Improvements in mechanical properties of collagen-based scaffolds for tissue engineering

Assembled collagen films modified using polyacrylic acid with improved mechanical properties via mineralization

The imperative task of enforcing collagen materials holds paramount significance in the field of hard tissue repair. We hereby present mineralized collagen fiber films via mineralization with improved mechanical properties. Self-extracted collagen was assembled into an array with an aligned fibrous pattern and then modified with polyacrylic acid (PAA) followed by mineralization in cationic polyacrylamide (CPAM)-SBF. Biomineralization occurred at the inner and outer surface of the assembled collagen fiber films. A tensile strength of up to 40.38 ± 3.08 MPa of mineralized collagen was obtained, for the first time, which may be attributed to the synergistic effect of polyanion and polycation on the mineralization process of assembled intrafibrillar collagen fibers. It was argued that PAA may facilitate the intra-fiber interaction of collagen, which extends the elongation at break of collagen fibers. This study introduces a pioneering approach for the preparation of mineralized collagen materials with superior mechanical properties, which would be beneficial for hard tissue repair.

Effects of mineralization on the hierarchical organization of collagen-a synchrotron X-ray scattering and polarized second harmonic generation study

The process of mineralization fundamentally alters collagenous tissue biomechanics. While the structure and organization of mineral particles have been widely studied, the impact of mineralization on collagen matrix structure, particularly at the molecular scale, requires further investigation. In this study, synchrotron X-ray scattering (XRD) and polarization-resolved second harmonic generation microscopy (pSHG) were used to study normally mineralizing turkey leg tendon in tissue zones representing different stages of mineralization. XRD data demonstrated statistically significant differences in collagen D-period, intermolecular spacing, fibril and molecular dispersion and relative supramolecular twists between non-mineralizing, early mineralizing and late mineralizing zones. pSHG analysis of the same tendon zones showed the degree of collagen fibril organization was significantly greater in early and late mineralizing zones compared to non-mineralizing zones. The combination of XRD and pSHG data provide new insights into hierarchical collagen-mineral interactions, notably concerning possible cleavage of intra- or interfibrillar bonds, occlusion and reorganization of collagen by mineral with time. The complementary application of XRD and fast, label-free and non-destructive pSHG optical measurements presents a pathway for future investigations into the dynamics of molecular scale changes in collagen in the presence of increasing mineral deposition.

Synthesis and Physicochemical Characterization of Gelatine-Based Biodegradable Aerogel-like Composites as Possible Scaffolds for Regenerative Medicine

Regenerative medicine is an interdisciplinary field aiming at restoring pathologically damaged tissues and whole organs by cell transplantation in combination with proper supporting scaffolds. Gelatine-based ones are very attractive due to their biocompatibility, rapid biodegradability, and lack of immunogenicity. Gelatine-based composite hydrogels, containing strengthening agents to improve their modest mechanical properties, have been demonstrated to act as extracellular matrices (ECMs), thus playing a critical role in "organ manufacturing". Inspired by the lysyl oxidase (LO)-mediated process of crosslinking, which occurs in nature to reinforce collagen, we have recently developed a versatile protocol to crosslink gelatine B (Gel B) in the presence or absence of LO, using properly synthesized polystyrene- and polyacrylic-based copolymers containing the amine or aldehyde groups needed for crosslinking reactions. Here, following the developed protocol with slight modifications, we have successfully crosslinked Gel B in different conditions, obtaining eight out of nine compounds in high yield (57-99%). The determined crosslinking degree percentage (CP%) evidenced a high CP% for compounds obtained in presence of LO and using the styrenic amine-containing (CP5/DMAA) and acrylic aldehyde-containing (CPMA/DMAA) copolymers as crosslinking agents. ATR-FTIR analyses confirmed the chemical structure of all compounds, while optical microscopy demonstrated cavernous, crater-like, and labyrinth-like morphologies and cavities with a size in the range 15-261 µm. An apparent density in the range 0.10-0.45 g/cm3 confirmed the aerogel-like structure of most samples. Although the best biodegradation profile was observed for the sample obtained using 10% CP5/DMAA (M3), high swelling and absorption properties, high porosity, and good biodegradation profiles were also observed for samples obtained using the 5-10% CP5/DMAA (M4, 5, 6) and 20% CPMA/DMAA (M9) copolymers. Collectively, in this work of synthesis and physicochemical characterization, new aerogel-like composites have been developed and, based on their characteristics, which fit well within the requirements for TE, five candidates (M3, M4, M5, M6, and M9) suitable for future biological experiments on cell adhesion, infiltration and proliferation, to confirm their effective functioning, have been identified.

Patterned collagen films loaded with miR-133b@MBG-NH2for potential applications in corneal stromal injury repair

Corneal stromal injury is a common surgical disease. With the development of tissue engineering materials, many artificial corneal scaffolds have been developed to replace allograft corneal transplantation and solve the problem of corneal donor shortage. However, few researchers have paid attention to corneal stromal wound healing. Herein, a nanocomposite of amino modified mesoporous bioactive glass (MBG-NH2) and microRNA-133b (miR-133b) was introduced into the patterned collagen films to achieve corneal stromal injury repair. MBG-NH2nanoparticles as a nano delivery carrier could efficiently load miR-133b and achieve the slow release of miR-133b. The physicochemical properties of collagen films were characterized and found the microgrooved collagen films loaded with miR-133b@MBG-NH2nanoparticles possessed similar swelling properties, optical clarity, and biodegradability to the natural cornea.In vitrocell experiments were also conducted and proved that the patterned collagen films with miR-133b@MBG-NH2possessed good biocompatibility, and miR-133b@MBG-NH2nanoparticles could be significantly uptake by rabbit corneal stromal cells (RCSCs) and have a significant impact on the orientation, proliferation, migration, and gene expression of RCSCs. More importantly, the patterned collagen films with miR-133b@MBG-NH2could effectively promote the migration of RCSCs and accelerate wound healing process, and down-regulate the expression levels ofα-SMA, COL-I, and CTGF genes associated with myofibroblast differentiation of corneal stromal cells, which has a potential application prospect in the repair of corneal stromal injury.

Synthesis and Characterization of Amine and Aldehyde-Containing Copolymers for Enzymatic Crosslinking of Gelatine

In tissue engineering (TE), the support structure (scaffold) plays a key role necessary for cell adhesion and proliferation. The protein constituents of the extracellular matrix (ECM), such as collagen, its derivative gelatine, and elastin, are the most attractive materials as possible scaffolds. To improve the modest mechanical properties of gelatine, a strategy consists of crosslinking it, as naturally occurs for collagen, which is stiffened by the oxidative action of lysyl oxidase (LO). Here, a novel protocol to crosslink gelatine has been developed, not using the commonly employed crosslinkers, but based on the formation of imine bonds or on aldolic condensation reactions occurring between gelatine and properly synthesized copolymers containing amine residues via LO-mediated oxidation. Particularly, we first synthesized and characterized an amino butyl styrene monomer (5), its copolymers with dimethylacrylamide (DMAA), and its terpolymer with DMAA and acrylic acid (AA). Three acryloyl amidoamine monomers (11a-c) and their copolymers with DMAA were then prepared. A methacrolein (MA)/DMAA copolymer already possessing the needed aldehyde groups was finally developed to investigate the relevance of LO in the crosslinking process. Oxidation tests of amine copolymers with LO were performed to identify the best substrates to be used in experiments of gelatine reticulation. Copolymers obtained with 5, 11b, and 11c were excellent substrates for LO and were employed with MA/DMAA copolymers in gelatine crosslinking tests in different conditions. Among the amine-containing copolymers, that obtained with 5 (CP5/DMMA-43.1) afforded a material (M21) with the highest crosslinking percentage (71%). Cytotoxicity experiments carried out on two cell lines (IMR-32 and SH SY5Y) with the analogous (P5) of the synthetic constituent of M21 (CP5/DMAA) had evidenced no significant reduction in cell viability, but proliferation promotion, thus establishing the biocompatibility of M21 and the possibility to develop it as a new scaffold for TE, upon further investigations.

3D edible scaffolds with yeast protein: A novel alternative protein scaffold for the production of high-quality cell-cultured meat

The purpose of this study was to develop a novel edible scaffold by utilizing yeast proteins, which could partially replace collagen and produce hypoallergenic, odorless, and highly nutritious cell-cultured meat that meets the demands of a more significant number of consumers. The scaffold comprised proanthocyanidins, dialdehyde chitosan, collagen, and different proportions of yeast proteins (YP). The results indicated that the scaffold possessed excellent mechanical properties and biocompatibility, and supported cell proliferation and myogenic differentiation. Additionally, we evaluated the texture characteristics of the cultured meat models and traditional beef and discovered that the YP30 cultured meat model had similar springiness and chewiness as beef. Subsequently, further analyzed the similarity between the cultured meat models and traditional beef in appearance, taste, and nutrition. Further results illustrated that the yeast protein cultured meat model exhibited a complete model structure and comparable color and taste to beef after frying. Moreover, it was concluded that the protein content of the YP30 cultured meat model was closer to that of beef. These findings suggested that the edible scaffold using yeast proteins has enormous potential to facilitate the sustainable development of the cell-cultured meat industry.

Mechanical properties, and in vitro biocompatibility assessment of biomimetic dual layered keratin/ hydroxyapatite scaffolds

A novel biomimetic dual layered keratin/hydroxyapatite (keratin/HA) scaffold was designed using iterative freeze-drying technique. The prepared scaffolds were studied using several analytical techniques to better understand the biological, structural, and mechanical properties. The developed multilayered, interconnected, porous keratin scaffold with different hydroxyapatite (HA) content in the outer and inner layer, mimics the inherent gradient structure of alveolar bone. SEM studies showed an interconnected porous architecture of the prepared scaffolds with seamless integration between the upper and lower layers. The incorporation of HA improved the mechanical properties keratin/HA scaffolds. The keratin/HA scaffolds exhibited superior mechanical properties in terms of Young's modulus and compressive strength in comparison to pure keratin scaffolds. The biocompatibility studies suggested that both keratin and keratin/HA scaffolds were cyto-compatible, in terms of cell proliferation. Furthermore, it showed that both the tested materials can served as an ideal substrate for the differentiation of Saos-2 cells, leading to mineralization of the extracellular matrix. In summary, ionic liquid based green technique was employed for keratin extraction to fabricate keratin/HA scaffolds and our detailed in vitro investigations suggest the great potential for these composite scaffolds for bone tissue engineering in future.

Physicochemical properties and cell proliferation and adhesive bioactivity of collagen-hyaluronate composite gradient membrane

Membrane materials were widely used in guided tissue regeneration (GTR) to prevent fibroblast invasion and form a confined area for preferentially growing of osteoblast. A novel collagen-hyaluronate composite gradient membrane was prepared by Tilapia (Oreochromis mossambicus) skin collagen and sodium hyaluronate for potential GTR applications and their bioactivities were investigated by cellular viability. SEM results indicated the membrane showed a dense outer and a porous inner surface for effectively guiding the growth of bone tissue. Physicochemical and biosafety experiments showed the tensile strength of membrane was 466.57 ± 44.31 KPa and contact angle was 74.11°, and the membrane showed perfect biocompatibility and cytocompatibility as well, which met the requirements of GTR material. Cell morphology revealed that the membrane could facilitate the adherence and proliferation of fibroblast and osteoblast. The results of qRT-PCR and ELISA demonstrated that the membrane could effectively activate TGF-β/Smad pathway in fibroblast, and promote the expressions of TGF-β1, FN1 and VEGF. Remarkably, RUNX2 was stimulated in BMP2 pathway by the membrane to regulate osteoblast differentiation. In summary, the collagen-hyaluronate composite gradient membrane not only fulfills the prerequisites for use as a GTR material but also demonstrates substantial potential for practical applications in the field.

Tailoring the multiscale mechanics of tunable decellularized extracellular matrix (dECM) for wound healing through immunomodulation

With the discovery of the pivotal role of macrophages in tissue regeneration through shaping the tissue immune microenvironment, various immunomodulatory strategies have been proposed to modify traditional biomaterials. Decellularized extracellular matrix (dECM) has been extensively used in the clinical treatment of tissue injury due to its favorable biocompatibility and similarity to the native tissue environment. However, most reported decellularization protocols may cause damage to the native structure of dECM, which undermines its inherent advantages and potential clinical applications. Here, we introduce a mechanically tunable dECM prepared by optimizing the freeze-thaw cycles. We demonstrated that the alteration in micromechanical properties of dECM resulting from the cyclic freeze-thaw process contributes to distinct macrophage-mediated host immune responses to the materials, which are recently recognized to play a pivotal role in determining the outcome of tissue regeneration. Our sequencing data further revealed that the immunomodulatory effect of dECM was induced via the mechnotrasduction pathways in macrophages. Next, we tested the dECM in a rat skin injury model and found an enhanced micromechanical property of dECM achieved with three freeze-thaw cycles significantly promoted the M2 polarization of macrophages, leading to superior wound healing. These findings suggest that the immunomodulatory property of dECM can be efficiently manipulated by tailoring its inherent micromechanical properties during the decellularization process. Therefore, our mechanics-immunomodulation-based strategy provides new insights into the development of advanced biomaterials for wound healing.

Cell-Laden 3D Hydrogels of Type I Collagen Incorporating Bacterial Nanocellulose Fibers

There is a growing interest in developing natural hydrogel-based scaffolds to culture cells in a three-dimensional (3D) millieu that better mimics the in vivo cells' microenvironment. A promising approach is to use hydrogels from animal tissues, such as decellularized extracellular matrices; however, they usually exhibit suboptimal mechanical properties compared to native tissue and their composition with hundreds of different protein complicates to elucidate which stimulus triggers cell's responses. As simpler scaffolds, type I collagen hydrogels are used to study cell behavior in mechanobiology even though they are also softer than native tissues. In this work, type I collagen is mixed with bacterial nanocellulose fibers (BCf) to develop reinforced scaffolds with mechanical properties suitable for 3D cell culture. BCf were produced from blended pellicles biosynthesized from Komagataeibacter xylinus. Then, BCf were mixed with concentrated collagen from rat-tail tendons to form composite hydrogels. Confocal laser scanning microscopy and scanning electron microscopy images confirmed the homogeneous macro- and microdistribution of both natural polymers. Porosity analysis confirmed that BCf do not disrupt the scaffold structure. Tensile strength and rheology measurements demonstrated the reinforcement action of BCf (43% increased stiffness) compared to the collagen hydrogel while maintaining the same viscoelastic response. Additionally, this reinforcement of collagen hydrogels with BCf offers the possibility to mix cells before gelation and then proceed to the culture of the 3D cell scaffolds. We obtained scaffolds with human bone marrow-derived mesenchymal stromal cells or human fibroblasts within the composite hydrogels, allowing a homogeneous 3D viable culture for at least 7 days. A smaller surface shrinkage in the reinforced hydrogels compared to type I collagen hydrogels confirmed the strengthening of the composite hydrogels. These collagen hydrogels reinforced with BCf might emerge as a promising platform for 3D in vitro organ modeling, tissue-engineering applications, and suitable to conduct fundamental mechanobiology studies.

Creation of Chemically Tri-Layered Collagen Crosslinked Membranes and Their Comparison with Ionically Tri-Layered Chitosan Crosslinked Membranes to Study Human Skin Properties

In 2009, a new European regulation came into force that forbade the use of animals in the cosmetics industry. As a result, new alternatives were sought, taking into account the new ethical considerations. The main objective of this article is to continue a line of research that aims to build a physical model of skin from a biomaterial scaffold composed of collagen, chitosan or a combination to investigate whether they offer similar behavior to human skin. Collagen, the major component in the dermis, was crosslinked with glutaraldehyde (GTA) to develop three formulations for studying some properties of the skin through rheological tests like swelling index, elasticity or water loss. In addition, this article makes a comparison with the results obtained in the previous article where the membranes were made of chitosan and tripolyphosphate (TPP). The results obtained highlight that the tri-layered membranes scaffold better than the mono-layered ones to increase the elastic modulus (G') and the permeability. Furthermore, they offer a protective effect against water loss compared to mono-layered membranes. As regards chitosan membranes, these have a higher G' modulus than collagen membranes when the degree of deacetylation (DDA) is 85%. However, collagen membranes are more elastic when the DDA of chitosan is 76%, and their linear viscoelastic limit (LVL) doubles that of chitosan membranes, both for the degree of acetylation of 76 and 85%.

The Use of Collagen-Based Materials in Bone Tissue Engineering

Synthetic bone substitute materials (BSMs) are becoming the general trend, replacing autologous grafting for bone tissue engineering (BTE) in orthopedic research and clinical practice. As the main component of bone matrix, collagen type I has played a critical role in the construction of ideal synthetic BSMs for decades. Significant strides have been made in the field of collagen research, including the exploration of various collagen types, structures, and sources, the optimization of preparation techniques, modification technologies, and the manufacture of various collagen-based materials. However, the poor mechanical properties, fast degradation, and lack of osteoconductive activity of collagen-based materials caused inefficient bone replacement and limited their translation into clinical reality. In the area of BTE, so far, attempts have focused on the preparation of collagen-based biomimetic BSMs, along with other inorganic materials and bioactive substances. By reviewing the approved products on the market, this manuscript updates the latest applications of collagen-based materials in bone regeneration and highlights the potential for further development in the field of BTE over the next ten years.

A comparative study of bone bioactivity and osteogenic potential of different bioceramics in methacrylated collagen hydrogels

Biomimetic scaffolds composed of bioactive ceramic-based materials incorporated within a polymeric framework have shown immense promise for use in bone tissue engineering (BTE) applications. However, studies on direct comparison of the efficacy of different bioceramics on bone bioactivity and osteogenic differentiation are lacking. Herein, we performed an in vitro direct comparison of three different bioceramics-Bioglass 45S5 (BG), Laponite XLG (LAP), and β-Tricalcium Phosphate (TCP)-on the physical properties and bone bioactivity of methacrylated collagen (CMA) hydrogels (10% w/w bioceramic:CMA). In addition, human MSCs (hMSCs) were encapsulated in bioceramic-laden CMA hydrogels and the effect of different bioceramics on osteogenic differentiation of hMSCs was investigated in two different culture medium-osteoconductive (without dexamethasone [DEX]) and osteoinductive (with DEX). Results showed that the stability of CMA hydrogels was maintained upon bioceramic addition. Compression testing revealed that BG incorporation significantly decreased (p < 0.05) the modulus of photochemically crosslinked CMA hydrogels. Incubation of TCP-CMA and LAP-CMA hydrogels in simulated body fluid showed deposition of hydroxycarbonate apatite layer on the surface indicating that these hydrogels may be more bone bioactive than BG-CMA and CMA only hydrogels. Cell cytoskeleton staining results showed greater cell spreading in TCP-CMA hydrogels. Furthermore, TCP incorporation significantly increased alkaline phosphatase activity (ALP; p < 0.05) in hMSCs. Together, these results indicate that TCP has superior osteogenic potential compared with BG and LAP and hence should be considered as a bioceramic of preferred choice for use in the biomimetic design of cell-laden hydrogels for BTE applications.

Development of Scaffolds from Bio-Based Natural Materials for Tissue Regeneration Applications: A Review

Tissue damage and organ failure are major problems that many people face worldwide. Most of them benefit from treatment related to modern technology's tissue regeneration process. Tissue engineering is one of the booming fields widely used to replace damaged tissue. Scaffold is a base material in which cells and growth factors are embedded to construct a substitute tissue. Various materials have been used to develop scaffolds. Bio-based natural materials are biocompatible, safe, and do not release toxic compounds during biodegradation. Therefore, it is highly recommendable to fabricate scaffolds using such materials. To date, there have been no singular materials that fulfill all the features of the scaffold. Hence, combining two or more materials is encouraged to obtain the desired characteristics. To design a reliable scaffold by combining different materials, there is a need to choose a good fabrication technique. In this review article, the bio-based natural materials and fine fabrication techniques that are currently used in developing scaffolds for tissue regeneration applications, along with the number of articles published on each material, are briefly discussed. It is envisaged to gain explicit knowledge of developing scaffolds from bio-based natural materials for tissue regeneration applications.

Natural Coatings and Surface Modifications on Magnesium Alloys for Biomedical Applications

Magnesium (Mg) alloys have great potential in biomedical applications due to their incomparable properties regarding other metals, such as stainless steels, Co-Cr alloys, and titanium (Ti) alloys. However, when Mg engages with body fluids, its degradation rate increases, inhibiting the complete healing of bone tissue. For this reason, it has been necessary to implement protective coatings to control the rate of degradation. This review focuses on natural biopolymer coatings used on Mg alloys for resorbable biomedical applications, as well as some modification techniques implemented before applying natural polymer coatings to improve their performance. Issues such as improving the corrosion resistance, cell adhesion, proliferation, and biodegradability of natural biopolymers are discussed through their basic comparison with inorganic-type coatings. Emphasis is placed on the expected biological behavior of each natural polymer described, to provide basic information as a reference on this topic.

Collagen Alignment via Electro-Compaction for Biofabrication Applications: A Review

As the most prevalent structural protein in the extracellular matrix, collagen has been extensively investigated for biofabrication-based applications. However, its utilisation has been impeded due to a lack of sufficient mechanical toughness and the inability of the scaffold to mimic complex natural tissues. The anisotropic alignment of collagen fibres has been proven to be an effective method to enhance its overall mechanical properties and produce biomimetic scaffolds. This review introduces the complicated scenario of collagen structure, fibril arrangement, type, function, and in addition, distribution within the body for the enhancement of collagen-based scaffolds. We describe and compare existing approaches for the alignment of collagen with a sharper focus on electro-compaction. Additionally, various effective processes to further enhance electro-compacted collagen, such as crosslinking, the addition of filler materials, and post-alignment fabrication techniques, are discussed. Finally, current challenges and future directions for the electro-compaction of collagen are presented, providing guidance for the further development of collagenous scaffolds for bioengineering and nanotechnology.

Discussing the final size and shape of the reconstructed tissues in tissue engineering

Tissue engineering (TE) has made a revolution in repairing, replacing, or regenerating tissues or organs, but it has still a long way ahead. The mechanical properties along with suitable physicochemical and biological characteristics are the initial criteria for scaffolds in TE that should be fulfilled. This research will provide another point of view toward TE challenges concerning the morphological and geometrical aspects of the reconstructed tissue and which parameters may affect it. Based on our survey, there is a high possibility that the final reconstructed tissue may be different in size and shape compared to the original design scaffold. Thereby, the 3D-printed scaffold might not guarantee an accurate tissue reconstruction. The main justification for this is the unpredicted behavior of cells, specifically in the outer layer of the scaffold. It can also be a concern when the scaffold is implanted while cell migration cannot be controlled through the in vivo signaling pathways, which might cause cancer challenges. To sum up, it is concluded that more studies are necessary to focus on the size and geometry of the final reconstructed tissue.

An overview of substrate stiffness guided cellular response and its applications in tissue regeneration

Cell-matrix interactions play a critical role in tissue repair and regeneration. With gradual uncovering of substrate mechanical characteristics that can affect cell-matrix interactions, much progress has been made to unravel substrate stiffness-mediated cellular response as well as its underlying mechanisms. Yet, as a part of cell-matrix interaction biology, this field remains in its infancy, and the detailed molecular mechanisms are still elusive regarding scaffold-modulated tissue regeneration. This review provides an overview of recent progress in the area of the substrate stiffness-mediated cellular responses, including 1) the physical determination of substrate stiffness on cell fate and tissue development; 2) the current exploited approaches to manipulate the stiffness of scaffolds; 3) the progress of recent researches to reveal the role of substrate stiffness in cellular responses in some representative tissue-engineered regeneration varying from stiff tissue to soft tissue. This article aims to provide an up-to-date overview of cell mechanobiology research in substrate stiffness mediated cellular response and tissue regeneration with insightful information to facilitate interdisciplinary knowledge transfer and enable the establishment of prognostic markers for the design of suitable biomaterials.

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Substrate stiffness physically determines cell fate and tissue development.

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Rational design of scaffolds requires the understanding of cell-matrix interactions.

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Substrate stiffness depends on scaffold molecular-constituent-structure interaction.

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Substrate stiffness-mediated cellular responses vary in different tissues.

Terpolymer-chitosan membranes as biomaterial

The present study shows a novel copolymer synthesis, its application in the membrane design and the physicochemical and biological characterization of the biomaterial obtained. Terpolymer starting diisopropyl fumarate (F), vinyl benzoate (V) and 2-hydroxyethyl methacrylate (H) was prepared by thermal radical polymerization. This polymer (FVH) was obtained in several monomer ratios and characterized by spectroscopic and chromatographic methods (FTIR, ¹ H-NMR and SEC). The best relationship of F:V:H was 5:4:1, which allows efficient interaction with chitosan through cross-linking with borax to achieve scaffolds for potential biomedical applications. The membranes were obtained by solvent casting and analyzed by scanning electron microscopy (SEM), swelling behavior and mechanical properties. In addition, we studied the possible cytotoxicity and biocompatibility of these materials using a murine macrophage-like cell line (RAW 264.7) and bone marrow mesenchymal progenitor cells (BMPC), respectively, taking into account their intended applications. The results of this study show that the terpolymer obtained and its combination with a natural polymer is a very interesting strategy to obtain a biomaterial with possible applications in regenerative medicine and this could be extended to other structurally related systems.

Recent Advances in Fiber-Hydrogel Composites for Wound Healing and Drug Delivery Systems

In the last decades, much research has been done to fasten wound healing and target-direct drug delivery. Hydrogel-based scaffolds have been a recurrent solution in both cases, with some reaching already the market, even though their mechanical stability remains a challenge. To overcome this limitation, reinforcement of hydrogels with fibers has been explored. The structural resemblance of fiber-hydrogel composites to natural tissues has been a driving force for the optimization and exploration of these systems in biomedicine. Indeed, the combination of hydrogel-forming techniques and fiber spinning approaches has been crucial in the development of scaffolding systems with improved mechanical strength and medicinal properties. In this review, a comprehensive overview of the recently developed fiber-hydrogel composite strategies for wound healing and drug delivery is provided. The methodologies employed in fiber and hydrogel formation are also highlighted, together with the most compatible polymer combinations, as well as drug incorporation approaches creating stimuli-sensitive and triggered drug release towards an enhanced host response.