Hydrogels with Appropriate/Tunable Properties for Biomedical Applications (2nd Edition)

A special issue of Gels (ISSN 2310-2861). This special issue belongs to the section "Gel Applications".

Deadline for manuscript submissions: 15 December 2024 | Viewed by 8521

Special Issue Editors

Department of Biophysics, School of Basic Medical Sciences, Health Science Center, Institute of Medical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Interests: biomaterials; hydrogel; wound treatment
Special Issues, Collections and Topics in MDPI journals
College of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China
Interests: hydrogel; double-network hydrogel; smart materials; biomedical materials; flexible sensor and tissue adhesive
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
Interests: adhesive; hydrogel; sealant; tumor treatment

Special Issue Information

Dear Colleagues, 

Initially, hydrogels attracted attention from biomaterial scientists mainly due to their porosity, high water ratio, and soft consistency, as they closely simulate the conditions of natural living tissue. In addition to those, more properties have been and are being developed to increase their potential in biomedical applications. Those include high mechanical strength, controllable degradation, bioadhesion property, and stimulation responsiveness, among others.

Although much research has been carried out to endow hydrogel with different properties, it seems that excessive attention has been paid to increasing the ‘intensity’ of their different properties, for example, developing bioadhesive hydrogel with extremely high adhesion strength, and designing tough hydrogels with solid bulk properties. A proper property is more vital for a certain application. A moderate but not high adhesion strength for bioadhesive-based wound dressing will allow the re-change or re-exposure of wounds more easily. For hydrogel scaffolds, a proper degradation speed that matches the tissue-healing speed will lead to a better outcome. For applications in different tissues, hydrogels are needed with various but not only high mechanical strength. Additionally, stretchable, light-responsive, and conductive hydrogels are appreciated in flexible and smart devices.

Fabricating hydrogels with appropriate/tunable properties is vital to expanding hydrogels’ applications in the biomedical field. Hence, within this topic, we aim to share up-to-date advances in developing hydrogels with different properties for biomedical applications. Both hydrogels with extremely ‘strong’ properties and those with appropriate/tunable ones are welcome for consideration in this Special Issue. It is believed that developing hydrogels with appropriate properties fitted to a specific application will accelerate the clinical translation of hydrogels.

Dr. Yazhong Bu
Dr. Yanyu Yang
Dr. Feifei Sun
Guest Editors

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Keywords

  • functional hydrogel
  • biomedical application
  • adhesive
  • smart hydrogel
  • medical device
  • health diagnosis

Published Papers (7 papers)

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Research

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20 pages, 3086 KiB  
Article
Topical Meloxicam Hydroxypropyl Guar Hydrogels Based on Low-Substituted Hydroxypropyl Cellulose Solid Dispersions
by Zaid Dahma, Carlos Torrado-Salmerón, Covadonga Álvarez-Álvarez, Víctor Guarnizo-Herrero, Borja Martínez-Alonso, Guillermo Torrado, Santiago Torrado-Santiago and Paloma Marina de la Torre-Iglesias
Gels 2024, 10(3), 207; https://doi.org/10.3390/gels10030207 - 18 Mar 2024
Viewed by 547
Abstract
Meloxicam (MX) is a poorly water-soluble drug with severe gastrointestinal side effects. Topical hydrogel of hydroxypropyl guar (HPG) was formulated using a solid dispersion (SD) of MX with hydroxypropyl cellulose (LHPC) as an alternative to oral administration. The development of a solid dispersion [...] Read more.
Meloxicam (MX) is a poorly water-soluble drug with severe gastrointestinal side effects. Topical hydrogel of hydroxypropyl guar (HPG) was formulated using a solid dispersion (SD) of MX with hydroxypropyl cellulose (LHPC) as an alternative to oral administration. The development of a solid dispersion with an adequate MX:LHPC ratio could increase the topical delivery of meloxicam. Solid dispersions showed high MX solubility values and were related to an increase in hydrophilicity. The drug/polymer and polymer/polymer interactions of solid dispersions within the HPG hydrogels were evaluated by SEM, DSC, FTIR, and viscosity studies. A porous structure was observed in the solid dispersion hydrogel MX:LHPC (1:2.5) and its higher viscosity was related to a high increase in hydrogen bonds among the –OH groups from LHPC and HPG with water molecules. In vitro drug release studies showed increases of 3.20 and 3.97-fold for hydrogels with MX:LHPC ratios of (1:1) and (1:2.5), respectively, at 2 h compared to hydrogel with pure MX. Finally, a fitting transition from zero to first-order model was observed for these hydrogels containing solid dispersions, while the n value of Korsmeyer–Peppas model indicated that release mechanism is governed by diffusion through an important relaxation of the polymer. Full article
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20 pages, 4786 KiB  
Article
pH-Responsive Cellulose/Silk/Fe3O4 Hydrogel Microbeads Designed for Biomedical Applications
by Seung Hyeon Weon, Yuhyeon Na, Jiwoo Han, Jeong Woo Lee, Hyung Joo Kim, Saerom Park and Sang Hyun Lee
Gels 2024, 10(3), 200; https://doi.org/10.3390/gels10030200 - 16 Mar 2024
Viewed by 685
Abstract
In this study, cellulose/Fe3O4 hydrogel microbeads were prepared through the sol–gel transition of a solvent-in-oil emulsion using various cellulose-dissolving solvents and soybean oil without surfactants. Particularly, 40% tetrabutylammonium hydroxide (TBAH) and 40% tetrabutylphosphonium hydroxide (TBPH) dissolved cellulose at room temperature [...] Read more.
In this study, cellulose/Fe3O4 hydrogel microbeads were prepared through the sol–gel transition of a solvent-in-oil emulsion using various cellulose-dissolving solvents and soybean oil without surfactants. Particularly, 40% tetrabutylammonium hydroxide (TBAH) and 40% tetrabutylphosphonium hydroxide (TBPH) dissolved cellulose at room temperature and effectively dispersed Fe3O4, forming cellulose/Fe3O4 microbeads with an average diameter of ~15 µm. Additionally, these solvents co-dissolved cellulose and silk, allowing for the manufacture of cellulose/silk/Fe3O4 hydrogel microbeads with altered surface characteristics. Owing to the negatively charged surface characteristics, the adsorption capacity of the cellulose/silk/Fe3O4 microbeads for the cationic dye crystal violet was >10 times higher than that of the cellulose/Fe3O4 microbeads. When prepared with TBAH, the initial adsorption rate of bovine serum albumin (BSA) on the cellulose/silk/Fe3O4 microbeads was 18.1 times higher than that on the cellulose/Fe3O4 microbeads. When preparing TBPH, the equilibrium adsorption capacity of the cellulose/silk/Fe3O4 microbeads for BSA (1.6 g/g) was 8.5 times higher than that of the cellulose/Fe3O4 microbeads. The pH-dependent BSA release from the cellulose/silk/Fe3O4 microbeads prepared with TBPH revealed 6.1-fold slower initial desorption rates and 5.2-fold lower desorption amounts at pH 2.2 than those at pH 7.4. Cytotoxicity tests on the cellulose and cellulose/silk composites regenerated with TBAH and TBPH yielded nontoxic results. Therefore, cellulose/silk/Fe3O4 microbeads are considered suitable pH-responsive supports for orally administered protein pharmaceuticals. Full article
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19 pages, 6248 KiB  
Article
The Release of Grape Pomace Phenolics from Alginate-Based Microbeads during Simulated Digestion In Vitro: The Influence of Coatings and Drying Method
by Josipa Martinović, Jasmina Lukinac, Marko Jukić, Rita Ambrus, Mirela Planinić, Gordana Šelo, Gabriela Perković and Ana Bucić-Kojić
Gels 2023, 9(11), 870; https://doi.org/10.3390/gels9110870 - 01 Nov 2023
Viewed by 1279
Abstract
Grape pomace is a byproduct of wineries and a sustainable source of bioactive phenolic compounds. Encapsulation of phenolics with a well-chosen coating may be a promising means of delivering them to the intestine, where they can then be absorbed and exert their health-promoting [...] Read more.
Grape pomace is a byproduct of wineries and a sustainable source of bioactive phenolic compounds. Encapsulation of phenolics with a well-chosen coating may be a promising means of delivering them to the intestine, where they can then be absorbed and exert their health-promoting properties, including antioxidant, anti-inflammatory, anticancer, cardioprotective, and antimicrobial effects. Ionic gelation of grape pomace extract with natural coatings (sodium alginate and its combination with maltodextrins, gelatin, chitosan, gums Tragacanth and Arabic) was performed, and the resulting hydrogel microbeads were then air-, vacuum-, and freeze-dried to prevent spoilage. Freeze-drying showed advantages in preserving the geometrical parameters and morphology of the microbeads compared to other drying techniques. A good relationship was found between the physicochemical properties of the dried microbeads and the in vitro release of phenolics. Freeze-dried microbeads showed the highest cumulative release of phenols in the intestinal phase (23.65–43.27 mgGAE/gMB), while the most suitable release dynamics in vitro were observed for alginate-based microbeads in combination with gelatin, gum Arabic, and 1.5% (w/v) chitosan. The results highlight the importance of developing encapsulated formulations containing a natural source of bioactive compounds that can be used in various functional foods and pharmaceutical products. Full article
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13 pages, 12986 KiB  
Article
Design of Pectin-Based Hydrogel Microspheres for Targeted Pulmonary Delivery
by Andy Chai, Keagan Schmidt, Gregory Brewster, Lu Shi Peng Xiong, Benjamin Church, Timothy Wahl, Hamed Sadabadi, Subha Kumpaty and Wujie Zhang
Gels 2023, 9(9), 707; https://doi.org/10.3390/gels9090707 - 01 Sep 2023
Viewed by 1967
Abstract
Pulmonary drug delivery via microspheres has gained growing interest as a noninvasive method for therapy. However, drug delivery through the lungs via inhalation faces great challenges due to the natural defense mechanisms of the respiratory tract, such as the removal or deactivation of [...] Read more.
Pulmonary drug delivery via microspheres has gained growing interest as a noninvasive method for therapy. However, drug delivery through the lungs via inhalation faces great challenges due to the natural defense mechanisms of the respiratory tract, such as the removal or deactivation of drugs. This study aims to develop a natural polymer-based microsphere system with a diameter of around 3 μm for encapsulating pulmonary drugs and facilitating their delivery to the deep lungs. Pectin was chosen as the foundational material due to its biocompatibility and degradability in physiological environments. Electrospray was used to produce the pectin-based hydrogel microspheres, and Design-Expert software was used to optimize the production process for microsphere size and uniformity. The optimized conditions were determined to be as follows: pectin/PEO ratio of 3:1, voltage of 14.4 kV, distance of 18.2 cm, and flow rate of 0.95 mL/h. The stability and responsiveness of the pectin-based hydrogel microspheres can be altered through coatings such as gelatin. Furthermore, the potential of the microspheres for pulmonary drug delivery (i.e., their responsiveness to the deep lung environment) was investigated. Successfully coated microspheres with 0.75% gelatin in 0.3 M mannitol exhibited improved stability while retaining high responsiveness in the simulated lung fluid (Gamble’s solution). A gelatin-coated pectin-based microsphere system was developed, which could potentially be used for targeted drug delivery to reach the deep lungs and rapid release of the drug. Full article
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19 pages, 3007 KiB  
Article
Carrageenan-Based Crowding and Confinement Combination Approach to Increase Collagen Deposition for In Vitro Tissue Development
by Joseph Krebs, Samuel Stealey, Alyssa Brown, Austin Krohn, Silviya Petrova Zustiak and Natasha Case
Gels 2023, 9(9), 705; https://doi.org/10.3390/gels9090705 - 01 Sep 2023
Cited by 1 | Viewed by 1278
Abstract
Connective tissue models grown from cell monolayers can be instrumental in a variety of biomedical fields such as drug screening, wound healing, and regenerative engineering. However, while connective tissues contain abundant fibrillar collagen, achieving a sufficient assembly and retention of fibrillar collagen in [...] Read more.
Connective tissue models grown from cell monolayers can be instrumental in a variety of biomedical fields such as drug screening, wound healing, and regenerative engineering. However, while connective tissues contain abundant fibrillar collagen, achieving a sufficient assembly and retention of fibrillar collagen in vitro is challenging. Unlike the dilute cell culture environment, the body’s environment is characterized by a high density of soluble macromolecules (crowding) and macromolecular networks (confinement), which contribute to extracellular matrix (ECM) assembly in vivo. Consequently, macromolecular crowding (MMC) has been successfully used to enhance the processing of type I procollagen, leading to significant increases in fibrillar collagen assembly and accumulation during in vitro culture of a variety of cell types. In this study, we developed a combination approach using a carrageenan hydrogel, which released soluble macromolecules and served as a confinement barrier. We first evaluated the local carrageenan release and then confirmed the effectiveness of this combination approach on collagen accumulation by the human MG-63 bone cell line. Additionally, computational modeling of oxygen and glucose transport within the culture system showed no negative effects of the hydrogel and its releasates on cell viability. Full article
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Review

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29 pages, 5054 KiB  
Review
Injectable Hydrogels for Nervous Tissue Repair—A Brief Review
by Gladys Arline Politrón-Zepeda, Gabriela Fletes-Vargas and Rogelio Rodríguez-Rodríguez
Gels 2024, 10(3), 190; https://doi.org/10.3390/gels10030190 - 09 Mar 2024
Cited by 1 | Viewed by 1125
Abstract
The repair of nervous tissue is a critical research field in tissue engineering because of the degenerative process in the injured nervous system. In this review, we summarize the progress of injectable hydrogels using in vitro and in vivo studies for the regeneration [...] Read more.
The repair of nervous tissue is a critical research field in tissue engineering because of the degenerative process in the injured nervous system. In this review, we summarize the progress of injectable hydrogels using in vitro and in vivo studies for the regeneration and repair of nervous tissue. Traditional treatments have not been favorable for patients, as they are invasive and inefficient; therefore, injectable hydrogels are promising for the treatment of damaged tissue. This review will contribute to a better understanding of injectable hydrogels as potential scaffolds and drug delivery system for neural tissue engineering applications. Full article
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34 pages, 2716 KiB  
Review
Advances in Hydrogels for Meniscus Tissue Engineering: A Focus on Biomaterials, Crosslinking, Therapeutic Additives
by Zhuxing Zhou, Jiajie Wang, Chaoqian Jiang, Kaiwang Xu, Tengjing Xu, Xinning Yu, Jinghua Fang, Yanyu Yang and Xuesong Dai
Gels 2024, 10(2), 114; https://doi.org/10.3390/gels10020114 - 01 Feb 2024
Viewed by 1255
Abstract
Meniscus tissue engineering (MTE) has emerged as a promising strategy for meniscus repair and regeneration. As versatile platforms, hydrogels have gained significant attention in this field, as they possess tunable properties that allow them to mimic native extracellular matrices and provide a suitable [...] Read more.
Meniscus tissue engineering (MTE) has emerged as a promising strategy for meniscus repair and regeneration. As versatile platforms, hydrogels have gained significant attention in this field, as they possess tunable properties that allow them to mimic native extracellular matrices and provide a suitable microenvironment. Additionally, hydrogels can be minimally invasively injected and can be adjusted to match the shape of the implant site. They can conveniently and effectively deliver bioactive additives and demonstrate good compatibility with other functional materials. These inherent qualities have made hydrogel a promising candidate for therapeutic approaches in meniscus repair and regeneration. This article provides a comprehensive review of the advancements made in the research on hydrogel application for meniscus tissue engineering. Firstly, the biomaterials and crosslinking strategies used in the formation of hydrogels are summarized and analyzed. Subsequently, the role of therapeutic additives, including cells, growth factors, and other active products, in facilitating meniscus repair and regeneration is thoroughly discussed. Furthermore, we summarize the key issues for designing hydrogels used in MTE. Finally, we conclude with the current challenges encountered by hydrogel applications and suggest potential solutions for addressing these challenges in the field of MTE. We hope this review provides a resource for researchers and practitioners interested in this field, thereby facilitating the exploration of new design possibilities. Full article
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