The mimicking of the architectonics of native tissue, biodegradable non-woven fibrous mats is one of the most promising forms of scaffolding for tissue engineering. The key properties needed for ...their successful application in vivo, such as biodegradability, biocompatibility, morphology, mechanical properties, etc., rely on their composition and appropriate 3D structure. A multicomponent system based on biodegradable synthetic (polycaprolactone, oligo-/polylactide) and natural (chitosan, gelatin) polymers, providing the desired processing characteristics and functionality to non-woven mats fabricated via the electrospinning technique, was developed. The solid-state reactive blending of these components provided a one-step synthesis of amphiphilic graft copolymer with an ability to form stable ultra-fine dispersions in chlorinated solvents, which could be successfully used as casting solvents for the electrospinning technique. The synthesized graft copolymer was analyzed with the aim of fractional analysis, dynamic laser scattering, FTIR-spectroscopy and DSC. Casting solution characteristics, namely viscosity, surface tension, and electroconductivity, as well as electrospinning parameters, were studied and optimized. The morphology, chemical structure of the surface layer, mechanical properties and cytocompatibility were analyzed to confirm the appropriate functionality of the formed fibrous materials as scaffolds for tissue engineering.
Objectives
The conversion of tissue engineering into a routine clinical tool cannot be achieved without a deep understanding of the interaction between cells and scaffolds during the process of ...tissue formation in an artificial environment. Here, we have investigated the cultivation conditions and structural features of the biodegradable non‐woven material in order to obtain a well‐differentiated human airway epithelium.
Materials and methods
The bilayered scaffold was fabricated by electrospinning technology. The efficiency of the scaffold has been evaluated using MTT cell proliferation assay, histology, immunofluorescence and electron microscopy.
Results
With the use of a copolymer of chitosan‐gelatin‐poly‐l‐lactide, a bilayered non‐woven scaffold was generated and characterized. The optimal structural parameters of both layers for cell proliferation and differentiation were determined. The basal airway epithelial cells differentiated into ciliary and goblet cells and formed pseudostratified epithelial layer on the surface of the scaffold. In addition, keratinocytes formed a skin equivalent when seeded on the same scaffold. A comparative analysis of growth and differentiation for both types of epithelium was performed.
Conclusions
The structural parameters of nanofibres should be selected experimentally depending on polymer composition. The major challenges on the way to obtain the well‐differentiated equivalent of respiratory epithelium on non‐woven scaffold include the following: the balance between scaffold permeability and thickness, proper combination of synthetic and natural components, and culture conditions sufficient for co‐culturing of airway epithelial cells and fibroblasts. For generation of skin equivalent, the lack of diffusion is not so critical as for pseudostratified airway epithelium.
Surface-enhanced Raman scattering (SERS) microspectroscopy is a very promising label-free, noncontact, and nondestructive method for real-time monitoring of extracellular matrix (ECM) development and ...cell integration in scaffolds for tissue engineering. Here, we prepare a new type of micrometer-sized SERS substrate, core–shell microparticles composed of solid carbonate core coated with silver nanoparticles and polyhedral multishell fullerene-like structure, astralen. Astralen has been assembled with polyallylamine hydrochloride (PAH) by the layer-by-layer manner followed by Ag nanoparticle formation by means of a silver mirror reaction, giving the final structure of composite particles CaCO3(PAH/astralen) x /Ag, where x = 1–3. The components of the microparticle carry multiple functionalities: (i) an easy identification by Raman imaging (photostable astralen) and (ii) SERS due to a rough surface of Ag nanoparticles. A combination of Ag and astralen nanoparticles provides an enhancement of astralen Raman signal by more than 1 order of magnitude. Raman signals of commonly used scaffold components such as polylactide and polyvinyl alcohol as well as ECM component (hyaluronic acid) are significantly enhanced. Thus, we demonstrate that new mechanically robust and easily detectable (by astralen signal or optically) core–shell microspheres based on biocompatible CaCO3 can be used as SERS platform. Particle design opens many future perspectives for fabrication of SERS platforms with multiple functions for biomedical applications, for example, for theranostic.
Surface plasma treatment of chitosan films is a widely used technique to control a variety of their properties, such as permeability, hemostatic activity and ability to support cell adhesion, ...proliferation and growth. Among other factors to be controlled, the chemical structure of initial chitosan is rarely taken into consideration. This work is aimed to highlight this factor by the example of low pressure direct‐current discharge of various chitosan film samples. Contact angle measurements, X‐ray photoelectron spectroscopy and scanning electron microscopy revealed differences in the film surface properties of the initial and plasma‐treated films. The effect of the plasma treatment on cell viability of L929 mouse fibroblasts was studied by MTT‐assay.
The manuscript deals with low‐temperature DC discharge treatment of film samples made of chitosans of various molecular weights and acetylation degrees. In spite of the similarity of the observed processes, such as surface hydrophilization, etching and oxidation, the samples showed different surface properties, morphology, chemical structure and an ability to support an adhesion, proliferation and growth of mouse fibroblasts L929..
The presented paper is focused on impregnation of chitosan and its derivatives with a biologically active triaryl imidazole model compound ((2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole) in the ...supercritical carbon dioxide medium. Since initial chitosan represents a polycation-exchange resin and does not swell in supercritical carbon dioxide, the impregnation was carried out in the presence of water (0.15–3.0 vol%). The maximum 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole concentration in a chitosan film was achieved at the ~5 × 10
−3
g/cm
3
water content in the reactor. We also used hydroxy carboxylic acid derivatives of chitosan and its copolymer with polylactide as matrices for introduction of hydrophobic 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole. We have shown that unmodified chitosan contains the greatest amount of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole, as compared with its hydrophobic derivatives. The kinetics of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole diffusion from a chitosan matrix was studied in acidified water with pH 1.6. We found that the complete release of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole into the aqueous phase from unmodified chitosan films occurred in 48 h, while its complete release from chitosan modified with hydroxy carboxylic acids occurred in 5 min or less.
Solvent-free N-allylation of chitosan with allyl bromide was performed under shear deformation in an extruder and the obtained chitosan derivatives were successfully used for the microfabrication of ...3D structures by laser stereolithography.
A novel approach to design chitosan-polyester materials is reported. The method is based on mechanical activation and effective intermixing of the substrates under high pressure and shear deformation ...in the course of solid-state reactive blending. The marked departure of this approach from previous practice resides on exploitation of a variety of chemical transformations of the solid polymers that become feasible under conditions of plastic flow. Low temperatures (above Tg but below the melting points of the crystalline polymers) are maintained throughout the process, minimizing mechanical and oxidative degradation of the polymers. Morphology as well as structural, mechanical, and relaxation properties of those prepared blends of chitosan with semicrystalline poly(L,L-lactide) and amorphous poly(D,L-lactide-co-glycolide) has been studied. Grafting of polyester moieties onto chitosan chains was found to occur under employed pressures and shear stresses. The prepared polymer blends have demonstrated an amphiphilic behavior with a propensity to disperse in organic solvents that widens possibilities to transform them into promising materials for various biomedical applications.
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