Gels

13 pages, 1746 KiB

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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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18 pages, 5530 KiB

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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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24 pages, 1484 KiB

Open AccessArticle

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

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))

19 pages, 3975 KiB

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessReview

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

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

Open AccessArticle

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

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

Open AccessReview

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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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