective of this work is to synthesize, characterize, and apply two controlled-release polymeric systems, focusing on the release of a phyto-pharmaceutical agent (herbicide) at varying pH levels. The copolymers were synthesized via free radical polymerization in solution, utilizing tetrahydrofuran (THF) as the organic solvent and benzoyl peroxide (BPO) as the initiator, without the use of a cross-linking agent. Initially, the herbicide was grafted onto the polymeric chains, and its release was subsequently tested across different pH environments in a heterogeneous phase using an ultrafiltration (UF) system. The development of these two controlled-release polymer systems aimed to measure the herbicide’s release across different pH levels. The goal is to adapt these materials for agricultural use, enhancing soil quality and promoting efficient water usage in farming practices. The results indicate that the release of the herbicide from the conjugate systems exceeded 90% of the bioactive compound after 8 days at pH 10 for both systems. Furthermore, the two polymeric systems demonstrated first-order kinetics for herbicide release in aqueous solutions at different pH levels. The kinetic constant was found to be higher at pH 7 and 10 compared to pH 3. These synthetic hydrogels are recognized as functional polymers suitable for the sustained release of herbicides in agricultural applications. Full article
(This article belongs to the Special Issue Designing Hydrogels and Hydrogel-Derived Materials for Agriculture and Water Sustainability)
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17 pages, 5542 KiB  
Article
Fabrication and Evaluation of Dissolving Hyaluronic Acid Microneedle Patches for Minimally Invasive Transdermal Drug Delivery by Nanoimprinting
by Sayaka Miura, Rio Yamagishi, Mano Ando, Yuna Hachikubo, Nor Amirrah Ibrahim, Nur Izzah Md Fadilah, Manira Maarof, Misaki Oshima, Sen Lean Goo, Hiryu Hayashi, Mayu Morita, Mh Busra Fauzi and Satoshi Takei
Gels 2025, 11(2), 89; https://doi.org/10.3390/gels11020089 - 23 Jan 2025
Viewed by 523
Abstract
Transdermal drug delivery minimizes pain and provides a controlled, stable release of drugs, but its effectiveness is limited by the skin’s natural barriers. Microneedles overcome this problem, enabling minimally invasive drug delivery. Microneedle patches (MNPs) with 80 µm-tall needles composed of hyaluronic acid [...] Read more.
Transdermal drug delivery minimizes pain and provides a controlled, stable release of drugs, but its effectiveness is limited by the skin’s natural barriers. Microneedles overcome this problem, enabling minimally invasive drug delivery. Microneedle patches (MNPs) with 80 µm-tall needles composed of hyaluronic acid (HA) were developed and evaluated for their formability, structural integrity, dissolution rate, skin penetration ability, and drug transmission capacity. The influence of the molecular weight of HA on these properties was also investigated. MNPs made from low-molecular-weight HA (30 kDa–50 kDa) demonstrated 12.5 times superior drug permeability in ex vivo human skin compared to needleless patches (NLPs). Furthermore, in the same test, low-molecular-weight HA MNPs had 1.7 times higher drug permeability than high-molecular-weight HA MNPs, suggesting superior transdermal administration. The molecular weight of HA significantly influenced its solubility and permeability, highlighting the potential effectiveness of MNPs as drug delivery systems. Puncture tests demonstrated a penetration depth of 50–60 µm, indicating minimal nerve irritation in the dermis and effective drug delivery to the superficial dermal layer. These results present a manufacturing technique for MNPs incorporating model drug compounds and highlight their potential as a novel and minimally invasive drug delivery method for the biomedical applications of soft gels. Full article
(This article belongs to the Special Issue Advanced Soft Gels with Enhanced Functionality for Biomedical and Additive Manufacturing Applications)
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34 pages, 5732 KiB  
Review
Synthesis of PVA-Based Hydrogels for Biomedical Applications: Recent Trends and Advances
by Mohammad Mizanur Rahman Khan and Md. Mahamudul Hasan Rumon
Gels 2025, 11(2), 88; https://doi.org/10.3390/gels11020088 - 23 Jan 2025
Viewed by 630
Abstract
There is ongoing research for biomedical applications of polyvinyl alcohol (PVA)-based hydrogels; however, the execution of this has not yet been achieved at an appropriate level for commercialization. Advanced perception is necessary for the design and synthesis of suitable materials, such as PVA-based [...] Read more.
There is ongoing research for biomedical applications of polyvinyl alcohol (PVA)-based hydrogels; however, the execution of this has not yet been achieved at an appropriate level for commercialization. Advanced perception is necessary for the design and synthesis of suitable materials, such as PVA-based hydrogel for biomedical applications. Among polymers, PVA-based hydrogel has drawn great interest in biomedical applications owing to their attractive potential with characteristics such as good biocompatibility, great mechanical strength, and apposite water content. By designing the suitable synthesis approach and investigating the hydrogel structure, PVA-based hydrogels can attain superb cytocompatibility, flexibility, and antimicrobial activities, signifying that it is a good candidate for tissue engineering and regenerative medicine, drug delivery, wound dressing, contact lenses, and other fields. In this review, we highlight the current progresses on the synthesis of PVA-based hydrogels for biomedical applications explaining their diverse usage across a variety of areas. We explain numerous synthesis techniques and related phenomena for biomedical applications based on these materials. This review may stipulate a wide reference for future acumens of PVA-based hydrogel materials for their extensive applications in biomedical fields. Full article
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19 pages, 19913 KiB  
Article
Thermal Reverse-Engineered Synthesis and Catalytic Activity of Nanogold-Containing Silica Aerogels
by Hanna Judit Csupász-Szabó, Boglárka Döncző, Máté Szarka, Lajos Daróczi and István Lázár
Gels 2025, 11(2), 87; https://doi.org/10.3390/gels11020087 - 23 Jan 2025
Viewed by 544
Abstract
Silica aerogels are extensively used as catalyst supports due to their mesoporous structure and chemical inertness. In this study, SiO2–AuNP aerogels containing gold nanoparticles (AuNPs) were synthesized using the sol-gel method followed by supercritical CO2 drying. The inclusion of polyvinyl [...] Read more.
Silica aerogels are extensively used as catalyst supports due to their mesoporous structure and chemical inertness. In this study, SiO2–AuNP aerogels containing gold nanoparticles (AuNPs) were synthesized using the sol-gel method followed by supercritical CO2 drying. The inclusion of polyvinyl pyrrolidone (PVP) as a stabilizing agent preserved the gold particle sizes during the gelation process. In contrast, aerogels synthesized without PVP contained enlarged AuNP aggregates, resulting in a shift in the plasmon resonance color from red to bluish or blue–grey. Thermal treatment of these bluish-colored aerogels at high temperatures restored their red coloration, visually indicating the breakdown of large gold clusters into individual nanoparticles. Both types of aerogels were characterized using SEM, TEM, 3D optical microscopy, UV–vis and ATR-IR spectroscopy, and N2 porosimetry, with their properties analyzed as a function of annealing temperature. Their catalytic activity was evaluated through the reduction of 4-nitrophenol with sodium borohydride, and both aerogel types demonstrated catalytic activity. This thermal conversion of large clusters into individual nanoparticles within an aerogel matrix introduces a new and promising approach for creating catalytically active nanogold-containing aerogel catalysts. Full article
(This article belongs to the Special Issue Aerogels—Preparation and Properties)
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17 pages, 3587 KiB  
Article
Effects of Extrusion Treatment on the Physicochemical and Baking Quality of Japonica Rice Batters and Rice Breads
by Wenxia He, Jingni Tang, Yang Chen, Guanhui Liu, Zhenni Li, Jie Tu and Yixuan Li
Gels 2025, 11(2), 86; https://doi.org/10.3390/gels11020086 - 22 Jan 2025
Viewed by 565
Abstract
Gluten-free rice bread made from japonica rice finds challenge in achieving a good shape and structure, presenting a significant obstacle in the baking industry. This study aims to improve the quality of rice bread with japonica rice flour by hot extrusion treatment (without [...] Read more.
Gluten-free rice bread made from japonica rice finds challenge in achieving a good shape and structure, presenting a significant obstacle in the baking industry. This study aims to improve the quality of rice bread with japonica rice flour by hot extrusion treatment (without additives). The effects of extrusion on the amylose content, gelatinization degree, hydration capacity, short-range molecular ordering, and microstructure of japonica rice flour were investigated. The results show that the amylose content of the extruded flour increased by 12.43% and the gelatinization degree of it increased by 13.23 times, showing disrupted starch granules, numerous pores, and a better hydration capacity. The addition of extruded flour improved the overall viscoelasticity of the batter. Compared to the control group, the specific volume and porosity of the optimized rice bread were increased by 19.46% and 61.92%, respectively. The gas cell density was increased by 4.63 times, and the average gas cell area of rice bread was reduced by 47.14%. The correlations among the raw material properties of rice flour, the batter properties, and the quality of rice bread products were revealed by principal component analysis. This study demonstrates that the addition of moderate amounts of extruded japonica rice flour could improve the quality of rice bread products. Full article
(This article belongs to the Special Issue State-of-the-Art Gel Research in China)
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16 pages, 5756 KiB  
Article
Performance Evaluation of Fluorescent Polymer Gel Microspheres as a Reservoir Conformance Control Agent
by Saya Shagymgereyeva, Bauyrzhan Sarsenbekuly, Wanli Kang and Sarsenbek Turtabayev
Gels 2025, 11(2), 85; https://doi.org/10.3390/gels11020085 - 22 Jan 2025
Viewed by 551
Abstract
This study introduces fluorescent polymer gel microspheres (FPMs) as a novel approach to enhance conformance control in oil reservoirs. Designed to address the challenges of high-permeability zones, FPMs were synthesized via inverse suspension polymerization, incorporating 2-acrylamido-2-methylpropane sulfonic acid (AMPS) to improve thermal stability [...] Read more.
This study introduces fluorescent polymer gel microspheres (FPMs) as a novel approach to enhance conformance control in oil reservoirs. Designed to address the challenges of high-permeability zones, FPMs were synthesized via inverse suspension polymerization, incorporating 2-acrylamido-2-methylpropane sulfonic acid (AMPS) to improve thermal stability and swelling and fluorescein to enable fluorescence. Characterization using FT-IR, SEM, fluorescence spectroscopy, and thermal analysis revealed that FPMs swell significantly in brine, with diameters increasing from 46 μm to 210 μm, and maintain thermal stability up to 110 °C. These advanced properties make FPMs highly effective in reducing permeability and facilitating real-time tracking, offering a promising solution for improved oil recovery and efficient reservoir management. Full article
(This article belongs to the Special Issue Chemical and Gels for Oil Drilling and Enhanced Recovery)
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18 pages, 5352 KiB  
Article
Facile Synthesis of Bioactive Silver Nanocomposite Hydrogels with Electro-Conductive and Wound-Healing Properties
by Solaiman, Tahmina Foyez, Syed Abdul Monim, Aminur Rahman and Abu Bin Imran
Gels 2025, 11(2), 84; https://doi.org/10.3390/gels11020084 - 22 Jan 2025
Viewed by 907
Abstract
Bioactive metal and metal oxide-based nanocomposite hydrogels exhibit significant antibacterial properties by interacting with microbial DNA and preventing bacterial replication. They offer potential applications as coating materials for human or animal skin injuries to prevent microbial growth and promote healing. In this study, [...] Read more.
Bioactive metal and metal oxide-based nanocomposite hydrogels exhibit significant antibacterial properties by interacting with microbial DNA and preventing bacterial replication. They offer potential applications as coating materials for human or animal skin injuries to prevent microbial growth and promote healing. In this study, silver nanoparticles (AgNPs) were synthesized using a chemical reduction method and incorporated into a polymer network to fabricate silver nanocomposite hydrogels (AgNCHGs) through a simple free radical polymerization method. N-isopropylacrylamide (NIPA), which has lower critical solution temperature (LCST) at about body temperature, or acrylamide (AAm) was used as the main monomer, while one or more ionic co-monomers, such as acrylic acid (AAc) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS), were incorporated to obtain AgNCHGs. AgNPs were introduced into the hydrogel network via three different approaches. In the first method, the synthesized hydrogel was immersed in a silver nitrate (AgNO3) solution and reduced in situ using sodium borohydride (NaBH4) as a reducing agent. The second method involved mixing AgNO3 with gel precursors before reduction with NaBH4 to form AgNPs within the hydrogel. The final approach synthesized the AgNCHGs directly in a dispersion of pre-fabricated AgNPs. The incorporation of AgNPs in different AgNCHGs was confirmed through various characterization techniques. Varying temperature and pH conditions can trigger the release of bioactive AgNPs from the hydrogels. Furthermore, the antimicrobial and wound-healing properties of the AgNCHGs were evaluated against bacteria and fungi, demonstrating their potential in biomedical applications. In addition, AgNCHGs exhibit excellent electrical conductivity. The electrical conductivity of the hydrogels can be finely tuned by adjusting the concentration of AgNPs, making these materials promising candidates for energy, sensor, and stretchable electronics applications. This study presents facile synthesis methods of AgNCHGs, which integrate bioactivity, wound healing, and electrical conductivity in the same matrix, addressing a significant challenge in designing multifunctional hydrogels for next-generation technologies. Full article
(This article belongs to the Special Issue Conductive Gels: Preparation, Properties and Applications)
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21 pages, 9128 KiB  
Article
Investigation of the Anti-Inflammatory and Anti-Oxidant Activities of a Novel Kaempferol-Liposome-Loaded Hydrogel for the Treatment of Acute Eczema
by Yuqing Fang, Yong Liu, Keang Cao, Wang Shen, Lu Wang, Bin Sun, Yongli Zhang, Qin Zhang and Hongmei Xia
Gels 2025, 11(2), 83; https://doi.org/10.3390/gels11020083 - 22 Jan 2025
Viewed by 405
Abstract
Kaempferol liposome hydrogel is a novel drug carrier designed to solve the problems of the poor water solubility and low bioavailability of kaempferol. By combining kaempferol with liposomes and further forming a hydrogel, this composite formulation not only improves the stability of the [...] Read more.
Kaempferol liposome hydrogel is a novel drug carrier designed to solve the problems of the poor water solubility and low bioavailability of kaempferol. By combining kaempferol with liposomes and further forming a hydrogel, this composite formulation not only improves the stability of the drug but also enhances its penetration and therapeutic effect on the skin. It was demonstrated that the liposomal hydrogel of kaempferol had ex vivo and in vivo antioxidant activities, which could effectively inhibit the inflammatory response and oxidative stress and, thus, showed significant efficacy in the treatment of acute eczema. In the acute eczema model, kaempferol liposome hydrogel significantly improved the skin condition of mice by reducing the symptoms of skin redness, swelling, and itching. The experimental results showed that the hydrogel was rapidly absorbed into the skin after application and continued to release the drug to maintain its efficacy for a longer period of time. In addition, the kaempferol liposome hydrogel also showed good physicochemical stability and was not easily discolored or separated, making it suitable for long-term use. As an innovative drug carrier for the treatment of acute eczema, the kaempferol liposome hydrogel shows good application prospects and provides a new treatment option for eczema patients. Full article
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24 pages, 2480 KiB  
Article
Development and Characterization of In Situ Gelling Nasal Cilostazol Spanlastics
by Maryana Salamah, Mária Budai-Szűcs, Bence Sipos, Balázs Volk, Gábor Katona, György Tibor Balogh and Ildikó Csóka
Gels 2025, 11(2), 82; https://doi.org/10.3390/gels11020082 - 22 Jan 2025
Viewed by 444
Abstract
Cilostazol (CIL), a BCS class II antiplatelet aggregation and vasodilator agent, is used for cerebrovascular diseases to minimize blood–brain barrier dysfunction, white matter-lesion formation, and motor deficits. The current work aimed to develop and optimize cilostazol-loaded spanlastics (CIL-SPA) for nose-to-brain delivery to overcome [...] Read more.
Cilostazol (CIL), a BCS class II antiplatelet aggregation and vasodilator agent, is used for cerebrovascular diseases to minimize blood–brain barrier dysfunction, white matter-lesion formation, and motor deficits. The current work aimed to develop and optimize cilostazol-loaded spanlastics (CIL-SPA) for nose-to-brain delivery to overcome the low solubility and absorption, the first pass-metabolism, and the adverse effects. The optimal CIL-SPA formulation was loaded into Phytagel® (SPA-PG), Poloxamer-407 (SPA-P407), and chitosan (SPA-CS) gel bases and characterized in terms of colloidal properties, encapsulation efficiency (EE%), mucoadhesive properties, and biopharmaceutical aspects. The developed in situ gelling formulations showed a <300 nm average hydrodynamic diameter, <0.5 polydispersity index, and >|±30| mV zeta potential with a high EE% (>99%). All formulations met the droplet size-distribution criteria of nasal requirements (<200 µm), and all formulations showed adequate mucoadhesion properties. Both the BBB-PAMPA and horizontal permeability study through an artificial membrane revealed that all formulations had higher CIL flux and cumulative permeability at in vitro nose-to-brain conditions compared to the initial CIL. The in vitro drug-release study showed that all formulations released ca. 100% of CIL after 2 h. Therefore, the developed formulations could be promising for improving the low bioavailability of CIL through nose-to-brain delivery. Full article
(This article belongs to the Special Issue Polymer-Based Hydrogels Applied in Drug Delivery)
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16 pages, 2655 KiB  
Review
Advancements in Tissue-Equivalent Gel Dosimeters
by Mustafa Erdem Sagsoz, Ozlem Korkut and Salvatore Gallo
Gels 2025, 11(2), 81; https://doi.org/10.3390/gels11020081 - 21 Jan 2025
Viewed by 503
Abstract
Tissue-equivalent hydrogel dosimeters represent a class of tools that hold significant promise, particularly in the precise measurement of three-dimensional dose distributions in radiotherapy. Due to their physical properties closely resembling those of human soft tissue, these dosimeters effectively replicate the energy transfer phenomena [...] Read more.
Tissue-equivalent hydrogel dosimeters represent a class of tools that hold significant promise, particularly in the precise measurement of three-dimensional dose distributions in radiotherapy. Due to their physical properties closely resembling those of human soft tissue, these dosimeters effectively replicate the energy transfer phenomena resulting from radiation interactions, such as atomic ionization and scattering by nuclei or electrons. Consequently, tissue-equivalent dosimeters, characterized by their linear energy transfer properties, have been extensively applied in medical physics, radiation oncology, and nuclear safety. Future advancements focusing on developing more stable, less toxic, normoxic, and cost-effective dosimeters could enable their broader adoption. This review provides a comprehensive overview of the key characteristics that make hydrogel dosimeters tissue-equivalent, highlighting their benefits, limitations, and primary application areas. Additionally, it explores current advancements in polymeric gel technology and discusses future directions aimed at optimizing their performance and accessibility for broader adoption. Full article
(This article belongs to the Special Issue Innovative Biopolymer-Based Hydrogels (2nd Edition))
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