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Smart Gels and Their Applications

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Materials Science".

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 18140

Special Issue Editor


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Guest Editor
1. Biorefining and Advanced Materials Research Centre, SRUC, Edinburgh EH9 3JG, UK
2. Enhanced Composites and Structures Center, School of Aerospace, Transport and Manufacturing, Cranfield University, Cranfield MK43 0AL, UK
Interests: biorefining, chemistry, nanotechnology, biomass, and waste; biomedical engineering; composites; sensors; manufacturing of functional materials; aerospace materials; nanomaterials; renewable energy; smart materials; surface engineering; water science and engineering; additive manufacturing of polymers and composites; multifunctional polymer composites and nanocomposites: self-healing, nanoelectronic materials; hydrogels; membranes; nanofiber; composites for extreme environments and manufacturing technology
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Special Issue Information

Dear Colleagues,

This Special Issue aims to provide a comprehensive collection of works on the recent advances and developments in the domain of gels, particularly as applied to the various research fields of science and engineering disciplines. It covers a broad range of topics related to gels, including polymer gels, protein gels, self-healing gels, colloidal gels, composite/nanocomposite gels, organogels, aerogels, metallogels, hydrogels, and micro/nanogels.

This Special Issue of IJMS aims to publish high-quality research papers covering the most recent advances in the field as well as comprehensive reviews addressing novel and state-of-the-art topics from active researchers in the field of gels, addressing a range of synthesis and characterization techniques that are critical for tailoring and broadening the various aspects of polymer gels, as well as the numerous advantages that polymer-gel-based materials offer. It will present a comprehensive collection of articles on the recent advances and developments in the science and fundamentals of both synthetic- and natural-polymer-based gels. Specific topics covered include but are not limited to the synthesis and structure of physically/chemically cross-linked polymer gels/polymeric nanogels; gel formation through non-covalent cross-linking; molecular design and characterization; polysaccharide-based polymer gels (synthesis, characterization, and properties); modified polysaccharide gels—silica-based polymeric gels as platforms for the delivery of pharmaceuticals; gel-based approaches in genomic and proteomic sciences; emulgels in drug delivery; and organogels. This Special Issue provides a cutting-edge resource for researchers and scientists working in various fields involving polymers, biomaterials, bio-nanotechnology, and functional materials.

Prof. Dr. Vijay Kumar Thakur
Guest Editor

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Keywords

  • polymer gels
  • protein gels
  • hydrogels
  • aerogels
  • composite/nanocomposite gels
  • micro/nano gels
  • self-healing gels
  • miscellaneous applications

Published Papers (9 papers)

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Research

15 pages, 2816 KiB  
Article
Non-Alcohol Hand Sanitiser Gels with Mandelic Acid and Essential Oils
by Pavlína Egner, Jana Pavlačková, Jana Sedlaříková, Pavel Pleva, Pavel Mokrejš and Magda Janalíková
Int. J. Mol. Sci. 2023, 24(4), 3855; https://doi.org/10.3390/ijms24043855 - 14 Feb 2023
Cited by 4 | Viewed by 1819
Abstract
Antimicrobial hand gels have become extremely popular in recent years due to the COVID-19 pandemic. Frequent use of hand sanitising gel can lead to dryness and irritation of the skin. This work focuses on the preparation of antimicrobial acrylic acid (Carbomer)-based gels enhanced [...] Read more.
Antimicrobial hand gels have become extremely popular in recent years due to the COVID-19 pandemic. Frequent use of hand sanitising gel can lead to dryness and irritation of the skin. This work focuses on the preparation of antimicrobial acrylic acid (Carbomer)-based gels enhanced by non-traditional compounds—mandelic acid and essential oils—as a substitute for irritating ethanol. Physicochemical properties (pH and viscosity), stability and sensory attributes of the prepared gels were investigated. Antimicrobial activity against representative Gram-positive and Gram-negative bacteria and yeasts was determined. The prepared gels with mandelic acid and essential oil (cinnamon, clove, lemon, and thyme) proved to have antimicrobial activity and even better organoleptic properties than commercial ethanol-based antimicrobial gel. Further, results confirmed that the addition of mandelic acid had a desirable effect on gel properties (antimicrobial, consistency, stability). It has been shown that the essential oil/mandelic acid combination can be a dermatologically beneficial hand sanitiser compared to commercial products. Thus, the produced gels can be used as a natural alternative to alcohol-based daily hand hygiene sanitisers. Full article
(This article belongs to the Special Issue Smart Gels and Their Applications)
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16 pages, 2300 KiB  
Article
Fibrin-Rhamnogalacturonan I Composite Gel for Therapeutic Enzyme Delivery to Intestinal Tumors
by Dzhigangir Faizullin, Yuliya Valiullina, Vadim Salnikov, Pavel Zelenikhin, Yuriy Zuev and Olga Ilinskaya
Int. J. Mol. Sci. 2023, 24(2), 926; https://doi.org/10.3390/ijms24020926 - 04 Jan 2023
Cited by 3 | Viewed by 1253
Abstract
Therapy of colorectal cancer with protein drugs, including targeted therapy using monoclonal antibodies, requires the preservation of the drug’s structure and activity in the gastrointestinal tract or bloodstream. Here, we confirmed experimentally the fundamental possibility of creating composite protein–polysaccharide hydrogels based on non-degrading [...] Read more.
Therapy of colorectal cancer with protein drugs, including targeted therapy using monoclonal antibodies, requires the preservation of the drug’s structure and activity in the gastrointestinal tract or bloodstream. Here, we confirmed experimentally the fundamental possibility of creating composite protein–polysaccharide hydrogels based on non-degrading rhamnogalacturonan I (RG) and fibrin as a delivery vehicle for antitumor RNase binase. The method is based on enzymatic polymerization of fibrin in the presence of RG with the inclusion of liposomes, containing an encapsulated enzyme drug, into the gel network. The proposed method for fabricating a gel matrix does not require the use of cytotoxic chemical cross-linking agents and divalent cations, and contains completely biocompatible and biodegradable components. The process proceeds under physiological conditions, excluding the effect of high temperatures, organic solvents and ultrasound on protein components. Immobilization of therapeutic enzyme binase in the carrier matrix by encapsulating it in liposomes made from uncharged lipid made it possible to achieve its prolonged release with preservation of activity for a long time. The release time of binase from the composite carrier can be regulated by variation of the fibrin and RG concentration. Full article
(This article belongs to the Special Issue Smart Gels and Their Applications)
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17 pages, 5176 KiB  
Article
Adjustable Thermo-Responsive, Cell-Adhesive Tissue Engineering Scaffolds for Cell Stimulation through Periodic Changes in Culture Temperature
by Ketpat Vejjasilpa, Iram Maqsood, Michaela Schulz-Siegmund and Michael C. Hacker
Int. J. Mol. Sci. 2023, 24(1), 572; https://doi.org/10.3390/ijms24010572 - 29 Dec 2022
Cited by 2 | Viewed by 1702
Abstract
A three-dimensional (3D) scaffold ideally provides hierarchical complexity and imitates the chemistry and mechanical properties of the natural cell environment. Here, we report on a stimuli-responsive photo-cross-linkable resin formulation for the fabrication of scaffolds by continuous digital light processing (cDLP), which allows for [...] Read more.
A three-dimensional (3D) scaffold ideally provides hierarchical complexity and imitates the chemistry and mechanical properties of the natural cell environment. Here, we report on a stimuli-responsive photo-cross-linkable resin formulation for the fabrication of scaffolds by continuous digital light processing (cDLP), which allows for the mechano-stimulation of adherent cells. The resin comprises a network-forming trifunctional acrylate ester monomer (trimethylolpropane triacrylate, or TMPTA), N-isopropyl acrylamide (NiPAAm), cationic dimethylaminoethyl acrylate (DMAEA) for enhanced cell interaction, and 4-acryloyl morpholine (AMO) to adjust the phase transition temperature (Ttrans) of the equilibrium swollen cross-polymerized scaffold. With glycofurol as a biocompatible solvent, controlled three-dimensional structures were fabricated and the transition temperatures were adjusted by resin composition. The effects of the thermally induced mechano-stimulation were investigated with mouse fibroblasts (L929) and myoblasts (C2C12) on printed constructs. Periodic changes in the culture temperature stimulated the myoblast proliferation. Full article
(This article belongs to the Special Issue Smart Gels and Their Applications)
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16 pages, 8198 KiB  
Article
Analysis of the Influence of Both the Average Molecular Weight and the Content of Crosslinking Agent on Physicochemical Properties of PVP-Based Hydrogels Developed as Innovative Dressings
by Magdalena Kędzierska, Mateusz Jamroży, Anna Drabczyk, Sonia Kudłacik-Kramarczyk, Magdalena Bańkosz, Mateusz Gruca, Piotr Potemski and Bożena Tyliszczak
Int. J. Mol. Sci. 2022, 23(19), 11618; https://doi.org/10.3390/ijms231911618 - 01 Oct 2022
Cited by 3 | Viewed by 1678
Abstract
Hydrogels belong to the group of polymers with a three-dimensional crosslinked structure, and their crosslinking density strongly affects their physicochemical properties. Here, we verified the impact of both the average molecular weight of crosslinking agents used during the photopolymerization of hydrogels and that [...] Read more.
Hydrogels belong to the group of polymers with a three-dimensional crosslinked structure, and their crosslinking density strongly affects their physicochemical properties. Here, we verified the impact of both the average molecular weight of crosslinking agents used during the photopolymerization of hydrogels and that of their content on selected properties of these materials. First, PVP-based hydrogels modified with Aloe vera juice and L-ascorbic acid were prepared using UV radiation. Next, their surface morphology was characterized via optical scanning electron microscopy, whereas their chemical structure was investigated by FT-IR spectroscopy. Moreover, we verified the tendency of the hydrogels to degrade in selected physiological liquids, as well as their tensile strength, percentage of elongation, and swelling capability. We found that the more crosslinking agent in the hydrogel matrix, the higher its tensile strength and the less elongation. The hydrogels showed the highest stability during incubation in SBF and 2% hemoglobin solution. A sharp decrease in the pH of distilled water observed during the incubation of the hydrogels was probably due to the release of Aloe vera juice from the hydrogel matrices. This was additionally confirmed by the decrease in the intensity of the absorption band derived from the polysaccharides included in this additive and by the decrease in the swelling ratio after 48 h. Importantly, all hydrogels demonstrated swelling properties, and it was proven that the higher content of the crosslinking agent in hydrogels, the lower their swelling ability. Full article
(This article belongs to the Special Issue Smart Gels and Their Applications)
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15 pages, 2019 KiB  
Article
Precision Control of Programmable Actuation of Thermoresponsive Nanocomposite Hydrogels with Multilateral Engineering
by Jisu Hong, Jiseok Han and Chaenyung Cha
Int. J. Mol. Sci. 2022, 23(9), 5044; https://doi.org/10.3390/ijms23095044 - 02 May 2022
Cited by 2 | Viewed by 1572
Abstract
Hydrogels capable of stimuli-responsive deformation are widely explored as intelligent actuators for diverse applications. It is still a significant challenge, however, to “program” these hydrogels to undergo highly specific and extensive shape changes with precision, because the mechanical properties and deformation mechanism of [...] Read more.
Hydrogels capable of stimuli-responsive deformation are widely explored as intelligent actuators for diverse applications. It is still a significant challenge, however, to “program” these hydrogels to undergo highly specific and extensive shape changes with precision, because the mechanical properties and deformation mechanism of the hydrogels are inherently coupled. Herein, two engineering strategies are simultaneously employed to develop thermoresponsive poly(N-isopropyl acrylamide) (PNIPAm)-based hydrogels capable of programmable actuation. First, PNIPAm is copolymerized with poly(ethylene glycol) diacrylate (PEGDA) with varying molecular weights and concentrations. In addition, graphene oxide (GO) or reduced graphene oxide (rGO) is incorporated to generate nanocomposite hydrogels. These strategies combine to allow the refined control of mechanical and diffusional properties of hydrogels over a broad range, which also directly influences variable thermoresponsive actuation. It is expected that this comprehensive design principle can be applied to a wide range of hydrogels for programmable actuation. Full article
(This article belongs to the Special Issue Smart Gels and Their Applications)
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10 pages, 2079 KiB  
Article
Optimization of Fibrin Scaffolds to Study Friction in Cultured Mesothelial Cells
by Francesca Bodega, Chiara Sironi, Luciano Zocchi and Cristina Porta
Int. J. Mol. Sci. 2022, 23(9), 4980; https://doi.org/10.3390/ijms23094980 - 29 Apr 2022
Cited by 1 | Viewed by 1319
Abstract
To study the friction of cell monolayers avoiding damage due to stress concentration, cells can be cultured on fibrin gels, which have a structure and viscoelasticity similar to that of the extracellular matrix. In the present research, we studied different gel compositions and [...] Read more.
To study the friction of cell monolayers avoiding damage due to stress concentration, cells can be cultured on fibrin gels, which have a structure and viscoelasticity similar to that of the extracellular matrix. In the present research, we studied different gel compositions and surface coatings in order to identify the best conditions to measure friction in vitro. We examined the adhesion and growth behavior of mesothelial cell line MET-5A on fibrin gels with different fibrinogen concentrations (15, 20, and 25 mg/mL) and with different adhesion coatings (5 μg/mL fibronectin, 10 μg/mL fibronectin, or 10 μg/mL fibronectin + 10 μg/mL collagen). We also investigated whether different substrates influenced the coefficient of friction and the ability of cells to stick to the gel during sliding. Finally, we studied the degradation rates of gels with and without cells. All substrates tested provided a suitable environment for the adherence and proliferation of mesothelial cells, and friction measurements did not cause significant cell damage or detachment. However, in gels with a lower fibrinogen concentration, cell viability was higher and cell detachment after friction measurement was lower. Fibrinolysis was negligible in all the substrates tested. Full article
(This article belongs to the Special Issue Smart Gels and Their Applications)
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24 pages, 5550 KiB  
Article
Swelling, Protein Adsorption, and Biocompatibility In Vitro of Gel Beads Prepared from Pectin of Hogweed Heracleum sosnówskyi Manden in Comparison with Gel Beads from Apple Pectin
by Sergey Popov, Nikita Paderin, Daria Khramova, Elizaveta Kvashninova, Olga Patova and Fedor Vityazev
Int. J. Mol. Sci. 2022, 23(6), 3388; https://doi.org/10.3390/ijms23063388 - 21 Mar 2022
Cited by 5 | Viewed by 1847
Abstract
The study aims to develop gel beads with improved functional properties and biocompatibility from hogweed (HS) pectin. HS4 and AP4 gel beads were prepared from the HS pectin and apple pectin (AP) using gelling with calcium ions. HS4 and AP4 gel beads swelled [...] Read more.
The study aims to develop gel beads with improved functional properties and biocompatibility from hogweed (HS) pectin. HS4 and AP4 gel beads were prepared from the HS pectin and apple pectin (AP) using gelling with calcium ions. HS4 and AP4 gel beads swelled in PBS in dependence on pH. The swelling degree of HS4 and AP4 gel beads was 191 and 136%, respectively, in PBS at pH 7.4. The hardness of HS4 and AP4 gel beads reduced 8.2 and 60 times, respectively, compared with the initial value after 24 h incubation. Both pectin gel beads swelled less in Hanks’ solution than in PBS and swelled less in Hanks’ solution containing peritoneal macrophages than in cell-free Hanks’ solution. Serum protein adsorption by HS4 and AP4 gel beads was 118 ± 44 and 196 ± 68 μg/cm2 after 24 h of incubation. Both pectin gel beads demonstrated low rates of hemolysis and complement activation. However, HS4 gel beads inhibited the LPS-stimulated secretion of TNF-α and the expression of TLR4 and NF-κB by macrophages, whereas AP4 gel beads stimulated the inflammatory response of macrophages. HS4 gel beads adsorbed 1.3 times more LPS and adhered to 1.6 times more macrophages than AP4 gel beads. Thus, HS pectin gel has advantages over AP gel concerning swelling behavior, protein adsorption, and biocompatibility. Full article
(This article belongs to the Special Issue Smart Gels and Their Applications)
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13 pages, 3627 KiB  
Communication
Printable Hydrogels Based on Alginate and Halloysite Nanotubes
by Giuseppe Cavallaro, Lorenzo Lisuzzo, Giuseppe Lazzara and Stefana Milioto
Int. J. Mol. Sci. 2022, 23(6), 3294; https://doi.org/10.3390/ijms23063294 - 18 Mar 2022
Cited by 9 | Viewed by 1654
Abstract
The design of hydrogels for the controlled release of active species is an attractive challenge. In this work, we prepared hybrid hydrogels composed of halloysite nanotubes as the inorganic component, and alginate as the organic counterpart. The reported procedure allowed us to provide [...] Read more.
The design of hydrogels for the controlled release of active species is an attractive challenge. In this work, we prepared hybrid hydrogels composed of halloysite nanotubes as the inorganic component, and alginate as the organic counterpart. The reported procedure allowed us to provide the resulting materials with a peculiar wire-like shape. Both optical and scanning electron microscopy were used to characterize the morphological properties of the hydrogel wires, whose diameters were ca. 0.19 and 0.47 mm, respectively. The possibility to be exploited as drug delivery systems was carried out by loading the nanoclay with salicylic acid and by studying the release profiles. Thermogravimetric experiments showed that the amount of encapsulated drug was 4.35 wt%, and the salicylic acid was thermally stabilized after the loading into the nanotubes, as observed by the shift of the degradation peak in the differential thermograms from 193 to 267 °C. The kinetics investigation was conducted using UV–Vis spectrophotometry, and it exhibited the profound effects of both the morphology and dimensions on the release of the drugs. In particular, the release of 50% of the payload occurred in 6 and 10 h for the filiform hydrogels, and it was slower compared to the bare drug-loaded halloysite, which occurred in 2 h. Finally, an induction period of 2 h was observed in the release profile from the thicker sample. Full article
(This article belongs to the Special Issue Smart Gels and Their Applications)
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17 pages, 5611 KiB  
Article
Chitosan/Alginate Hydrogel Dressing Loaded FGF/VE-Cadherin to Accelerate Full-Thickness Skin Regeneration and More Normal Skin Repairs
by Lai Wei, Jianying Tan, Li Li, Huanran Wang, Sainan Liu, Junying Chen, Yajun Weng and Tao Liu
Int. J. Mol. Sci. 2022, 23(3), 1249; https://doi.org/10.3390/ijms23031249 - 23 Jan 2022
Cited by 37 | Viewed by 3516
Abstract
The process of full-thickness skin regeneration is complex and has many parameters involved, which makes it difficult to use a single dressing to meet the various requirements of the complete regeneration at the same time. Therefore, developing hydrogel dressings with multifunction, including tunable [...] Read more.
The process of full-thickness skin regeneration is complex and has many parameters involved, which makes it difficult to use a single dressing to meet the various requirements of the complete regeneration at the same time. Therefore, developing hydrogel dressings with multifunction, including tunable rheological properties and aperture, hemostatic, antibacterial and super cytocompatibility, is a desirable candidate in wound healing. In this study, a series of complex hydrogels were developed via the hydrogen bond and covalent bond between chitosan (CS) and alginate (SA). These hydrogels exhibited suitable pore size and tunable rheological properties for cell adhesion. Chitosan endowed hemostatic, antibacterial properties and great cytocompatibility and thus solved two primary problems in the early stage of the wound healing process. Moreover, the sustained cytocompatibility of the hydrogels was further investigated after adding FGF and VE-cadherin via the co-culture of L929 and EC for 12 days. The confocal 3D fluorescent images showed that the cells were spherical and tended to form multicellular spheroids, which distributed in about 40–60 μm thick hydrogels. Furthermore, the hydrogel dressings significantly accelerate defected skin turn to normal skin with proper epithelial thickness and new blood vessels and hair follicles through the histological analysis of in vivo wound healing. The findings mentioned above demonstrated that the CS/SA hydrogels with growth factors have great potential as multifunctional hydrogel dressings for full-thickness skin regeneration incorporated with hemostatic, antibacterial, sustained cytocompatibility for 3D cell culture and normal skin repairing. Full article
(This article belongs to the Special Issue Smart Gels and Their Applications)
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