Gels | Special Issue : Smart Polymer Hydrogels: Synthesis, Properties and Applications (2nd Edition)

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24 pages, 5530 KiB

Open AccessArticle

Microgel with a Core—Shell Particulate Structure Formed via Spinodal Decomposition of a Diblock Ionomer Containing a Doped Hydrophobic Moiety

by David Julius, Jim Yang Lee and Liang Hong

Gels 2025, 11(4), 231; https://doi.org/10.3390/gels11040231 - 22 Mar 2025

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Abstract

This study explored the formation of soft colloidal particles from a diblock ionomer (DI) with the monomeric composition (acrylonitrile)_x-co-(glycidyl methacrylate)_y-b-(3-sulfopropyl methacrylate potassium)_z—abbreviated as (A_xG_y)S_z, where x >> z > y. A [...] Read more.

This study explored the formation of soft colloidal particles from a diblock ionomer (DI) with the monomeric composition (acrylonitrile)_x-co-(glycidyl methacrylate)_y-b-(3-sulfopropyl methacrylate potassium)_z—abbreviated as (A_xG_y)S_z, where x >> z > y. A colloidal dispersion was generated by introducing water into the pre-prepared DMSO solutions of DI, which led to micelle formation and subsequent coagulation. The assembly of the hydrophobic (A_xG_y) blocks was influenced by water content and chain conformational flexibility (the ability to adopt various forms of conformation). The resulting microgel structure (in particle form) consists of coagulated micelles characterized by discrete internal hydrophobic gel domains and continuous external hydrophilic gel layers. Characterization methods included light scattering, zeta potential analysis, and particle size distribution measurements. In contrast, the copolymer (A_xG_y) chains form random coil aggregates in DMSO–H₂O mixtures, displaying a chain packing state distinct from the hydrophobic gel domains as aforementioned. Additionally, the amphiphilic glycidyl methacrylate (G) units within the (A_xG_y) block were found to modulate the microgel dimensions. Notably, the nanoscale hydrogel corona exhibits high accessibility to reactive species in aqueous media. The typical microgel has a spherical shape with a diameter ranging from 50 to 120 nm. It exhibits a zeta potential of −65 mV in a neutral aqueous medium; however, it may precipitate if the metastable colloidal dispersion state cannot be maintained. Its properties could be tailored through adjusting the internal chain conformation, highlighting its potential for diverse applications. Full article

(This article belongs to the Special Issue Smart Polymer Hydrogels: Synthesis, Properties and Applications (2nd Edition))

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13 pages, 6013 KiB

Open AccessArticle

Gold Nanorod-Coated Hydrogel Brush Valves in Macroporous Silicon Membranes for NIR-Driven Localized Chemical Modulation

by Nafis Mustakim, Youngsik Song and Sang-Woo Seo

Gels 2025, 11(1), 25; https://doi.org/10.3390/gels11010025 - 1 Jan 2025

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Abstract

A two-dimensional array of microfluidic ports with remote-controlled valve actuation is of great interest for applications involving localized chemical stimulation. Herein, a macroporous silicon-based platform where each pore contains an independently controllable valve made from poly(N-isopropylacrylamide) (PNIPAM) brushes is proposed. These valves are [...] Read more.

A two-dimensional array of microfluidic ports with remote-controlled valve actuation is of great interest for applications involving localized chemical stimulation. Herein, a macroporous silicon-based platform where each pore contains an independently controllable valve made from poly(N-isopropylacrylamide) (PNIPAM) brushes is proposed. These valves are coated with silica-encapsulated gold nanorods (GNRs) for NIR-actuated switching capability. The layer-by-layer (LBL) electrostatic deposition technique was used to attach the GNRs to the PNIPAM brushes. The deposition of GNRs was confirmed by dark-field optical microscopy, and the localized surface plasmon resonance (LSPR) of the deposited GNRs was analyzed using UV-Vis spectra. To evaluate the chemical release behaviors, fluorescein dye was employed as a model substance. The chemical release properties, like OFF-state diffusion through the valve, the ratio between ON-state and OFF-state chemical release, and the rapidness of chemical modulation of the valve, were investigated, varying the PNIPAM brush thickness. The results indicate that enhancing the thickness of the PNIPAM brush in our platform improves control over the chemical modulation properties. However, excessive increases in brush length may lead to entanglement, which negatively impacts the chemical modulation efficiency. Full article

(This article belongs to the Special Issue Smart Polymer Hydrogels: Synthesis, Properties and Applications (2nd Edition))

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16 pages, 4724 KiB

Open AccessEditor’s ChoiceArticle

Various Hydrogel Types as a Potential In Vitro Angiogenesis Model

by Chloé Radermacher, Annika Rohde, Vytautas Kucikas, Eva Miriam Buhl, Svenja Wein, Danny Jonigk, Willi Jahnen-Dechent and Sabine Neuss

Gels 2024, 10(12), 820; https://doi.org/10.3390/gels10120820 - 12 Dec 2024

Cited by 1 | Viewed by 1380

Abstract

Angiogenesis, the formation of new blood vessels, is a fundamental process in both physiological repair mechanisms and pathological conditions, including cancer and chronic inflammation. Hydrogels are commonly used as in vitro models to mimic the extracellular matrix (ECM) and support endothelial cell behavior [...] Read more.

Angiogenesis, the formation of new blood vessels, is a fundamental process in both physiological repair mechanisms and pathological conditions, including cancer and chronic inflammation. Hydrogels are commonly used as in vitro models to mimic the extracellular matrix (ECM) and support endothelial cell behavior during angiogenesis. Mesenchymal stem cells further augment cell and tissue growth and are therefore widely used in regenerative medicine. Here we examined the combination of distinct hydrogel types—fibrin, collagen, and human platelet lysate (HPL)—on the formation of capillaries in a co-culture system containing human umbilical vein endothelial cells (HUVECs) and bone marrow-derived mesenchymal stem cells (BM-MSCs). The mechanical properties and structural changes of the hydrogels were characterized through scanning electron microscopy (SEM) and nanoindentation over 10 days. Fibrin and HPL gels sustained complex network formations, with HPL gels promoting even vascular tube formation of up to 10-fold capillary caliber. Collagen gels supported negligible angiogenesis. Our results suggest that HPL gels in combination with MSC-EC co-culture may be employed to obtain robust vascularization in tissue engineering. This study provides a comparative analysis of fibrin, collagen, and HPL hydrogels, focusing on their ability to support angiogenesis under identical conditions. Our findings demonstrate the superior performance of HPL gels in promoting robust vascular structures, highlighting their potential as a versatile tool for in vitro angiogenesis modeling. Full article

(This article belongs to the Special Issue Smart Polymer Hydrogels: Synthesis, Properties and Applications (2nd Edition))

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22 pages, 3287 KiB

Open AccessArticle

The Use of AgNP-Containing Nanocomposites Based on Galactomannan and κ-Carrageenan for the Creation of Hydrogels with Antiradical Activity

by Marina Zvereva

Gels 2024, 10(12), 800; https://doi.org/10.3390/gels10120800 - 6 Dec 2024

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Abstract

Series of composites containing 2.5–17.0% Ag and consisting of spherical silver nanoparticles with sizes ranging from 5.1 to 18.3 nm and from 6.4 to 21.8 nm for GM- and κ-CG-based composites, respectively, were prepared using the reducing and stabilizing ability of the natural [...] Read more.

Series of composites containing 2.5–17.0% Ag and consisting of spherical silver nanoparticles with sizes ranging from 5.1 to 18.3 nm and from 6.4 to 21.8 nm for GM- and κ-CG-based composites, respectively, were prepared using the reducing and stabilizing ability of the natural polysaccharides galactomannan (GM) and κ-carrageenan (κ-CG). The antiradical activity of the obtained composites was evaluated using the decolorization of ABTS+^· solution. It was found that the IC₅₀ value of a composite’s aqueous solution depends on the type of stabilizing ligand, the amount of inorganic phases, and the average size of AgNPs, and varies in the range of 0.015–0.08 mg·mL⁻¹ and 0.03–0.59 mg·mL⁻¹ for GM-AgNPs − κ-CG-AgNPs composites, respectively. GM-AgNPs − κ-CG-AgNPs hydrogels were successfully prepared and characterized on the basis of composites containing 2.5% Ag (demonstrating the most pronounced antiradical activity in terms of IC₅₀ values per mole amount of Ag). It was found that the optimal ratio of composites that provided the best water-holding capacity and prolonged complete release of AgNPs from the hydrogel composition was 1:1. The influence of Ca²⁺ cations on the co-gel formation of the GM-AgNPs − κ-CG-AgNPs system, as well as the expression of their water-holding capacity and the rate of AgNPs release from the hydrogel carrier, was evaluated. Full article

(This article belongs to the Special Issue Smart Polymer Hydrogels: Synthesis, Properties and Applications (2nd Edition))

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17 pages, 6630 KiB

Open AccessArticle

Conductive Biocomposite Made by Two-Photon Polymerization of Hydrogels Based on BSA and Carbon Nanotubes with Eosin-Y

by Mikhail S. Savelyev, Artem V. Kuksin, Denis T. Murashko, Ekaterina P. Otsupko, Ulyana E. Kurilova, Sergey V. Selishchev and Alexander Yu. Gerasimenko

Gels 2024, 10(11), 711; https://doi.org/10.3390/gels10110711 - 3 Nov 2024

Cited by 1 | Viewed by 1540

Abstract

Currently, tissue engineering technologies are promising for the restoration of damaged organs and tissues. For regeneration of electrically conductive tissues or neural interfaces, it is necessary to provide electrical conductivity for the transmission of electrophysiological signals. The developed biocomposite structures presented in this [...] Read more.

Currently, tissue engineering technologies are promising for the restoration of damaged organs and tissues. For regeneration of electrically conductive tissues or neural interfaces, it is necessary to provide electrical conductivity for the transmission of electrophysiological signals. The developed biocomposite structures presented in this article possess such properties. Their composition includes bovine serum albumin (BSA), gelatin, eosin-Y and single-walled carbon nanotubes (SWCNTs). For the first time, a biocomposite structure was formed from the proposed hydrogel using a nanosecond laser, and a two-photon absorption cross section value of 580 GM was achieved. Increased viscosity over 3 mPa∙s and self-focusing with a nonlinear refractive index of 42 × 10⁻¹² cm²/W make it possible to create a biocomposite structure over the entire specified area. The obtained electrical conductivity value was 19 mS∙cm⁻¹, due to the formation of effective electrically conductive networks. For a biocomposite with a concentration of gelatin 3 wt. %, formed by low-energy near-IR pulses, the survival of Neuro 2A nerve tissue cells was confirmed. The obtained results are important for the creation of new tissue engineering structures and neural interfaces from a biopolymer hydrogel based on the organic dye eosin-Y and carbon nanotubes by two-photon polymerization. Full article

(This article belongs to the Special Issue Smart Polymer Hydrogels: Synthesis, Properties and Applications (2nd Edition))

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13 pages, 4296 KiB

Open AccessArticle

Enhancing the Mechanical Properties of Injectable Nanocomposite Hydrogels by Adding Boronic Acid/Boronate Ester Dynamic Bonds at the Nanoparticle–Polymer Interface

by Jesús Sánchez, Jose Ulloa, Yessenia Oyarzún, Matías Ceballos, Carla Ruiz, Bruno Boury and Bruno F. Urbano

Gels 2024, 10(10), 638; https://doi.org/10.3390/gels10100638 - 2 Oct 2024

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Abstract

Incorporating nanoparticles into injectable hydrogels is a well-known technique for improving the mechanical properties of these materials. However, significant differences in the mechanical properties of the polymer matrix and the nanoparticles can result in localized stress concentrations at the polymer–nanoparticle interface. This situation [...] Read more.

Incorporating nanoparticles into injectable hydrogels is a well-known technique for improving the mechanical properties of these materials. However, significant differences in the mechanical properties of the polymer matrix and the nanoparticles can result in localized stress concentrations at the polymer–nanoparticle interface. This situation can lead to problems such as particle–matrix debonding, void formation, and material failure. This work introduces boronic acid/boronate ester dynamic covalent bonds (DCBs) as energy dissipation sites to mitigate stress concentrations at the polymer–nanoparticle interface. Once boronic acid groups were immobilized on the surface of SiO₂ nanoparticles (SiO₂-BA) and incorporated into an alginate matrix, the nanocomposite hydrogels exhibited enhanced viscoelastic properties. Compared to unmodified SiO₂ nanoparticles, introducing SiO₂ nanoparticles with boronic acid on their surface improved the structural integrity and stability of the hydrogel. In addition, nanoparticle-reinforced hydrogels showed increased stiffness and deformation resistance compared to controls. These properties were dependent on nanoparticle concentration. Injectability tests showed shear-thinning behavior for the modified hydrogels with injection force within clinically acceptable ranges and superior recovery. Full article

(This article belongs to the Special Issue Smart Polymer Hydrogels: Synthesis, Properties and Applications (2nd Edition))

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17 pages, 4473 KiB

Open AccessArticle

The Diels-Alder Cross-Linked Gelatin/Dextran Nanocomposite Hydrogels with Silver Nanoparticles for Wound Healing Applications: Synthesis, Characterization, and In Vitro Evaluation

by Iman Gholamali, Sung-Han Jo, Won Han, Juhee Lim, Ali Rizwan, Sang-Hyug Park and Kwon Taek Lim

Gels 2024, 10(6), 408; https://doi.org/10.3390/gels10060408 - 19 Jun 2024

Cited by 2 | Viewed by 2124

Abstract

Wound healing involves a sophisticated biological process that relies on ideal conditions to advance through various stages of repair. Modern wound dressings are designed to imitate the natural surroundings around cells and offer properties such as moisture regulation, strength, and antimicrobial defense to [...] Read more.

Wound healing involves a sophisticated biological process that relies on ideal conditions to advance through various stages of repair. Modern wound dressings are designed to imitate the natural surroundings around cells and offer properties such as moisture regulation, strength, and antimicrobial defense to boost healing. A recent research project unveiled a new type of gelatin (Gel)/dextran (Dex) hydrogels, linked through Diels-Alder (D-A) reactions, loaded with silver nanoparticles (Ag-NPs) for cutting-edge wound treatment. Gel and Dex were chemically modified to form the hydrogels via the D-A reaction. The hydrogels were enriched with Ag-NPs at varying levels. Thorough analyses of the hydrogels using methods like NMR, FT-IR, and SEM were carried out to assess their structure and nanoparticle integration. Rheological tests displayed that the hydrogels had favorable mechanical attributes, particularly when Ag-NPs were included. The hydrogels demonstrated controlled swelling, responsiveness to pH changes, and were non-toxic. Testing against E. coli showcased the strong antibacterial activity of the nanocomposite hydrogels in a concentration-dependent manner. This investigation showcased the promise of these bioactive nanocomposite hydrogels in promoting speedy wound healing by maintaining a moist environment, offering an antimicrobial shield, and ensuring mechanical support at the wound site. Full article

(This article belongs to the Special Issue Smart Polymer Hydrogels: Synthesis, Properties and Applications (2nd Edition))

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19 pages, 3040 KiB

Open AccessArticle

Removal of Malachite Green by Poly(acrylamide-co-acrylic acid) Hydrogels: Analysis of Coulombic and Hydrogen Bond Donor–Acceptor Interactions

by Salah Hamri, Bouchra Bouzi, Djahida Lerari, Fayçal Dergal, Tewfik Bouchaour, Khaldoun Bachari, Zohra Bouberka and Ulrich Maschke

Gels 2023, 9(12), 946; https://doi.org/10.3390/gels9120946 - 1 Dec 2023

Viewed by 1656

Abstract

Water pollution caused by dyes poses a significant threat to life on earth. Poly(acrylamide-co-acrylic acid) hydrogels are widely used to treat wastewater from various pollutants. This study aims to examine the removal of malachite green (MG), a harmful and persistent dye that could [...] Read more.

Water pollution caused by dyes poses a significant threat to life on earth. Poly(acrylamide-co-acrylic acid) hydrogels are widely used to treat wastewater from various pollutants. This study aims to examine the removal of malachite green (MG), a harmful and persistent dye that could cause extensive environmental damage, from an aqueous solution by adjusting the initial concentration of acrylamide (AM) and the degree of copolymer crosslinking. The copolymer hydrogels efficiently eliminate MG in a brief timeframe. The most successful hydrogel accomplished a removal rate exceeding 96%. The copolymer of 4 wt % 1,6-hexanediol diacrylate and a concentration of 100 mg/mL AM was effective. The degree of swelling was affected by crosslinking density as expected, with low crosslinking ratios resulting in significant swelling and high ratios resulting in less swelling. To evaluate the results, a docking approach was used which presented three crosslinked models: low, medium, and high. The copolymer–dye hydrogel system displayed robust hydrogen bonding interactions, as confirmed by the high quantities of both donors and acceptors. It was determined that MG contains six rotatable bonds, enabling it to adapt and interact with the copolymer chains. The dye and copolymer enhance H-bond formation by providing two hydrogen bond donors and 16 hydrogen bond acceptors, respectively. Through capitalizing on cationic and anionic effects, the ionic MG/copolymer hydrogel system improves retention efficiency by enhancing attraction between opposing charges. It is interesting to note that the synthesized copolymer is able to remove 96.4% of MG from aqueous media within one hour of contact time. Full article

(This article belongs to the Special Issue Smart Polymer Hydrogels: Synthesis, Properties and Applications (2nd Edition))

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