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General chemical structure of gelatin and its modification reaction for preparation of thiolated gelatin (gel-SH).
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The combination of natural and synthetic polymers to form hybrid hydrogels offers the potential of fabricating new materials that possess a combination of properties resulting from both types of polymer classes. Within this work, two alkene-functionalized poly(2-alkyl/aryl–2-oxazoline) (PAOx) copolymers and one gelatin derivative, thiolated gelatin...
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Context 1
... the development of the second base material, gelatin was functionalized by modification of the primary amines with N-acetylhomocysteine thiolactone at 40 °C, resulting in thiolated gelatin (i.e., gel-SH), as depicted in Figure 8. The modification strategy for the synthesis of thiolated gelatin type B was based on a previously reported aminolysis reaction with N-acetylhomocysteine thiolactone [60,61]. ...
Context 2
... the development of the second base material, gelatin was functionalized by modification of the primary amines with N-acetylhomocysteine thiolactone at 40 • C, resulting in thiolated gelatin (i.e., gel-SH), as depicted in Figure 8. The modification strategy for the synthesis of thiolated gelatin type B was based on a previously reported aminolysis reaction with N-acetylhomocysteine thiolactone [60,61]. ...
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The 3D bioprinting technique consists of obtaining three-dimensional structures of fibers stacked layer after layer, and this work presents the use of an alginate/gelatin hydrogel to print porous scaffolds. However, the bioprinting process requires a customized approach in the crosslinking stage, and that is why our work lies in the implementation...
Citations
... 1.6. Characteristics of gels [14,15] 1.6.1. Swelling The gel expands and absorbs liquid as it increases in volume. ...
The goal of this review was to compile recent literature with a special emphasis on a rational approach to topical formulation and basic components of topical drug delivery systems. Topical drug delivery systems include a wide range of pharmaceutical dosage forms such as semisolids, liquid preparations, sprays, and solid powders. A gel is a cross linked polymer network that has swollen in a liquid medium. Its properties are heavily influenced by the interaction of the solid-state polymer and the liquid component. The I.P. defines Gels are homogeneous, semisolid preparations usually consisting of solutions or dispersions of one or more medicaments in suitable hydrophilic or hydrophobic bases. As per the definition of U.S.P. Gels as a semisolid system consisting of dispersion made up of either small inorganic particle or large organic molecule enclosing and interpenetrated by liquid.The inorganic particles form a three-dimensional "house of cards" structure. As far as structure is concerned, Gels consist of two-phase system in which inorganic particles are not dissolved but merely dispersed throughout the continuous phase and large organic particles are dissolved in the continuous phase, randomly coiled in the flexible chains. Gels are typically formed from a liquid phase that has been thickened with other components. They are normally prepared with the aid of suitable gelling agents like HPMC, Carbopol and Sodium CMC etc. Substances such as antioxidants, stabilizers and antimicrobial preservatives are used as additives in the formulation of gels.
... A hybrid hydrogel was made using a mixture of synthetic and natural polymer building blocks (gelatin and PAOx used as precursor materials). These polymers were chosen to use a combination of the mechanical stability of synthetic polymers with the cell-interactive properties of natural polymers [81]. Thiolated gelatin (SH-gel) was prepared and a hybrid hydrogel obtained using thiolene radical crosslinking, which ensured the interconnectivity of PAOx and gelatin precursors. ...
... Figure 7 shows the formation of the hybrid hydrogel composed by gelatin and functionalized with thiol and PAOx, which have been functionalized with alkene. The obtained material showed an increased mechanical stability as well as a thermosensitive behaviour at temperature variations around 30 °C [81]. ...
... Schematic representation of the formation of a hybrid hydrogel[81]. ...
Polymer gels are a valuable class of polymeric materials that have recently attracted significant interest due to the exceptional properties such as versatility, soft-structure, flexibility and stimuli-responsive, biodegradability, and biocompatibility. Based on their properties, polymer gels can be used in a wide range of applications: food industry, agriculture, biomedical, and biosensors. The utilization of polymer gels in different medical and industrial applications requires a better understanding of the formation process, the factors which affect the gel’s stability, and the structure-rheological properties relationship. The present review aims to give an overview of the polymer gels, the classification of polymer gels’ materials to highlight their important features, and the recent development in biomedical applications. Several perspectives on future advancement of polymer hydrogel are offered.
Poly(cyclic imino ether)s (PCIEs) including poly(2-alkyl-2-oxazoline) (POx), poly(2-alkyl-2-oxazine) (POz) and poly(2,4-dialkyl-2-oxazoline) (PdOx) are a rapidly emerging polymer class for use in biomedical and therapeutic applications due to the biocompatibility and...
Hydrogels are highly hydrated three dimensional networks with the ability to mimic the extracellular matrix of bodily tissues and have thus found application in a wide range of biomedical applications. Unique physiochemical properties such as biocompatibility, water permeability, stimuli responsiveness and self-healing characteristics make them especially useful for use as scaffolds and matrices drug delivery, tissue engineering/regeneration and sensing. Their weak and brittle nature, however, often limits their widespread application where improved mechanical strength is required.
To resolve this problem, there has been a significant amount of research into the improvement of their mechanical properties. Among these efforts, versatile multicomponent hydrogels have received much attention as their physiochemical properties can be structurally engineered to provide a wide range of desired properties. These multicomponent formulations also allow for the combination of natural and synthetic polymers, which offers the scope to exploit the advantages of each component, with the synergistic effects resulting from mutual interactions.
This book critically discusses the fundamental chemistry, synthesis, characterisation, physiochemical and biological properties of various types of multicomponent hydrogels. It reviews the different strategies employed in designing and synthesizing cutting-edge multicomponent hydrogels and their key applications in biomedical fields.
The work is suitable for researchers working in the specific area of multicomponent hydrogels, and also more generally for those working in materials science, biomedical engineering, biomaterials science and tissue engineering.
The mechanical microenvironment plays a crucial role in the evolution of colorectal cancer, a complex disease characterized by heterogeneous tumors with varying elasticity. Toward setting up distinct scenarios, herein, we describe the preparation and characterization of gelatin methacrylamide (GelMA)-based hydrogels via two different mechanisms: free-radical photopolymerization and photo-induced thiol-ene reaction. A precise stiffness modulation of covalently crosslinked scaffolds was achieved through the application of well-defined irradiation times while keeping the intensity constant. Besides, the incorporation of thiol chemistry strongly increased stiffness with low to moderate curing times. This wide range of finely tuned mechanical properties successfully covered from healthy tissue to colorectal cancer stages. Hydrogels prepared in phosphate-buffered saline or Dulbecco's modified Eagle's medium resulted in different mechanical and swelling properties, although a similar trend was observed for both conditions: thiol-ene systems exhibited higher stiffness and, at the same time, higher swelling capacity than free-radical photopolymerized networks. In terms of biological behavior, three of the substrates showed good cell proliferation rates according to the formation of a confluent monolayer of Caco-2 cells after 14 days of cell culture. Likewise, a characteristic apical-basal polarization of cells was observed for these three hydrogels. These results demonstrate the versatility of the presented platform of biomimetic materials as in vitro cell culture scaffolds.
Thiolactones are often described as latent thiols. They can be ring-opened by hydroxy or amine groups releasing thiols, which can further react with a large variety of functional groups. Based on this one-pot cascade reaction, versatile and powerful tools have been developed for macromolecular engineering. This review covers the different uses of γ-thiobutyrolactones in polymer chemistry either as thiolation agents, as linkers, as ring-opening polymerization monomers, as reactant in stepwise polymerization, as components of initiating systems, or as functional handles for double post-modification reactions.
Anionically modified gelatin-based multi-responsive hybrid gels were prepared by free radical copolymerization of acrylamide (AAm) and itaconic acid (IA) in varying amounts of gelatin (GLN). Influence of composition on physicochemical and mechanical properties was assessed. Maximum degradation temperatures of hybrids increased with addition of GLN to PAAm/IA network. Equilibrium swelling of hybrid PAAm/IA-GLNs was studied in water as a function of GLN content in the range of 0.075 - 0.750% (w/v). By examining the variation of the compression elastic modulus of hybrids with GLN, a correlation was obtained for the dependence of the effective crosslink density on the GLN content. pH sensitive swelling of hybrids exhibited a double-step increase with the S-shaped curve around pH 4.7 and 8.0. In studies evaluating the swelling tendency in various solvents, Hofmeister series and various swelling temperatures, it was found that swelling kinetics in NaNO3 solutions proceeds by Fickian diffusion and Schott's pseudo-second order model can be effectively used to evaluate swelling kinetics. Hybrid gels were applied to adsorption of cationic methylene blue (MB) and malachite green (MG) as model contaminating dyes from aqueous solutions. Accordingly, GLN-based hybrid gels could be a good adsorbent for the removal of cationic dyes from the contaminated waters.
