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Gels, Volume 8, Issue 11 (November 2022) – 73 articles

Cover Story (view full-size image): Composites involving reduced graphene oxide (rGO) aerogels supporting Pt/TiO2 nanoparticles were fabricated using a one-pot supercritical CO2 gelling and drying method. Electron microscopy images and N2 adsorption–desorption isotherms indicated the formation of 3D monolithic aerogels with a meso/macroporous morphology. A comprehensive evaluation of the synthesized photocatalyst was carried out with a focus on the target application: the photocatalytic production of H2 from methanol in aqueous media. The reaction conditions, together with the aerogel composition and architecture, were varied to optimize the process. In the most favorable conditions, using rGO aerogels as the catalyst support, remarkably high values of H2 production rate were obtained. View this paper
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18 pages, 3318 KiB  
Article
Cr(III) Ion-Imprinted Hydrogel Membrane for Chromium Speciation Analysis in Water Samples
by Ivanka Dakova, Penka Vasileva and Irina Karadjova
Gels 2022, 8(11), 757; https://doi.org/10.3390/gels8110757 - 21 Nov 2022
Cited by 5 | Viewed by 1505
Abstract
Novel Cr(III)-imprinted poly(vinyl alcohol)/sodium alginate/AuNPs hydrogel membranes (Cr(III)-IIMs) were obtained and characterized and further applied as a sorbent for chromium speciation in waters. Cr(III)-IIMs were prepared via solution blending method using blends of poly(vinyl alcohol) and sodium alginate as film-forming materials, poly(ethylene glycol) [...] Read more.
Novel Cr(III)-imprinted poly(vinyl alcohol)/sodium alginate/AuNPs hydrogel membranes (Cr(III)-IIMs) were obtained and characterized and further applied as a sorbent for chromium speciation in waters. Cr(III)-IIMs were prepared via solution blending method using blends of poly(vinyl alcohol) and sodium alginate as film-forming materials, poly(ethylene glycol) as a porogen agent, sodium alginate stabilized gold nanoparticles (SA-AuNPs) as a crosslinking and mechanically stabilizing component, and Cr(III) ions as a template species. The physicochemical characteristics of pre-synthesized AuNPs and obtained hydrogel membranes Cr(III)-IIM were studied by UV-vis and FTIR spectroscopy, TEM and SEM observations, N2 adsorption–desorption measurements, and XRD analysis. The mechanism of the adsorption process toward Cr(III) was best described by pseudo-first-order kinetic and Langmuir models. Experiments performed showed that quantitative retention of Cr(III) is attained in 20 h at pH 6 and temperature 40 °C. Under the same conditions, the adsorption of Cr(VI) is below 5%. A simple and sensitive analytical procedure was developed for the speciation of Cr in an aquatic environment using dispersive solid phase extraction of Cr(III) by Cr(III)-IIM prior to selective Cr(VI) measurement by ETAAS in the supernatants. The detection limits and reproducibility achieved for the Cr speciation analysis fulfill the requirements for their monitoring in waters under the demand of the Water Framework Directive. Full article
(This article belongs to the Special Issue Gels for Removal and Adsorption)
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14 pages, 1892 KiB  
Article
The Use of Biopolymers as a Natural Matrix for Incorporation of Essential Oils of Medicinal Plants
by Roxana Gheorghita Puscaselu, Andrei Lobiuc, Ioan Ovidiu Sirbu and Mihai Covasa
Gels 2022, 8(11), 756; https://doi.org/10.3390/gels8110756 - 21 Nov 2022
Cited by 3 | Viewed by 1807
Abstract
The benefits of using biopolymers for the development of films and coatings are well known. The enrichment of these material properties through various natural additions has led to their applicability in various fields. Essential oils, which are well-known for their beneficial properties, are [...] Read more.
The benefits of using biopolymers for the development of films and coatings are well known. The enrichment of these material properties through various natural additions has led to their applicability in various fields. Essential oils, which are well-known for their beneficial properties, are widely used as encapsulating agents in films based on biopolymers. In this study, we developed biopolymer-based films and tested their properties following the addition of 7.5% and 15% (w/v) essential oils of lemon, orange, grapefruit, cinnamon, clove, chamomile, ginger, eucalyptus or mint. The samples were tested immediately after development and after one year of storage in order to examine possible long-term property changes. All films showed reductions in mass, thickness and microstructure, as well as mechanical properties. The most considerable variations in physical properties were observed in the 7.5% lemon oil sample and the 15% grapefruit oil sample, with the largest reductions in mass (23.13%), thickness (from 109.67 µm to 81.67 µm) and density (from 0.75 g/cm3 to 0.43 g/cm3). However, the microstructure of the sample was considerably improved. Although the addition of lemon essential oil prevented the reduction in mass during the storage period, it favored the degradation of the microstructure and the loss of elasticity (from 16.7% to 1.51% for the sample with 7.5% lemon EO and from 18.28% to 1.91% for the sample with 15% lemon EO). Although the addition of essential oils of mint and ginger resulted in films with a more homogeneous microstructure, the increase in concentration favored the appearance of pores and modifications of color parameters. With the exception of films with added orange, cinnamon and clove EOs, the antioxidant capacity of the films decreased during storage. The most obvious variations were identified in the samples with lemon, mint and clove EOs. The most unstable samples were those with added ginger (95.01%), lemon (92%) and mint (90.22%). Full article
(This article belongs to the Special Issue Bioactive Gel Films and Coatings Applied in Active Food Packaging)
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16 pages, 5626 KiB  
Article
Preparation of Bio-Based Aerogel and Its Adsorption Properties for Organic Dyes
by Penghui Li, Chi Yang, Xuewen Xu, Chen Miao, Tianjiao He, Bo Jiang and Wenjuan Wu
Gels 2022, 8(11), 755; https://doi.org/10.3390/gels8110755 - 21 Nov 2022
Cited by 10 | Viewed by 2255
Abstract
The effective utilization of biomass and the purification of dye wastewater are urgent problems. In this study, a biomass aerogel (CaCO3@starch/polyacrylamide/TEMPO-oxidized nanocellulose, CaCO3@STA/PAM/TOCN) was prepared by combining nanocellulose with starch and introducing calcium carbonate nanoparticles, which exhibited a rich [...] Read more.
The effective utilization of biomass and the purification of dye wastewater are urgent problems. In this study, a biomass aerogel (CaCO3@starch/polyacrylamide/TEMPO-oxidized nanocellulose, CaCO3@STA/PAM/TOCN) was prepared by combining nanocellulose with starch and introducing calcium carbonate nanoparticles, which exhibited a rich three-dimensional layered porous structure with a very light mass. Starch and nanocellulose can be grafted onto the molecular chain of acrylamide, while calcium carbonate nanopores can make the gel pore size uniform and have excellent swelling properties. Here, various factors affecting the adsorption behavior of this aerogel, such as pH, contact time, ambient temperature, and initial concentration, are investigated. From the kinetic data, it can be obtained that the adsorption process fits well with the pseudo-second-order. The Langmuir isotherm model can fit the equilibrium data well. The thermodynamic data also demonstrated the spontaneous and heat-absorbing properties of anionic and cationic dyes on CaCO3@STA/PAM/TOCN aerogels. The adsorption capacity of Congo red (CR) and methylene blue (MB) by CaCO3@STA/PAM/TOCN was 277.76 mg/g and 101.01 mg/g, respectively. Therefore, cellulose and starch-based aerogels can be considered promising adsorbents for the treatment of dye wastewater. Full article
(This article belongs to the Special Issue Recent Advances in Aerogels)
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16 pages, 9342 KiB  
Article
In Situ Biosynthesis of Photothermal Parasite for Fluorescence Imaging-Guided Photothermal Therapy of Tumors
by Yaqiong Wang, Haiyan Pan, Zhaowei Meng and Cai Zhang
Gels 2022, 8(11), 754; https://doi.org/10.3390/gels8110754 - 21 Nov 2022
Cited by 1 | Viewed by 1483
Abstract
Photothermal therapy (PTT) has been widely known as a promising therapeutic strategy for cancer treatment in recent decades. However, some organic and inorganic photothermal agents exhibit shortcomings including potential long-term toxicity and lack of biodegradability. Biocompatible extracts from plants and animals provide several [...] Read more.
Photothermal therapy (PTT) has been widely known as a promising therapeutic strategy for cancer treatment in recent decades. However, some organic and inorganic photothermal agents exhibit shortcomings including potential long-term toxicity and lack of biodegradability. Biocompatible extracts from plants and animals provide several alternatives for the reformation of photothermal agents. Bio-inspired products still have inherent problems such as low accumulation in tumors, easy diffusion, and fast elimination. Herein, we aim to develop a biocompatible photothermal agent with tumor enrichment. Enlightened by “parasitized snails”, in situ biosynthesis of photothermal agents and fluorescence imaging-guided PTT are achieved with the assistance of alginate–calcium–genipin (ACG) hydrogel. ACG hydrogel is a mixture of alginate (ALG), calcium (Ca), and genipin (GP). Given that the crosslinking product of GP and protein displays fluorescent/photothermal features, the constructed ACG hydrogel can gradually react with the tumor and then “light up” and “ignite” the tumor under specific light excitation. The ACG hydrogel can be seen as a photothermal parasite, eventually leading to the death of tumor. The photothermal therapeutic effects of ACG hydrogel reacting with tumors are successfully proven in vivo. The naturally derived GP and ALG ensure the biosafety of the ACG hydrogel-based bio-application. This work is another successful practice of nature-inspired methodological strategy for in situ biosynthesis of the photothermal agent. Full article
(This article belongs to the Special Issue Biofunctional Gels)
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18 pages, 2689 KiB  
Article
Spontaneous and Electrically Induced Anisotropy of Composite Agarose Gels
by Alexandar M. Zhivkov and Svetlana H. Hristova
Gels 2022, 8(11), 753; https://doi.org/10.3390/gels8110753 - 21 Nov 2022
Viewed by 1246
Abstract
Agarose gels containing and not bacteriorhodopsin purple membranes (incorporated before gelling) manifest spontaneous optical anisotropy. The dependencies of the anisotropy on the agarose concentration and time have been studied. The rise in the anisotropy is explained by the predominant orientation of the agarose [...] Read more.
Agarose gels containing and not bacteriorhodopsin purple membranes (incorporated before gelling) manifest spontaneous optical anisotropy. The dependencies of the anisotropy on the agarose concentration and time have been studied. The rise in the anisotropy is explained by the predominant orientation of the agarose fibers during the gelling and subsequent deformation of the gel net. In the electric field, additional optical anisotropy rises, which is caused by the orientation of the membranes. A procedure has been developed to separate electrically induced and spontaneous anisotropy in composite gels. The isoelectric points and surface electric potential of bacteriorhodopsin trimer and purple membranes are calculated by the method of protein electrostatics to explain their electric asymmetry, which leads to perpendicular orientation in the direct electric field and longitudinal in the kilohertz sinusoidal field. The results allow for an increase in the separation capability of composite gels of electrophoresis for macromolecules with different sizes by applying an appropriate electric field to modulate the effective pore size. Full article
(This article belongs to the Special Issue Physical and Mechanical Properties of Polymer Gels)
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12 pages, 1302 KiB  
Article
Gelling Power Alteration on Kappa-Carrageenan Dispersion through Esterification Method with Different Fatty Acid Saturation
by Yoga W. Wardhana, Nuur Aanisah, Iyan Sopyan, Rini Hendriani and Anis Y. Chaerunisaa
Gels 2022, 8(11), 752; https://doi.org/10.3390/gels8110752 - 21 Nov 2022
Cited by 4 | Viewed by 2025
Abstract
The physicochemical properties of κ-carrageenan gels and their ester forms derived from different fatty-acid saturations were characterized and compared with those of native κ-carrageenan. Furthermore, stearic and oleic acids were used as the saturated and unsaturated fatty acids, respectively. Fourier-transform infrared (FTIR) spectra [...] Read more.
The physicochemical properties of κ-carrageenan gels and their ester forms derived from different fatty-acid saturations were characterized and compared with those of native κ-carrageenan. Furthermore, stearic and oleic acids were used as the saturated and unsaturated fatty acids, respectively. Fourier-transform infrared (FTIR) spectra confirmed the introduction of the ester into the κ-carrageenan backbone. The thermogravimetric analysis showed that thermal stability increased along with the level of unsaturation, but there was a decrease in viscosity, hardness, and syneresis, which caused the consistency of the product to become more elastic. The results also showed that the ester form still has a swelling ability that is almost the same as that of κ-carrageenan. After being formulated into a gel dosage form, the product was successfully produced from the ester with unsaturated fatty acids, and it was more elastic than native κ-carrageenan and had good physical properties with spreadability that meets the requirements for topical preparations. Full article
(This article belongs to the Special Issue Gel Formation and Processing Technologies for Material Applications)
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10 pages, 2454 KiB  
Article
A Polyvinyl Alcohol–Tannic Acid Gel with Exceptional Mechanical Properties and Ultraviolet Resistance
by Chunqing Si, Xintong Tian, Yan Wang, Zhigang Wang, Xinfang Wang, Dongjun Lv, Aili Wang, Fang Wang, Longlong Geng, Jing Zhao, Ruofei Hu and Qingzeng Zhu
Gels 2022, 8(11), 751; https://doi.org/10.3390/gels8110751 - 20 Nov 2022
Cited by 5 | Viewed by 3251
Abstract
Design and preparation of gels with excellent mechanical properties has garnered wide interest at present. In this paper, preparation of polyvinyl alcohol (PVA)–tannic acid (TA) gels with exceptional properties is documented. The crystallization zone and hydrogen bonding acted as physical crosslinkages fabricated by [...] Read more.
Design and preparation of gels with excellent mechanical properties has garnered wide interest at present. In this paper, preparation of polyvinyl alcohol (PVA)–tannic acid (TA) gels with exceptional properties is documented. The crystallization zone and hydrogen bonding acted as physical crosslinkages fabricated by a combination of freeze–thaw treatment and a tannic acid compound. The effect of tannic acid on mechanical properties of prepared PVA–TA gels was investigated and analyzed. When the mass fraction of PVA was 20.0 wt% and soaking time was 12 h in tannic acid aqueous solution, tensile strength and the elongation at break of PVA–TA gel reached 5.97 MPa and 1450%, respectively. This PVA–TA gel was far superior to a pure 20.0 wt% PVA hydrogel treated only with the freeze–thaw process, as well as most previously reported PVA–TA gels. The toughness of a PVA–TA gel is about 14 times that of a pure PVA gel. In addition, transparent PVA–TA gels can effectively prevent ultraviolet-light-induced degradation. This study provides a novel strategy and reference for design and preparation of high-performance gels that are promising for practical application. Full article
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19 pages, 3571 KiB  
Article
Development of Thermoresponsive-Gel-Matrix-Embedded Amoxicillin Trihydrate-Loaded Bovine Serum Albumin Nanoparticles for Local Intranasal Therapy
by Sandra Aulia Mardikasari, Mária Budai-Szűcs, László Orosz, Katalin Burián, Ildikó Csóka and Gábor Katona
Gels 2022, 8(11), 750; https://doi.org/10.3390/gels8110750 - 19 Nov 2022
Cited by 6 | Viewed by 1796
Abstract
A high dose of amoxicillin is recommended as the first-line therapy for acute bacterial rhinosinusitis (ABR). However, oral administration of amoxicillin is connected to many adverse reactions coupled with moderate bioavailability (~60%). Therefore, this study aimed to develop a topical nasal preparation of [...] Read more.
A high dose of amoxicillin is recommended as the first-line therapy for acute bacterial rhinosinusitis (ABR). However, oral administration of amoxicillin is connected to many adverse reactions coupled with moderate bioavailability (~60%). Therefore, this study aimed to develop a topical nasal preparation of amoxicillin, employing a thermoresponsive nanogel system to increase nasal residence time and prolong drug release. Rheological investigations revealed that formulations containing 21–23% w/w Poloxamer 407 (P407) were in accordance with the requirement of nasal administration (gelling temperature ~35 °C). The average hydrodynamic diameter (<200 nm), pH (6.7–6.9), and hypertonic osmolality (611–663 mOsmol/L) of the in situ gelling nasal nanogel appeared as suitable characteristics for local rhinosinusitis treatment. Moreover, taking into account the mucoadhesive strength and drug release studies, the 21% w/w P407 could be considered as an optimized concentration for effective nasal delivery. Antibacterial activity studies showed that the ability of amoxicillin-loaded in situ gelling nasal nanogel to inhibit bacterial growth (five common ABR pathogens) preserved its effectiveness in comparison to 1 mg/mL amoxicillin aqueous solution as a positive control. Altogether, the developed amoxicillin-loaded in situ gelling thermoresponsive nasal nanogel can be a potential candidate for local antibiotic therapy in the nasal cavity. Full article
(This article belongs to the Special Issue Drug-Loaded Hydrogel Biomaterials)
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17 pages, 7712 KiB  
Article
The Feasibility of Shellac Wax Emulsion Oleogels as Low-Fat Spreads Analyzed by Means of Multidimensional Statistical Analysis
by Andreea Puşcaş and Vlad Mureşan
Gels 2022, 8(11), 749; https://doi.org/10.3390/gels8110749 - 18 Nov 2022
Cited by 6 | Viewed by 1637
Abstract
Shellac wax-based oleogel emulsions were studied with a three level two factorial design in order to find an optimal formulation for a spread formulation. Rheological, textural, colorimetry, and stability analysis were conducted to assess the performance of oleogel emulsions. FTIR spectra were also [...] Read more.
Shellac wax-based oleogel emulsions were studied with a three level two factorial design in order to find an optimal formulation for a spread formulation. Rheological, textural, colorimetry, and stability analysis were conducted to assess the performance of oleogel emulsions. FTIR spectra were also compared. The similarities between the samples were studied using cluster analysis. Analysis of variance (ANOVA) demonstrates that (i) the texture is influenced by the wax concentration, (ii) the rheology and stability by both the considered numeric factors (wax and water concentration) and their interaction, and (iii) the color by both factors. The emulsions containing 7% (m/m) shellac oleogels behaved like the strongest systems, (G′ & GLVR > 30,000 Pa) and exhibited the highest value of the G′-G″ cross-over. The lowest oil binding capacity (OBC) was 99.88% for the sample with 3% (m/m) shellac and 20% (m/m) water. The whiteness index (Windex) varied between 58.12 and 78.50. The optimization process indicated that a formulation based on 4.29% (m/m) shellac wax and 24.13% (m/m) water was suitable as a low-fat spread. Full article
(This article belongs to the Special Issue Recent Progress on Oleogels and Organogels)
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29 pages, 6125 KiB  
Review
Natural Materials for 3D Printing and Their Applications
by Chunyu Su, Yutong Chen, Shujing Tian, Chunxiu Lu and Qizhuang Lv
Gels 2022, 8(11), 748; https://doi.org/10.3390/gels8110748 - 17 Nov 2022
Cited by 13 | Viewed by 3841
Abstract
In recent years, 3D printing has gradually become a well-known new topic and a research hotspot. At the same time, the advent of 3D printing is inseparable from the preparation of bio-ink. Natural materials have the advantages of low toxicity or even non-toxicity, [...] Read more.
In recent years, 3D printing has gradually become a well-known new topic and a research hotspot. At the same time, the advent of 3D printing is inseparable from the preparation of bio-ink. Natural materials have the advantages of low toxicity or even non-toxicity, there being abundant raw materials, easy processing and modification, excellent mechanical properties, good biocompatibility, and high cell activity, making them very suitable for the preparation of bio-ink. With the help of 3D printing technology, the prepared materials and scaffolds can be widely used in tissue engineering and other fields. Firstly, we introduce the natural materials and their properties for 3D printing and summarize the physical and chemical properties of these natural materials and their applications in tissue engineering after modification. Secondly, we discuss the modification methods used for 3D printing materials, including physical, chemical, and protein self-assembly methods. We also discuss the method of 3D printing. Then, we summarize the application of natural materials for 3D printing in tissue engineering, skin tissue, cartilage tissue, bone tissue, and vascular tissue. Finally, we also express some views on the research and application of these natural materials. Full article
(This article belongs to the Special Issue 3D Printing of Gel-Based Materials)
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14 pages, 2049 KiB  
Article
Effect of Composite Chitosan/Sodium Alginate Gel Coatings on the Quality of Fresh-Cut Purple-Flesh Sweet Potato
by Chit-Swe Chit, Ibukunoluwa Fola Olawuyi, Jong Jin Park and Won Young Lee
Gels 2022, 8(11), 747; https://doi.org/10.3390/gels8110747 - 17 Nov 2022
Cited by 5 | Viewed by 1758
Abstract
In this study, single-layer coating using chitosan (Ch) and sodium alginate (SA) solutions and their gel coating (ChCSA) formed by layer-by-layer (LbL) electrostatic deposition using calcium chloride (C) as a cross linking agent were prepared to improve storage qualities and shelf-life of fresh-cut [...] Read more.
In this study, single-layer coating using chitosan (Ch) and sodium alginate (SA) solutions and their gel coating (ChCSA) formed by layer-by-layer (LbL) electrostatic deposition using calcium chloride (C) as a cross linking agent were prepared to improve storage qualities and shelf-life of fresh-cut purple-flesh sweet potatoes (PFSP). The preservative effects of single-layer coating in comparison with LbL on the quality parameters of fresh-cut PFSP, including color change, weight loss, firmness, microbial analysis, CO2 production, pH, solid content, total anthocyanin content (TAC), and total phenolic content (TPC) were evaluated during 16 days of storage at 5 °C. Uncoated samples were applicable as a control. The result established the effectiveness of coating in reducing microbial proliferation (~2 times), color changes (~3 times), and weight loss (~4 times) with negligible firmness losses after the storage period. In addition, TAC and TPC were better retained in the coated samples than in the uncoated samples. In contrast, quality deterioration was observed in the uncoated fresh cuts, which progressed with storage time. Relatively, gel-coating ChCSA showed superior effects in preserving the quality of fresh-cut PFSP and could be suggested as a commercial method for preserving fresh-cut purple-flesh sweet potato and other similar roots. Full article
(This article belongs to the Special Issue Bioactive Gel Films and Coatings Applied in Active Food Packaging)
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20 pages, 5550 KiB  
Article
In Vitro and Ex Vivo Evaluation of Fluocinolone Acetonide–Acitretin-Coloaded Nanostructured Lipid Carriers for Topical Treatment of Psoriasis
by Hassan Raza, Shefaat Ullah Shah, Zakir Ali, Atif Ullah Khan, Irfa Basharat Rajput, Arshad Farid, Mohammed Al Mohaini, Abdulkhaliq J. Alsalman, Maitham A. Al Hawaj, Saima Mahmood, Abid Hussain and Kifayat Ullah Shah
Gels 2022, 8(11), 746; https://doi.org/10.3390/gels8110746 - 17 Nov 2022
Cited by 5 | Viewed by 1923
Abstract
Psoriasis is chronic autoimmune disease that affects 2–5% of the global population. Fluocinolone acetonide (FLU) and acitretin (ACT) are widely used antipsoriatic drugs that belong to BCS classes II and IV, respectively. FLU exhibits side effects, such as skin irritation and a burning [...] Read more.
Psoriasis is chronic autoimmune disease that affects 2–5% of the global population. Fluocinolone acetonide (FLU) and acitretin (ACT) are widely used antipsoriatic drugs that belong to BCS classes II and IV, respectively. FLU exhibits side effects, such as skin irritation and a burning sensation. ACT also shows adverse effects, such as gingivitis, teratogenic effects and xerophthalmia. In the present study, topical nanostructured lipid carriers (NLCs) were fabricated to reduce the side effects and enhance the therapeutic efficacy. FLU–ACT-coloaded NLCs were prepared by the modified microemulsion method and optimized by the Box–Behnken model of Design Expert® version 12. The optimization was based on the particle size (PS), zeta potential (ZP) and percentage of encapsulation efficiency (%EE). The physicochemical analyses were performed by TEM, FTIR, XRD and DSC to assess the morphology, chemical interactions between excipients, crystallinity and thermal behavior of the optimized FLU–ACT-coloaded NLCs. The FLU–ACT-coloaded NLCs were successfully loaded into gel and characterized appropriately. The dialysis bag method and Franz diffusion cells were used for the in vitro release and ex vivo permeation studies, respectively. The optimized FLU–ACT-coloaded NLCs had the desired particle size of 288.2 ± 2.3 nm, ZP of −34.2 ± 1.0 mV and %EE values of 81.6 ± 1.1% for ACT and 75 ± 1.3% for FLU. The TEM results confirmed the spherical morphology, while the FTIR results showed the absence of chemical interactions of any type among the ingredients of the FLU–ACT-coloaded NLCs. The XRD and DSC analyses confirmed the amorphous nature and thermal behavior. The in vitro study showed the sustained release of the FLU and ACT from the optimized FLU–ACT-coloaded NLCs and FLU–ACT-coloaded NLC gel compared with the FLU–ACT suspension and conventional gel. The ex vivo study confirmed the minimal permeation of both drugs from the FLU–ACT-coloaded NLC gel. Full article
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13 pages, 4375 KiB  
Article
Facile Construction of Hybrid Hydrogels with High Strength and Biocompatibility for Cranial Bone Regeneration
by Shuai Chang, Jiedong Wang, Nanfang Xu, Shaobo Wang, Hong Cai, Zhongjun Liu and Xing Wang
Gels 2022, 8(11), 745; https://doi.org/10.3390/gels8110745 - 17 Nov 2022
Cited by 5 | Viewed by 1799
Abstract
The significant efforts being made towards the utilization of artificial soft materials holds considerable promise for developing tissue engineering scaffolds for bone-related diseases in clinics. However, most of these biomaterials cannot simultaneously satisfy the multiple requirements of high mechanics, good compatibility, and biological [...] Read more.
The significant efforts being made towards the utilization of artificial soft materials holds considerable promise for developing tissue engineering scaffolds for bone-related diseases in clinics. However, most of these biomaterials cannot simultaneously satisfy the multiple requirements of high mechanics, good compatibility, and biological osteogenesis. In this study, an osteogenic hybrid hydrogel between the amine-functionalized bioactive glass (ABG) and 4-armed poly(ethylene glycol) succinimidyl glutarate-gelatin network (SGgel) is introduced to flexibly adhere onto the defective tissue and to subsequently guide bone regeneration. Relying on the rapid ammonolysis reaction between amine groups (-NH2) of gelatin and ABG components and N-hydroxysuccinimide (NHS)-ester of tetra-PEG-SG polymer, the hydrogel networks were formed within seconds, offering a multifunctional performance, including easy injection, favorable biocompatibility, biological and mechanical properties (compressive strength: 4.2 MPa; storage modulus: 104 kPa; adhesive strength: 56 kPa), which could facilitate the stem cell viability, proliferation, migration and differentiation into osteocytes. In addition, the integration between the SGgel network and ABG moieties within a nano-scale level enabled the hybrid hydrogel to form adhesion to tissue, maintain the durable osteogenesis and accelerate bone regeneration. Therefore, a robust approach to the simultaneously satisfying tough adhesion onto the tissue defects and high efficiency for bone regeneration on a mouse skull was achieved, which may represent a promising strategy to design therapeutic scaffolds for tissue engineering in clinical applications. Full article
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13 pages, 7214 KiB  
Article
Preparation and Properties of Highly Transparent SiO2 Aerogels for Thermal Insulation
by Baolu Shi, Long Xie, Bin Ma, Zhiliang Zhou, Baosheng Xu and Lijie Qu
Gels 2022, 8(11), 744; https://doi.org/10.3390/gels8110744 - 16 Nov 2022
Cited by 7 | Viewed by 2998
Abstract
SiO2 aerogels have attracted extensive attention due to their unique structural characteristics, which exhibit many special properties, especially good optical transparency. As far as we know, the sol-gel stage during the synthesis of aerogel plays an important role in the construction of [...] Read more.
SiO2 aerogels have attracted extensive attention due to their unique structural characteristics, which exhibit many special properties, especially good optical transparency. As far as we know, the sol-gel stage during the synthesis of aerogel plays an important role in the construction of the gel skeleton. In this study, we adjusted the amount of silicon source and catalyst to explore the best scheme for preparing highly transparent SiO2 aerogels, and further clarify the effects of both on the properties of SiO2 aerogels. Results indicated that the pore size distribution was between 10 and 20 nm, the thermal conductivity was between 0.0135 and 0.021 W/(m·K), and the transmittance reached 97.78% at 800 nm of the aerogels, better than most studies. Therefore, it has the potential to be used in aerogel glass for thermal insulation. Full article
(This article belongs to the Special Issue Gels as High-Performance Thermal Insulation Materials)
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19 pages, 6743 KiB  
Article
Influence of Copper-Strontium Co-Doping on Bioactivity, Cytotoxicity and Antibacterial Activity of Mesoporous Bioactive Glass
by Akrity Anand, Susanta Sengupta, Hana Kaňková, Anna Švančárková, Ana M. Beltrán, Dušan Galusek, Aldo R. Boccaccini and Dagmar Galusková
Gels 2022, 8(11), 743; https://doi.org/10.3390/gels8110743 - 16 Nov 2022
Cited by 13 | Viewed by 1953
Abstract
Mesoporous bioactive glass (MBG) is an extensively studied biomaterial used for the healing of bone defects. Its biological applications can be tailored by introducing metallic ions, such as strontium (Sr) and copper (Cu), which can enhance its functionalities, including osteogenetic, angiogenetic and antibacterial [...] Read more.
Mesoporous bioactive glass (MBG) is an extensively studied biomaterial used for the healing of bone defects. Its biological applications can be tailored by introducing metallic ions, such as strontium (Sr) and copper (Cu), which can enhance its functionalities, including osteogenetic, angiogenetic and antibacterial functionalities. In this study, Cu and Sr ions were co-doped (ratio 1:1) with x = 0.5, 1 and 2 mol% each in glass with an intended nominal composition of 80SiO2-(15-2x)CaO-5P2O5-xCuO-xSrO and synthesized with an evaporation-induced self-assembly (EISA)-based sol-gel technique. XRD confirmed the amorphous nature of the glass, while compositional analysis using ICP-OES confirmed the presence of dopant ions with the required amounts. A TEM study of the MBG powders showed fringes that corresponded to the formation of a highly ordered mesoporous structure. The Cu-Sr-doped MBG showed a positive effect on apatite formation when immersed in SBF, although the release of Cu and Sr ions was relatively slow for 1 mol% of each co-dopant, which signified a stable network structure in the glass. The impact of the Cu and Sr ions on the osteoblast-like cell line MG-63 was assessed. At the particle concentrations of 1 wt./vol.% or lower, the cell viability was above 50%. An antibacterial test was conducted against Gram-negative E. coli and Gram-positive S. aureus bacteria. With a sequential increase in the co-doped ion content in the glass, the zone of inhibition for bacteria increased. The results suggest that the doping of MBG with Cu and Sr ions at up to 2 mol% can result in tailored sustained release of ions to enhance the applicability of the studied glass as a functional biomaterial for bone regeneration applications. Full article
(This article belongs to the Special Issue High-Surface Area Advanced Materials and Their Applications)
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16 pages, 2298 KiB  
Article
A Top-Down Procedure for Synthesizing Calcium Carbonate-Enriched Chitosan from Shrimp Shell Wastes
by Andreea Miron, Andrei Sarbu, Anamaria Zaharia, Teodor Sandu, Horia Iovu, Radu Claudiu Fierascu, Ana-Lorena Neagu, Anita-Laura Chiriac and Tanta-Verona Iordache
Gels 2022, 8(11), 742; https://doi.org/10.3390/gels8110742 - 15 Nov 2022
Cited by 9 | Viewed by 2546
Abstract
Chitosan is used in medicine, pharmaceuticals, cosmetics, agriculture, water treatment, and food due to its superior biocompatibility and biodegradability. Nevertheless, the complex and relatively expensive extraction costs hamper its exploitation and, implicitly, the recycling of marine waste, the most abundant source of chitosan. [...] Read more.
Chitosan is used in medicine, pharmaceuticals, cosmetics, agriculture, water treatment, and food due to its superior biocompatibility and biodegradability. Nevertheless, the complex and relatively expensive extraction costs hamper its exploitation and, implicitly, the recycling of marine waste, the most abundant source of chitosan. In the spirit of developing environmental-friendly and cost-effective procedures, the present study describes one method worth consideration to deliver calcium-carbonate-enriched chitosan from shrimp shell waste, which proposes to maintain the native minerals in the structure of chitin in order to improve the thermal stability and processability of chitosan. Therefore, a synthesis protocol was developed starting from an optimized deacetylation procedure using commercial chitin. The ultimate chitosan product from shrimp shells, containing native calcium carbonate, was further compared to commercial chitosan and chitosan synthesized from commercial chitin. Finally, the collected data during the study pointed out that the prospected method succeeded in delivering calcium-carbonate-enriched chitosan with high deacetylation degree (approximately 75%), low molecular weight (Mn ≈ 10.000 g/ mol), a crystallinity above 59 calculated in the (020) plane, high thermal stability (maximum decomposition temperature over 300 °C), and constant viscosity on a wide range of share rates (quasi-Newtonian behavior), becoming a viable candidate for future chitosan-based materials that can expand the application horizon. Full article
(This article belongs to the Special Issue Chitosan Functional Hydrogels: Synthesis and Applications)
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24 pages, 3797 KiB  
Review
Developments on the Smart Hydrogel-Based Drug Delivery System for Oral Tumor Therapy
by Yiwen Zhao, Bei Ran, Xi Xie, Wanrong Gu, Xiuwen Ye and Jinfeng Liao
Gels 2022, 8(11), 741; https://doi.org/10.3390/gels8110741 - 15 Nov 2022
Cited by 14 | Viewed by 3392
Abstract
At present, an oral tumor is usually treated by surgery combined with preoperative or postoperative radiotherapies and chemotherapies. However, traditional chemotherapies frequently result in substantial toxic side effects, including bone marrow suppression, malfunction of the liver and kidneys, and neurotoxicity. As a new [...] Read more.
At present, an oral tumor is usually treated by surgery combined with preoperative or postoperative radiotherapies and chemotherapies. However, traditional chemotherapies frequently result in substantial toxic side effects, including bone marrow suppression, malfunction of the liver and kidneys, and neurotoxicity. As a new local drug delivery system, the smart drug delivery system based on hydrogel can control drug release in time and space, and effectively alleviate or avoid these problems. Environmentally responsive hydrogels for smart drug delivery could be triggered by temperature, photoelectricity, enzyme, and pH. An overview of the most recent research on smart hydrogels and their controlled-release drug delivery systems for the treatment of oral cancer is given in this review. It is anticipated that the local drug release method and environment-responsive benefits of smart hydrogels will offer a novel technique for the low-toxicity and highly effective treatment of oral malignancy. Full article
(This article belongs to the Special Issue Gels: Applications in Drug Delivery and Tissue Engineering)
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15 pages, 6055 KiB  
Article
Stress and Strain Characteristics under the Large Deformation of Surimi Gel during Penetration and Extension Tests Using Digital Image Correlation and the Numerical Simulation Method
by Hwabin Jung, Timilehin Martins Oyinloye and Won Byong Yoon
Gels 2022, 8(11), 740; https://doi.org/10.3390/gels8110740 - 15 Nov 2022
Cited by 2 | Viewed by 1545
Abstract
The stress and strain properties of surimi gels (72.49% moisture content) under large deformation were analyzed during penetration (cylindrical, conical, and spherical puncture) and extension (ring tensile) tests. Mechanical measurements were compared and validated using digital image correlation (DIC) and numerical simulations. The [...] Read more.
The stress and strain properties of surimi gels (72.49% moisture content) under large deformation were analyzed during penetration (cylindrical, conical, and spherical puncture) and extension (ring tensile) tests. Mechanical measurements were compared and validated using digital image correlation (DIC) and numerical simulations. The DIC and the finite element method reflected the influence of the probe shape and the surface area in contact with the gel during the measurements. In puncture tests, a larger probe surface increased the strain concentration at the puncture point. In the extension test, the strain distribution was symmetrical. The strain values observed during penetration tests were comparable in both the DIC and numerical simulation. The tensile failure characteristics observed in DIC and numerical simulations are similar to those found in the experiment. The study demonstrated that the extension method with the ring tensile device did not show a stress concentration during the measurement, and DIC and numerical simulation can be effective tools in analyzing the textural properties of surimi gel during the puncture and ring tensile tests. Full article
(This article belongs to the Special Issue Recent Advance in Food Gels)
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14 pages, 2124 KiB  
Article
Sodium Alginate-Quaternary Polymethacrylate Composites: Characterization of Dispersions and Calcium Ion Cross-Linked Gel Beads
by Wanwisa Khunawattanakul, Napaphak Jaipakdee, Thitiphorn Rongthong, Narin Chansri, Pathomthat Srisuk, Padungkwan Chitropas and Thaned Pongjanyakul
Gels 2022, 8(11), 739; https://doi.org/10.3390/gels8110739 - 15 Nov 2022
Cited by 3 | Viewed by 1272
Abstract
The objective of this work was to examine the effect of quaternary polymethacrylate (QPM), a water-insoluble polymer with a positive charge, on the characteristics of the sodium alginate (SA) dispersions and the calcium alginate (CA) gel beads containing propranolol HCl (PPN). The SA-QPM [...] Read more.
The objective of this work was to examine the effect of quaternary polymethacrylate (QPM), a water-insoluble polymer with a positive charge, on the characteristics of the sodium alginate (SA) dispersions and the calcium alginate (CA) gel beads containing propranolol HCl (PPN). The SA-QPM composite dispersions presented the formation of flocculates with a negative charge due to the electrostatic interaction of both substances. The QPM addition did not affect the SA dispersions’ Newtonian flow, but the composite dispersions’ viscosity enhancement was found. The PPN-loaded CA-QPM gel beads had more spherical than the PPN-loaded CA gel beads. The incorporation of QPM caused a bigger particle size, higher drug entrapment efficiency, and greater particle strength of the gel beads. Despite the similar water uptake property, the PPN-loaded CA-QPM gel beads displayed lower burst release and slower drug release rate than the PPN-loaded CA gel beads. However, the drug release from the PPN-loaded CA-QPM gel beads involved drug diffusion and matrix swelling mechanisms. This study demonstrated that adding QPM into the SA dispersions leads to a viscosity synergism. The CA-QPM gel beads display a good potential for use as a bioactive compound delivery system. Full article
(This article belongs to the Special Issue Physically Cross-Linked Gels and Their Applications)
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15 pages, 2585 KiB  
Article
The Rheological Properties and Texture of Agar Gels with Canola Oil—Effect of Mixing Rate and Addition of Lecithin
by Ewa Jakubczyk, Anna Kamińska-Dwórznicka and Anna Kot
Gels 2022, 8(11), 738; https://doi.org/10.3390/gels8110738 - 15 Nov 2022
Cited by 6 | Viewed by 2585
Abstract
This study aimed to determine the effect of different mixing rates and the addition of lecithin on the rheological mechanical, and acoustic properties of agar gels with the addition of canola oil. The mixing rate of the agar–oil mixture was changed from 10,000 [...] Read more.
This study aimed to determine the effect of different mixing rates and the addition of lecithin on the rheological mechanical, and acoustic properties of agar gels with the addition of canola oil. The mixing rate of the agar–oil mixture was changed from 10,000 to 13,000 rpm. Additionally, agar gels with the addition of lecithin from 1 to 5% were prepared. The frequency sweep test was used (at 4 and 50 °C) within the linear viscoelastic region (LVR) in oscillatory measurement. The agar–oil mixture was cooled from 80 to 10 °C, enabling the obtainment of the gelling temperature. Texture profile analysis (TPA) and compression tests, as well as the acoustic emission method, were applied to analyse the texture of the gels. The syneresis and stability of gels during storage were also measure. The increase in mixing rate in the case of agar gel with canola oil causes an increase in the elastic component of materials as well hardness and gumminess. Also, samples prepared with the higher mixing rate have more uniform and stable structures, with small bubbles. The increase in the concentration of lecithin is ineffective due to the formation of gels with a weak matrix and low hardness, gumminess, and stability during storage. Full article
(This article belongs to the Special Issue Novel Gels for Food Product Development)
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20 pages, 3710 KiB  
Article
Ginger Extract-Loaded Sesame Oil-Based Niosomal Emulgel: Quality by Design to Ameliorate Anti-Inflammatory Activity
by Marwa H. Abdallah, Hanaa A. Elghamry, Nasrin E. Khalifa, Weam M. A. Khojali, El-Sayed Khafagy, Amr S. Abu Lila, Hemat El-Sayed El-Horany and Shaimaa El-Housiny
Gels 2022, 8(11), 737; https://doi.org/10.3390/gels8110737 - 14 Nov 2022
Cited by 8 | Viewed by 2367
Abstract
Ginger, a natural plant belonging to the Zingeberaceae family, has been reported to have reasonable anti-inflammatory effects. The current study aimed to examine ginger extract transdermal delivery by generating niosomal vesicles as a promising nano-carrier incorporated into emulgel prepared with sesame oil. Particle [...] Read more.
Ginger, a natural plant belonging to the Zingeberaceae family, has been reported to have reasonable anti-inflammatory effects. The current study aimed to examine ginger extract transdermal delivery by generating niosomal vesicles as a promising nano-carrier incorporated into emulgel prepared with sesame oil. Particle size, viscosity, in vitro release, and ex vivo drug penetration experiments were performed on the produced formulations (ginger extract loaded gel, ginger extract loaded emulgel, ginger extract niosomal gel, and ginger extract niosomal emulgel). Carrageenan-induced edema in rat hind paw was employed to estimate the in vivo anti-inflammatory activity. The generated ginger extract formulations showed good viscosity and particle size. The in vitro release of ginger extract from niosomal formulation surpassed other formulations. In addition, the niosomal emulgel formulation showed improved transdermal flux and increased drug permeability through rabbit skin compared to other preparations. Most importantly, carrageenan-induced rat hind paw edema test confirmed the potential anti-inflammatory efficacy of ginger extract niosomal emulgel, compared to other formulations, as manifested by a significant decrease in paw edema with a superior edema inhibition potency. Overall, our findings suggest that incorporating a niosomal formulation within sesame oil-based emulgel might represent a plausible strategy for effective transdermal delivery of anti-inflammatory drugs like ginger extract. Full article
(This article belongs to the Special Issue Liposomal and Ethosomal Gels: From Design to Application)
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11 pages, 1139 KiB  
Article
Herbal Fennel Essential Oil Nanogel: Formulation, Characterization and Antibacterial Activity against Staphylococcus aureus
by Aftab Alam, Ahmed I. Foudah, Mohammad Ayman Salkini, Mohammad Raish and Jyotiram Sawale
Gels 2022, 8(11), 736; https://doi.org/10.3390/gels8110736 - 12 Nov 2022
Cited by 7 | Viewed by 2042
Abstract
Antimicrobial resistance (AMR) is one of the greatest threats to humanity in the world. Antibiotic-resistant bacteria spread easily in communities and hospitals. Staphylococcus aureus (S. aureus) is a serious human infectious agent with threatening broad-spectrum resistance to many commonly used antibiotics. [...] Read more.
Antimicrobial resistance (AMR) is one of the greatest threats to humanity in the world. Antibiotic-resistant bacteria spread easily in communities and hospitals. Staphylococcus aureus (S. aureus) is a serious human infectious agent with threatening broad-spectrum resistance to many commonly used antibiotics. To prevent the spread of pathogenic microorganisms, alternative strategies based on nature have been developed. Essential oils (EOs) are derived from numerous plant parts and have been described as antibacterial agents against S. aureus. Fennel essential oils were selected as antibacterial agents encapsulated in nanoparticles of polylactic acid and glycolic acid (PLGA). The optimum size of the formulation after loading with the active ingredient was 123.19 ± 6.1595 nm with a zeta potential of 0.051 ± 0.002 (23 ± 1.15 mV). The results of the encapsulation efficiency analysis showed high encapsulation of EOs, i.e., 66.4 ± 3.127. To obtain promising carrier materials for the delivery of fennel EOs, they were incorporated in the form of nanogels. The newly developed fennel oils in PLGANPs nanogels have good drug release and MIC against S. aureus. These results indicate the potential of this novel delivery system for antimicrobial therapy. Full article
(This article belongs to the Special Issue Recent Advances in Antimicrobial Hydrogels)
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15 pages, 2872 KiB  
Article
New Zwitterionic Polymer as a Highly Effective Salt- and Calcium-Resistant Fluid Loss Reducer in Water-Based Drilling Fluids
by Luman Liu, Jinsheng Sun, Ren Wang, Fan Liu, Shifeng Gao, Jie Yang, Han Ren, Yuanzhi Qu, Rongchao Cheng, Yuan Geng and Zhenbo Feng
Gels 2022, 8(11), 735; https://doi.org/10.3390/gels8110735 - 11 Nov 2022
Cited by 7 | Viewed by 1919
Abstract
To control the filtration loss of drilling fluids in salt–gypsum formations, a novel type of zwitterionic polymer gel (DNDAP) was synthesized by free radical polymerization, which was used as a salt- and calcium-resistant fluid loss reducer for water-based drilling fluids (WBDF). DNDAP was [...] Read more.
To control the filtration loss of drilling fluids in salt–gypsum formations, a novel type of zwitterionic polymer gel (DNDAP) was synthesized by free radical polymerization, which was used as a salt- and calcium-resistant fluid loss reducer for water-based drilling fluids (WBDF). DNDAP was prepared with N, N-dimethylacrylamide (DMAA), N-vinylpyrrolidone (NVP), Diallyl dimethyl ammonium chloride (DMDAAC), 2-acrylamide-2-methylpropaneonic acid (AMPS), and isopentenol polyether (TPEG) as raw materials. Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (1H-NMR) were used to characterize the composition and structure of the DNDAP copolymer. The thermal stability of DNDAP was evaluated by the use of thermogravimetric analysis (TGA). WBDF with DNDAP was analyzed for zeta potential and particle size and the corresponding filter cake underwent energy dispersive spectrum (EDS) analysis and scanning electron microscope (SEM) analysis. The results showed that the thermal decomposition of DNDAP mainly occurred above 303 °C. DNDAP exhibits excellent rheological and filtration properties in water-based drilling fluids, even under high-temperature aging (up to 200 °C) and high salinity (20 wt% NaCl or 5 wt% CaCl2) environments. The strong adsorption effect of DNDAP makes the particle size of bentonite reasonably distributed to form a dense mud cake that reduces filtration losses. Full article
(This article belongs to the Special Issue Gels for Oil Drilling and Enhanced Recovery)
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16 pages, 3230 KiB  
Article
Encapsulation of Grape (Vitis vinifera L.) Pomace Polyphenols in Soybean Extract-Based Hydrogel Beads as Carriers of Polyphenols and pH-Monitoring Devices
by Gianluca Viscusi, Elena Lamberti, Carmela Gerardi, Giovanna Giovinazzo and Giuliana Gorrasi
Gels 2022, 8(11), 734; https://doi.org/10.3390/gels8110734 - 11 Nov 2022
Cited by 4 | Viewed by 1717
Abstract
In this work, novel bio-based hydrogel beads were fabricated by using soybean extract as raw waste material loaded with Lambrusco extract, an Italian grape cultivar. The phenolic profile and the total amount of anthocyanins from the Lambrusco extract were evaluated before encapsulating it [...] Read more.
In this work, novel bio-based hydrogel beads were fabricated by using soybean extract as raw waste material loaded with Lambrusco extract, an Italian grape cultivar. The phenolic profile and the total amount of anthocyanins from the Lambrusco extract were evaluated before encapsulating it in soybean extract-based hydrogels produced through an ionotropic gelation technique. The physical properties of the produced hydrogel beads were then studied in terms of their morphological and spectroscopic properties. Swelling degree was evaluated in media with different pH levels. The release kinetics of Lambrusco extract were then studied over time as a function of pH of the release medium, corroborating that the acidity/basicity could affect the release rate of encapsulated molecules, as well as their counter-diffusion. The pH-sensitive properties of wine extract were studied through UV-Vis spectroscopy while the colorimetric responses of loaded hydrogel beads were investigated in acidic and basic solutions. Finally, in the framework of circular economy and sustainability, the obtained data open routes to the design and fabrication of active materials as pH-indicator devices from food industry by-products. Full article
(This article belongs to the Special Issue Hydrogels as Controlled Drug Delivery Systems)
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24 pages, 8457 KiB  
Article
A Pharmaco-Technical Investigation of Thymoquinone and Peat-Sourced Fulvic Acid Nanoemulgel: A Combination Therapy
by Rahmuddin Khan, Mohd Aamir Mirza, Mohd Aqil, Nazia Hassan, Foziyah Zakir, Mohammad Javed Ansari and Zeenat Iqbal
Gels 2022, 8(11), 733; https://doi.org/10.3390/gels8110733 - 10 Nov 2022
Cited by 10 | Viewed by 1893
Abstract
Thymoquinone has a multitude of pharmacological effects and has been researched for a wide variety of indications, but with limited clinical success. It is associated with pharmaco-technical caveats such as hydrophobicity, high degradation, and a low oral bioavailability. A prudent approach warrants its [...] Read more.
Thymoquinone has a multitude of pharmacological effects and has been researched for a wide variety of indications, but with limited clinical success. It is associated with pharmaco-technical caveats such as hydrophobicity, high degradation, and a low oral bioavailability. A prudent approach warrants its usage through an alternative dermal route in combination with functional excipients to harness its potential for treating dermal afflictions, such as psoriasis. Henceforth, the present study explores a nanoformulation approach for designing a fulvic acid (peat-sourced)-based thymoquinone nanoemulsion gel (FTQ-NEG) for an enhanced solubility and improved absorption. The excipients, surfactant/co-surfactant, and oil selected for the o/w nanoemulsion (FTQ-NE) are Tween 80/Transcutol-P and kalonji oil. The formulation methodology includes high-energy ultrasonication complemented with a three-dimensional/factorial Box–Behnken design for guided optimization. The surface morphology assessment through scanning/transmission electron microscopy and fluorescence microscopy revealed a 100 nm spherical, globule-like structure of the prepared nanoemulsion. Furthermore, the optimized FTQ-NE had a zeta potential of −2.83 ± 0.14 Mv, refractive index of 1.415 ± 0.036, viscosity of 138.5 ± 3.08 mp, and pH of 5.8 ± 0.16, respectively. The optimized FTQ-NE was then formulated as a gel using Carbopol 971® (1%). The in vitro release analysis of the optimized FTQ-NEG showed a diffusion-dominant drug release (Higuchi model) for 48 h. The drug permeation flux observed for FTQ-NEG (3.64 μg/cm2/h) was much higher compared to that of the pure drug (1.77 mg/cm2/h). The results were further confirmed by confocal microscopy studies, which proved the improved penetration of thymoquinone through mice skin. Long-term stability studies of the purported formulation were also conducted and yielded satisfactory results. Full article
(This article belongs to the Special Issue Advance in Supramolecular Gels)
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20 pages, 5551 KiB  
Article
X-ray Tomography Coupled with Finite Elements, A Fast Method to Design Aerogel Composites and Prove Their Superinsulation Experimentally
by Genevieve Foray, Jaona Harifidy Randrianalisoa, Jerome Adrien and Eric Maire
Gels 2022, 8(11), 732; https://doi.org/10.3390/gels8110732 - 10 Nov 2022
Cited by 1 | Viewed by 1335
Abstract
Composite aerogels can include fibers, opacifiers and binders but are rarely designed and optimized to achieve the best thermal/mechanical efficiency. This paper proposes a three-dimensional X-ray tomography-based method for designing composites. Two types of models are considered: classical and inexpensive homogenization models and [...] Read more.
Composite aerogels can include fibers, opacifiers and binders but are rarely designed and optimized to achieve the best thermal/mechanical efficiency. This paper proposes a three-dimensional X-ray tomography-based method for designing composites. Two types of models are considered: classical and inexpensive homogenization models and more refined finite element models. XrFE is based on the material’s real three-dimensional microstructure and/or its twin numerical microstructure, and calculates the effective conductivity of the material. First, the three-dimensional sample is meshed and labeled. Then, a finite element method is used to calculate the heat flow in the samples. The entire three-dimensional microstructure of a real or fictitious sample is thus associated with a heat flow and an effective conductivity. Parametric studies were performed to understand the relationship between microstructure and thermal efficiency. They highlighted how quickly a low volume fraction addition can improve or ruin thermal conductivity. A reduced set of three formulations was developed and fully characterized. The mechanical behavior was higher than 50 KPa, with thermal efficiencies ranging from 14 to 15 mW·m·K1. Full article
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19 pages, 5806 KiB  
Article
The Effect of Hydrogels with Different Chemical Compositions on the Behavior of Alkali-Activated Slag Pastes
by Joshua Prabahar, Babak Vafaei and Ali Ghahremaninezhad
Gels 2022, 8(11), 731; https://doi.org/10.3390/gels8110731 - 10 Nov 2022
Cited by 5 | Viewed by 1416
Abstract
The effect of in-house synthesized hydrogels with different chemical compositions on the properties of alkali-activated slag pastes was examined. It was found that the teabag test and modified teabag test as a direct method and the flow test as an indirect method showed [...] Read more.
The effect of in-house synthesized hydrogels with different chemical compositions on the properties of alkali-activated slag pastes was examined. It was found that the teabag test and modified teabag test as a direct method and the flow test as an indirect method showed a similar trend in hydrogel absorption; however, the absorption values differ noticeably between the direct and indirect methods. The alkali-activated slag pastes with hydrogels demonstrated a significant reduction in autogenous shrinkage compared to the pastes without hydrogels. The creation of macrovoids by the hydrogels and change in pore structure resulted in a decrease in compressive strength and electrical resistivity of the pastes with hydrogels. The absorption and desorption of hydrogels in the pastes were tracked using X-ray microcomputed tomography (micro-CT), and it was shown that the onset of hydrogel desorption approximately coincided with the final setting time of the pastes. Full article
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15 pages, 1488 KiB  
Review
Hydrogels for Salivary Gland Tissue Engineering
by Sangeeth Pillai, Jose G. Munguia-Lopez and Simon D. Tran
Gels 2022, 8(11), 730; https://doi.org/10.3390/gels8110730 - 10 Nov 2022
Cited by 3 | Viewed by 3306
Abstract
Mimicking the complex architecture of salivary glands (SGs) outside their native niche is challenging due their multicellular and highly branched organization. However, significant progress has been made to recapitulate the gland structure and function using several in vitro and ex vivo models. Hydrogels [...] Read more.
Mimicking the complex architecture of salivary glands (SGs) outside their native niche is challenging due their multicellular and highly branched organization. However, significant progress has been made to recapitulate the gland structure and function using several in vitro and ex vivo models. Hydrogels are polymers with the potential to retain a large volume of water inside their three-dimensional structure, thus simulating extracellular matrix properties that are essential for the cell and tissue integrity. Hydrogel-based culture of SG cells has seen a tremendous success in terms of developing platforms for cell expansion, building an artificial gland, and for use in transplantation to rescue loss of SG function. Both natural and synthetic hydrogels have been used widely in SG tissue engineering applications owing to their properties that support the proliferation, reorganization, and polarization of SG epithelial cells. While recent improvements in hydrogel properties are essential to establish more sophisticated models, the emphasis should still be made towards supporting factors such as mechanotransduction and associated signaling cues. In this concise review, we discuss considerations of an ideal hydrogel-based biomaterial for SG engineering and their associated signaling pathways. We also discuss the current advances made in natural and synthetic hydrogels for SG tissue engineering applications. Full article
(This article belongs to the Special Issue Engineering Hydrogel for Biomedical Applications)
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16 pages, 4418 KiB  
Article
From Macro to Micro: Comparison of Imaging Techniques to Detect Vascular Network Formation in Left Ventricle Decellularized Extracellular Matrix Hydrogels
by Meng Zhang, Vasilena E. Getova, Francisco Drusso Martinez-Garcia, Theo Borghuis, Janette K. Burgess and Martin C. Harmsen
Gels 2022, 8(11), 729; https://doi.org/10.3390/gels8110729 - 10 Nov 2022
Cited by 2 | Viewed by 1679
Abstract
Background: Angiogenesis is a crucial process in physiological maintenance and tissue regeneration. To understand the contribution of angiogenesis, it is essential to replicate this process in an environment that reproduces the biochemical and physical properties which are largely governed by the extracellular matrix [...] Read more.
Background: Angiogenesis is a crucial process in physiological maintenance and tissue regeneration. To understand the contribution of angiogenesis, it is essential to replicate this process in an environment that reproduces the biochemical and physical properties which are largely governed by the extracellular matrix (ECM). We investigated vascularization in cardiac left ventricular ECM hydrogels to mimic post-myocardial repair. We set out to assess and compare different destructive and non-destructive methods, optical as well as non-optical, to visualize angiogenesis and associated matrix remodeling in myocardial ECM hydrogels. Methods: A total of 100,000, 300,000, and 600,000 Human Pulmonary Microvascular Endothelial Cells (HPMEC) were seeded in left ventricular cardiac ECM hydrogel in 48-well plates. After 1, 7, and 14 days of culture, the HPMEC were imaged by inverted fluorescence microscopy and 3D confocal laser scanning microscopy (Zeiss Cell Discoverer 7). In addition, cell-seeded ECM hydrogels were scanned by optical coherence tomography (OCT). Fixed and paraffin-embedded gels were thin-sectioned and assessed for ECM components via H&E, picrosirius red histochemical staining, and immunostaining for collagen type I. ImageJ-based densitometry was used to quantify vascular-like networks and GraphPad was used for statistical analyses. Results: Qualitative analyses were realized through fluoromicrographs obtained by the confocal laser scanning microscope which allowed us to visualize the extensive vascular-like networks that readily appeared at all seeding densities. Quantification of networks was only possible using fluoromicrographs from inverted microscopy. These showed that, after three days, the number of master junctions was seeding density-dependent. The resolution of optical coherence tomography was too low to distinguish between signals caused by the ECM and cells or networks, yet it did show that gels, irrespective of cells, were heterogeneous. Interestingly, (immuno)histochemistry could clearly distinguish between the cast cardiac-derived matrix and newly deposited ECM in the hydrogels. The H&E staining corroborated the presence of vascular-like network structures, albeit that sectioning inevitably led to the loss of 3D structure. Conclusions: Except for OCT, all methods had complementary merit and generated qualitative and quantitative data that allowed us to understand vascular network formation in organ-derived ECM hydrogels. Full article
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12 pages, 4512 KiB  
Article
A Modified Sol–Gel Synthesis of Anatase {001}-TiO2/Au Hybrid Nanocomposites for Enhanced Photodegradation of Organic Contaminants
by Abubakar Katsina Usman, Diana-Luciana Cursaru, Gheorghe Brănoiu, Raluca Şomoghi, Ana-Maria Manta, Dănuţa Matei and Sonia Mihai
Gels 2022, 8(11), 728; https://doi.org/10.3390/gels8110728 - 10 Nov 2022
Cited by 6 | Viewed by 1758
Abstract
A sol–gel synthesis technique was employed for the preparation of anatase phase {001}-TiO2/Au hybrid nanocomposites (NCs). The scalable, schematic, and cost-efficient method was successfully modified using HF and NH4OH capping agents. The photocatalytic activity of the as-synthesized {001}-TiO2 [...] Read more.
A sol–gel synthesis technique was employed for the preparation of anatase phase {001}-TiO2/Au hybrid nanocomposites (NCs). The scalable, schematic, and cost-efficient method was successfully modified using HF and NH4OH capping agents. The photocatalytic activity of the as-synthesized {001}-TiO2/Au NCs were tested over 2-cycle degradation of methylene blue (MB) dye and pharmaceutical active compounds (PhACs) of ibuprofen and naproxen under direct sunlight illumination at 35 °C and 44,000 lx. Transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), fast Fourier transform (FFT), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) were employed for the characterization of the as-prepared sample. The characterization results from the TEM, XPS, and XRD studies established both the distribution of Au colloids on the surface of TiO2 material, and the presence of the highly crystalline structure of anatase {001}-TiO2/Au NCs. Photodegradation results from the visible light irradiation of MB indicate an enhanced photocatalytic performance of Au/TiO2 NCs over TiO2. The results from the photocatalytic activity test performed under direct sunlight exposure exhibited promising photodegradation efficiencies. In the first cycle, the sol–gel synthesized material exhibited relatively better efficiencies (91%) with the MB dye and ibuprofen, while the highest degradation efficiency for the second cycle was 79% for the MB dye. Pseudo first-order photodegradation rates from the first cycle were determined to be comparatively slower than those from the second degradation cycle. Full article
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