Special Issue "Hydrogels and Gels for Biomedical and Sustainable Applications"

A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: closed (25 January 2019).

Special Issue Editors

Dr. Miroslava Dušková-Smrčková
Website
Guest Editor
Department of Polymer Networks and Gels, Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Prague, Czech Republic,
Interests: keywords: formation-structure-properties of polymer gels a networks—experiment&theory; hydrogels for tissue engineering; interaction of polymer gels and networks with solvents and water; polymeric coating systems; phase separation in gels and networks; application of statistical theory of branching processes; mechanical properties and viscoelasticity of polymer networks and gels
Dr. Radka Hobzová
Website
Guest Editor
Department of Polymer Networks and Gels, Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Prague, Czech Republi
Interests: biomedical hydrogels; hydrogels for drug delivery; polymer synthesis and characterization; biomaterials

Special Issue Information

Dear Colleagues,

Macromolecular networks and gels, especially hydrogels, synthetic or natural, specially designed, hybrid or interpenetrating are intriguing materials which inspire researchers by their similarity to natural tissues, living matter which provides large scale of advanced functions of life. The topic of crosslinked state of matter utilized in swelling materials and devices now attracts great attention of scientific community.

The recent 82nd Prague Meeting on Macromolecules - Polymer Networks and Gels 2018 and 24th meeting of the international Polymer Networks Group brought together researchers of the large international community from both academia and industry engaged in science and technology of polymer gels and networks, both synthetic and natural. The emphasis of the conference centered on experimental and theoretical studies of the relations between the formation, chemical composition, structure, and properties of polymer networks and gels. There were many interesting lectures and poster contributions which deserve to be collected in one dedicated volume.

We therefore want to compose a special issue of the Polymers journal. The forum is open to contributions from the area of polymer networks with special emphasis on hydrogels in biomedical applications, such as their responsivity, drug delivery, tissue engineering and their structure, swelling, mechanical, and other properties. Also, contributions related to cross-linked materials for energy storage, water purification and those coming from natural renewable resources and contributing to sustainable technology and life are welcome.

The possible keywords for contributions are:

  • Preparation and chemical design of hydrogels and gels
    controlled polymerization methods, organic and organic-inorganic gels, micro- and nanocomposites, biopolymer gels, synthesis of hybrid systems with biopolymer motifs, physical gels, gel formation and reaction kinetics
  • Gelation, gel formation, and properties
    structure changes during physical and chemical gelation; static and dynamic properties, swelling behavior: equilibrium and dynamics, gel state of matter: from liquids to soft solids on time/temperature scales; simulation and modeling of build-up and properties of covalent and physical gels, structure organization, micro- and macrophase separation, constraint gels
  • Hydrogels and gels at work/service
    gels in life sciences, controlled drug release and targeting, responsive gels in biomedical and diagnostic applications, gel constructs, contact lenses and eye devices, networks and gels from renewable resources, crosslinked layers, coatings and thermosets, computational design of gel materials

We hope that you will find this idea of a common project of putting together a special issue of Polymers interesting and we are looking forward to your contribution!

Miroslava Dušková-Smčková and Radka Hobzová
Guest Editors

Manuscript Submission Information

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Keywords

  • hydrogels for biomedical application
  • tissue engineering, interpenetrating/double network hydrogels
  • hydrogels for water treatment
  • hydrogels for sustaining environment
  • characterization of hydrogels
  • mechanical behavior
  • hydrogel synthesis
  • gel polyelectrolytes
  • responsive hydrogels

Published Papers (11 papers)

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Research

Open AccessArticle
Microscopic Structure of Swollen Hydrogels by Scanning Electron and Light Microscopies: Artifacts and Reality
Polymers 2020, 12(3), 578; https://doi.org/10.3390/polym12030578 - 05 Mar 2020
Cited by 1
Abstract
The exact knowledge of hydrogel microstructure, mainly its pore topology, is a key issue in hydrogel engineering. For visualization of the swollen hydrogels, the cryogenic or high vacuum scanning electron microscopies (cryo-SEM or HVSEM) are frequently used while the possibility of artifact-biased images [...] Read more.
The exact knowledge of hydrogel microstructure, mainly its pore topology, is a key issue in hydrogel engineering. For visualization of the swollen hydrogels, the cryogenic or high vacuum scanning electron microscopies (cryo-SEM or HVSEM) are frequently used while the possibility of artifact-biased images is frequently underestimated. The major cause of artifacts is the formation of ice crystals upon freezing of the hydrated gel. Some porous hydrogels can be visualized with SEM without the danger of artifacts because the growing crystals are accommodated within already existing primary pores of the gel. In some non-porous hydrogels the secondary pores will also not be formed due to rigid network structure of gels that counteracts the crystal nucleation and growth. We have tested the limits of true reproduction of the hydrogel morphology imposed by the swelling degree and mechanical strength of gels by investigating a series of methacrylate hydrogels made by crosslinking polymerization of glycerol monomethacrylate and 2-hydroxyethyl methacrylate including their interpenetrating networks. The hydrogel morphology was studied using cryo-SEM, HVSEM, environmental scanning electron microscopy (ESEM), laser scanning confocal microscopy (LSCM) and classical wide-field light microscopy (LM). The cryo-SEM and HVSEM yielded artifact-free micrographs for limited range of non-porous hydrogels and for macroporous gels. A true non-porous structure was observed free of artifacts only for hydrogels exhibiting relatively low swelling and high elastic modulus above 0.5 MPa, whereas for highly swollen and/or mechanically weak hydrogels the cryo-SEM/HVSEM experiments resulted in secondary porosity. In this contribution we present several cases of severe artifact formation in PHEMA and PGMA hydrogels during their visualization by cryo-SEM and HVSEM. We also put forward empirical correlation between hydrogel morphological and mechanical parameters and the occurrence and intensity of artifacts. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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Open AccessArticle
A Composite Hydrogel with High Mechanical Strength, Fluorescence, and Degradable Behavior for Bone Tissue Engineering
Polymers 2019, 11(7), 1112; https://doi.org/10.3390/polym11071112 - 01 Jul 2019
Cited by 5
Abstract
In this work, to obtain a novel composite hydrogel with high mechanical strength, fluorescence and degradable behavior for bone tissue engineering, we prepare a nanofiller and double-network (DN) structure co-enhanced carbon dots/hydroxyapatite/poly (vinyl alcohol) (CDs/HA/PVA) DN hydrogel. The composite hydrogels are fabricated by [...] Read more.
In this work, to obtain a novel composite hydrogel with high mechanical strength, fluorescence and degradable behavior for bone tissue engineering, we prepare a nanofiller and double-network (DN) structure co-enhanced carbon dots/hydroxyapatite/poly (vinyl alcohol) (CDs/HA/PVA) DN hydrogel. The composite hydrogels are fabricated by a combination of two fabrication techniques including chemical copolymerization and freezing‒thawing cycles, and further characterized by FTIR, XRD, etc. Additional investigations focus on the mechanical properties of the hydrogel with varying mass ratios of CDs to PVA, HA to PVA and different numbers of freezing/thawing cycles. The results show that the as-prepared CDs3.0/HA0.6/PVA DN9 hydrogel has optimized compression properties (Compression strength = 3.462 MPa, Young’s modulus = 4.5 kPa). This is mainly caused by the synergism effect of the nanofiller and chemical and physical co-crosslinking. The water content and swelling ratio of the CDs/HA/PVA SN and DN gels are also systematically investigated to reveal the relationship of their microstructural features and mechanical behavior. In addition, in vitro degradation tests of the CDs/HA/PVA DN hydrogel show that the DN hydrogels have a prominent degradable behavior. So, they have potential to be used as high-strength, self-tracing bone substitutes in the biomedical engineering field. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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Open AccessArticle
Hydrogel Tissue Expanders for Stomatology. Part II. Poly(styrene-maleic anhydride) Hydrogels
Polymers 2019, 11(7), 1087; https://doi.org/10.3390/polym11071087 - 26 Jun 2019
Abstract
Self-inflating soft tissue expanders represent a valuable modality in reconstructive surgery. For this purpose, particularly synthetic hydrogels that increase their volume by swelling in aqueous environment are used. The current challenge in the field is to deliver a material with a suitable protracted [...] Read more.
Self-inflating soft tissue expanders represent a valuable modality in reconstructive surgery. For this purpose, particularly synthetic hydrogels that increase their volume by swelling in aqueous environment are used. The current challenge in the field is to deliver a material with a suitable protracted swelling response, ideally with an induction period (for sutured wound healing) followed by a linear increase in volume lasting several days for required tissue reconstruction. Here, we report on synthesis, swelling, thermal, mechanical and biological properties of novel hydrogel tissue expanders based on poly(styrene-alt-maleic anhydride) copolymers covalently crosslinked with p-divinylbenzene. The hydrogels exerted hydrolysis-driven swelling response with induction period over the first two days with minimal volume change and gradual volume growth within 30 days in buffered saline solution. Their final swollen volume reached more than 14 times the dry volume with little dependence on the crosslinker content. The mechanical coherence of samples during swelling and in their fully swollen state was excellent, the compression modulus of elasticity being between 750 and 850 kPa. In vitro cell culture experiments and in vivo evaluation in mice models showed excellent biocompatibility and suitable swelling responses meeting thus the application requirements as soft tissue expanders. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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Open AccessArticle
Influence of Hydrophobicity of Backbone Polymer in Thermo-Responsive Hydrogel with Immobilized Amine on Cycle Capacity for Absorption and Recovery of CO2
Polymers 2019, 11(6), 1024; https://doi.org/10.3390/polym11061024 - 10 Jun 2019
Abstract
The chemisorption process with amines is the major separation and recovery method of CO2 because of its high processing capacity and simplicity. However, large energy consumption for the desorption of CO2 is also associated with the process. To develop a separation [...] Read more.
The chemisorption process with amines is the major separation and recovery method of CO2 because of its high processing capacity and simplicity. However, large energy consumption for the desorption of CO2 is also associated with the process. To develop a separation and recovery process that is capable of desorbing CO2 at low temperatures and with minimal energy consumption, polymer hydrogels with a lower critical solution temperature (LCST) polymer network and amine groups immobilized in the polymer network of the hydrogels were exploited. Thermo-responsive amine gels with a series of hydrophobicity of polymer networks were systematically synthesized, and the influence of the hydrophobicity of the gels on the CO2 desorption temperature and cycle capacity (CO2 amount that can be separated and recovered by 1 cycle of temperature swing operation) was investigated using slurries with the series of gels. A significant decrease in the CO2 desorption temperature and increase in the cycle capacity occurred simultaneously by lowering the LCST of the gels via hydrophobisation of the polymer network. Based on an equilibrium adsorption model representing the CO2 separation and a recovery system with the gel slurries, an analysis of the system dynamics was performed in order to understand the recovery mechanism in the process. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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Open AccessArticle
Preparation of Hydrogel/Silver Nanohybrids Mediated by Tunable-Size Silver Nanoparticles for Potential Antibacterial Applications
Polymers 2019, 11(4), 716; https://doi.org/10.3390/polym11040716 - 19 Apr 2019
Cited by 5
Abstract
In this study, a versatile synthesis of silver nanoparticles of well-defined size by using hydrogels as a template and stabilizer of nanoparticle size is reported. The prepared hydrogels are based on polyvinyl alcohol and maleic acid as crosslinker agents. Three hydrogels with the [...] Read more.
In this study, a versatile synthesis of silver nanoparticles of well-defined size by using hydrogels as a template and stabilizer of nanoparticle size is reported. The prepared hydrogels are based on polyvinyl alcohol and maleic acid as crosslinker agents. Three hydrogels with the same nature were synthesized, however, the crosslinking degree was varied. The silver nanoparticles were synthesized into each prepared hydrogel matrix achieving three significant, different-sized nanoparticles that were spherical in shape with a narrow size distribution. It is likely that the polymer network stabilized the nanoparticles. It was determined that the hydrogel network structure can control the size and shape of the nanoparticles. The hydrogel/silver nanohybrids were characterized by swelling degree, Thermal Gravimetric Analysis (TGA), Fourier Transform Infrared (FT-IR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscope (TEM). Antibacterial activity against Staphylococcus aureus was evaluated, confirming antimicrobial action of the encapsulated silver nanoparticles into the hydrogels. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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Open AccessArticle
Controlled Electron-Beam Synthesis of Transparent Hydrogels for Drug Delivery Applications
Polymers 2019, 11(3), 501; https://doi.org/10.3390/polym11030501 - 14 Mar 2019
Abstract
In this study, we highlight hydrogels prepared by electron-beam polymerization. In general, the electron-beam-polymerized hydrogels showed improved mechanical and optical transmittances compared to the conventional UV-cured hydrogels. They were more elastic and had a higher crosslinking density. Additionally, they were transparent over a [...] Read more.
In this study, we highlight hydrogels prepared by electron-beam polymerization. In general, the electron-beam-polymerized hydrogels showed improved mechanical and optical transmittances compared to the conventional UV-cured hydrogels. They were more elastic and had a higher crosslinking density. Additionally, they were transparent over a broader wavelength range. The dependence of the mechanical and optical properties of the hydrogels on the number of single differential and total irradiation doses was analyzed in detail. The hydrogels were prepared for usage as a drug delivery material with methylene blue as a drug model. In the first set of experiments, methylene blue was loaded reversibly after the hydrogel synthesis. Electron-beam-polymerized hydrogels incorporated twice as much methylene blue compared to the UV-polymerized gels. Furthermore, the release of the model drug was found to depend on the crosslinking degree of the hydrogels. In addition, electron-beam polymerization enabled the irreversible binding of the drug molecules if they were mixed with monomers before polymerization. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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Open AccessArticle
Self-Healing Hydrogels with both LCST and UCST through Cross-Linking Induced Thermo-Response
Polymers 2019, 11(3), 490; https://doi.org/10.3390/polym11030490 - 13 Mar 2019
Cited by 3
Abstract
Self-healing hydrogels have drawngreat attention in the past decade since the self-healing property is one of the characteristics of living creatures. In this study, poly(acrylamide-stat-diacetone acrylamide) P(AM-stat-DAA) with a pendant ketone group was synthesized from easy accessible monomers, and thermo-responsive self-healing [...] Read more.
Self-healing hydrogels have drawngreat attention in the past decade since the self-healing property is one of the characteristics of living creatures. In this study, poly(acrylamide-stat-diacetone acrylamide) P(AM-stat-DAA) with a pendant ketone group was synthesized from easy accessible monomers, and thermo-responsive self-healing hydrogels were prepared through a series of diacylhydrazide compounds cross-linking without any additional stimulus. Although the copolymers do not show thermo-response, the hydrogels became thermo-responsive andboth the lower critical solution temperature (LCST) and upper critical solution temperature (UCST) varied with the composition of the copolymer and structure of cross-linkers. With a dynamic covalent bond connection, the hydrogel showed gel-sol-gel transition triggered by acidity, redox, and ketone to acylhydrazide group ratios. This is another interesting cross-linking induced thermo-responsive (CIT) hydrogel with different properties compared to PNIPAM-based thermo-responsive hydrogels. The self-healing hydrogel with CIT properties could have great potential for application in areas related to bioscience, life simulation, and temperature switching. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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Open AccessArticle
Regenerated Antheraea pernyi Silk Fibroin/Poly(N-isopropylacrylamide) Thermosensitive Composite Hydrogel with Improved Mechanical Strength
Polymers 2019, 11(2), 302; https://doi.org/10.3390/polym11020302 - 11 Feb 2019
Cited by 3
Abstract
At present, Antheraea pernyi silk fibroin (ASF) has attracted research efforts to investigate it as a raw material for fabrication of biomedical devices because of its superior cytocompatibility. Nevertheless, native ASF is not easily processed into a hydrogel without any crosslinking agent, and [...] Read more.
At present, Antheraea pernyi silk fibroin (ASF) has attracted research efforts to investigate it as a raw material for fabrication of biomedical devices because of its superior cytocompatibility. Nevertheless, native ASF is not easily processed into a hydrogel without any crosslinking agent, and a single hydrogel shows poor mechanical properties. In this paper, a series of ASF/poly (N-isopropylacrylamide) (PNIPAAm) composite hydrogels with different ASF contents were manufactured by a simple in situ polymerization method without any crosslinking agent. Meanwhile, the structures, morphologies and thermal properties of composite hydrogels were investigated by XRD, FTIR, SEM, DSC and TGA, respectively. The results indicate that the secondary structure of silk in the composite hydrogel can be controlled by changing the ASF content and the thermal stability of composite hydrogels is enhanced with an increase in crystalline structure. The composite hydrogels showed similar lower critical solution temperatures (LCST) at about 32 °C, which matched well with the LCST of PNIPAAm. Finally, the obtained thermosensitive composite hydrogels exhibited enhanced mechanical properties, which can be tuned by varying the content of ASF. This strategy to prepare an ASF-based responsive composite hydrogel with enhanced mechanical properties represents a valuable route for developing the fields of ASF, and, furthermore, their attractive applications can meet the needs of different biomaterial fields. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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Open AccessArticle
Evaluating the Effects of Nanosilica on Mechanical and Tribological Properties of Polyvinyl Alcohol/Polyacrylamide Polymer Composites for Artificial Cartilage from an Atomic Level
Polymers 2019, 11(1), 76; https://doi.org/10.3390/polym11010076 - 06 Jan 2019
Cited by 4
Abstract
Due to the superior performances of nanosilica particles, this research has been designed to study their effects on the mechanical and trigological properties of a PVA/PAM polymer composite by a molecular dynamics simulation method. To realize the research objectives mentioned above, the molecular [...] Read more.
Due to the superior performances of nanosilica particles, this research has been designed to study their effects on the mechanical and trigological properties of a PVA/PAM polymer composite by a molecular dynamics simulation method. To realize the research objectives mentioned above, the molecular models of amorphous cells and sandwiched friction models for pure polyvinyl alcohol (PVA)/polyacrylamide (PAM) (component weight ratio is 1:1) and PVA/PAM/nanosilica (component weight ratio is 5.75:5.75:1) polymer composites were constructed and simulated, respectively. The simulation results of the mechanical properties show increases about 31.6% in the bulk modulus, 53.1% in the shear modulus, and 50.1% in the Young’s modulus by incorporating a nanosilica particle into a pure PVA/PAM polymer composite. Meanwhile, the changes in Cauchy pressure, B/G ratio, and Poisson’s ratio values indicate that incorporating a nanosilica particle into pure PVA/PAM weakened the ductility of the composite. Incorporating a nanosilica particle into a pure PVA/PAM composite also showed a decrease about 28.2% in the abrasion rates and relative concentration distributions of polymer molecules in the final friction models. Additionally, the binding energy and the pair correlation functions between a nanosilica particle and the polymer chains in a cubic cell demonstrate that incorporating nanosilica into PVA/PAM polymer composites improves the internal binding strength between different components through the forming hydrogen bonds. As a result, the mechanical and tribological properties of PVA/PAM polymer composites can be enhanced by incorporating nanosilica particles. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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Open AccessArticle
Synthesis, Characterization, and Antifogging Application of Polymer/Al2O3 Nanocomposite Hydrogels with High Strength and Self-Healing Capacity
Polymers 2018, 10(12), 1362; https://doi.org/10.3390/polym10121362 - 08 Dec 2018
Cited by 1
Abstract
Hydrogels with outstanding mechanical performance, self-healing capacity, and special functionality are highly desirable for their practical applications. However, it remains a great challenge to achieve such hydrogels by a facile approach. Here, we report a new type of nanocomposite hydrogels by in situ [...] Read more.
Hydrogels with outstanding mechanical performance, self-healing capacity, and special functionality are highly desirable for their practical applications. However, it remains a great challenge to achieve such hydrogels by a facile approach. Here, we report a new type of nanocomposite hydrogels by in situ copolymerization of acrylic acid (AA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) using alumina nanoparticles (Al2O3 NPs) as the cross-linkers. The obtained hydrogels are highly stretchable and compressible, which could sustain large-scale extension (>1700%) or compression (90%) without failure, and exhibit tensile and compressive strength up to 660 kPa and 8.3 MPa, respectively. Furthermore, this kind of hydrogel also display considerable self-healing capacity due to their noncovalent cross-linking mechanism, as well as the hydrogen-bonding interactions between polymer chains. More interestingly, it was found that the resultant gels possess a long-lasting antifogging property that could prevent the formation of fog on the glass plate above hot water for at least 90 min. It is expected that this novel type of hydrogel would show great promise for various applications, including soft robots, artificial muscles, and optical devices. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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Open AccessArticle
Fibrin Hydrogels for Endothelialized Liver Tissue Engineering with a Predesigned Vascular Network
Polymers 2018, 10(10), 1048; https://doi.org/10.3390/polym10101048 - 20 Sep 2018
Cited by 8
Abstract
The design and manufacture of a branched vascular network is essential for bioartificial organ implantation, which provides nutrients and removes metabolites for multi-cellular tissues. In the present study, we present a technology to manufacture endothelialized liver tissues using a fibrin hydrogel and a [...] Read more.
The design and manufacture of a branched vascular network is essential for bioartificial organ implantation, which provides nutrients and removes metabolites for multi-cellular tissues. In the present study, we present a technology to manufacture endothelialized liver tissues using a fibrin hydrogel and a rotational combined mold. Both hepatocytes and adipose-derived stem cells (ADSCs) encapsulated in a fibrin hydrogel were assembled into a spindle construct with a predesigned multi-branched vascular network. An external overcoat of poly(dl-lactic-co-glycolic acid) was used to increase the mechanical properties of the construct as well as to act as an impervious and isolating membrane around the construct. Cell survivability reached 100% in the construct after 6 days of in vitro culture. ADSCs in the spindle construct were engaged into endothelial cells/tissues using a cocktail growth factor engagement approach. Mechanical property comparison and permeability evaluation tests all indicated that this was a viable complex organ containing more than two heterogeneous tissue types and a functional vascular network. It is, therefore, the first time an implantable bioartificial liver, i.e., endothelialized liver tissue, along with a hierarchical vascular network, has been created. Full article
(This article belongs to the Special Issue Hydrogels and Gels for Biomedical and Sustainable Applications)
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