Advances in Chemistry and Physics of Hydrogels

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

Deadline for manuscript submissions: 30 May 2024 | Viewed by 14438

Special Issue Editor


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Guest Editor
Biomimetic Materials and Tissue Engineering Laboratory, Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208, USA
Interests: bioinspired gels; gels for stem cell delivery; self-assembled micelles for growth factor immobilization; models gels to control cell microenvironment; composite materials with structure at multiple length scales; skeletal tissue engineering
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Special Issue Information

Dear Colleagues, 

Hydrogels are hydrophilic macromolecular networks that retain a significant fraction of water in their structure in a physiological solution without being dissolved. Nutrient molecules, oxygen, carbon dioxide, drug molecules, hormones, cytokines, peptides, proteins, nucleic acids, and other biomolecules readily diffuse through the water-filled volume of hydrogels. Due to their exceptional water content, diffusivity, and elasticity, hydrogels resemble the extracellular matrix (ECM) of living tissues. Human cells encapsulated in hydrogels display viability and function in the same way as their natural ECM. This Special Issue highlights the advances in the chemistry and physics of hydrogels as biomaterials used for tissue repair and reconstruction, as depots for drug delivery, and as scaffolds in regenerative medicine. The relevant topics include, but are not limited to, the hierarchical structure and scaling in natural, biological, and synthetic hydrogels, and their effects on pore size, shape, and size distribution; nano-, meso-, micro-particulate and sheet formations; layering and patterning; diffusivity; uptake and release of active agents; liquid transport; elasticity and stiffness; electric and magnetic susceptibility; swelling and deswelling; biocompatibility and biodegradability; surface tension; protein adsorption; cell and tissue interaction; drug, protein, and cell encapsulation; stimuli sensitivity; immune modulation; and foreign-body response.

Prof. Dr. Esmaiel Jabbari
Guest Editor

Manuscript Submission Information

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Keywords

  • hydrogel
  • chemistry
  • physics
  • natural hydrogels
  • synthetic hydrogels
  • biological hydrogels
  • nanogels
  • microgels
  • hierarchical structure
  • diffusivity and transport
  • biocompatibility
  • biodegradability
  • protein adsorption
  • swelling and deswelling
  • immune modulation
  • foreign-body response
  • stimuli sensitivity
  • functional implant
  • drug delivery
  • tissue regeneration

Published Papers (9 papers)

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Research

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17 pages, 3098 KiB  
Article
Incorporation of Resveratrol-Hydroxypropyl-β-Cyclodextrin Complexes into Hydrogel Formulation for Wound Treatment
by Lyubomira Radeva, Yordan Yordanov, Ivanka Spassova, Daniela Kovacheva, Ivanka Pencheva-El Tibi, Maya M. Zaharieva, Mila Kaleva, Hristo Najdenski, Petar D. Petrov, Virginia Tzankova and Krassimira Yoncheva
Gels 2024, 10(5), 346; https://doi.org/10.3390/gels10050346 - 18 May 2024
Viewed by 420
Abstract
Resveratrol could be applied in wound healing therapies because of its antioxidant, anti-inflammatory and antibacterial effects. However, the main limitation of resveratrol is its low aqueous solubility. In this study, resveratrol was included in hydroxypropyl-β-cyclodextrin complexes and further formulated in Pluronic F-127 hydrogels [...] Read more.
Resveratrol could be applied in wound healing therapies because of its antioxidant, anti-inflammatory and antibacterial effects. However, the main limitation of resveratrol is its low aqueous solubility. In this study, resveratrol was included in hydroxypropyl-β-cyclodextrin complexes and further formulated in Pluronic F-127 hydrogels for wound treatment therapy. IR-spectroscopy and XRD analysis confirmed the successful incorporation of resveratrol into complexes. The wound-healing ability of these complexes was estimated by a scratch assay on fibroblasts, which showed a tendency for improvement of the effect of resveratrol after complexation. The antimicrobial activity of resveratrol in aqueous dispersion and in the complexes was evaluated on methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Candida albicans strains. The results revealed a twofold decrease in the MIC and stronger inhibition of the metabolic activity of MRSA after treatment with resveratrol in the complexes compared to the suspended drug. Furthermore, the complexes were included in Pluronic hydrogel, which provided efficient drug release and appropriate viscoelastic properties. The formulated hydrogel showed excellent biocompatibility which was confirmed via skin irritation test on rabbits. In conclusion, Pluronic hydrogel containing resveratrol included in hydroxypropyl-β-cyclodextrin complexes is a promising topical formulation for further studies directed at wound therapy. Full article
(This article belongs to the Special Issue Advances in Chemistry and Physics of Hydrogels)
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14 pages, 2520 KiB  
Article
Sequential Fabrication of a Three-Layer Retina-like Structure
by Yahel Shechter, Roni Cohen, Michael Namestnikov, Assaf Shapira, Adiel Barak, Aya Barzelay and Tal Dvir
Gels 2024, 10(5), 336; https://doi.org/10.3390/gels10050336 - 15 May 2024
Viewed by 821
Abstract
Tissue engineering is considered a promising approach to treating advanced degenerative maculopathies such as nonexudative age-related macular degeneration (AMD), the leading cause of blindness worldwide. The retina consists of several hierarchical tissue layers, each of which is supported by a layer underneath. Each [...] Read more.
Tissue engineering is considered a promising approach to treating advanced degenerative maculopathies such as nonexudative age-related macular degeneration (AMD), the leading cause of blindness worldwide. The retina consists of several hierarchical tissue layers, each of which is supported by a layer underneath. Each of these layers has a different morphology and requires distinct conditions for proper assembly. In fact, a prerequisite step for the assembly of each of these layers is the organization of the layer underneath. Advanced retinal degeneration includes degeneration of the other retina layers, including the choroid, the retinal pigmented epithelium (RPE), and the photoreceptors. Here, we report a step-by-step fabrication process of a three-layer retina-like structure. The process included the 3D printing of a choroid-like structure in an extracellular matrix (ECM) hydrogel, followed by deposition of the RPE monolayer. After the formation of the blood vessel–RPE interface, the photoreceptor cells were deposited to interact with the RPE layer. At the end of the fabrication process, each layer was characterized for its morphology and expression of specific markers, and the integration of the three-layer retina was evaluated. We envision that such a retina-like structure may be able to attenuate the deterioration of a degenerated retina and improve engraftment and regeneration. This retinal implant may potentially be suitable for a spectrum of macular degenerative diseases for which there are currently no cures and may save millions from complete blindness. Full article
(This article belongs to the Special Issue Advances in Chemistry and Physics of Hydrogels)
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27 pages, 6141 KiB  
Article
Development of Poly(sorbitol adipate)-g-poly(ethylene glycol) Mono Methyl Ether-Based Hydrogel Matrices for Model Drug Release
by Haroon Rashid, Henrike Lucas, Karsten Busse, Jörg Kressler, Karsten Mäder and Marie-Luise Trutschel
Gels 2024, 10(1), 17; https://doi.org/10.3390/gels10010017 - 23 Dec 2023
Viewed by 1086
Abstract
Hydrogels were prepared by Steglich esterification and by crosslinking pre-synthesized poly(sorbitol adipate)-graft-poly(ethylene glycol) mono methyl ether (PSA-g-mPEG) using different-chain-length-based disuccinyl PEG. PSA and PSA-g-mPEG were investigated for polymer degradation as a function of time at different temperatures. [...] Read more.
Hydrogels were prepared by Steglich esterification and by crosslinking pre-synthesized poly(sorbitol adipate)-graft-poly(ethylene glycol) mono methyl ether (PSA-g-mPEG) using different-chain-length-based disuccinyl PEG. PSA and PSA-g-mPEG were investigated for polymer degradation as a function of time at different temperatures. PSA-g-mPEG hydrogels were then evaluated for their most crucial properties of swelling that rendered them suitable for many pharmaceutical and biomedical applications. Hydrogels were also examined for their Sol-Gel content in order to investigate the degree of cross-linking. Physical structural parameters of the hydrogels were theoretically estimated using the modified Flory–Rehner theory to obtain approximate values of polymer volume fraction, the molecular weight between two crosslinks, and the mesh size of the hydrogels. X-ray diffraction was conducted to detect the presence or absence of crystalline regions in the hydrogels. PSA-g-mPEG hydrogels were then extensively examined for higher and lower molecular weight solute release through analysis by fluorescence spectroscopy. Finally, the cytotoxicity of the hydrogels was also investigated using a resazurin reduction assay. Experimental results show that PSA-g-mPEG provides an option as a biocompatible polymer to be used for pharmaceutical applications. Full article
(This article belongs to the Special Issue Advances in Chemistry and Physics of Hydrogels)
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13 pages, 2070 KiB  
Article
Factors That Influence Base-Catalyzed Thiol-Ene Hydrogel Synthesis
by Nolan Morrison and Brandon M. Vogel
Gels 2023, 9(11), 917; https://doi.org/10.3390/gels9110917 - 20 Nov 2023
Cited by 1 | Viewed by 1810
Abstract
Injectable, localized drug delivery using hydrogels made from ethoxylated trimethylolpropane tri-3-mercaptopropionate (ETTMP) and poly(ethylene glycol) diacrylate (PEGDA) has shown great potential due to these hydrogels’ ability to exhibit non-swelling behavior and tunable drug release properties. However, current synthesis methods in the literature suffer [...] Read more.
Injectable, localized drug delivery using hydrogels made from ethoxylated trimethylolpropane tri-3-mercaptopropionate (ETTMP) and poly(ethylene glycol) diacrylate (PEGDA) has shown great potential due to these hydrogels’ ability to exhibit non-swelling behavior and tunable drug release properties. However, current synthesis methods in the literature suffer from poor ETTMP solubility in water, slow gelation times exceeding 20 min, and a lack of reproducibility. To address these limitations, we have developed a reliable synthesis procedure and conducted a sensitivity analysis of key variables. This has enabled us to synthesize ETTMP-PEGDA hydrogels in a polymer concentration range of 15 to 90 wt% with gelation times of less than 2 min and moduli ranging from 3.5 to 190 kPa. We overcame two synthesis limitations by identifying the impact of residual mercaptopropionic acid and alumina purification column height on gelation time and by premixing ETTMP and PEGDA to overcome low ETTMP solubility in water. Our ETTMP-PEGDA mixture can be stored at −20 °C for up to 2 months without crosslinking, allowing easy storage and shipment. These and previous results demonstrate the potential of ETTMP-PEGDA hydrogels as promising candidates for injectable, localized drug delivery with tunable drug release properties. Full article
(This article belongs to the Special Issue Advances in Chemistry and Physics of Hydrogels)
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18 pages, 12108 KiB  
Article
Flexible Topical Hydrogel Patch Loaded with Antimicrobial Drug for Accelerated Wound Healing
by Sana Saeed, Kashif Barkat, Muhammad Umer Ashraf, Maryam Shabbir, Irfan Anjum, Syed Faisal Badshah, Muhammad Aamir, Nadia Shamshad Malik, Akash Tariq and Riaz Ullah
Gels 2023, 9(7), 567; https://doi.org/10.3390/gels9070567 - 12 Jul 2023
Cited by 1 | Viewed by 2385
Abstract
A hydrogel topical patch of neomycin was developed by using sodium alginate (SA) and hydroxyethylcellulose (HEC) as polymers. Free radical polymerization in an aqueous medium was initiated by using acrylic acid (AA) and N,N′-methylenebisacrylamide (MBA). Prepared hydrogels were characterized for pH sensitivity and [...] Read more.
A hydrogel topical patch of neomycin was developed by using sodium alginate (SA) and hydroxyethylcellulose (HEC) as polymers. Free radical polymerization in an aqueous medium was initiated by using acrylic acid (AA) and N,N′-methylenebisacrylamide (MBA). Prepared hydrogels were characterized for pH sensitivity and sol–gel analysis. In addition, the effect of reactant contents on the developed formulation was evaluated by swelling behavior. SEM assay showed the rough structure of the hydrogel-based polymeric matrix, which directly enhances the ability to uptake fluid. FTIR spectra revealed the formation of a new polymeric network between reactant contents. TGA and DSC verified that fabricated polymeric patches were more thermodynamically stable than pure components. Gel fractions increased with increases in polymer, monomer, and cross-linker contents. The swelling study showed the pH-dependent swelling behavior of patches at pH 5.5, 6.5, and 7.4. The release pattern of the drug followed zero-order kinetics, with diffusion-controlled drug release patterns according to the Korsmeyer–Peppas (KP) model. Ex vivo studies across excised rabbit skin verified the drug retention in the skin layers. The hydrogel patch effectively healed the wounds produced on the rabbit skin, whereas the formulation showed no sign of irritation on intact skin. Therefore, neomycin hydrogel patches can be a potential candidate for controlled delivery for efficient wound healing. Full article
(This article belongs to the Special Issue Advances in Chemistry and Physics of Hydrogels)
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14 pages, 7891 KiB  
Article
Alginate-Chitosan Hydrogels Containing shRNA Plasmid for Inhibition of CTNNB1 Expression in Breast Cancer Cells
by Birnur Cömez and Suna Özbaş
Gels 2023, 9(7), 541; https://doi.org/10.3390/gels9070541 - 4 Jul 2023
Viewed by 1198
Abstract
The hydrogels prepared with alginate and chitosan polymers were prepared to deliver the shRNA-encoding plasmid (pshRNA) to MDA-MB-231 cells for the inhibition of β-catenin (CTNNB1), which was reported to be overexpressed in breast cancer. Polyion complex hydrogels prepared using sodium alginate and chitosan [...] Read more.
The hydrogels prepared with alginate and chitosan polymers were prepared to deliver the shRNA-encoding plasmid (pshRNA) to MDA-MB-231 cells for the inhibition of β-catenin (CTNNB1), which was reported to be overexpressed in breast cancer. Polyion complex hydrogels prepared using sodium alginate and chitosan were characterized by Fourier transform infrared spectrometry (FTIR) analysis, scanning electron microscope (SEM) analysis, swelling, and degradation properties. After the release properties and serum stability of pshRNA-loaded hydrogels were determined, their cytotoxicity, transfection efficacy, and effects on CTNNB1 expression were investigated in MDA-MB-231 cells. All hydrogels were shown to protect pshRNA from the enzymatic activity of serum and to deliver pshRNA to cells efficiently. As a result of transfection studies, pshRNA-loaded hydrogels reduced CTNNB1 expression by up to 30.25%. Cell viability also decreased by 38% in cells treated with 2.5% (w/v) alginate-chitosan hydrogel containing pshRNA targeting CTNNB1. Alginate-chitosan hydrogels were shown to be a suitable matrix system for local gene delivery. Full article
(This article belongs to the Special Issue Advances in Chemistry and Physics of Hydrogels)
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Review

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22 pages, 1973 KiB  
Review
Dancing with Nucleobases: Unveiling the Self-Assembly Properties of DNA and RNA Base-Containing Molecules for Gel Formation
by Pasqualina Liana Scognamiglio, Caterina Vicidomini and Giovanni N. Roviello
Gels 2024, 10(1), 16; https://doi.org/10.3390/gels10010016 - 23 Dec 2023
Cited by 1 | Viewed by 1396
Abstract
Nucleobase-containing molecules are compounds essential in biology due to the fundamental role of nucleic acids and, in particular, G-quadruplex DNA and RNA in life. Moreover, some molecules different from nucleic acids isolated from different vegetal sources or microorganisms show nucleobase moieties in their [...] Read more.
Nucleobase-containing molecules are compounds essential in biology due to the fundamental role of nucleic acids and, in particular, G-quadruplex DNA and RNA in life. Moreover, some molecules different from nucleic acids isolated from different vegetal sources or microorganisms show nucleobase moieties in their structure. Nucleoamino acids and peptidyl nucleosides belong to this molecular class. Closely related to the above, nucleopeptides, also known as nucleobase-bearing peptides, are chimeric derivatives of synthetic origin and more rarely isolated from plants. Herein, the self-assembly properties of a vast number of structures, belonging to the nucleic acid and nucleoamino acid/nucleopeptide family, are explored in light of the recent scientific literature. Moreover, several technologically relevant properties, such as the hydrogelation ability of some of the nucleobase-containing derivatives, are reviewed in order to make way for future experimental investigations of newly devised nucleobase-driven hydrogels. Nucleobase-containing molecules, such as mononucleosides, DNA, RNA, quadruplex (G4)-forming oligonucleotides, and nucleopeptides are paramount in gel and hydrogel formation owing to their distinctive molecular attributes and ability to self-assemble in biomolecular nanosystems with the most diverse applications in different fields of biomedicine and nanotechnology. In fact, these molecules and their gels present numerous advantages, underscoring their significance and applicability in both material science and biomedicine. Their versatility, capability for molecular recognition, responsiveness to stimuli, biocompatibility, and biodegradability collectively contribute to their prominence in modern nanotechnology and biomedicine. In this review, we emphasize the critical role of nucleobase-containing molecules of different nature in pioneering novel materials with multifaceted applications, highlighting their potential in therapy, diagnostics, and new nanomaterials fabrication as required for addressing numerous current biomedical and nanotechnological challenges. Full article
(This article belongs to the Special Issue Advances in Chemistry and Physics of Hydrogels)
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18 pages, 1739 KiB  
Review
Application of Hydrogels in the Device of Ophthalmic Iontophoresis: Theory, Developments and Perspectives
by Dong Wei, Ning Pu, Si-Yu Li, Na Zhao, Zong-Ming Song and Ye Tao
Gels 2023, 9(7), 519; https://doi.org/10.3390/gels9070519 - 26 Jun 2023
Cited by 1 | Viewed by 1439
Abstract
The human eye is a consolidated organ with delicate structures and unique immune privileges. Ocular diseases are intractable due to the intrinsic biological barriers within the eyeball. Hydrogels are excellent drug-carrying substances with soft material and excellent properties. They have been extensively used [...] Read more.
The human eye is a consolidated organ with delicate structures and unique immune privileges. Ocular diseases are intractable due to the intrinsic biological barriers within the eyeball. Hydrogels are excellent drug-carrying substances with soft material and excellent properties. They have been extensively used to deliver drugs into ocular tissue via iontophoresis devices. Ophthalmic iontophoresis is an electrochemical technique using tiny electrical currents to deliver drugs into the eye non-invasively. The early infantile iontophoresis technique often required long applying time to achieve therapeutic dose in the posterior ocular segment. The potential limitations in the initial drug concentration and the maximum safe currents would also impede the efficiency and safety of iontophoresis. Moreover, the poor patient compliance always leads to mechanical damage to the cornea and sclera during application. Advantageously, the flexible drug-carrying hydrogel can be in direct contact with the eye during iontophoresis, thereby reducing mechanical damage to the ocular surface. Moreover, the water absorption and adjustable permeability of hydrogels can reduce the electrochemical (EC) reactions and enhance the efficiency of iontophoresis. In this review, we focus on recent developments of hydrogels iontophoresis in ophthalmologic practice. Refinements of the knowledge would provide an outlook for future application of hydrogels in treating ocular disease. Full article
(This article belongs to the Special Issue Advances in Chemistry and Physics of Hydrogels)
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Other

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21 pages, 2592 KiB  
Systematic Review
Green Synthesis of Silver Nanoparticles Loaded Hydrogel for Wound Healing; Systematic Review
by Fahad M. Aldakheel, Marwa M. El Sayed, Dalia Mohsen, Mohammed H. Fagir and Dalia K. El Dein
Gels 2023, 9(7), 530; https://doi.org/10.3390/gels9070530 - 29 Jun 2023
Cited by 8 | Viewed by 2845
Abstract
Wound healing is a biological process that involves a series of consecutive process, and its impairment can lead to chronic wounds and various complications. Recently, there has been a growing interest in employing nanotechnology to enhance wound healing. Silver nanoparticles (AgNPs) have expanded [...] Read more.
Wound healing is a biological process that involves a series of consecutive process, and its impairment can lead to chronic wounds and various complications. Recently, there has been a growing interest in employing nanotechnology to enhance wound healing. Silver nanoparticles (AgNPs) have expanded significant attention due to their wide range of applications in the medical field. The advantages of AgNPs include their easy synthesis, change their shape, and high surface area. Silver nanoparticles are very efficient for topical drug administration and wound healing because of their high ratio of surface area to volume. The efficiency of AgNPs depends on the synthesis method and the intended application. Green synthesis methods offer an eco-friendly approach by utilizing natural sources such as plant extracts and fungus. The characterization of nanoparticles plays an important character, and it is accomplished through the use of several characterization methods such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). These techniques are employed to confirm the specific characters of the prepared Silver Nanoparticles. Additionally, the review addresses the challenges and future perspectives of utilizing green-synthesized AgNPs loaded in Polyacrylamide hydrogel for wound healing applications, including the optimization of nanoparticle size, and release kinetics. Overall, this review highlights the potential of green-synthesized AgNPs loaded in Polyacrylamide hydrogel as promising for advanced wound healing therapies. There are different approaches of usage of AgNPs for wound healing such as polyacrylamide -hydrogels, and the mechanism after their antibacterial action, have been exposed. Full article
(This article belongs to the Special Issue Advances in Chemistry and Physics of Hydrogels)
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