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Gels, Volume 9, Issue 6 (June 2023) – 74 articles

Cover Story (view full-size image): First-generation amperometric xanthine biosensors, assembled via layer-by-layer methodology and featuring xerogels doped with gold nanoparticles, were effective for xanthine detection in both clinical (disease diagnosis) and industrial (meat freshness) applications. Embedding the xerogel layer with a network of alkanthiolate- monolayer-protected gold nanoparticles enhanced biosensor performance, with improved sensitivity, linear range, and response time. Additionally, the biosensors exhibited stable sensitivity and discrimination against common interferent species over time. Signal deconvolution, critical to deciphering xanthine within the natural purine metabolism mechanism, along with the portability, low cost, and small size, are all attributes of the presented sensor. View this paper
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22 pages, 8745 KiB  
Article
Hydrocolloids of Egg White and Gelatin as a Platform for Hydrogel-Based Tissue Engineering
by Karinna Georgiana Pele, Hippolyte Amaveda, Mario Mora, Carlos Marcuello, Anabel Lostao, Pilar Alamán-Díez, Salvador Pérez-Huertas, María Ángeles Pérez, José Manuel García-Aznar and Elena García-Gareta
Gels 2023, 9(6), 505; https://doi.org/10.3390/gels9060505 - 20 Jun 2023
Cited by 11 | Viewed by 2727
Abstract
Innovative materials are needed to produce scaffolds for various tissue engineering and regenerative medicine (TERM) applications, including tissue models. Materials derived from natural sources that offer low production costs, easy availability, and high bioactivity are highly preferred. Chicken egg white (EW) is an [...] Read more.
Innovative materials are needed to produce scaffolds for various tissue engineering and regenerative medicine (TERM) applications, including tissue models. Materials derived from natural sources that offer low production costs, easy availability, and high bioactivity are highly preferred. Chicken egg white (EW) is an overlooked protein-based material. Whilst its combination with the biopolymer gelatin has been investigated in the food technology industry, mixed hydrocolloids of EW and gelatin have not been reported in TERM. This paper investigates these hydrocolloids as a suitable platform for hydrogel-based tissue engineering, including 2D coating films, miniaturized 3D hydrogels in microfluidic devices, and 3D hydrogel scaffolds. Rheological assessment of the hydrocolloid solutions suggested that temperature and EW concentration can be used to fine-tune the viscosity of the ensuing gels. Fabricated thin 2D hydrocolloid films presented globular nano-topography and in vitro cell work showed that the mixed hydrocolloids had increased cell growth compared with EW films. Results showed that hydrocolloids of EW and gelatin can be used for creating a 3D hydrogel environment for cell studies inside microfluidic devices. Finally, 3D hydrogel scaffolds were fabricated by sequential temperature-dependent gelation followed by chemical cross-linking of the polymeric network of the hydrogel for added mechanical strength and stability. These 3D hydrogel scaffolds displayed pores, lamellae, globular nano-topography, tunable mechanical properties, high affinity for water, and cell proliferation and penetration properties. In conclusion, the large range of properties and characteristics of these materials provide a strong potential for a large variety of TERM applications, including cancer models, organoid growth, compatibility with bioprinting, or implantable devices. Full article
(This article belongs to the Special Issue Hydrogel-Based Scaffolds with a Focus on Medical Use)
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11 pages, 1036 KiB  
Communication
Effect of Gelatin-Based Hemostats on Fibroblasts and Relevant Growth Factors in Wound Healing
by Waseem Garabet, Polina Shabes, Katharina Henrika Wolters, Julian-Dario Rembe, Wiebke Ibing, Markus Udo Wagenhäuser, Florian Simon, Hubert Schelzig and Alexander Oberhuber
Gels 2023, 9(6), 504; https://doi.org/10.3390/gels9060504 - 20 Jun 2023
Cited by 2 | Viewed by 1352
Abstract
Gelatin-based hemostats have been used in various surgical fields and showed advantageous effects on central aspects of wound healing when compared to cellulose-based hemostats. Nevertheless, the influence of gelatin-based hemostats on wound healing has not been fully explored yet. Hemostats were applied to [...] Read more.
Gelatin-based hemostats have been used in various surgical fields and showed advantageous effects on central aspects of wound healing when compared to cellulose-based hemostats. Nevertheless, the influence of gelatin-based hemostats on wound healing has not been fully explored yet. Hemostats were applied to fibroblast cell cultures for 5, 30, 60 min, 24 h, 7 and 14 days and measurements were taken at 3, 6, 12, 24 h and 7 or 14 days, respectively. Cell proliferation was quantified after different exposure times and a contraction assay was conducted to measure the extent of the extracellular matrix over time. We further assessed quantitative levels of vascular endothelial growth factor and basic fibroblast growth factor using enzyme-linked immunosorbent assay. Fibroblast counts decreased significantly at 7 and 14 days independent of the application duration (p < 0.001 for 5 min application). The gelatin-based hemostat did not have a negative impact on cell matrix contraction. After application of gelatin-based hemostat, the basic fibroblast growth factor did not change; yet, the vascular endothelial growth factor significantly increased after a prolonged 24 h application time when compared to controls or to a 6 h exposure (p < 0.05). Gelatin-based hemostats did not impair contraction of the extracellular matrix or growth factor production (vascular endothelial growth factor and basic fibroblast growth factor), while cell proliferation diminished at late time points. In conclusion, the gelatin-based material seems to be compatible with central aspects of wound healing. For further clinical assessment, future animal and human studies are necessary. Full article
(This article belongs to the Special Issue Gels for Wound Healing)
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22 pages, 7035 KiB  
Article
Effects of Aluminosilicate Gel Treatment and TiO2 Loading on Photocatalytic Properties of Au–TiO2/Zeolite Y
by Gabriela Petcu, Florica Papa, Elena Maria Anghel, Irina Atkinson, Silviu Preda, Simona Somacescu, Daniela C. Culita, Adriana Baran, Elena Madalina Ciobanu, Luiza Maria Jecu, Mariana Constantin and Viorica Parvulescu
Gels 2023, 9(6), 503; https://doi.org/10.3390/gels9060503 - 20 Jun 2023
Cited by 2 | Viewed by 1609
Abstract
The present work reports the synthesis of efficient Ti–Au/zeolite Y photocatalysts by different processing of aluminosilicate gel and studies the effect of titania content on the structural, morphological, textural, and optical properties of the materials. The best characteristics of zeolite Y were obtained [...] Read more.
The present work reports the synthesis of efficient Ti–Au/zeolite Y photocatalysts by different processing of aluminosilicate gel and studies the effect of titania content on the structural, morphological, textural, and optical properties of the materials. The best characteristics of zeolite Y were obtained by aging the synthesis gel in static conditions and mixing the precursors under magnetic stirring. Titania (5, 10, 20%) and gold (1%) species were incorporated in zeolite Y support by the post-synthesis method. The samples were characterized by X-ray diffraction, N2-physisorption, SEM, Raman, UV–Vis and photoluminescence spectroscopy, XPS, H2-TPR, and CO2-TPD. The photocatalyst with the lowest TiO2 loading shows only metallic Au on the outermost surface layer, while a higher content favors the formation of additional species such as: cluster type Au, Au1+, and Au3+. A high TiO2 content contributes to increasing the lifetime of photogenerated charge careers, and the adsorption capacity of the pollutant. Therefore, an increase in the photocatalytic performances (evaluated in degradation of amoxicillin in water under UV and visible light) was evidenced with the titania content. The effect is more significant in visible light due to the surface plasmon resonance (SPR) effect of gold interacting with the supported titania. Full article
(This article belongs to the Special Issue Designing Gels for Catalysts)
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11 pages, 2149 KiB  
Article
Cryopreservation of 3D Bioprinted Scaffolds with Temperature-Controlled-Cryoprinting
by Linnea Warburton and Boris Rubinsky
Gels 2023, 9(6), 502; https://doi.org/10.3390/gels9060502 - 20 Jun 2023
Cited by 3 | Viewed by 2124
Abstract
Temperature-Controlled-Cryoprinting (TCC) is a new 3D bioprinting technology that allows for the fabrication and cryopreservation of complex and large cell-laden scaffolds. During TCC, bioink is deposited on a freezing plate that descends further into a cooling bath, keeping the temperature at the nozzle [...] Read more.
Temperature-Controlled-Cryoprinting (TCC) is a new 3D bioprinting technology that allows for the fabrication and cryopreservation of complex and large cell-laden scaffolds. During TCC, bioink is deposited on a freezing plate that descends further into a cooling bath, keeping the temperature at the nozzle constant. To demonstrate the effectiveness of TCC, we used it to fabricate and cryopreserve cell-laden 3D alginate-based scaffolds with high cell viability and no size limitations. Our results show that Vero cells in a 3D TCC bioprinted scaffold can survive cryopreservation with a viability of 71%, and cell viability does not decrease as higher layers are printed. In contrast, previous methods had either low cell viability or decreasing efficacy for tall or thick scaffolds. We used an optimal temperature profile for freezing during 3D printing using the two-step interrupted cryopreservation method and evaluated drops in cell viability during the various stages of TCC. Our findings suggest that TCC has significant potential for advancing 3D cell culture and tissue engineering. Full article
(This article belongs to the Special Issue 3D Printing of Gels: Applications and Properties)
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14 pages, 3059 KiB  
Article
Synthesis and Characterization of Hydrogel Droplets Containing Magnetic Nano Particles, in a Microfluidic Flow-Focusing Chip
by Fereshteh Moharramzadeh, Seyyed Ali Seyyed Ebrahimi, Vahid Zarghami, Zahra Lalegani and Bejan Hamawandi
Gels 2023, 9(6), 501; https://doi.org/10.3390/gels9060501 - 19 Jun 2023
Viewed by 1616
Abstract
Magnetic hybrid hydrogels have exhibited remarkable efficacy in various areas, particularly in the biomedical sciences, where these inventive substances exhibit intriguing prospects for controlled drug delivery, tissue engineering, magnetic separation, MRI contrast agents, hyperthermia, and thermal ablation. Additionally, droplet-based microfluidic technology enables the [...] Read more.
Magnetic hybrid hydrogels have exhibited remarkable efficacy in various areas, particularly in the biomedical sciences, where these inventive substances exhibit intriguing prospects for controlled drug delivery, tissue engineering, magnetic separation, MRI contrast agents, hyperthermia, and thermal ablation. Additionally, droplet-based microfluidic technology enables the fabrication of microgels possessing monodisperse characteristics and controlled morphological shapes. Here, alginate microgels containing citrated magnetic nanoparticles (MNPs) were produced by a microfluidic flow-focusing system. Superparamagnetic magnetite nanoparticles with an average size of 29.1 ± 2.5 nm and saturation magnetization of 66.92 emu/g were synthesized via the co-precipitation method. The hydrodynamic size of MNPs was changed from 142 nm to 826.7 nm after the citrate group’s attachment led to an increase in dispersion and the stability of the aqueous phase. A microfluidic flow-focusing chip was designed, and the mold was 3D printed by stereo lithographic technology. Depending on inlet fluid rates, monodisperse and polydisperse microgels in the range of 20–120 μm were produced. Different conditions of droplet generation in the microfluidic device (break-up) were discussed considering the model of rate-of-flow-controlled-breakup (squeezing). Practically, this study indicates guidelines for generating droplets with a predetermined size and polydispersity from liquids with well-defined macroscopic properties, utilizing a microfluidic flow-focusing device (MFFD). Fourier transform infrared spectrometer (FT-IR) results indicated a chemical attachment of citrate groups on MNPs and the existence of MNPs in the hydrogels. Magnetic hydrogel proliferation assay after 72 h showed a better rate of cell growth in comparison to the control group (p = 0.042). Full article
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26 pages, 6879 KiB  
Review
Bile Acid Sequestrants Based on Natural and Synthetic Gels
by Magdalena-Cristina Stanciu, Marieta Nichifor and Carmen-Alice Teacă
Gels 2023, 9(6), 500; https://doi.org/10.3390/gels9060500 - 19 Jun 2023
Cited by 5 | Viewed by 2573
Abstract
Bile acid sequestrants (BASs) are non-systemic therapeutic agents used for the management of hypercholesterolemia. They are generally safe and not associated with serious systemic adverse effects. Usually, BASs are cationic polymeric gels that have the ability to bind bile salts in the small [...] Read more.
Bile acid sequestrants (BASs) are non-systemic therapeutic agents used for the management of hypercholesterolemia. They are generally safe and not associated with serious systemic adverse effects. Usually, BASs are cationic polymeric gels that have the ability to bind bile salts in the small intestine and eliminate them by excretion of the non-absorbable polymer–bile salt complex. This review gives a general presentation of bile acids and the characteristics and mechanisms of action of BASs. The chemical structures and methods of synthesis are shown for commercial BASs of first- (cholestyramine, colextran, and colestipol) and second-generation (colesevelam and colestilan) and potential BASs. The latter are based on either synthetic polymers such as poly((meth)acrylates/acrylamides), poly(alkylamines), poly(allylamines) and vinyl benzyl amino polymers or biopolymers, such as cellulose, dextran, pullulan, methylan, and poly(cyclodextrins). A separate section is dedicated to molecular imprinting polymers (MIPs) because of their great selectivity and affinity for the template molecules used in the imprinting technique. Focus is given to the understanding of the relationships between the chemical structure of these cross-linked polymers and their potential to bind bile salts. The synthetic pathways used in obtaining BASs and their in vitro and in vivo hypolipidemic activities are also introduced. Full article
(This article belongs to the Special Issue Biofunctional Gels)
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25 pages, 6388 KiB  
Article
Synthesis of New Hydrogels Involving Acrylic Acid and Acrylamide Grafted Agar-Agar and Their Application in the Removal of Cationic Dyes from Wastewater
by Amina Betraoui, Nesrinne Seddiki, Rafika Souag, Nabila Guerfi, Abdelhabib Semlali, Taieb Aouak and Djamel Aliouche
Gels 2023, 9(6), 499; https://doi.org/10.3390/gels9060499 - 19 Jun 2023
Cited by 6 | Viewed by 1781
Abstract
Polyacrylic Acid grafted Agar-agar (AAc-graf-Agar), and polyacrylamide grafted Agar-Agar (AAm-graf-Agar) have been synthesised by free radical polymerisation route initiated by ammonium peroxodisulphate (APS), the grafted polymers were characterised by FTIR, TGA and SEM methods. The swelling properties were studied [...] Read more.
Polyacrylic Acid grafted Agar-agar (AAc-graf-Agar), and polyacrylamide grafted Agar-Agar (AAm-graf-Agar) have been synthesised by free radical polymerisation route initiated by ammonium peroxodisulphate (APS), the grafted polymers were characterised by FTIR, TGA and SEM methods. The swelling properties were studied in deionised water and saline solution at room temperature. The prepared hydrogels were examined by removing cationic methylene blue (MB) dye from the aqueous solution, in which the adsorption kinetics and isotherms models were also investigated. It was found that the pseudo-second-order and Langmuir equations are the most suitable for the different sorption processes. The maximum dye adsorption capacity was 1035.96 mg∙g−1 for AAc-graf-Agar in pH medium 12 and 1015.7 mg∙g−1 for AAm-graf-Agar in neutral pH medium. This indicates that the AAc-graf-Agar hydrogel could be an excellent adsorbent for removing MB from aqueous solutions. Full article
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14 pages, 5036 KiB  
Article
Application of Red Onion Peel Extract for Green Synthesis of Silver Nanoparticles in Hydrogels Exhibiting Antimicrobial Properties
by Judita Puišo, Algimantas Paškevičius, Jonas Žvirgždas, Todorka L. Dimitrova, Andrejus Litvakas and Diana Adliene
Gels 2023, 9(6), 498; https://doi.org/10.3390/gels9060498 - 19 Jun 2023
Cited by 2 | Viewed by 2352
Abstract
UV-initiated green synthesis of metal nanoparticles by using plant extracts as photoreducing agents is of particular interest since it is an environmentally friendly, easy-to-maintain, and cost-effective method. Plant molecules that act as reducing agents are assembled in a highly controlled way which makes [...] Read more.
UV-initiated green synthesis of metal nanoparticles by using plant extracts as photoreducing agents is of particular interest since it is an environmentally friendly, easy-to-maintain, and cost-effective method. Plant molecules that act as reducing agents are assembled in a highly controlled way which makes them suitable for metal nanoparticle synthesis. Depending on the plant species, their application for green synthesis of metal nanoparticles for diverse applications may contribute to the mediation/reduction in organic waste amounts, thus enabling the implementation of the circular economy concept. In this work, UV-initiated green synthesis of Ag nanoparticles in hydrogels and hydrogel’s thin films containing gelatin (matrix), red onion peel extract of different concentrations, water, and a small amount of 1 M AgNO3 have been investigated and characterized using UV-Vis spectroscopy, SEM and EDS analysis, XRD technique, performing swelling experiments and antimicrobial tests using bacteria (Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa), yeasts (Candida parapsilosis, Candida albicans) and microscopic fungi (Aspergillus flavus, Aspergillus fumigatus). It was found that the antimicrobial effectiveness of the silver-enriched red onion peel extract–gelatin films was higher at lower AgNO3 concentrations as compared to those usually used in the commercially available antimicrobial products. The enhancement of the antimicrobial effectiveness was analyzed and discussed, assuming the synergy between photoreducing agent (red onion peel extract) and silver nitrate (AgNO3) in the initial gel solutions leading to the intensification of Ag nanoparticles production. Full article
(This article belongs to the Special Issue Advance in Composite Gels (2nd Edition))
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16 pages, 3195 KiB  
Article
Selenite Removal from Aqueous Solution Using Silica–Iron Oxide Nanocomposite Adsorbents
by Georgiana Mladin, Mihaela Ciopec, Adina Negrea, Narcis Duteanu, Petru Negrea, Paula Svera (m. Ianăşi) and Cătălin Ianăşi
Gels 2023, 9(6), 497; https://doi.org/10.3390/gels9060497 - 19 Jun 2023
Cited by 2 | Viewed by 998
Abstract
In recent years, during industrial development, the expanding discharge of harmful metallic ions from different industrial wastes (such as arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, or zinc) into different water bodies has caused serious concern, with one of the [...] Read more.
In recent years, during industrial development, the expanding discharge of harmful metallic ions from different industrial wastes (such as arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, or zinc) into different water bodies has caused serious concern, with one of the problematic elements being represented by selenium (Se) ions. Selenium represents an essential microelement for human life and plays a vital role in human metabolism. In the human body, this element acts as a powerful antioxidant, being able to reduce the risk of the development of some cancers. Selenium is distributed in the environment in the form of selenate (SeO42–) and selenite (SeO32–), which are the result of natural/anthropogenic activities. Experimental data proved that both forms present some toxicity. In this context, in the last decade, only several studies regarding selenium’s removal from aqueous solutions have been conducted. Therefore, in the present study, we aim to use the sol–gel synthesis method to prepare a nanocomposite adsorbent material starting from sodium fluoride, silica, and iron oxide matrices (SiO2/Fe(acac)3/NaF), and to further test it for selenite adsorption. After preparation, the adsorbent material was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The mechanism associated with the selenium adsorption process has been established based on kinetic, thermodynamic, and equilibrium studies. Pseudo second order is the kinetic model that best describes the obtained experimental data. Also, from the intraparticle diffusion study, it was observed that with increasing temperature the value of the diffusion constant, Kdiff, also increases. Sips isotherm was found to best describe the experimental data obtained, the maximum adsorption capacity being ~6.00 mg Se(IV) per g of adsorbent material. From a thermodynamic point of view, parameters such as ΔG0, ΔH0, and ΔS0 were evaluated, proving that the process studied is a physical one. Full article
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0 pages, 3999 KiB  
Article
Functionalized Collagen/Poly(ethylene glycol) Diacrylate Interpenetrating Network Hydrogel Enhances Beta Pancreatic Cell Sustenance
by Natalia Moreno-Castellanos, Elías Cuartas-Gómez and Oscar Vargas-Ceballos
Gels 2023, 9(6), 496; https://doi.org/10.3390/gels9060496 - 19 Jun 2023
Cited by 1 | Viewed by 1536
Abstract
Three-dimensional matrices are a new strategy used to tackle type I diabetes, a chronic metabolic disease characterized by the destruction of beta pancreatic cells. Type I collagen is an abundant extracellular matrix (ECM), a component that has been used to support cell growth. [...] Read more.
Three-dimensional matrices are a new strategy used to tackle type I diabetes, a chronic metabolic disease characterized by the destruction of beta pancreatic cells. Type I collagen is an abundant extracellular matrix (ECM), a component that has been used to support cell growth. However, pure collagen possesses some difficulties, including a low stiffness and strength and a high susceptibility to cell-mediated contraction. Therefore, we developed a collagen hydrogel with a poly (ethylene glycol) diacrylate (PEGDA) interpenetrating network (IPN), functionalized with vascular endothelial growth factor (VEGF) to mimic the pancreatic environment for the sustenance of beta pancreatic cells. We analyzed the physicochemical characteristics of the hydrogels and found that they were successfully synthesized. The mechanical behavior of the hydrogels improved with the addition of VEGF, and the swelling degree and the degradation were stable over time. In addition, it was found that 5 ng/mL VEGF-functionalized collagen/PEGDA IPN hydrogels sustained and enhanced the viability, proliferation, respiratory capacity, and functionality of beta pancreatic cells. Hence, this is a potential candidate for future preclinical evaluation, which may be favorable for diabetes treatment. Full article
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22 pages, 6199 KiB  
Article
Lincomycin HCl-Loaded Borneol-Based In Situ Gel for Periodontitis Treatment
by Napaphol Puyathorn, Nutdanai Lertsuphotvanit, Takron Chantadee, Wiwat Pichayakorn and Thawatchai Phaechamud
Gels 2023, 9(6), 495; https://doi.org/10.3390/gels9060495 - 19 Jun 2023
Cited by 2 | Viewed by 1393
Abstract
Solvent exchange-induced in situ forming gel (ISG) has emerged as a versatile drug delivery system, particularly for periodontal pocket applications. In this study, we developed lincomycin HCl-loaded ISGs using a 40% borneol-based matrix and N-methyl pyrrolidone (NMP) as a solvent. The physicochemical properties [...] Read more.
Solvent exchange-induced in situ forming gel (ISG) has emerged as a versatile drug delivery system, particularly for periodontal pocket applications. In this study, we developed lincomycin HCl-loaded ISGs using a 40% borneol-based matrix and N-methyl pyrrolidone (NMP) as a solvent. The physicochemical properties and antimicrobial activities of the ISGs were evaluated. The prepared ISGs exhibited low viscosity and reduced surface tension, allowing for easy injection and spreadability. Gel formation increased the contact angle on agarose gel, while higher lincomycin HCl content decreased water tolerance and facilitated phase separation. The drug-loading influenced solvent exchange and matrix formation, resulting in thinner and inhomogeneous borneol matrices with slower gel formation and lower gel hardness. The lincomycin HCl-loaded borneol-based ISGs demonstrated sustained drug release above the minimum inhibitory concentration (MIC) for 8 days, following Fickian diffusion and fitting well with Higuchi’s equation. These formulations exhibited dose-dependent inhibition of Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 8739, and Prophyromonas gingivalis ATCC 33277, and the release of NMP effectively inhibited Candida albicans ATCC 10231. Overall, the 7.5% lincomycin HCl-loaded 40% borneol-based ISGs hold promise as localized drug delivery systems for periodontitis treatment. Full article
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23 pages, 6922 KiB  
Article
Optimization of Potential Nanoemulgels for Boosting Transdermal Glimepiride Delivery and Upgrading Its Anti-Diabetic Activity
by Marwa H. Abdallah, Amr S. Abu Lila, Hanan M. El-Nahas and Tarek M. Ibrahim
Gels 2023, 9(6), 494; https://doi.org/10.3390/gels9060494 - 18 Jun 2023
Cited by 1 | Viewed by 1404
Abstract
Transdermal drug delivery has been widely adopted as a plausible alternative to the oral route of administration, especially for drugs with poor systemic bioavailability. The objective of this study was to design and validate a nanoemulsion (NE) system for transdermal administration of the [...] Read more.
Transdermal drug delivery has been widely adopted as a plausible alternative to the oral route of administration, especially for drugs with poor systemic bioavailability. The objective of this study was to design and validate a nanoemulsion (NE) system for transdermal administration of the oral hypoglycemic drug glimepiride (GM). The NEs were prepared using peppermint/bergamot oils as the oil phase and tween 80/transcutol P as the surfactant/co-surfactant mixture (Smix). The formulations were characterized using various parameters such as globule size, zeta potential, surface morphology, in vitro drug release, drug-excipient compatibility studies, and thermodynamic stability. The optimized NE formulation was then incorporated into different gel bases and examined for gel strength, pH, viscosity, and spreadability. The selected drug-loaded nanoemulgel formulation was then screened for ex vivo permeation, skin irritation, and in vivo pharmacokinetics. Characterization studies revealed the spherical shape of NE droplets with an average size of ~80 nm and a zeta potential of −11.8 mV, which indicated good electrokinetic stability of NE. In vitro release studies revealed enhanced drug release from the NE formulation compared to the plain drug. GM-loaded nanoemulgel showed a 7-fold increment in drug transdermal flux compared to plain drug gel. In addition, the GM-loaded nanoemulgel formulation did not elicit any signs of inflammation and/or irritation on the applied skin, suggesting its safety. Most importantly, the in vivo pharmacokinetic study emphasized the potential of nanoemulgel formulation to potentiate the systemic bioavailability of GM, as manifested by a 10-fold rise in the relative bioavailability compared to control gel. Collectively, transdermal NE-based GM gel might represent a promising alternative to oral therapy in the management of diabetes. Full article
(This article belongs to the Special Issue Gel Encapsulated Nanoparticles)
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16 pages, 4548 KiB  
Article
Comparative Electrokinetic Study of Alginate-Coated Colloidal Particles
by Viktoria Milkova
Gels 2023, 9(6), 493; https://doi.org/10.3390/gels9060493 - 16 Jun 2023
Cited by 1 | Viewed by 1105
Abstract
Alginates are a family of natural polysaccharides with promising potential in biomedical applications and tissue regeneration. The design of versatile alginate-based structures or hydrogels and their stability and functionality depend on the polymer’s physicochemical characteristics. The main features of alginate chains that determine [...] Read more.
Alginates are a family of natural polysaccharides with promising potential in biomedical applications and tissue regeneration. The design of versatile alginate-based structures or hydrogels and their stability and functionality depend on the polymer’s physicochemical characteristics. The main features of alginate chains that determine their bioactive properties are the molar ratio of mannuronic and glucuronic residues (M/G ratio) and their distribution along the polymer chain (MM-, GG-, and MG blocks). The present study is focused on investigating the influence of the physicochemical characteristics of alginate (sodium salt) on the electrical properties and stability of the dispersion of polymer-coated colloidal particles. Ultrapure and well-characterized biomedical-grade alginate samples were used in the investigation. The dynamics of counterion charge near the vicinity of adsorbed polyion is studied via electrokinetic spectroscopy. The results show that the experimental values of the frequency of relaxation of the electro-optical effect are higher compared to the theoretical ones. Therefore, it was supposed that polarization of the condensed Na+ counterions occurs at specific distances according to the molecular structure (G-, M-, or MG-blocks). In the presence of Ca2+, the electro-optical behavior of the particles with adsorbed alginate molecules almost does not depend on the polymer characteristics but was affected by the presence of divalent ions in the polymer layer. Full article
(This article belongs to the Special Issue Alginate-Based Gels: Preparation, Characterization and Application)
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13 pages, 2290 KiB  
Article
Hollow Particles Obtained by Prilling and Supercritical Drying as a Potential Conformable Dressing for Chronic Wounds
by Maria Rosaria Sellitto, Chiara Amante, Rita Patrizia Aquino, Paola Russo, Rosalía Rodríguez-Dorado, Monica Neagu, Carlos A. García-González, Renata Adami and Pasquale Del Gaudio
Gels 2023, 9(6), 492; https://doi.org/10.3390/gels9060492 - 16 Jun 2023
Cited by 3 | Viewed by 1222
Abstract
The production of aerogels for different applications has been widely known, but the use of polysaccharide-based aerogels for pharmaceutical applications, specifically as drug carriers for wound healing, is being recently explored. The main focus of this work is the production and characterization of [...] Read more.
The production of aerogels for different applications has been widely known, but the use of polysaccharide-based aerogels for pharmaceutical applications, specifically as drug carriers for wound healing, is being recently explored. The main focus of this work is the production and characterization of drug-loaded aerogel capsules through prilling in tandem with supercritical extraction. In particular, drug-loaded particles were produced by a recently developed inverse gelation method through prilling in a coaxial configuration. Particles were loaded with ketoprofen lysinate, which was used as a model drug. The core-shell particles manufactured by prilling were subjected to a supercritical drying process with CO2 that led to capsules formed by a wide hollow cavity and a tunable thin aerogel layer (40 μm) made of alginate, which presented good textural properties in terms of porosity (89.9% and 95.3%) and a surface area up to 417.0 m2/g. Such properties allowed the hollow aerogel particles to absorb a high amount of wound fluid moving very quickly (less than 30 s) into a conformable hydrogel in the wound cavity, prolonging drug release (till 72 h) due to the in situ formed hydrogel that acted as a barrier to drug diffusion. Full article
(This article belongs to the Special Issue Preparation, Properties and Applications of Functional Hydrogels)
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21 pages, 2195 KiB  
Article
Propranolol-Loaded Limonene-Based Microemulsion Thermo-Responsive Mucoadhesive Nasal Nanogel: Design, In Vitro Assessment, Ex Vivo Permeation, and Brain Biodistribution
by Kawthar K. Abla, Souraya Domiati, Rania El Majzoub and Mohammed M. Mehanna
Gels 2023, 9(6), 491; https://doi.org/10.3390/gels9060491 - 15 Jun 2023
Cited by 6 | Viewed by 1739
Abstract
Propranolol is the first-line drug for managing migraine attacks. D-limonene is a citrus oil known for its neuroprotective mechanism. Thus, the current work aims to design a thermo-responsive intranasal limonene-based microemulsion mucoadhesive nanogel to improve propranolol efficacy. Microemulsion was fabricated using limonene and [...] Read more.
Propranolol is the first-line drug for managing migraine attacks. D-limonene is a citrus oil known for its neuroprotective mechanism. Thus, the current work aims to design a thermo-responsive intranasal limonene-based microemulsion mucoadhesive nanogel to improve propranolol efficacy. Microemulsion was fabricated using limonene and Gelucire® as the oily phase, Labrasol®, Labrafil®, and deionized water as the aqueous phase, and was characterized regarding its physicochemical features. The microemulsion was loaded in thermo-responsive nanogel and evaluated regarding its physical and chemical properties, in vitro release, and ex vivo permeability through sheep nasal tissues. Its safety profile was assessed via histopathological examination, and its capability to deliver propranolol effectively to rats’ brains was examined using brain biodistribution analysis. Limonene-based microemulsion was of 133.7 ± 0.513 nm diametric size with unimodal size distribution and spheroidal shape. The nanogel showed ideal characteristics with good mucoadhesive properties and in vitro controlled release with 1.43-fold enhancement in ex vivo nasal permeability compared with the control gel. Furthermore, it displayed a safe profile as elucidated by the nasal histopathological features. The nanogel was able to improve propranolol brain availability with Cmax 970.3 ± 43.94 ng/g significantly higher than the control group (277.7 ± 29.71 ng/g) and with 382.4 % relative central availability, which confirms its potential for migraine management. Full article
(This article belongs to the Special Issue Designing Nanogels for Drug Delivery Systems)
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15 pages, 6272 KiB  
Article
Anticorrosion and Antimicrobial Evaluation of Sol-Gel Hybrid Coatings Containing Clitoria ternatea Modified Clay
by Milad Sheydaei, Milad Edraki and Seyyed Mehdi Radeghi Mehrjou
Gels 2023, 9(6), 490; https://doi.org/10.3390/gels9060490 - 14 Jun 2023
Cited by 2 | Viewed by 1574
Abstract
In this study, Clitoria ternatea (CT) was incorporated into the structure of sodium montmorillonite (Na+-MMT), then these new nanoparticles (CT-MMT) were added to sol-gel-based hybrid silanol coatings (SGC). The results of the CT-MMT investigation using Fourier transform infrared spectroscopy (FTIR), X-ray [...] Read more.
In this study, Clitoria ternatea (CT) was incorporated into the structure of sodium montmorillonite (Na+-MMT), then these new nanoparticles (CT-MMT) were added to sol-gel-based hybrid silanol coatings (SGC). The results of the CT-MMT investigation using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM) confirmed the presence of CT in the structure. The results of polarization and electrochemical impedance spectroscopy (EIS) tests showed that the presence of CT-MMT in the matrix improves corrosion resistance. The EIS results showed that the coating resistance (Rf) of the sample containing 3 wt.% CT-MMT after immersion was 687 Ω·cm2, while this value was 218 Ω·cm2 for pure coating. CT and MMT compounds improve corrosion resistance by blocking anodic and cathodic regions, respectively. Additionally, the presence of CT in the structure created antimicrobial properties. CT contains phenolic compounds that have the ability to suppress by membrane perturbation, reduction of host ligands adhesion, and neutralizing bacterial toxins. Therefore, CT-MMT showed inhibitory effects and killing of Staphylococcus aureus (gram-positive bacteria) and Salmonella paratyphi-A serotype (gram-negative bacteria), and also improved corrosion resistance. Full article
(This article belongs to the Special Issue Antibacterial Gels)
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11 pages, 2925 KiB  
Article
Study on Water-Soluble Phenolic Resin Gels for High-Temperature and High-Salinity Oil Reservoir
by Yunling Ran, Guicai Zhang, Ping Jiang and Haihua Pei
Gels 2023, 9(6), 489; https://doi.org/10.3390/gels9060489 - 14 Jun 2023
Cited by 5 | Viewed by 1288
Abstract
High water cut of produced fluid is one of the most common problems in reservoir development. At present, injecting plugging agents and other profile control and water plugging technologies are the most widely used solutions. With the development of deep oil and gas [...] Read more.
High water cut of produced fluid is one of the most common problems in reservoir development. At present, injecting plugging agents and other profile control and water plugging technologies are the most widely used solutions. With the development of deep oil and gas resources, high-temperature and high-salinity (HTHS) reservoirs are becoming increasingly common. Conventional polymers are prone to hydrolysis and thermal degradation under HTHS conditions, making polymer flooding or polymer-based gels less effective. Phenol–aldehyde crosslinking agent gels can be applied to different reservoirs with a wide range of salinity, but there exist the disadvantage of high cost of gelants. The cost of water-soluble phenolic resin gels is low. Based on the research of former scientists, copolymers consisting of acrylamide (AM) and 2-Acrylamido-2-Methylpropanesulfonic acid (AMPS) and modified water-soluble phenolic resin were used to prepare gels in the paper. The experimental results show that the gelant with 1.0 wt% AM-AMPS copolymer (AMPS content is 47%), 1.0 wt% modified water-soluble phenolic resin and 0.4 wt% thiourea has gelation time of 7.5 h, storage modulus of 18 Pa and no syneresis after aging for 90 days at 105 °C in simulated Tahe water of 22 × 104 mg/L salinity. By comprehensively comparing the effectiveness of the gels prepared by a kind of phenolic aldehyde composite crosslinking agent and modified water-soluble phenolic resin, it is found that the gel constructed by the modified water-soluble phenolic resin not only reduces costs, but also has shorter gelation time and higher gel strength. The oil displacement experiment with a visual glass plate model proves that the forming gel has good plugging ability and thus improves the sweep efficiency. The research expands the application range of water-soluble phenolic resin gels, which has an important implication for profile control and water plugging in the HTHS reservoirs. Full article
(This article belongs to the Special Issue Gels for Oil and Gas Industry Applications (2nd Edition))
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8 pages, 10072 KiB  
Communication
Synthesis and Investigation of Novel Optical Active SiO2 Glasses with Entrapped YAG:Ce Synthesized via Sol–Gel Method
by Monika Skruodiene, Meldra Kemere, Greta Inkrataite, Madara Leimane, Rimantas Ramanauskas, Ramunas Skaudzius and Anatolijs Sarakovskis
Gels 2023, 9(6), 488; https://doi.org/10.3390/gels9060488 - 13 Jun 2023
Viewed by 1155
Abstract
We present a crack-free optically active SiO2 glass-composite material containing YAG:Ce synthesized via a modified sol–gel technique. A glass-composite material consisting of yttrium aluminum garnet doped with Ce3+ (YAG:Ce) was entrapped into a SiO2 xerogel. This composite material was prepared [...] Read more.
We present a crack-free optically active SiO2 glass-composite material containing YAG:Ce synthesized via a modified sol–gel technique. A glass-composite material consisting of yttrium aluminum garnet doped with Ce3+ (YAG:Ce) was entrapped into a SiO2 xerogel. This composite material was prepared using a sol–gel technique with modified gelation and a drying process to obtain crack-free optically active SiO2 glass. The concentration of the YAG:Ce was from 0.5 to 2.0 wt%. All synthesized samples were characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, confirming their exceptional quality and structural integrity. The luminescence properties of the obtained materials were studied. Overall, the prepared samples’ excellent structural and optical quality makes them great candidates for further investigation, or even potential practical application. Furthermore, boron-doped YAG:Ce glass was synthesized for the first time. Full article
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12 pages, 581 KiB  
Article
Determination of Physicochemical, Textural, and Sensory Properties of Date-Based Sports Energy Gel
by Syahrul Anis Hazwani Mohd Baroyi, Yus Aniza Yusof, Nashratul Shera Mohamad Ghazali, Alhussein M. Al-Awaadh, Kazunori Kadota, Shuhaimi Mustafa, Hazizi Abu Saad, Nor Nadiah Abdul Karim Shah and Mohammad Fikry
Gels 2023, 9(6), 487; https://doi.org/10.3390/gels9060487 - 13 Jun 2023
Viewed by 1763
Abstract
Applying energy supplements in gel form may circumvent gastric discomfort and thus it is a practical alternative. The main objective of this investigation was to develop date-based sports energy gels consisting of highly nutritious ingredients such as black seed (Nigella sativa L.) [...] Read more.
Applying energy supplements in gel form may circumvent gastric discomfort and thus it is a practical alternative. The main objective of this investigation was to develop date-based sports energy gels consisting of highly nutritious ingredients such as black seed (Nigella sativa L.) extract and honey. Three date cultivars (Sukkary, Medjool, and Safawi) were used and characterized for their physical and mechanical properties. The sports energy gels were prepared with addition of xanthan gum (0.5% w/w) as the gelling agent. The newly developed date-based sports energy gels were then analysed for proximate composition, pH level, colour, viscosity, and texture profile analysis (TPA). A sensory test was also conducted with 10 panellists who analysed the appearance, texture, odour, sweetness, and overall acceptability of the gel using a hedonic scale. The results showed that different types of date cultivars affect the physical and mechanical properties of the new developed gels. The outputs of the sensory evaluation revealed that the date-based sports energy gel prepared from Medjool received the highest mean score, followed closely by those prepared from Safawi and Sukkary, indicating that, overall, all three cultivars are acceptable to consumers, but the date-based sports energy gel prepared from Medjool is the most preferred one. Full article
(This article belongs to the Special Issue Women’s Special Issue Series: Gels)
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15 pages, 4523 KiB  
Article
Nanocomposite Hydrogels with Polymer Grafted Silica Nanoparticles, Using Glucose Oxidase
by Ali A. Mohammed, Siwei Li, Tian Sang, Julian R. Jones and Alessandra Pinna
Gels 2023, 9(6), 486; https://doi.org/10.3390/gels9060486 - 13 Jun 2023
Cited by 1 | Viewed by 1600
Abstract
Nanocomposite hydrogels offer remarkable potential for applications in bone tissue engineering. They are synthesized through the chemical or physical crosslinking of polymers and nanomaterials, allowing for the enhancement of their behaviour by modifying the properties and compositions of the nanomaterials involved. However, their [...] Read more.
Nanocomposite hydrogels offer remarkable potential for applications in bone tissue engineering. They are synthesized through the chemical or physical crosslinking of polymers and nanomaterials, allowing for the enhancement of their behaviour by modifying the properties and compositions of the nanomaterials involved. However, their mechanical properties require further enhancement to meet the demands of bone tissue engineering. Here, we present an approach to improve the mechanical properties of nanocomposite hydrogels by incorporating polymer grafted silica nanoparticles into a double network inspired hydrogel (gSNP Gels). The gSNP Gels were synthesised via a graft polymerization process using a redox initiator. gSNP Gels were formed by grafting 2-acrylamido-2-methylpropanesulfonic acid (AMPS) as the first network gel followed by a sequential second network acrylamide (AAm) onto amine functionalized silica nanoparticles (ASNPs). We utilized glucose oxidase (GOx) to create an oxygen-free atmosphere during polymerization, resulting in higher polymer conversion compared to argon degassing. The gSNP Gels showed excellent compressive strengths of 13.9 ± 5.5 MPa, a strain of 69.6 ± 6.4%, and a water content of 63.4% ± 1.8. The synthesis technique demonstrates a promising approach to enhance the mechanical properties of hydrogels, which can have significant implications for bone tissue engineering and other soft tissue applications. Full article
(This article belongs to the Special Issue Hydrogels for Bone Regeneration)
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16 pages, 2603 KiB  
Article
Rheological Characteristics of Soluble Cress Seed Mucilage and β-Lactoglobulin Complexes with Salts Addition: Rheological Evidence of Structural Rearrangement
by Afsaneh Taheri, Mahdi Kashaninejad, Ali Mohammad Tamaddon, Juan Du and Seid Mahdi Jafari
Gels 2023, 9(6), 485; https://doi.org/10.3390/gels9060485 - 13 Jun 2023
Cited by 2 | Viewed by 1491
Abstract
Functional, physicochemical, and rheological properties of protein–polysaccharide complexes are remarkably under the influence of the quality of solvent or cosolute in a food system. Here, a comprehensive description of the rheological properties and microstructural peculiarities of cress seed mucilage (CSM)-β-lactoglobulin (Blg) complexes are [...] Read more.
Functional, physicochemical, and rheological properties of protein–polysaccharide complexes are remarkably under the influence of the quality of solvent or cosolute in a food system. Here, a comprehensive description of the rheological properties and microstructural peculiarities of cress seed mucilage (CSM)-β-lactoglobulin (Blg) complexes are discussed in the presence of CaCl2 (2–10 mM), (CSM–Blg–Ca), and NaCl (10–100 mM) (CSM–Blg–Na). Our results on steady-flow and oscillatory measurements indicated that shear thinning properties can be fitted well by the Herschel–Bulkley model and by the formation of highly interconnected gel structures in the complexes, respectively. Analyzing the rheological and structural features simultaneously led to an understanding that formations of extra junctions and the rearrangement of the particles in the CSM–Blg–Ca could enhance elasticity and viscosity, as compared with the effect of CSM–Blg complex without salts. NaCl reduced the viscosity and dynamic rheological properties and intrinsic viscosity through the salt screening effect and dissociation of structure. Moreover, the compatibility and homogeneity of complexes were approved by dynamic rheometry based on the Cole–Cole plot supported by intrinsic viscosity and molecular parameters such as stiffness. The results outlined the importance of rheological properties as criteria for investigations that determine the strength of interaction while facilitating the fabrication of new structures in salt-containing foods that incorporate protein–polysaccharide complexes. Full article
(This article belongs to the Special Issue Advances in Polymer Rheology)
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10 pages, 3741 KiB  
Article
Preparation and Characterization of Porous Cellulose Acetate Nanofiber Hydrogels
by Lijie Jiang, Xingyu Huang, Chaochao Tian, Yidan Zhong, Ming Yan, Chen Miao, Ting Wu and Xiaofan Zhou
Gels 2023, 9(6), 484; https://doi.org/10.3390/gels9060484 - 13 Jun 2023
Cited by 7 | Viewed by 2477
Abstract
The currently reported methods for preparing cellulose acetate hydrogels use chemical reagents as cross-linking agents, and the prepared ones are non-porous structured cellulose acetate hydrogels. Nonporous cellulose acetate hydrogels limit the range of applications, such as limiting cell attachment and nutrient delivery in [...] Read more.
The currently reported methods for preparing cellulose acetate hydrogels use chemical reagents as cross-linking agents, and the prepared ones are non-porous structured cellulose acetate hydrogels. Nonporous cellulose acetate hydrogels limit the range of applications, such as limiting cell attachment and nutrient delivery in tissue engineering. This research creatively proposed a facile method to prepare cellulose acetate hydrogels with porous structures. Water was added to the cellulose acetate–acetone solution as an anti-solvent to induce the phase separation of the cellulose acetate–acetone solution to obtain a physical gel with a network structure, where the cellulose acetate molecules undergo re-arrangement during the replacement of acetone by water to obtain hydrogels. The SEM and BET test results showed that the hydrogels are relatively porous. The maximum pore size of the cellulose acetate hydrogel is 380 nm, and the specific surface area reaches 62 m2/g. The porosity of the hydrogel is significantly higher than that of the cellulose acetate hydrogel reported in the previous literature. The XRD results show that the nanofibrous morphology of cellulose acetate hydrogels is caused by the deacetylation reaction of cellulose acetate. Full article
(This article belongs to the Special Issue Advances in Cellulose-Based Hydrogels (2nd Edition))
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14 pages, 3008 KiB  
Article
Evaluation of Propolis Hydrogel for the Treatment of Dentinal Sensitivity: A Clinical Study
by Saad Mohammed AlQahtani, Raghavendra Reddy Nagate, Manae Musa Musleh Al-Ahmari, Mohammad Al. Magbol, Shankar T. Gokhale, Shreyas Tikare and Saurabh Chaturvedi
Gels 2023, 9(6), 483; https://doi.org/10.3390/gels9060483 - 12 Jun 2023
Cited by 1 | Viewed by 1597
Abstract
Background: Propolis is a natural resinous substance collected by honeybees, chiefly from buds and the leaves, branches, and bark of trees. Its role as a wound-healing gel has been studied, but the use of a propolis hydrogel in the treatment of dentinal hypersensitivity [...] Read more.
Background: Propolis is a natural resinous substance collected by honeybees, chiefly from buds and the leaves, branches, and bark of trees. Its role as a wound-healing gel has been studied, but the use of a propolis hydrogel in the treatment of dentinal hypersensitivity has not been evaluated. Dentin hypersensitivity (DH) is commonly treated via iontophoresis using fluoridated desensitizers. The aim of the present study was to compare and evaluate the effects of a 10% propolis hydrogel, 2% sodium fluoride (NaF), and 1.23% acidulated phosphate fluoride (APF) when used in conjunction with iontophoresis for the treatment of cervical dentin hypersensitivity (DH). Methods: Systemically healthy patients complaining of DH were selected for this single-centre, parallel, double-blind randomized clinical trial. Three substances were selected as desensitizers for study in the present trial: a 10% propolis hydrogel, 2% sodium fluoride, and 1.23% acidulated phosphate fluoride, all in conjunction with iontophoresis. Any decrease in DH following the application of specific stimuli was assessed at baseline, before and after application, on the 14th day following use, and on the 28th day following the intervention. Results: Intra-group comparisons show diminished values of DH at maximum post-op follow-up intervals which were significantly trimmed down from the baseline (p < 0.05). The 2% NaF demonstrated a significant reduction in DH over 1.23% APF and the 10% propolis hydrogel (p < 0.05). However, there was no statistically significant difference in the mean difference between the APF and propolis hydrogel groups assessed via tactile, cold, and air tests (p > 0.05). Conclusion: All three desensitizers have proved to be useful when used in conjugation with iontophoresis. Within the limitations of this study, a 10% propolis hydrogel can be used as a naturally occurring alternative to commercially available fluoridated desensitizers. Full article
(This article belongs to the Special Issue Functional Gel Materials and Applications)
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27 pages, 3757 KiB  
Review
3D Bioprinting as a Powerful Technique for Recreating the Tumor Microenvironment
by Ilaria Parodi, Donatella Di Lisa, Laura Pastorino, Silvia Scaglione and Marco Massimo Fato
Gels 2023, 9(6), 482; https://doi.org/10.3390/gels9060482 - 12 Jun 2023
Cited by 5 | Viewed by 2468
Abstract
In vitro three-dimensional models aim to reduce and replace animal testing and establish new tools for oncology research and the development and testing of new anticancer therapies. Among the various techniques to produce more complex and realistic cancer models is bioprinting, which allows [...] Read more.
In vitro three-dimensional models aim to reduce and replace animal testing and establish new tools for oncology research and the development and testing of new anticancer therapies. Among the various techniques to produce more complex and realistic cancer models is bioprinting, which allows the realization of spatially controlled hydrogel-based scaffolds, easily incorporating different types of cells in order to recreate the crosstalk between cancer and stromal components. Bioprinting exhibits other advantages, such as the production of large constructs, the repeatability and high resolution of the process, as well as the possibility of vascularization of the models through different approaches. Moreover, bioprinting allows the incorporation of multiple biomaterials and the creation of gradient structures to mimic the heterogeneity of the tumor microenvironment. The aim of this review is to report the main strategies and biomaterials used in cancer bioprinting. Moreover, the review discusses several bioprinted models of the most diffused and/or malignant tumors, highlighting the importance of this technique in establishing reliable biomimetic tissues aimed at improving disease biology understanding and high-throughput drug screening. Full article
(This article belongs to the Special Issue Cancer Cell Biology in Biological Hydrogel)
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11 pages, 1937 KiB  
Article
Modulating the Viscoelastic Properties of Covalently Crosslinked Protein Hydrogels
by Rossana Boni and Lynne Regan
Gels 2023, 9(6), 481; https://doi.org/10.3390/gels9060481 - 12 Jun 2023
Cited by 1 | Viewed by 1234
Abstract
Protein engineering allows for the programming of specific building blocks to form functional and novel materials with customisable physical properties suitable for tailored engineering applications. We have successfully designed and programmed engineered proteins to form covalent molecular networks with defined physical characteristics. Our [...] Read more.
Protein engineering allows for the programming of specific building blocks to form functional and novel materials with customisable physical properties suitable for tailored engineering applications. We have successfully designed and programmed engineered proteins to form covalent molecular networks with defined physical characteristics. Our hydrogel design incorporates the SpyTag (ST) peptide and SpyCatcher (SC) protein that spontaneously form covalent crosslinks upon mixing. This genetically encodable chemistry allowed us to easily incorporate two stiff and rod-like recombinant proteins in the hydrogels and modulate the resulting viscoelastic properties. We demonstrated how differences in the composition of the microscopic building blocks change the macroscopic viscoelastic properties of the hydrogels. We specifically investigated how the identity of the protein pairs, the molar ratio of ST:SC, and the concentration of the proteins influence the viscoelastic response of the hydrogels. By showing tuneable changes in protein hydrogel rheology, we increased the capabilities of synthetic biology to create novel materials, allowing engineering biology to interface with soft matter, tissue engineering, and material science. Full article
(This article belongs to the Special Issue Advances in Biomedical Hydrogels)
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20 pages, 9651 KiB  
Article
Synthesis and Performance Evaluation of Alginate-Coated Temperature-Sensitive Polymer Gel Microspheres
by Zhaozheng Song, Junhang Hu, Ping Liu and Yili Sun
Gels 2023, 9(6), 480; https://doi.org/10.3390/gels9060480 - 12 Jun 2023
Cited by 2 | Viewed by 1252
Abstract
With the long-term water-flooding development of the reservoir, the non-homogeneity of the formation is increasing and the reservoir environment is deteriorating; the microspheres used for deep plugging have shown disadvantages, such as poor temperature and salt resistance and faster expansion. In this study, [...] Read more.
With the long-term water-flooding development of the reservoir, the non-homogeneity of the formation is increasing and the reservoir environment is deteriorating; the microspheres used for deep plugging have shown disadvantages, such as poor temperature and salt resistance and faster expansion. In this study, a polymeric microsphere was synthesized that is resistant to high temperature and high salt and can achieve slow expansion and slow release for deep migration. P(AA-AM-SA)@TiO2 polymer gel/inorganic nanoparticle microspheres were prepared by reversed-phase microemulsion polymerization using acrylamide (AM) and acrylic acid (AA) as monomers, 3-methacryloxypropyltrimethoxysilane (KH-570)-modified TiO2 as the inorganic core, and sodium alginate (SA) as a temperature-sensitive coating material. Through single-factor analysis of the polymerization process, the optimal synthesis conditions were determined as follows: the oil(Cyclohexane)-water volume ratio was 8:5, the emulsifier mass ratio (Span-80:Tween-80) was 3:1 (10 wt% of the total system amount), the stirring speed was 400 r/min, the reaction temperature was 60 °C, and the initiator (ammonium persulfate and sodium bisulfite) dosage was 0.6 wt%. The size of the dried polymer gel/inorganic nanoparticle microspheres prepared by the optimized synthesis conditions was 10~40 μm with uniform particle size. The observation of P(AA-AM-SA)@TiO2 microspheres reveals that the Ca elements are uniformly distributed on the microspheres, and FT-IR indicates that the synthesized product is the target product. TGA shows that the polymer gel/inorganic nanoparticle microspheres have better thermal stability after the addition of TiO2, with a larger mass loss at 390 °C, which can adapt to the medium-high permeability reservoir environment. The thermal and aqueous salinity resistance of the P(AA-AM-SA)@TiO2 microspheres was tested, and the cracking temperature of P(AA-AM-SA)@TiO2 microsphere temperature-sensitive material was 90 °C. It still has favorable water absorption and swelling performance under the sodium salt concentration of 2.5 × 104 mg/L and can tolerate calcium salt up to 2.0 × 104 mg/L. Plugging Performance Test results show that the microspheres have good injectability between the permeability of 1.23 and 2.35 μm2 and good plugging effect near the permeability of 2.20 μm2. At high temperature and high salinity, P(AA-AM-SA)@TiO2 microspheres have a remarkable effect on profile control and water shutoff, the plugging rate reaches 95.3%, and the oil recovery rate is increased by 12.89% compared with water flooding, achieving the effect of slow swelling and slow release. Full article
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13 pages, 4458 KiB  
Article
Synthesis and Performance Evaluation of a Novel Nanoparticle Coupling Expanded Granule Plugging Agent
by Xuejiao Li, Qi Li, Meilong Fu, Li Li, Lingyang Su and Yingyang Wang
Gels 2023, 9(6), 479; https://doi.org/10.3390/gels9060479 - 12 Jun 2023
Cited by 1 | Viewed by 1020
Abstract
This study focuses on the characteristics of fractured and vuggy high-temperature and high-salt reservoirs in the Tahe Oilfield. The Acrylamide/2-acrylamide-2-methylpropanesulfonic copolymer salt was selected as a polymer; the hydroquinone and hexamethylene tetramine was selected as the crosslinking agent with a ratio of 1:1; [...] Read more.
This study focuses on the characteristics of fractured and vuggy high-temperature and high-salt reservoirs in the Tahe Oilfield. The Acrylamide/2-acrylamide-2-methylpropanesulfonic copolymer salt was selected as a polymer; the hydroquinone and hexamethylene tetramine was selected as the crosslinking agent with a ratio of 1:1; the nanoparticle SiO2 was selected, and its dosage was optimized to 0.3%; Additionally, a novel nanoparticle coupling polymer gel was independently synthesized. The surface of the gel was a three-dimensional network structure, with grids arranged in pieces and interlaced with each other, and the structure was very stable. The SiO2 nanoparticles were attached to the gel skeleton, forming effective coupling and enhancing the strength of the gel skeleton. To solve the problem of complex gel preparation and transportation, the novel gel is compressed, pelletized, and dried into expanded particles through industrial granulation, and the disadvantage of the rapid expansion of expanded particles is optimized through physical film coating treatment. Finally, a novel nanoparticle coupling expanded granule plugging agent was developed. Evaluation of the performance of the novel nanoparticle coupling expanded granule plugging agent. With an increase in temperature and mineralization, the expansion multiplier of granules decreases; aged under high-temperature and high-salt conditions for 30 days, the expansion multiplier of granules can still reach 3.5 times, the toughness index is 1.61, and the long-term stability of the granules can be good; the water plugging rate of granules is 97.84%, which is superior to other widely used particle-based plugging agents. Full article
(This article belongs to the Special Issue Gels for Oil and Gas Industry Applications (2nd Edition))
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17 pages, 1855 KiB  
Article
Gelation and Orientation Dynamics Induced by Contact of Protein Solution with Transglutaminase Solution
by Kasumi Kakinoki, Ryuta Kurasawa, Yasuyuki Maki, Toshiaki Dobashi and Takao Yamamoto
Gels 2023, 9(6), 478; https://doi.org/10.3390/gels9060478 - 12 Jun 2023
Viewed by 957
Abstract
Gel growth induced by contact of polymer solutions with crosslinker solutions yields an emerging class of anisotropic materials with many potential applications. Here, we report the case of a study on the dynamics in forming anisotropic gels using this approach with an enzyme [...] Read more.
Gel growth induced by contact of polymer solutions with crosslinker solutions yields an emerging class of anisotropic materials with many potential applications. Here, we report the case of a study on the dynamics in forming anisotropic gels using this approach with an enzyme as a trigger of gelation and gelatin as the polymer. Unlike the previously studied cases of gelation, the isotropic gelation was followed by gel polymer orientation after a lag time. The isotropic gelation dynamics did not depend on concentrations of the polymer turning into gel and of the enzyme inducing gelation, whereas, for the anisotropic gelation, the square of the gel thickness was a linear function of the elapsed time, and the slope increased with polymer concentration. The gelation dynamics of the present system was explained by a combination of diffusion-limited gelation followed by free-energy-limited orientation of polymer molecules. Full article
(This article belongs to the Special Issue Shaping and Structuring of Polymer Gels)
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16 pages, 2776 KiB  
Article
Developing Biomimetic Hydrogels of the Arterial Wall as a Prothrombotic Substrate for In Vitro Human Thrombosis Models
by Jacob Ranjbar, Wanjiku Njoroge, Jonathan M. Gibbins, Paul Roach, Ying Yang and Alan G. S. Harper
Gels 2023, 9(6), 477; https://doi.org/10.3390/gels9060477 - 10 Jun 2023
Cited by 1 | Viewed by 1551
Abstract
Current in vitro thrombosis models utilise simplistic 2D surfaces coated with purified components of the subendothelial matrix. The lack of a realistic humanised model has led to greater study of thrombus formation in in vivo tests in animals. Here we aimed to develop [...] Read more.
Current in vitro thrombosis models utilise simplistic 2D surfaces coated with purified components of the subendothelial matrix. The lack of a realistic humanised model has led to greater study of thrombus formation in in vivo tests in animals. Here we aimed to develop 3D hydrogel-based replicas of the medial and adventitial layers of the human artery to produce a surface that can optimally support thrombus formation under physiological flow conditions. These tissue-engineered medial- (TEML) and adventitial-layer (TEAL) hydrogels were developed by culturing human coronary artery smooth muscle cells and human aortic adventitial fibroblasts within collagen hydrogels, both individually and in co-culture. Platelet aggregation upon these hydrogels was studied using a custom-made parallel flow chamber. When cultured in the presence of ascorbic acid, the medial-layer hydrogels were able to produce sufficient neo-collagen to support effective platelet aggregation under arterial flow conditions. Both TEML and TEAL hydrogels possessed measurable tissue factor activity and could trigger coagulation of platelet-poor plasma in a factor VII-dependent manner. Biomimetic hydrogel replicas of the subendothelial layers of the human artery are effective substrates for a humanised in vitro thrombosis model that could reduce animal experimentation by replacing current in vivo models. Full article
(This article belongs to the Special Issue Biomimetic Hydrogels)
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27 pages, 3213 KiB  
Article
Exploring the Impact of Alginate—PVA Ratio and the Addition of Bioactive Substances on the Performance of Hybrid Hydrogel Membranes as Potential Wound Dressings
by Diana Stan, Elena Codrici, Ana-Maria Enciu, Ewa Olewnik-Kruszkowska, Georgiana Gavril, Lavinia Liliana Ruta, Carmen Moldovan, Oana Brincoveanu, Lorena-Andreea Bocancia-Mateescu, Andreea-Cristina Mirica, Dana Stan and Cristiana Tanase
Gels 2023, 9(6), 476; https://doi.org/10.3390/gels9060476 - 9 Jun 2023
Cited by 2 | Viewed by 2150
Abstract
Healthcare professionals face an ongoing challenge in managing both acute and chronic wounds, given the potential impact on patients’ quality of life and the limited availability of expensive treatment options. Hydrogel wound dressings offer a promising solution for effective wound care due to [...] Read more.
Healthcare professionals face an ongoing challenge in managing both acute and chronic wounds, given the potential impact on patients’ quality of life and the limited availability of expensive treatment options. Hydrogel wound dressings offer a promising solution for effective wound care due to their affordability, ease of use, and ability to incorporate bioactive substances that enhance the wound healing process. Our study aimed to develop and evaluate hybrid hydrogel membranes enriched with bioactive components such as collagen and hyaluronic acid. We utilized both natural and synthetic polymers and employed a scalable, non-toxic, and environmentally friendly production process. We conducted extensive testing, including an in vitro assessment of moisture content, moisture uptake, swelling rate, gel fraction, biodegradation, water vapor transmission rate, protein denaturation, and protein adsorption. We evaluated the biocompatibility of the hydrogel membranes through cellular assays and performed instrumental tests using scanning electron microscopy and rheological analysis. Our findings demonstrate that the biohybrid hydrogel membranes exhibit cumulative properties with a favorable swelling ratio, optimal permeation properties, and good biocompatibility, all achieved with minimal concentrations of bioactive agents. Full article
(This article belongs to the Special Issue Engineering Hydrogel for Biomedical Applications)
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