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Gels, Volume 10, Issue 10 (October 2024) – 64 articles

Cover Story (view full-size image): Dehydrotripeptides containing a N-terminal lysine residue Nα,ε-bis-capped with either carboxybenzyl (Cbz) or 2-naphthylacetyl (2-Naph) aromatic moieties, the former an aspartic acid residue and the latter a C-terminal dehydrophenylalanine residue, respectively, were synthesized as diastereomeric mixtures (L,L,Z and L,D,Z). The diastereomeric dehydropeptide mixtures afforded exceptionally elastic self-healing hydrogels at remarkably low concentrations. The Cbz-capped dehydrotripeptide diastereomers undergo co-assembly into a fibrillar 3D network. The 2-Naph-capped diastereomers undergo self-sorting, originating a fibril network with embedded spheroidal nanostructures. A mechanical stimulus triggers the rearrangement of the spheroidal nanostructures into fibers. The properties, size, and aromaticity of the N-capping group directs the self-assembly fate of the individual diastereomers. View this paper
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29 pages, 11641 KB  
Article
Process Mapping of the Sol–Gel Transition in Acid-Initiated Sodium Silicate Solutions
by Marzieh Matinfar and John A. Nychka
Gels 2024, 10(10), 673; https://doi.org/10.3390/gels10100673 - 21 Oct 2024
Cited by 7 | Viewed by 3660
Abstract
Fabricating large-scale porous bioactive glass bone scaffolds presents significant challenges. This study aims to develop formable, in situ setting scaffolds with a practical gelation time of about 10 min by mixing 45S5 bioactive glass with sodium silicate (waterglass) and an acid initiator. The [...] Read more.
Fabricating large-scale porous bioactive glass bone scaffolds presents significant challenges. This study aims to develop formable, in situ setting scaffolds with a practical gelation time of about 10 min by mixing 45S5 bioactive glass with sodium silicate (waterglass) and an acid initiator. The effects of pH (2–11), waterglass concentration (15–50 wt.%), and acid initiator type (phosphoric or boric acid) were examined to optimize gelation kinetics and microstructure. A 10 min gelation time was achieved with boric acid and phosphoric acid at various pH levels by adjusting the waterglass concentration. Exponential and polynomial models were proposed to predict gelation times in basic and acidic environments, respectively. The optical properties of the gels were studied qualitatively and quantitatively, providing insights into gelation kinetics and structure. Acidic gels formed smaller particles in a dense network (pores < 550 nm) with higher light transmittance, while basic gels had larger aggregates (pores ~5 µm) and lower transmittance. As the waterglass concentration decreased, pore size and transmittance converged in both groups. The onset of gelation was detected around 8 min using the derivative of light transmittance. This work identifies the key factors controlling waterglass gelation and their impact on gel structure, enabling the tailored creation of formable, in situ setting bioactive glass bone scaffolds. Full article
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20 pages, 7024 KB  
Article
Dual-Action Gemcitabine Delivery: Chitosan–Magnetite–Zeolite Capsules for Targeted Cancer Therapy and Antibacterial Defense
by Yuly Andrea Guarín-González, Gerardo Cabello-Guzmán, José Reyes-Gasga, Yanko Moreno-Navarro, Luis Vergara-González, Antonia Martin-Martín, Rodrigo López-Muñoz, Galo Cárdenas-Triviño and Luis F. Barraza
Gels 2024, 10(10), 672; https://doi.org/10.3390/gels10100672 - 21 Oct 2024
Cited by 3 | Viewed by 1971
Abstract
Cancer and infectious diseases are two of the world’s major public health problems. Gemcitabine (GEM) is an effective chemotherapeutic agent against several types of cancer. In this study, we developed macrocapsules incorporating GEM into a chitosan matrix blended with magnetite and zeolite by [...] Read more.
Cancer and infectious diseases are two of the world’s major public health problems. Gemcitabine (GEM) is an effective chemotherapeutic agent against several types of cancer. In this study, we developed macrocapsules incorporating GEM into a chitosan matrix blended with magnetite and zeolite by ionic gelation. Physicochemical characterization was performed using HRTEM-ED, XRD, FESEM–EDS, FT-IR, TGA, encapsulation efficiency (%E.E.), and release profiles at pHs 7.4 and 5.0. Cell viability tests against A549 and H1299 cell lines, and microbiological properties against staphylococcal strains were performed. Our results revealed the successful production of hemispherical capsules with an average diameter of 1.22 mm, a rough surface, and characteristic FT-IR material interaction bands. The macrocapsules showed a high GEM encapsulation efficiency of over 86% and controlled release over 24 h. Cell viability assays revealed that similar cytotoxic effects to free GEM were achieved with a 45-fold lower GEM concentration, suggesting reduced dosing requirements and potentially fewer side effects. Additionally, the macrocapsules demonstrated potent antimicrobial activity, reducing Staphylococcus epidermidis growth by over 90%. These results highlight the macrocapsules dual role as a chemotherapeutic and antimicrobial agent, offering a promising strategy for treating lung cancer in patients at risk of infectious diseases or who are immunosuppressed. Full article
(This article belongs to the Special Issue Hydrogels, Microgels and Nanogels Emerging Platforms for Drug Delivery, Antibacterial Properties and Tissue Engineering)
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22 pages, 1407 KB  
Review
Emulsion Structural Remodeling in Milk and Its Gelling Products: A Review
by Dexing Yao, Le-Chang Sun, Ling-Jing Zhang, Yu-Lei Chen, Song Miao, Ming-Jie Cao and Duanquan Lin
Gels 2024, 10(10), 671; https://doi.org/10.3390/gels10100671 - 21 Oct 2024
Viewed by 5617
Abstract
The fat covered by fat globule membrane is scattered in a water phase rich in lactose and milky protein, forming the original emulsion structure of milk. In order to develop low-fat milk products with good performance or dairy products with nutritional reinforcement, the [...] Read more.
The fat covered by fat globule membrane is scattered in a water phase rich in lactose and milky protein, forming the original emulsion structure of milk. In order to develop low-fat milk products with good performance or dairy products with nutritional reinforcement, the original emulsion structure of milk can be restructured. According to the type of lipid and emulsion structure in milk, the remolded emulsion structure can be divided into three types: restructured single emulsion structure, mixed emulsion structure, and double emulsion structure. The restructured single emulsion structure refers to the introduction of another kind of lipid to skim milk, and the mixed emulsion structure refers to adding another type of oil or oil-in-water (O/W) emulsion to milk containing certain levels of milk fat, whose final emulsion structure is still O/W emulsion. In contrast, the double emulsion structure of milk is a more complicated structural remodeling method, which is usually performed by introducing W/O emulsion into skim milk (W2) to obtain milk containing (water-in-oil-in-water) W1/O/W2 emulsion structure in order to encapsulate more diverse nutrients. Causal statistical analysis was used in this review, based on previous studies on remodeling the emulsion structures in milk and its gelling products. In addition, some common processing technologies (including heat treatment, high-pressure treatment, homogenization, ultrasonic treatment, micro-fluidization, freezing and membrane emulsification) may also have a certain impact on the microstructure and properties of milk and its gelling products with four different emulsion structures. These processing technologies can change the size of the dispersed phase of milk, the composition and structure of the interfacial layer, and the composition and morphology of the aqueous phase substance, so as to regulate the shelf-life, stability, and sensory properties of the final milk products. This research on the restructuring of the emulsion structure of milk is not only a cutting-edge topic in the field of food science, but also a powerful driving force in promoting the transformation and upgrading of the dairy industry to achieve high-quality and multi-functional dairy products, in order to meet the diversified needs of consumers for health and taste. Full article
(This article belongs to the Special Issue Food Gels: Fabrication, Characterization, and Application)
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14 pages, 3751 KB  
Article
Microencapsulation Efficiency of Carboxymethylcellulose, Gelatin, Maltodextrin, and Acacia for Aroma Preservation in Jasmine Instant Tea
by Muneeba Naseer Chaudhary, Xiaolin Li, Siyue Yang, Damao Wang, Liyong Luo, Liang Zeng and Wei Luo
Gels 2024, 10(10), 670; https://doi.org/10.3390/gels10100670 - 21 Oct 2024
Cited by 5 | Viewed by 2705
Abstract
Enhancing the sensory appeal of jasmine instant tea, particularly its aroma, poses a significant challenge due to the loss of volatile organic compounds during conventional processing. This study introduces a novel approach to address this issue through the application of microencapsulation techniques, aimed [...] Read more.
Enhancing the sensory appeal of jasmine instant tea, particularly its aroma, poses a significant challenge due to the loss of volatile organic compounds during conventional processing. This study introduces a novel approach to address this issue through the application of microencapsulation techniques, aimed at preserving these key aromatic elements. Our investigation focused on the encapsulating agents gelatin, acacia gum, carboxymethylcellulose (CMC), and maltodextrin, chosen for their compatibility with the volatile organic compounds of tea. A statistical analysis was conducted on the analytical results through comprehensive analytical techniques like Principal Component Analysis (PCA), Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA), and Variable Importance in Projection (VIP) analysis for microcapsule characterization. The statistical analysis revealed gelatin to be a particularly effective encapsulating medium, preserving an aroma profile more akin to fresh tea. The statistical analysis confirmed the reliability of these findings, highlighting the potential of microencapsulation in refining the quality of jasmine instant tea products. The results of this research suggest that microencapsulation could be instrumental in improving the sensory quality and shelf life of instant tea products, offering new opportunities for product enhancement in the beverage industry. Full article
(This article belongs to the Special Issue Recent Developments in Food Gels (2nd Edition))
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18 pages, 3659 KB  
Article
pH-Responsive Alginate/Chitosan Gel Films: An Alternative for Removing Cadmium and Lead from Water
by Silvia Carolina Moreno-Rivas, María José Ibarra-Gutiérrez, Daniel Fernández-Quiroz, Armando Lucero-Acuña, Alexel J. Burgara-Estrella and Paul Zavala-Rivera
Gels 2024, 10(10), 669; https://doi.org/10.3390/gels10100669 - 19 Oct 2024
Cited by 6 | Viewed by 3513
Abstract
Biosorption, a non-expensive and easy method for removing potentially toxic metal ions from water, has been the subject of extensive research. In this context, this study introduces a novel approach using sodium alginate and chitosan, versatile biopolymers that have shown excellent results as [...] Read more.
Biosorption, a non-expensive and easy method for removing potentially toxic metal ions from water, has been the subject of extensive research. In this context, this study introduces a novel approach using sodium alginate and chitosan, versatile biopolymers that have shown excellent results as biosorbents. The challenge of maintaining high efficiencies and reuse is addressed by developing alginate/chitosan-based films. These films, prepared using solvent casting and crosslinking methods, form a hydrogel network. The alginate/chitosan-based films, obtained using the eco-friendly polyelectrolyte complex method, were characterized by FTIR, SEM, TGA, and DSC. The study of their swelling pH response, adsorption, and desorption behavior revealed promising results. The adsorption of Pb was significantly enhanced by the presence of both biopolymers (98%) in a shorter time (15 min) at pH = 6.5. The adsorption of both ions followed a pseudo-second-order kinetic and the Langmuir isotherm model. The desorption efficiencies for Cd and Pb were 98.8% and 77.6% after five adsorption/desorption cycles, respectively. In conclusion, the alginate/chitosan-based films present a highly effective and novel approach for removing Cd and Pb from water, with a promising potential for reuse, demonstrating their strong potential in potentially toxic metal removal. Full article
(This article belongs to the Special Issue Advances in Gel Films)
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22 pages, 5499 KB  
Article
Development of Polyvinyl Alcohol Hydrogels for Controlled Glucose Release in Biomedical Applications
by Rosa M. Quispe-Siccha, Osvaldo I. Medina-Sandoval, Abraham Estrada-Tinoco, Jorge A. Pedroza-Pérez, Adolfo Martínez-Tovar, Irma Olarte-Carrillo, Rafael Cerón-Maldonado, Arturo Reding-Bernal and Juan C. López-Alvarenga
Gels 2024, 10(10), 668; https://doi.org/10.3390/gels10100668 - 19 Oct 2024
Cited by 4 | Viewed by 2731
Abstract
Polyvinyl alcohol (PVA) hydrogels have a wide range of applications in the pharmaceutical and biomedicine fields due to their exceptional biophysical properties. The study focuses on preparing and characterizing capsule-shaped PVA hydrogels to enhance their biocompatibility and porosity for controlled glucose release and [...] Read more.
Polyvinyl alcohol (PVA) hydrogels have a wide range of applications in the pharmaceutical and biomedicine fields due to their exceptional biophysical properties. The study focuses on preparing and characterizing capsule-shaped PVA hydrogels to enhance their biocompatibility and porosity for controlled glucose release and cell proliferation. The hydrogels were prepared using different concentrations (Cs) and molecular weights (MWs) of PVA, with two different lengths, A (10 mm) and B (20 mm), to control glucose release over 60 min. The preparation process involved PVA gel preparation and PVA hydrogel formation. A total of 500 µL of glucose was injected into all dehydrated hydrogels in groups A and B. Glucose release was studied by immersing the hydrogels in saline at 37 °C with stirring at 500 rpm. The SUP-B15 cell line was grown in six A1 hydrogels for biocompatibility testing. The results indicate that all hydrogels remained stable at 37 °C without degrading. Those with a higher C and MW exhibited a denser and less porous structure, lower glucose storage capacity, and higher elongation at break. Significant differences in glucose release, diffusion speed, and flux were observed, which were more evident in A1 > A4, B1 > B4, and B1 > A1 over 60 min. A1 and B1 had higher values because their higher porosity distribution allowed glucose to diffuse more easily. B1, being larger, has more glucose due to its increased length. The cell growth response and viability at 48 h in contact with the hydrogels was similar to that of the control (4.5 × 105 cells/mL, 98.5% vs. 4.8 × 105 cells/mL, 99.7% viability), thus demonstrating biocompatibility. The hydrogels effectively released glucose over 60 min, with variations based on porosity, C, MW, and length, and demonstrated good biocompatibility with the cell line. Full article
(This article belongs to the Special Issue Hydrogelated Matrices: Structural, Functional and Applicative Aspects)
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16 pages, 6476 KB  
Article
Cross-Linked Polyimide Aerogels with Excellent Thermal and Mechanical Properties
by Haoran Qian, Zhiqi Li and Song He
Gels 2024, 10(10), 667; https://doi.org/10.3390/gels10100667 - 19 Oct 2024
Cited by 4 | Viewed by 2782
Abstract
With the increasing development of productivity, new materials that allow for the efficient use of energy are slowly becoming a sought-after goal, as well as a challenge that is currently being faced. For this reason, we have made aerogels as the target of [...] Read more.
With the increasing development of productivity, new materials that allow for the efficient use of energy are slowly becoming a sought-after goal, as well as a challenge that is currently being faced. For this reason, we have made aerogels as the target of our research and prepared different series (CLPI (1–5)) of cross-linked polyimide aerogels by mixing and cross-linking the heat-insulating cross-linking agent 1,3,5-tris(4-aminobenzylamino)benzene (TAB) with polyamic acid solution. We created a three-dimensional spatial organization by using vacuum freeze-drying and programmed high-temperature drying, then controlled the concentration of the polyamidate solution to investigate the concentration and TAB’s influence on aerogel-related properties. Among them, the shrinkage is reduced from 40% in CLPI-1 to 28% in CLPI-5, and it also shows excellent mechanical characteristics, the highest compression strength (CLPI-5) reaches 0.81 MPa and specific modulus reaches 41.95 KN m/Kg. In addition, adding TAB improves the aerogel thermal resistance, T5 in N2 from PI-2 519 °C to CLPI-2 556 °C. The three-dimensional network-type structure of the aerogel shows an excellent thermal insulation effect, where the thermal conductivity can be as low as 24.4 mWm−1 K−1. Compared with some protective materials, cross-linked polyimide aerogel presents better flame-retardant properties, greatly improving the scope of its application in the industrial protection. Full article
(This article belongs to the Section Gel Chemistry and Physics)
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30 pages, 9043 KB  
Article
Bone Spheroid Development Under Flow Conditions with Mesenchymal Stem Cells and Human Umbilical Vein Endothelial Cells in a 3D Porous Hydrogel Supplemented with Hydroxyapatite
by Soukaina El Hajj, Martial Bankoué Ntaté, Cyril Breton, Robin Siadous, Rachida Aid, Magali Dupuy, Didier Letourneur, Joëlle Amédée, Hervé Duval and Bertrand David
Gels 2024, 10(10), 666; https://doi.org/10.3390/gels10100666 - 18 Oct 2024
Cited by 4 | Viewed by 3194
Abstract
Understanding the niche interactions between blood and bone through the in vitro co-culture of osteo-competent cells and endothelial cells is a key factor in unraveling therapeutic potentials in bone regeneration. This can be additionally supported by employing numerical simulation techniques to assess local [...] Read more.
Understanding the niche interactions between blood and bone through the in vitro co-culture of osteo-competent cells and endothelial cells is a key factor in unraveling therapeutic potentials in bone regeneration. This can be additionally supported by employing numerical simulation techniques to assess local physical factors, such as oxygen concentration, and mechanical stimuli, such as shear stress, that can mediate cellular communication. In this study, we developed a Mesenchymal Stem Cell line (MSC) and a Human Umbilical Vein Endothelial Cell line (HUVEC), which were co-cultured under flow conditions in a three-dimensional, porous, natural pullulan/dextran scaffold that was supplemented with hydroxyapatite crystals that allowed for the spontaneous formation of spheroids. After 2 weeks, their viability was higher under the dynamic conditions (>94%) than the static conditions (<75%), with dead cells central in the spheroids. Mineralization and collagen IV production increased under the dynamic conditions, correlating with osteogenesis and vasculogenesis. The endothelial cells clustered at the spheroidal core by day 7. Proliferation doubled in the dynamic conditions, especially at the scaffold peripheries. Lattice Boltzmann simulations showed negligible wall shear stress in the hydrogel pores but highlighted highly oxygenated zones coinciding with cell proliferation. A strong oxygen gradient likely influenced endothelial migration and cell distribution. Hypoxia was minimal, explaining high viability and spheroid maturation in the dynamic conditions. Full article
(This article belongs to the Special Issue Hydrogel-Based Scaffolds with a Focus on Medical Use (2nd Edition))
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21 pages, 4324 KB  
Article
Development of Personalised Immediate-Release Gel-Based Formulations Using Semi-Solid Extrusion
by Morenikeji Aina, Fabien Baillon, Romain Sescousse, Noelia M. Sanchez-Ballester, Sylvie Begu, Ian Soulairol and Martial Sauceau
Gels 2024, 10(10), 665; https://doi.org/10.3390/gels10100665 - 17 Oct 2024
Cited by 6 | Viewed by 2052
Abstract
Precision in dosing is crucial for optimizing therapeutic outcomes and preventing overdosing, especially in preterm infants. Traditional manual adjustments to adapt the dose often lead to inaccuracies, contamination risks, and reduced precision. To overcome these challenges, semi-solid extrusion 3D printing was used to [...] Read more.
Precision in dosing is crucial for optimizing therapeutic outcomes and preventing overdosing, especially in preterm infants. Traditional manual adjustments to adapt the dose often lead to inaccuracies, contamination risks, and reduced precision. To overcome these challenges, semi-solid extrusion 3D printing was used to create personalised gel-based caffeine dosage forms. The hydrogels, made from agar and hydroxypropyl methylcellulose, demonstrated excellent rheological properties, ensuring uniform extrusion and accurate shape retention during and after printing. This gel formulation allowed for precise adjustments of caffeine volume and content tailored to a neonate weighing 1.36 kg, achieving a recovery of 103.46%, well within acceptable limits. Additionally, three production batches confirmed the process’s reproducibility with minimal variability. Forced degradation studies showed that both pure caffeine and caffeine in the gel matrix exhibited similar stability profiles, confirming the drug’s chemical integrity. The printed gel dosage forms also displayed immediate-release characteristics, with over 80% of caffeine released within 45 min, highlighting their suitability for rapid therapeutic action. These findings emphasise the potential of SSE 3DP and gel-based formulations to produce personalised drug delivery systems with high precision, reproducibility, and reliability. Full article
(This article belongs to the Special Issue Biosoursed and Bioinspired Gels for Biomedical Applications (2nd Edition))
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16 pages, 9169 KB  
Article
The Effect of Acetic Acid as a Solvent on the Structure and Properties of Poly(3-hydroxybutyrate)—Based Dried Gels
by Vsevolod Zhuikov and Yulia Zhuikova
Gels 2024, 10(10), 664; https://doi.org/10.3390/gels10100664 - 17 Oct 2024
Cited by 2 | Viewed by 2971
Abstract
Poly(3-hydroxybutyrate) (PHB) is a microbially derived polyhydroxyalkanoate that is widely used in biomedical applications. In this study, we investigated the use of acetic acid (aa) as an alternative environmentally friendly solvent for the preparation of gels from PHB (PHB aa) and compared their [...] Read more.
Poly(3-hydroxybutyrate) (PHB) is a microbially derived polyhydroxyalkanoate that is widely used in biomedical applications. In this study, we investigated the use of acetic acid (aa) as an alternative environmentally friendly solvent for the preparation of gels from PHB (PHB aa) and compared their characteristics with PHB products dissolved in chloroform (PHB chl) using such methods as DSC, FTIR, SEM, rheometry, biodegradation, and cytocompatibility assay. A slight decrease in the degree of the crystallinity of the PHB from 61% to 50.8% was found when the acetic acid was used. This resulted in a greater mass loss for the PHB aa (11%) during enzymatic degradation over 180 days. Gels prepared from PHB in the different solvents showed differences in the microstructure and porosity of the samples, which affected their viscoelastic properties. The storage modulus (G′) for the PHB aa gels was higher by 35% compared to that for the PHB chl, and Young’s modulus in compression was 101.5 and 41.3 kPa for the PHB aa and PHB chl, respectively. The porosity of the PHB aa was 97.7%, which was 5.2% higher than that for the PHB chl. The presence of low molecular weight polymers in the PHB aa had an effect on mesenchymal stem cells’ viability, expressed as a threefold increase in the number of attached cells after 7 days of incubation compared to the PHB chl. Thus, the proposed method of PHB-based materials’ preparation is a promising, more environmentally friendly analog of the extensively used method of preparation from chloroform. Full article
(This article belongs to the Special Issue Chemical Properties and Application of Gel Materials)
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37 pages, 2953 KB  
Review
Harmonizing Innovations: An In-Depth Comparative Review on the Formulation, Applications, and Future Perspectives of Aerogels and Hydrogels in Pharmaceutical Sciences
by Nour Alhuda Alaghawani, Hala Alkhatib, Layla Elmancy and Anis Daou
Gels 2024, 10(10), 663; https://doi.org/10.3390/gels10100663 - 17 Oct 2024
Cited by 5 | Viewed by 3393
Abstract
Gels, specifically hydrogels and aerogels, have emerged as versatile materials with profound implications in pharmaceutical sciences. This comprehensive review looks into detail at hydrogels and aerogels, providing a general introduction to gels as a foundation. The paper is then divided into distinct sections [...] Read more.
Gels, specifically hydrogels and aerogels, have emerged as versatile materials with profound implications in pharmaceutical sciences. This comprehensive review looks into detail at hydrogels and aerogels, providing a general introduction to gels as a foundation. The paper is then divided into distinct sections for hydrogels and aerogels, each delving into their unique formulations, advantages, disadvantages, and applications. In the realm of hydrogels, we scrutinize the intricacies of formulation, highlighting the versatile advantages they offer. Conversely, potential limitations are explored, paving the way for a detailed discussion on their applications, with a specific focus on their role in antimicrobial applications. Shifting focus to aerogels, a thorough overview is presented, followed by a detailed explanation of the complex formulation process involving sol–gel chemistry; aging; solvent exchange; and drying techniques, including freeze drying, supercritical drying, and ambient-pressure drying (APD). The intricacies of drug loading and release from aerogels are addressed, providing insights into their pharmaceutical potential. The advantages and disadvantages of aerogels are examined, accompanied by an exploration of their applications, with a specific emphasis on antimicrobial uses. The review culminates in a comparative analysis, juxtaposing the advantages and disadvantages of hydrogels and aerogels. Furthermore, the current research and development trends in the applications of these gels in pharmaceutical sciences are discussed, providing a holistic view of their potential and impact. This review serves as a comprehensive guide for researchers, practitioners, and enthusiasts, seeking a deeper understanding of the distinctive attributes and applications of hydrogels and aerogels in the ever-evolving research concerning pharmaceutical sciences. Full article
(This article belongs to the Section Gel Analysis and Characterization)
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21 pages, 2519 KB  
Review
Advancements in Hydrogels for Corneal Healing and Tissue Engineering
by Kevin Y. Wu, Shu Yu Qian, Anne Faucher and Simon D. Tran
Gels 2024, 10(10), 662; https://doi.org/10.3390/gels10100662 - 16 Oct 2024
Cited by 12 | Viewed by 4434
Abstract
Hydrogels have garnered significant attention for their versatile applications across various fields, including biomedical engineering. This review delves into the fundamentals of hydrogels, exploring their definition, properties, and classification. Hydrogels, as three-dimensional networks of crosslinked polymers, possess tunable properties such as biocompatibility, mechanical [...] Read more.
Hydrogels have garnered significant attention for their versatile applications across various fields, including biomedical engineering. This review delves into the fundamentals of hydrogels, exploring their definition, properties, and classification. Hydrogels, as three-dimensional networks of crosslinked polymers, possess tunable properties such as biocompatibility, mechanical strength, and hydrophilicity, making them ideal for medical applications. Uniquely, this article offers original insights into the application of hydrogels specifically for corneal tissue engineering, bridging a gap in current research. The review further examines the anatomical and functional complexities of the cornea, highlighting the challenges associated with corneal pathologies and the current reliance on donor corneas for transplantation. Considering the global shortage of donor corneas, this review discusses the potential of hydrogel-based materials in corneal tissue engineering. Emphasis is placed on the synthesis processes, including physical and chemical crosslinking, and the integration of bioactive molecules. Stimuli-responsive hydrogels, which react to environmental triggers, are identified as promising tools for drug delivery and tissue repair. Additionally, clinical applications of hydrogels in corneal pathologies are explored, showcasing their efficacy in various trials. Finally, the review addresses the challenges of regulatory approval and the need for further research to fully realize the potential of hydrogels in corneal tissue engineering, offering a promising outlook for future developments in this field. Full article
(This article belongs to the Collection Hydrogel in Tissue Engineering and Regenerative Medicine)
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20 pages, 2552 KB  
Review
Advances and Functional Integration of Hydrogel Composites as Drug Delivery Systems in Contemporary Dentistry
by Dragos Nicolae Fratila, Dragos Ioan Virvescu, Ionut Luchian, Monica Hancianu, Elena Raluca Baciu, Oana Butnaru and Dana Gabriela Budala
Gels 2024, 10(10), 661; https://doi.org/10.3390/gels10100661 - 16 Oct 2024
Cited by 6 | Viewed by 3973
Abstract
This study explores the recent advances of and functional insights into hydrogel composites, materials that have gained significant attention for their versatile applications across various fields, including contemporary dentistry. Hydrogels, known for their high water content and biocompatibility, are inherently soft but often [...] Read more.
This study explores the recent advances of and functional insights into hydrogel composites, materials that have gained significant attention for their versatile applications across various fields, including contemporary dentistry. Hydrogels, known for their high water content and biocompatibility, are inherently soft but often limited by mechanical fragility. Key areas of focus include the customization of hydrogel composites for biomedical applications, such as drug delivery systems, wound dressings, and tissue engineering scaffolds, where improved mechanical properties and bioactivity are critical. In dentistry, hydrogels are utilized for drug delivery systems targeting oral diseases, dental adhesives, and periodontal therapies due to their ability to adhere to the mucosa, provide localized treatment, and support tissue regeneration. Their unique properties, such as mucoadhesion, controlled drug release, and stimuli responsiveness, make them ideal candidates for treating oral conditions. This review highlights both experimental breakthroughs and theoretical insights into the structure–property relationships within hydrogel composites, aiming to guide future developments in the design and application of these multifunctional materials in dentistry. Ultimately, hydrogel composites represent a promising frontier for advancing materials science with far-reaching implications in healthcare, environmental technology, and beyond. Full article
(This article belongs to the Special Issue Properties of Hydrogels, Aerogels, and Cryogels Composites (2nd Edition))
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13 pages, 2636 KB  
Article
Leveraging Deep Learning and Generative AI for Predicting Rheological Properties and Material Compositions of 3D Printed Polyacrylamide Hydrogels
by Sakib Mohammad, Rafee Akand, Kaden M. Cook, Sabrina Nilufar and Farhan Chowdhury
Gels 2024, 10(10), 660; https://doi.org/10.3390/gels10100660 - 15 Oct 2024
Cited by 7 | Viewed by 2818
Abstract
Artificial intelligence (AI) has the ability to predict rheological properties and constituent composition of 3D-printed materials with appropriately trained models. However, these models are not currently available for use. In this work, we trained deep learning (DL) models to (1) predict the rheological [...] Read more.
Artificial intelligence (AI) has the ability to predict rheological properties and constituent composition of 3D-printed materials with appropriately trained models. However, these models are not currently available for use. In this work, we trained deep learning (DL) models to (1) predict the rheological properties, such as the storage (G’) and loss (G”) moduli, of 3D-printed polyacrylamide (PAA) substrates, and (2) predict the composition of materials and associated 3D printing parameters for a desired pair of G’ and G”. We employed a multilayer perceptron (MLP) and successfully predicted G’ and G” from seven gel constituent parameters in a multivariate regression process. We used a grid-search algorithm along with 10-fold cross validation to tune the hyperparameters of the MLP, and found the R2 value to be 0.89. Next, we adopted two generative DL models named variational autoencoder (VAE) and conditional variational autoencoder (CVAE) to learn data patterns and generate constituent compositions. With these generative models, we produced synthetic data with the same statistical distribution as the real data of actual hydrogel fabrication, which was then validated using Student’s t-test and an autoencoder (AE) anomaly detector. We found that none of the seven generated gel constituents were significantly different from the real data. Our trained DL models were successful in mapping the input–output relationship for the 3D-printed hydrogel substrates, which can predict multiple variables from a handful of input variables and vice versa. Full article
(This article belongs to the Special Issue Functional Gel Materials: Chemistry, Processing, Mechanical Performance, and Applications)
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14 pages, 1891 KB  
Article
Impact of κ-Carrageenan on the Freshwater Mussel (Solenaia oleivora) Protein Emulsion Gels: Gel Formation, Stability, and Curcumin Delivery
by Wanwen Chen, Wu Jin, Xueyan Ma, Haibo Wen, Gangchun Xu, Pao Xu and Hao Cheng
Gels 2024, 10(10), 659; https://doi.org/10.3390/gels10100659 - 14 Oct 2024
Cited by 2 | Viewed by 1276
Abstract
Protein-based emulsion gels are an ideal delivery system due to their unique structure, remarkable encapsulation efficiency, and tunable digestive behavior. Freshwater mussel (Solenaia oleivora) protein isolate (SoPI), an emerging sustainable protein with high nutritional value, possesses unique value in the development [...] Read more.
Protein-based emulsion gels are an ideal delivery system due to their unique structure, remarkable encapsulation efficiency, and tunable digestive behavior. Freshwater mussel (Solenaia oleivora) protein isolate (SoPI), an emerging sustainable protein with high nutritional value, possesses unique value in the development of functional foods. Herein, composite emulsion gels were fabricated with SoPI and κ-carrageenan (κ-CG) for the delivery of curcumin. SoPI/κ-CG stabilized emulsions possessed a high encapsulation efficiency of curcumin with a value of around 95%. The addition of κ-CG above 0.50% facilitated the emulsion gel formation and significantly improved the gel strength with 1326 g. Furthermore, the storage and digestive stability of curcumin were significantly improved as the κ-CG concentration increased. At 1.50% κ-CG, around 80% and 90% curcumin remained after 21-day storage at 45 °C and the 6 h in vitro gastrointestinal digestion, respectively. The addition of 0.50% κ-CG obtained the highest bioaccessibility of curcumin (~60%). This study illustrated the potential of SoPI emulsion gels as a carrier for stabilizing and delivering hydrophobic polyphenols. Full article
(This article belongs to the Section Gel Applications)
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12 pages, 1307 KB  
Article
Development and Evaluation of the Acaricidal Activity of Xantan Gum-Based Hydrogel and Polymeric Nanoparticles Containing Achyrocline satureioides Extract
by Rafaela Regina Fantatto, Annelize Rodrigues Gomes, João Vitor Carvalho Constantini, Camila Fernanda Rodero, Marlus Chorilli, Ana Carolina de Souza Chagas, Ana Melero and Rosemeire Cristina Linhari Rodrigues Pietro
Gels 2024, 10(10), 658; https://doi.org/10.3390/gels10100658 - 14 Oct 2024
Cited by 1 | Viewed by 1498
Abstract
The Rhipicephalus microplus tick causes enormous economic losses in livestock farming around the world. Despite several promising studies carried out with plant extracts such as Achyrocline satureioides against this ectoparasite, a major obstacle is related to pharmaceutical presentation forms. There is no study [...] Read more.
The Rhipicephalus microplus tick causes enormous economic losses in livestock farming around the world. Despite several promising studies carried out with plant extracts such as Achyrocline satureioides against this ectoparasite, a major obstacle is related to pharmaceutical presentation forms. There is no study showing xantan gum-based hydrogel and polycaprolactone nanoparticles containing A. satureioides extract against R. microplus larvae. The objective of this study was to incorporate A. satureioides extract to develop a nanoformulation (AScn) and a hydrogel (ASlh) and evaluate them against R. microplus larvae with the purpose of increasing the contact time of the extract with the larvae and improve the effectiveness. The ethanolic extracts were incorporated in polycaprolactone nanoparticles and characterized via analysis of the mean hydrodinamic diameter and polidispersity index. The xanthan gum-based hydrogel formulation was prepared with crude extract of A. satureioides 40 mg/mL, 0.25% xanthan gum, and 8% poloxamer, to determine the bioadhesiveness of the formulation in bovine leather and the flow rate of the formulation in the animal. The results in larvae demonstrated that when evaluated in the form of a hydrogel (ASlh), mortality was higher, with 91.48% mortality at a concentration of 20 mg/mL presenting itself as an interesting alternative for controlling this ectoparasite. Full article
(This article belongs to the Special Issue Recent Advances in Biopolymer Gels)
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9 pages, 2815 KB  
Brief Report
An Adhesive Hydrogel Technology for Enhanced Cartilage Repair: A Preliminary Proof of Concept
by Peyman Karami, Robin Martin, Alexis Laurent, Hui Yin Nam, Virginie Philippe, Lee Ann Applegate and Dominique P. Pioletti
Gels 2024, 10(10), 657; https://doi.org/10.3390/gels10100657 - 14 Oct 2024
Cited by 5 | Viewed by 4433
Abstract
Knee cartilage has limited natural healing capacity, complicating the development of effective treatment plans. Current non-cell-based therapies (e.g., microfracture) result in poor repair cartilage mechanical properties, low durability, and suboptimal tissue integration. Advanced treatments, such as autologous chondrocyte implantation, face challenges including cell [...] Read more.
Knee cartilage has limited natural healing capacity, complicating the development of effective treatment plans. Current non-cell-based therapies (e.g., microfracture) result in poor repair cartilage mechanical properties, low durability, and suboptimal tissue integration. Advanced treatments, such as autologous chondrocyte implantation, face challenges including cell leakage and inhomogeneous distribution. Successful cell therapy relies on prolonged retention of therapeutic biologicals at the implantation site, yet the optimal integration of implanted material into the surrounding healthy tissue remains an unmet need. This study evaluated the effectiveness of a newly developed photo-curable adhesive hydrogel for cartilage repair, focusing on adhesion properties, integration performance, and ability to support tissue regeneration. The proposed hydrogel design exhibited significant adhesion strength, outperforming commercial adhesives such as fibrin-based glues. An in vivo goat model was used to evaluate the hydrogels’ adhesion properties and long-term integration into full-thickness cartilage defects over six months. Results showed that cell-free hydrogel-treated defects achieved superior integration with surrounding tissue and enhanced cartilage repair, with notable lateral integration. In vitro results further demonstrated high cell viability, robust matrix production, and successful cell encapsulation within the hydrogel matrix. These findings highlight the potential of adhesive hydrogel formulations to improve the efficacy of cell-based therapies, offering a potentially superior treatment for knee cartilage defects. Full article
(This article belongs to the Special Issue Recent Advances in Biopolymer Gels)
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15 pages, 1749 KB  
Review
The Sol–Gel Process, a Green Method Used to Obtain Hybrid Materials Containing Phosphorus and Zirconium
by Petru Merghes, Gheorghe Ilia, Bianca Maranescu, Narcis Varan and Vasile Simulescu
Gels 2024, 10(10), 656; https://doi.org/10.3390/gels10100656 - 13 Oct 2024
Cited by 2 | Viewed by 3486
Abstract
The sol–gel process is a green method used in the last few decades to synthesize new organic–inorganic phosphorus-containing hybrid materials. The sol–gel synthesis is a green method because it takes place in mild conditions, mostly by using water or alcohol as solvents, at [...] Read more.
The sol–gel process is a green method used in the last few decades to synthesize new organic–inorganic phosphorus-containing hybrid materials. The sol–gel synthesis is a green method because it takes place in mild conditions, mostly by using water or alcohol as solvents, at room temperature. Therefore, the sol–gel method is, among others, a promising route for obtaining metal-phosphonate networks. In addition to phosphorus, the obtained hybrid materials could also contain titanium, zirconium, boron, and other elements, which influence their properties. The sol–gel process has two steps: first, the sol formation, and second, the transition to the gel phase. In other words, the sol–gel process converts the precursors into a colloidal solution (sol), followed by obtaining a network (gel). By using the sol–gel method, different organic moieties could be introduced into an inorganic matrix, resulting in organic–inorganic hybrid structures (sometimes they are also referred as organic–inorganic copolymers). Full article
(This article belongs to the Special Issue Smart Hydrogels: From Rational Design to Applications (2nd Edition))
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20 pages, 5258 KB  
Article
Tuning Antioxidant Function through Dynamic Design of Chitosan-Based Hydrogels
by Manuela Maria Iftime, Gabriela Liliana Ailiesei and Daniela Ailincai
Gels 2024, 10(10), 655; https://doi.org/10.3390/gels10100655 - 13 Oct 2024
Cited by 6 | Viewed by 1470
Abstract
Dynamic chitosan-based hydrogels with enhanced antioxidant activity were synthesized through the formation of reversible imine linkages with 5-methoxy-salicylaldehyde. These hydrogels exhibited a porous structure and swelling capacity, influenced by the crosslinking degree, as confirmed by SEM and POM analysis. The dynamic nature of [...] Read more.
Dynamic chitosan-based hydrogels with enhanced antioxidant activity were synthesized through the formation of reversible imine linkages with 5-methoxy-salicylaldehyde. These hydrogels exhibited a porous structure and swelling capacity, influenced by the crosslinking degree, as confirmed by SEM and POM analysis. The dynamic nature of the imine bonds was characterized through NMR, swelling studies in various media, and aldehyde release measurements. The hydrogels demonstrated significantly improved antioxidant activity compared to unmodified chitosan, as evaluated by the DPPH method. This research highlights the potential of developing pH–responsive chitosan-based hydrogels for a wide range of biomedical applications. Full article
(This article belongs to the Special Issue Eco-Friendly Gels for Adsorption)
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15 pages, 8517 KB  
Article
Design of Aerated Oleogel–Hydrogel Mixtures for 3D Printing of Personalized Cannabis Edibles
by Eleftherios G. Andriotis, Adamantini Paraskevopoulou, Dimitrios G. Fatouros, Hui Zhang and Christos Ritzoulis
Gels 2024, 10(10), 654; https://doi.org/10.3390/gels10100654 - 13 Oct 2024
Cited by 5 | Viewed by 2236
Abstract
Cannabis seed oil oleogel structured with Glycerol Monostearate (20% w/w) was mixed with xanthan gum hydrogel (2% w/w) at different ratios ranging from 0% w/w hydrogel to 75% w/w hydrogel, using a syringe-to-syringe [...] Read more.
Cannabis seed oil oleogel structured with Glycerol Monostearate (20% w/w) was mixed with xanthan gum hydrogel (2% w/w) at different ratios ranging from 0% w/w hydrogel to 75% w/w hydrogel, using a syringe-to-syringe apparatus, for the preparation of 3D-printable food inks. This process enabled the simultaneous blend of oleogel and hydrogel phases and the incorporation of air in a reproducible and accurate manner. The printability of bigel inks with different mass ratios was evaluated by using a conventional benchtop food 3D printer. The printability of the inks was found to be negatively affected by the presence of higher portions of the hydrogel phase, while the printing performance of pure cannabis seed oil oleogel was superior compared to the printing performance of the bigel inks. The physicochemical properties of hybrid gels were investigated with rheological studies, thermophysical studies (Differential Scanning Calorimetry), Polarized Light Microscopy, and Confocal Laser Scanning Microscopy. The microstructure of the aerated inks was affected by the presence of a higher oleogel fraction, in terms of air bubble shape and distribution. The addition of hydrogel at concentrations higher than 50% w/w had a strong negative effect on the mechanical properties of the inks leading to a partial collapse of the printed structures and subsequently to poor printing performance. Full article
(This article belongs to the Special Issue Oleogels, Bigels, and Emulgels: Fabrication, Application and Research Trends)
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14 pages, 632 KB  
Review
Hydrogel-Based Vascularized Organ Tissue Engineering: A Systematized Review on Abdominal Organs
by Filippos F. Karageorgos, Maria Alexiou, Georgios Tsoulfas and Aleck H. Alexopoulos
Gels 2024, 10(10), 653; https://doi.org/10.3390/gels10100653 - 12 Oct 2024
Cited by 5 | Viewed by 3122
Abstract
Background: Biomedical engineering, especially tissue engineering, is trying to provide an alternative solution to generate functional organs/tissues for use in various applications. These include beyond the final goal of transplantation, disease modeling and drug discovery as well. The aim of this study is [...] Read more.
Background: Biomedical engineering, especially tissue engineering, is trying to provide an alternative solution to generate functional organs/tissues for use in various applications. These include beyond the final goal of transplantation, disease modeling and drug discovery as well. The aim of this study is to comprehensively review the existing literature on hydrogel-based vascularized organ (i.e., liver, pancreas, kidneys, intestine, stomach and spleen) tissue engineering of the abdominal organs. Methods: A comprehensive literature search was conducted on the Scopus database (latest search 1 September 2024). The research studies including hydrogel-based vascularized organ tissue engineering in the organs examined here were eligible for the review. Results: Herein, 18 studies were included. Specifically, 10 studies included the liver or hepatic tissue, 5 studies included the pancreas or pancreatic islet tissue, 3 studies included the kidney or renal tissue, 1 study included the intestine or intestinal or bowel tissue, 1 study included the stomach or gastric tissue, and 0 studies included spleen tissue. Conclusion: Hydrogels are biocompatible materials with ideal characteristics for use as scaffolds. Even though organ tissue engineering is a rapidly growing field, there are still many obstacles to overcome to create a fully functional and long-lasting organ. Full article
(This article belongs to the Special Issue Advanced Gel Materials for Bioengineering)
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13 pages, 3132 KB  
Article
Shear-Thinning Extrudable Hydrogels Based on Star Polypeptides with Antimicrobial Properties
by Dimitrios Skoulas, Muireann Fallon, Katelyn J. Genoud, Fergal J. O’Brien, Deirdre Fitzgerald Hughes and Andreas Heise
Gels 2024, 10(10), 652; https://doi.org/10.3390/gels10100652 - 11 Oct 2024
Viewed by 1697
Abstract
Hydrogels with low toxicity, antimicrobial potency and shear-thinning behavior are promising materials to combat the modern challenges of increased infections. Here, we report on 8-arm star block copolypeptides based on poly(L-lysine), poly(L-tyrosine) and poly(S-benzyl-L-cysteine) blocks. Three star block copolypeptides were synthesized with poly(S-benzyl-L-cysteine) [...] Read more.
Hydrogels with low toxicity, antimicrobial potency and shear-thinning behavior are promising materials to combat the modern challenges of increased infections. Here, we report on 8-arm star block copolypeptides based on poly(L-lysine), poly(L-tyrosine) and poly(S-benzyl-L-cysteine) blocks. Three star block copolypeptides were synthesized with poly(S-benzyl-L-cysteine) always forming the outer block. The inner block comprised either two individual blocks of poly(L-lysine) and poly(L-tyrosine) or a statistical block copolypeptide from both amino acids. The star block copolypeptides were synthesized by the Ring Opening Polymerization (ROP) of the protected amino acid N-carboxyanhydrides (NCAs), keeping the overall ratio of monomers constant. All star block copolypeptides formed hydrogels and Scanning Electron Microscopy (SEM) confirmed a porous morphology. The investigation of their viscoelastic characteristics, water uptake and syringe extrudability revealed superior properties of the star polypeptide with a statistical inner block of L-lysine and L-tyrosine. Further testing of this sample confirmed no cytotoxicity and demonstrated antimicrobial activity of 1.5-log and 2.6-log reduction in colony-forming units, CFU/mL, against colony-forming reference laboratory strains of Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, respectively. The results underline the importance of controlling structural arrangements in polypeptides to optimize their physical and biological properties. Full article
(This article belongs to the Special Issue Hydrogels, Microgels and Nanogels Emerging Platforms for Drug Delivery, Antibacterial Properties and Tissue Engineering)
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21 pages, 5514 KB  
Article
Long-Term Investigation of Nano-Silica Gel for Water Shut-Off in Fractured Reservoirs
by Ahmed Ali, Mustafa Al Ramadan and Murtada Saleh Aljawad
Gels 2024, 10(10), 651; https://doi.org/10.3390/gels10100651 - 11 Oct 2024
Cited by 1 | Viewed by 1648
Abstract
Silicate gels have long been utilized as water shut-off agents in petroleum fields to address excessive water production. In recent years, nano-silica gel has emerged as a promising alternative to traditional silicate gels, offering potentially improved plugging performance. However, the long-term effectiveness of [...] Read more.
Silicate gels have long been utilized as water shut-off agents in petroleum fields to address excessive water production. In recent years, nano-silica gel has emerged as a promising alternative to traditional silicate gels, offering potentially improved plugging performance. However, the long-term effectiveness of these gels remains uncertain, posing challenges to sustained profitability. Therefore, a comprehensive study spanning 6 months was conducted on fractured and induced channel samples treated with nano-silica gel of 75/25 wt% (silica/activator) at 200 °F. A comparative analysis was performed with samples treated using polyacrylamide/polyethyleneimine PAM/PEI gel (9/1 wt%) to compare the performance of both systems. Throughout the aging period in formation water at 167 °F, endurance tests were conducted at regular intervals, complemented by computed tomography (CT) scans to monitor any potential degradation. The results revealed nano-silica gel’s superior long-term performance in plugging fractures and channels compared to PAM/PEI gel. Even after 6 months, the nano-silica gel maintained a remarkable 100% plugging efficiency at 1000 psi, with a maximum leak-off rate of 0.088 cc/min in the mid-fractured sample and 0.027 in the induced channel sample. In comparison, PAM/PEI gel exhibited a reduction in efficiency to 99.15% in the fractured sample (5.5 cc/min maximum leak-off rate) and 99.99% in the induced channel sample (0.036 cc/min maximum leak-off rate). These findings highlight the potential of nano-silica gel as a more durable water shut-off agent for managing water production in fractures and channels. Full article
(This article belongs to the Special Issue Gels for Oil and Gas Industry Applications (3rd Edition))
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13 pages, 7025 KB  
Article
Structural Build-Up and Stability of Hybrid Monoglyceride–Triglyceride Oleogels
by Kato Rondou, Antonia Dewettinck, Koen Dewettinck and Filip Van Bockstaele
Gels 2024, 10(10), 650; https://doi.org/10.3390/gels10100650 - 11 Oct 2024
Viewed by 1438
Abstract
Oleogelation is an alternative oil structuring route to formulate (semi-)solid fats with a reduced amount of saturated fats. Monoglycerides have been identified as effective gelators; however, their application potential can be limited due to challenges regarding mechanical strength and long-term stability. Therefore, the [...] Read more.
Oleogelation is an alternative oil structuring route to formulate (semi-)solid fats with a reduced amount of saturated fats. Monoglycerides have been identified as effective gelators; however, their application potential can be limited due to challenges regarding mechanical strength and long-term stability. Therefore, the formulation of hybrid fat blends is a promising way to improve the functionality of oleogels. This research focuses on the interaction between mono- and triglycerides (MAGs and TAGs) in hybrid oleogels. A total gelator concentration of 10% (w/w) with changing MAGs–TAGs ratios (increase by 25% on a molar basis; M0-T100, M25-T75, M50-T50, M75-T25, M100-T0) was used. First, the oleogels were produced without shear to unravel the crystallization behavior (DSC, SAXS, WAXS). Next, the oleogels were crystallized with shear to assess the interactions between MAGs and TAGs on macroscale properties (rigidity, oil binding capacity) during storage of 1 day, 1 week, and 4 weeks. A clear distinction could be made between the MAG crystals and TAG crystals in the blends M50-T50 and M75-T25 based on WAXS, SAXS, and phase contrast microscopy. This indicates that both gelators crystallize separately. During the follow-up study of the dynamically produced samples, a synergistic effect was found for Dy-M50-T50 and Dy-M75-T25; however, it was not maintained upon storage. The initial rigidity of 2.4 × 104 Pa and 2.0 × 104 Pa decreased to 1.5 × 104 Pa and 1.0 × 104 Pa for Dy-M50-T50 and Dy-M75-T25, respectively. Full article
(This article belongs to the Special Issue Recent Progress on Oleogels and Organogels)
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22 pages, 7308 KB  
Article
Dual-Self-Crosslinking Effect of Alginate-Di-Aldehyde with Natural and Synthetic Co-Polymers as Injectable In Situ-Forming Biodegradable Hydrogel
by Bushra Begum, Trideva Sastri Koduru, Syeda Noor Madni, Noor Fathima Anjum, Shanmuganathan Seetharaman, Balamuralidhara Veeranna and Vishal Kumar Gupta
Gels 2024, 10(10), 649; https://doi.org/10.3390/gels10100649 - 11 Oct 2024
Cited by 6 | Viewed by 3315
Abstract
Injectable, in situ-forming hydrogels, both biocompatible and biodegradable, have garnered significant attention in tissue engineering due to their potential for creating adaptable scaffolds. The adaptability of these hydrogels, made from natural proteins and polysaccharides, opens up a world of possibilities. In this study, [...] Read more.
Injectable, in situ-forming hydrogels, both biocompatible and biodegradable, have garnered significant attention in tissue engineering due to their potential for creating adaptable scaffolds. The adaptability of these hydrogels, made from natural proteins and polysaccharides, opens up a world of possibilities. In this study, sodium alginate was used to synthesize alginate di-aldehyde (ADA) through periodate oxidation, resulting in a lower molecular weight and reduced viscosity, with different degrees of oxidation (54% and 70%). The dual-crosslinking mechanism produced an injectable in situ hydrogel. Initially, physical crosslinking occurred between ADA and borax via borax complexation, followed by chemical crosslinking with gelatin through a Schiff’s base reaction, which takes place between the amino groups of gelatin and the aldehyde groups of ADA, without requiring an external crosslinking agent. The formation of Schiff’s base was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. At the same time, the aldehyde groups in ADA were characterized using FT-IR, proton nuclear magnetic resonance (¹H NMR), and gel permeation chromatography (GPC), which determined its molecular weight. Furthermore, borax complexation was validated through boron-11 nuclear magnetic resonance (¹¹B NMR). The hydrogel formulation containing 70% ADA, polyethylene glycol (PEG), and 9% gelatin exhibited a decreased gelation time at physiological temperature, attributed to the increased gelatin content and higher degree of oxidation. Rheological analysis mirrored these findings, showing a correlation with gelation time. The swelling capacity was also enhanced due to the increased oxidation degree of PEG and the system’s elevated gelatin content and hydrophilicity. The hydrogel demonstrated an average pore size of 40–60 µm and a compressive strength of 376.80 kPa. The lower molecular weight and varied pH conditions influenced its degradation behavior. Notably, the hydrogel’s syringeability was deemed sufficient for practical applications, further enhancing its potential in tissue engineering. Given these properties, the 70% ADA/gelatin/PEG hydrogel is a promising candidate and a potential game-changer for injectable, self-crosslinking applications in tissue engineering. Its potential to revolutionize the field is inspiring and should motivate further exploration. Full article
(This article belongs to the Special Issue Gel-Related Papers from the 9th Asian Conference on Colloid and Interface Science 2023 (ACCIS 2023))
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23 pages, 16247 KB  
Article
Sol–Gel Derived Alumina Particles for the Reinforcement of Copper Films on Brass Substrates
by Samah Sasi Maoloud Mohamed, Marija M. Vuksanović, Dana G. Vasiljević-Radović, Ljiljana Janković Mandić, Radmila M. Jančić Heinneman, Aleksandar D. Marinković and Ivana O. Mladenović
Gels 2024, 10(10), 648; https://doi.org/10.3390/gels10100648 - 11 Oct 2024
Cited by 2 | Viewed by 2019
Abstract
The aim of this study is to provide tailored alumina particles suitable for reinforcing the metal matrix film. The sol–gel method was chosen to prepare particles of submicron size and to control crystal structure by calcination. In this study, copper-based metal matrix composite [...] Read more.
The aim of this study is to provide tailored alumina particles suitable for reinforcing the metal matrix film. The sol–gel method was chosen to prepare particles of submicron size and to control crystal structure by calcination. In this study, copper-based metal matrix composite (MMC) films are developed on brass substrates with different electrodeposition times and alumina concentrations. Scanning electron microscopy (FE-SEM) with energy-dispersive spectroscopy (EDS), TEM, and X-ray diffraction (XRD) were used to characterize the reinforcing phase. The MMC Cu-Al2O3 films were synthesized electrochemically using the co-electrodeposition method. Microstructural and topographical analyses of pure (alumina-free) Cu films and the Cu films with incorporated Al2O3 particles were performed using FE-SEM/EDS and AFM, respectively. Hardness and adhesion resistance were investigated using the Vickers microindentation test and evaluated by applying the Chen–Gao (C-G) mathematical model. The sessile drop method was used for measuring contact angles for water. The microhardness and adhesion of the MMC Cu-Al2O3 films are improved when Al2O3 is added. The concentration of alumina particles in the electrolyte correlates with an increase in absolute film hardness in the way that 1.0 wt.% of alumina in electrolytes results in a 9.96% increase compared to the pure copper film, and the improvement is maximal in the film obtained from electrolytes containing 3.0 wt.% alumina giving the film 2.128 GPa, a 134% hardness value of that of the pure copper film. The surface roughness of the MMC film increased from 2.8 to 6.9 times compared to the Cu film without particles. The decrease in the water contact angle of Cu films with incorporated alumina particles relative to the pure Cu films was from 84.94° to 58.78°. Full article
(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))
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14 pages, 3147 KB  
Article
Biocompatible Hydrogel Coating on Silicone Rubber with Improved Antifouling and Durable Lubricious Properties
by Shuai Gao, Zheng Liu, Wei Zeng, Yunfeng Zhang, Fanjun Zhang, Dimeng Wu and Yunbing Wang
Gels 2024, 10(10), 647; https://doi.org/10.3390/gels10100647 - 11 Oct 2024
Cited by 5 | Viewed by 3067
Abstract
Silicone rubber is widely used in various medical applications. However, silicone rubber is prone to biofouling due to their affinity for lipids and has a high friction coefficient, which can significantly impact their efficacy and performance used as medical devices. Thus, the development [...] Read more.
Silicone rubber is widely used in various medical applications. However, silicone rubber is prone to biofouling due to their affinity for lipids and has a high friction coefficient, which can significantly impact their efficacy and performance used as medical devices. Thus, the development of hydrogels with antifouling and lubricious abilities for the modification of silicone rubber is in high demand. We herein prepared a variety of hydrogel coatings mainly based on polyvinylpyrrolidone (PVP) and poly (ethylene glycol) diacrylate (PEGDA). We modified the silicone rubber using the prepared hydrogel coatings and cured it using a heating method. Then, we characterized its surface and evaluated the antifouling property, lubricious property, cytotoxicity, sensitization, and vaginal irritation. The results of water contact angle (WCA), protein adsorption, and friction coefficient indicated the success of the modification of the silicone rubber, leading to a significant decrease in the corresponding test values. Meanwhile, the results of cytotoxicity, sensitization, and vaginal irritation tests showed that the hydrogel coating-modified silicone rubbers have an excellent biocompatibility. This study describes how the silicone rubber could be modified with a biocompatible hydrogel coating. The hydrogel coating-modified silicone rubbers have improved antifouling and durable lubricious properties. Full article
(This article belongs to the Special Issue State-of-the-Art Gel Research in China)
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37 pages, 16800 KB  
Review
An Overview of Microorganisms Immobilized in a Gel Structure for the Production of Precursors, Antibiotics, and Valuable Products
by Dmitriy Berillo, Turganova Malika, Baiken B. Baimakhanova, Amankeldi K. Sadanov, Vladimir E. Berezin, Lyudmila P. Trenozhnikova, Gul B. Baimakhanova, Alma A. Amangeldi and Bakhytzhan Kerimzhanova
Gels 2024, 10(10), 646; https://doi.org/10.3390/gels10100646 - 10 Oct 2024
Cited by 9 | Viewed by 5909
Abstract
Using free microorganisms for industrial processes has some limitations, such as the extensive consumption of substrates for growth, significant sensitivity to the microenvironment, and the necessity of separation from the product and, therefore, the cyclic process. It is widely acknowledged that confining or [...] Read more.
Using free microorganisms for industrial processes has some limitations, such as the extensive consumption of substrates for growth, significant sensitivity to the microenvironment, and the necessity of separation from the product and, therefore, the cyclic process. It is widely acknowledged that confining or immobilizing cells in a matrix or support structure enhances enzyme stability, facilitates recycling, enhances rheological resilience, lowers bioprocess costs, and serves as a fundamental prerequisite for large-scale applications. This report summarizes the various cell immobilization methods, including several synthetic (polyvinylalcohol, polyethylenimine, polyacrylates, and Eudragit) and natural (gelatin, chitosan, alginate, cellulose, agar–agar, carboxymethylcellulose, and other polysaccharides) polymeric materials in the form of thin films, hydrogels, and cryogels. Advancements in the production of well-known antibiotics like penicillin and cephalosporin by various strains were discussed. Additionally, we highlighted cutting-edge research related to strain producers of peptide-based antibiotics (polymyxin B, Subtilin, Tyrothricin, varigomycin, gramicidin S, friulimicin, and bacteriocin), glusoseamines, and polyene derivatives. Crosslinking agents, especially covalent linkers, significantly affect the activity and stability of biocatalysts (penicillin G acylase, penicillinase, deacetoxycephalosporinase, L-asparaginase, β-glucosidase, Xylanase, and urease). The molecular weight of polymers is an important parameter influencing oxygen and nutrient diffusion, the kinetics of hydrogel formation, rigidity, rheology, elastic moduli, and other mechanical properties crucial for long-term utilization. A comparison of stability and enzymatic activity between immobilized enzymes and their free native counterparts was explored. The discussion was not limited to recent advancements in the biopharmaceutical field, such as microorganism or enzyme immobilization, but also extended to methods used in sensor and biosensor applications. In this study, we present data on the advantages of cell and enzyme immobilization over microorganism (bacteria and fungi) suspension states to produce various bioproducts and metabolites—such as antibiotics, enzymes, and precursors—and determine the efficiency of immobilization processes and the optimal conditions and process parameters to maximize the yield of the target products. Full article
(This article belongs to the Special Issue Gel Film and Its Wide Range of Applications)
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26 pages, 5444 KB  
Article
Development, Optimization, and Evaluation of New Gel Formulations with Cyclodextrin Complexes and Volatile Oils with Antimicrobial Activity
by Alina Ionela Stancu, Eliza Oprea, Lia Mara Dițu, Anton Ficai, Cornelia-Ioana Ilie, Irinel Adriana Badea, Mihaela Buleandra, Oana Brîncoveanu, Mihaela Violeta Ghica, Ionela Avram, Cristina Elena Dinu Pîrvu and Magdalena Mititelu
Gels 2024, 10(10), 645; https://doi.org/10.3390/gels10100645 - 10 Oct 2024
Cited by 8 | Viewed by 5310
Abstract
This study aimed to develop and evaluate hydrogels containing a cyclodextrin complex with clove essential oil and other free volatile oils with antimicrobial properties (tea tree and rosemary essential oils), focusing on their pharmaco-technical and rheological characteristics. The formulations varied in the Carbopol [...] Read more.
This study aimed to develop and evaluate hydrogels containing a cyclodextrin complex with clove essential oil and other free volatile oils with antimicrobial properties (tea tree and rosemary essential oils), focusing on their pharmaco-technical and rheological characteristics. The formulations varied in the Carbopol 940 (a hydrophilic polymer) and volatile oils’ concentrations. Rheological analysis indicated that the gels displayed pseudoplastic behavior, with the flow index (n) values below 1, ensuring appropriate consistency and handling. The results showed that increasing the Carbopol concentration significantly enhanced the yield stress, consistency index, and viscosity, with gel B, containing 1% Carbopol, 1.5% tea tree essential oil, and 1.5% rosemary essential oil, demonstrating optimal stability and rheological properties. At the same time, the concentration of volatile oils was found to modulate the gels’ flow parameters, but their effect was less pronounced than that of the gel-forming polymer. Antimicrobial testing revealed that both gel B and gel E (containing 1% Carbopol, 2% tea tree essential oil, and 2% rosemary essential oil) exhibited antimicrobial activity against Gram-positive, Gram-negative bacteria, and Candida spp., with gel E showing superior efficacy against Candida tropicalis. The antimicrobial effects were likely influenced by the higher concentrations of tea tree and rosemary essential oils in gel E. Overall, the study demonstrates that the concentration of Carbopol 940 primarily determines the gel’s rheological behavior, while volatile oil concentration modulates antimicrobial effectiveness. Full article
(This article belongs to the Special Issue Hydrogel for Sustained Delivery of Therapeutic Agents (2nd Edition))
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Review
Gel-Based Suspension Medium Used in 3D Bioprinting for Constructing Tissue/Organ Analogs
by Yang Luo, Rong Xu, Zeming Hu, Renhao Ni, Tong Zhu, Hua Zhang and Yabin Zhu
Gels 2024, 10(10), 644; https://doi.org/10.3390/gels10100644 - 10 Oct 2024
Cited by 2 | Viewed by 2119
Abstract
Constructing tissue/organ analogs with natural structures and cell types in vitro offers a valuable strategy for the in situ repair of damaged tissues/organs. Three-dimensional (3D) bioprinting is a flexible method for fabricating these analogs. However, extrusion-based 3D bioprinting faces the challenge of balancing [...] Read more.
Constructing tissue/organ analogs with natural structures and cell types in vitro offers a valuable strategy for the in situ repair of damaged tissues/organs. Three-dimensional (3D) bioprinting is a flexible method for fabricating these analogs. However, extrusion-based 3D bioprinting faces the challenge of balancing the use of soft bioinks with the need for high-fidelity geometric shapes. To address these challenges, recent advancements have introduced various suspension mediums based on gelatin, agarose, and gellan gum microgels. The emergence of these gel-based suspension mediums has significantly advanced the fabrication of tissue/organ constructs using 3D bioprinting. They effectively stabilize and support soft bioinks, enabling the formation of complex spatial geometries. Moreover, they provide a stable, cell-friendly environment that maximizes cell viability during the printing process. This minireview will summarize the properties, preparation methods, and potential applications of gel-based suspension mediums in constructing tissue/organ analogs, while also addressing current challenges and providing an outlook on the future of 3D bioprinting. Full article
(This article belongs to the Special Issue 3D Printing of Gel-Based Materials)
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