Gels | Special Issue : Chemical Properties and Application of Gel Materials

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19 pages, 9166 KiB

Open AccessArticle

Optimization of Celery Tail Waste-Based Hydrogels and Application in Soil Water Retention

by Yuqin Wang, Yuan Zhong, Jun Wu, Yufan Xie, Shiwei Fang and Liqun Cai

Gels 2025, 11(4), 248; https://doi.org/10.3390/gels11040248 - 27 Mar 2025

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Abstract

In order to meet the demand for coordinated development of agricultural waste utilization and water-saving agriculture, this study utilized waste celery tailings (CT) to make a super-absorbent hydrogel by chemical cross-linking. The hydrogel was optimized and screened. The study demonstrated the optimal CT-gel [...] Read more.

In order to meet the demand for coordinated development of agricultural waste utilization and water-saving agriculture, this study utilized waste celery tailings (CT) to make a super-absorbent hydrogel by chemical cross-linking. The hydrogel was optimized and screened. The study demonstrated the optimal CT-gel synthesis method: 7.5 wt% CT, 0.05 wt% MBA cross-linker, and 70 °C for 2 h. The optimized gel had a water absorption of 708 g/g and a water retention of more than 20% at 25 °C on day 10. The soil water retention of the CT-gel increased with time and dosage. In sandy soils, 0.6% CT-gel was most effective. The pot experiment showed that 2% of the gel significantly increased the height and growth rate of radish seedlings. This study effectively utilized various components of CT and provided a scalable approach for converting agricultural waste into functional materials, which is valuable for arid soil improvement and sustainable agriculture. Full article

(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)

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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

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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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16 pages, 9169 KiB

Open AccessArticle

The Effect of Acetic Acid as a Solvent on the Structure and Properties of Poly(3-hydroxybutyrate)—Based Dried Gels

by Vsevolod Zhuikov and Yulia Zhuikova

Gels 2024, 10(10), 664; https://doi.org/10.3390/gels10100664 - 17 Oct 2024

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Abstract

Poly(3-hydroxybutyrate) (PHB) is a microbially derived polyhydroxyalkanoate that is widely used in biomedical applications. In this study, we investigated the use of acetic acid (aa) as an alternative environmentally friendly solvent for the preparation of gels from PHB (PHB aa) and compared their [...] Read more.

Poly(3-hydroxybutyrate) (PHB) is a microbially derived polyhydroxyalkanoate that is widely used in biomedical applications. In this study, we investigated the use of acetic acid (aa) as an alternative environmentally friendly solvent for the preparation of gels from PHB (PHB aa) and compared their characteristics with PHB products dissolved in chloroform (PHB chl) using such methods as DSC, FTIR, SEM, rheometry, biodegradation, and cytocompatibility assay. A slight decrease in the degree of the crystallinity of the PHB from 61% to 50.8% was found when the acetic acid was used. This resulted in a greater mass loss for the PHB aa (11%) during enzymatic degradation over 180 days. Gels prepared from PHB in the different solvents showed differences in the microstructure and porosity of the samples, which affected their viscoelastic properties. The storage modulus (G′) for the PHB aa gels was higher by 35% compared to that for the PHB chl, and Young’s modulus in compression was 101.5 and 41.3 kPa for the PHB aa and PHB chl, respectively. The porosity of the PHB aa was 97.7%, which was 5.2% higher than that for the PHB chl. The presence of low molecular weight polymers in the PHB aa had an effect on mesenchymal stem cells’ viability, expressed as a threefold increase in the number of attached cells after 7 days of incubation compared to the PHB chl. Thus, the proposed method of PHB-based materials’ preparation is a promising, more environmentally friendly analog of the extensively used method of preparation from chloroform. Full article

(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)

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14 pages, 7042 KiB

Open AccessArticle

Sol–Gel Synthesis of TiO₂ with Pectin and Their Efficiency in Solar Cells Sensitized by Quantum Dots

by Jean Flores-Gómez, Silvia Mota-Macías, Juan P. Guerrero-Jiménez, Victor Hugo Romero-Arellano and Juan Morales-Rivera

Gels 2024, 10(7), 470; https://doi.org/10.3390/gels10070470 - 17 Jul 2024

Cited by 2 | Viewed by 1584

Abstract

In this study, titanium oxide TiO₂ nanoparticles were produced using the sol–gel approach of green synthesis with pectin as the reducing agent. The synthetized TiO₂ nanoparticles with pectin were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), visible light absorption [...] Read more.

In this study, titanium oxide TiO₂ nanoparticles were produced using the sol–gel approach of green synthesis with pectin as the reducing agent. The synthetized TiO₂ nanoparticles with pectin were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), visible light absorption (UV–Vis) and the BET method. The structure and morphology of the TiO₂ powder were described with SEM, revealing uniform monodisperse grains with a distribution of 80% regarding sizes < 250 nm; the resulting crystal phase of synthetized TiO₂ was identified as an anatase and rutile phase with a crystallinity size estimated between 27 and 40 nm. Also, the surface area was determined by nitrogen adsorption–desorption using the Brown–Emmet–Teller method, with a surface area calculated as 19.56 m²/g, typical of an IV type isotherm, indicating mesoporous NPs. UV–Vis spectra showed that sol–gel synthesis reduced the band gap from the 3.2 eV common value to 2.22 eV after estimating the optical band gap energy using the adsorption coefficient; this translates to a possible extended photo response to the visible region, improving photoactivity. In addition, the power conversion of the photoelectrode was compared based on similar assembly techniques of TiO₂ electrode deposition. Quantum dot crystals were deposited ionically on the electrode surface, as two different paste formulations based on a pectin emulsifier were studied for layer deposition. The results confirm that the TiO₂ paste with TiO₂-synthesized powder maintained good connections between the nanocrystalline mesoporous grains and the deposited layers, with an efficiency of 1.23% with the transparent paste and 2.27% with the opaque paste. These results suggest that pectin could be used as a low-cost, functional sol–gel catalysis agent for the synthesis of controlled NPs of metal oxide. It demonstrates interesting optical properties, such as an increase in photo response, suggesting further applications to photocatalysts and biomedical features. Full article

(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)

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15 pages, 4651 KiB

Open AccessArticle

Influence of Thermal Treatment on the Chemical and Structural Properties of Geopolymer Gels Doped with Nd₂O₃ and Sm₂O₃

by Miloš Nenadović, Sanja Knežević, Marija Ivanović, Snežana Nenadović, Danilo Kisić, Maja Popović and Jelena Potočnik

Gels 2024, 10(7), 468; https://doi.org/10.3390/gels10070468 - 17 Jul 2024

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Abstract

In this research, the influence of the thermal treatment of geopolymer gels at 300 °C, 600 °C and 900 °C when incorporated with 5% rare earth elements (REEs) in the form of (GP-Sm) Sm₂O₃ and (GP-Nd) Nd₂O₃ [...] Read more.

In this research, the influence of the thermal treatment of geopolymer gels at 300 °C, 600 °C and 900 °C when incorporated with 5% rare earth elements (REEs) in the form of (GP-Sm) Sm₂O₃ and (GP-Nd) Nd₂O₃ was investigated. Changes in the chemical and structural properties of the geopolymer gels during thermal treatment for 1 h were monitored. Physico-chemical characterization was performed using the following methods: diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), scanning electron microscopy with energy dispersive spectrometry (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). Besides the characterization of the fundamental properties, some practical macroscopic properties were analyzed as well: sorptivity, open porosity, and Archimedean density. The stretching vibrations of Nd–O–Si and Sm–O–Si were confirmed at a value of around 680 cm⁻¹and an Nd–O–Si absorption band at a higher value, together with the most dominant band of Si–O stretching vibration similar for all the samples. No significant chemical changes occurred. Structural analysis showed that for GP-Nd, the largest pore diameter was obtained at 900 °C, while for GP-Sm, the largest pore diameter was obtained at 600 °C. EDS confirmed the amount of dopant to be about 5%. X-ray photoelectron spectroscopy showed that for GP-Nd, the ratio of Si and Al changed the most, while for GP-Sm, the ratio of Si and Al decreased with increasing temperature. The contributions of both dopants in the GP-gel structure remained almost unchanged and stable at high temperatures. The atomic percentages obtained by XPS analysis were in accordance with the expected trend; the amount of Si increased with the temperature, while the amount of Al decreased with increasing temperature. The sorptivity and open porosity showed the highest values at 600 °C, while the density of both geopolymers decreased linearly with increasing temperature. Full article

(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)

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12 pages, 3682 KiB

Open AccessCommunication

Assessment of Alginate Gel Films as the Orodispersible Dosage Form for Meloxicam

by Barbara Jadach, Martyna Kowalczyk and Anna Froelich

Gels 2024, 10(6), 379; https://doi.org/10.3390/gels10060379 - 2 Jun 2024

Cited by 2 | Viewed by 1111

Abstract

The aim of this study was to obtain films based on sodium alginate (SA) for disintegration in the oral cavity. The films were prepared with a solvent-casting method, and meloxicam (MLX) as the active ingredient was suspended in a 3% sodium alginate solution. [...] Read more.

The aim of this study was to obtain films based on sodium alginate (SA) for disintegration in the oral cavity. The films were prepared with a solvent-casting method, and meloxicam (MLX) as the active ingredient was suspended in a 3% sodium alginate solution. Two different solid-dosage-form additives containing different disintegrating agents, i.e., VIVAPUR 112^® (MCC; JRS Pharma, Rosenberg, Germany) and Prosolve EASYtabs SP^® (MIX; JRS Pharma, Rosenberg, Germany), were used, and four different combinations of drying time and temperature were tested. The influence of the used disintegrant on the properties of the ODFs (orodispersible films) was investigated. The obtained films were studied for their appearance, elasticity, mass uniformity, water content, meloxicam content and, finally, disintegration time, which was studied using two different methods. The films obtained with the solvent-casting method were flexible and homogeneous in terms of MLX content. Elasticity was slightly better when MIX was used as a disintegrating agent. However, these samples also revealed worse uniformity and mechanical durability. It was concluded that the best properties of the films were achieved using the mildest drying conditions. The type of the disintegrating agent had no effect on the amount of water remaining in the film after drying. The water content depended on the drying conditions. The disintegration time was not affected by the disintegrant type, but some differences were observed when various drying conditions were applied. However, regardless of the formulation type and manufacturing conditions, the analyzed films could not be classified as fast disintegrating films, as the disintegration time exceeded 30 s in all of the tested formulations. Full article

(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)

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18 pages, 7250 KiB

Open AccessArticle

Study of the Synthesis of Multi-Cationic Sm-Co-O, Sm-Ni-O, Al-Co-O, Al-Ni-O, and Al-Co-Ni-O Aerogels and Their Catalytic Activity in the Dry Reforming of Methane

by Jaroslav Cihlar, Serhii Tkachenko, Vendula Bednarikova, Jaroslav Cihlar, Jr., Klara Castkova, Martin Trunec and Ladislav Celko

Gels 2024, 10(5), 328; https://doi.org/10.3390/gels10050328 - 11 May 2024

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Abstract

Dense multi-cationic Sm-Co-O, Sm-Ni-O, Al-Co-O, Al-Ni-O, and Al-Ni-Co-O oxide aerogels were prepared by epoxide-driven sol–gel synthesis. Catalysts for dry reformation of methane, Sm₂O₃/Co, Sm₂O₃/Ni, Al₂O₃/Co, Al₂O₃/Ni, Al [...] Read more.

Dense multi-cationic Sm-Co-O, Sm-Ni-O, Al-Co-O, Al-Ni-O, and Al-Ni-Co-O oxide aerogels were prepared by epoxide-driven sol–gel synthesis. Catalysts for dry reformation of methane, Sm₂O₃/Co, Sm₂O₃/Ni, Al₂O₃/Co, Al₂O₃/Ni, Al₂O₃/Co, and Ni were prepared by reduction of aerogels with hydrogen and their catalytic activities and C-deposition during dry reformation of methane were tested. Catalytic tests showed high methane conversion (93–98%) and C-deposition (0.01–4.35 mg C/g_cat^.h). The highest content of C-deposits after catalytic tests was determined for Al₂O₃/Co and Al₂O₃/Ni catalysts, which was related to the formation of Al alloys with Co and Ni. A uniform distribution of Co⁰ and Ni⁰ nanoparticles (in the form of a CoNi alloy) was found only for the Al₂O₃/Co and Ni catalysts, which showed the highest activity as well as low C deposition. Full article

(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)

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Review

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41 pages, 8848 KiB

Open AccessReview

Applications of Hydrogels in Emergency Therapy

by Mariana Chelu, Monica Popa and José María Calderón Moreno

Gels 2025, 11(4), 234; https://doi.org/10.3390/gels11040234 - 23 Mar 2025

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Abstract

Interest in developing new, effective materials for emergency hemostasis and wound healing is steadily increasing, particularly for use in emergency, surgical, and military situations. Hydrogels, with their unique retention, swelling, and biocompatibility properties, have emerged as essential materials in emergency therapy. This review [...] Read more.

Interest in developing new, effective materials for emergency hemostasis and wound healing is steadily increasing, particularly for use in emergency, surgical, and military situations. Hydrogels, with their unique retention, swelling, and biocompatibility properties, have emerged as essential materials in emergency therapy. This review provides a comprehensive examination of recent hydrogel applications in acute medical scenarios, including hemostasis, wound management, drug delivery, soft tissue replacement, and tissue engineering. We discuss the physicochemical properties that make hydrogels suitable for rapid response situations, such as their tunable mechanical strength, adhesiveness, responsiveness to environmental stimuli, and ability to encapsulate and release therapeutic agents. Additionally, the article explores recent advancements in smart hydrogels with self-healing and antimicrobial properties, providing insights into their potential to revolutionize emergency care and increase survival rates in both civilian and military applications. Through a critical evaluation of current clinical trials and practical deployments, this review highlights both the successes and the challenges faced in integrating hydrogels into emergency medical protocols, providing a roadmap for future research and development in this dynamic field. Full article

(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)

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