Despite a lot of intensive research in the field of polymer nanofibers as wound-healing and tissue-regeneration materials, the behavior of cells in contact with nanofibers in vitro as well as in vivo is still not well understood. However, this knowledge is crucial for the design of nanofibrillar materials that are suitable for biomedical applications. Therefore, in this study we present the preparation of poly(vinyl alcohol) (PVA) nanofibers from a physico-chemically characterized polymer solution by electrospinning together with a stabilization method to preserve the morphology of the nanofibers in aqueous conditions. An investigation of the effects of a nanofibrillar scaffold on the growth of human keratinocytes showed that randomly oriented PVA nanofibers delay the keratinocytes adhesion but improve their strength, greatly alter their morphology, increase their metabolic activity and limit their mobility. We have shown that due to the small interfiber pores, the whole cells are unable to penetrate into nanofibrillar network efficiently. However, flexible cell parts can penetrate into the nanofibrillar network, whereas the cell nuclei stay on the surface of electrospun scaffold. Additional reason for poor cell mobility is random orientation of nanofibers, which does not provide continuous routes for successful cell infiltration. Therefore, nanofibrillar support with nanosized interfiber pores could potentially be used to enable an efficient cell proliferation and accelerate surface-wound healing, but not for 3D tissue regeneration. Finally, we showed that aligned nanofibers can successfully direct the migration and proliferation of cells, which is a crucial property of nanomaterials for the successful regeneration of tissues with a highly organized structure.
COBISS.SI-ID: 3339121
Electrospun polymer nanofibers are gaining increasing importance in tissue engineering, wound dressing and drug delivery. Here, we present a thorough rheological study of polymer solutions in the bulk and at the interface to find correlations between those properties and the electrospinnability of the solutions and the morphology of the resultant nanofibers. Our results indicate that blended solutions of chitosan or alginate with poly (ethylene oxide) (PEO) are appropriate for electrospinning when they form conductive, unstructured fluids displaying plasticity, rather than elasticity, in the bulk and at the interface. The interfacial rheological parameters are three orders of magnitude lower than those in the bulk. We demonstrate for the first time that interfacial, rather than bulk, rheological parameters show improved correlation and can be used to predict the success of the electrospinning process. Using the interfacial parameters of samples with homologous compositions, different groups of solutions can be identified that form smooth nanofibers. However, rheological parameters of the bulk and at the interface provide complimentary information. The bulk parameters are determined by polymer concentration and directly affect jet initiation, while the interfacial behaviour determines the continuation of the jet and fibre formation. We propose that interfacial parameters are indispensible tools for the design of electrospinning experiments.
COBISS.SI-ID: 3248753
The subject of nanomedicine has seen a surge in research activity over the past decade, with nanofibers being a particularly active field. Nanofibers aresolid, dry fibers with nanometer diameters, made of various polymers, whereas electrospinning is a versatile, simple, elegant, reproducible, continuous and scalable technology for their preparation. Nanofibers are a unique class of materials in the biomedical field, since they provide a biomimetic environment on the nanometer scale, a three-dimensional architecture with the desired surface properties on the micrometer scale, combined with mechanical strength and physiological acceptability on the macroscale. In particular, their ability to imitate the fibrillar elements of a natural extracellular matrix in a very realistic way is crucial. In this paper we introduce the fundamental aspects of the electrospinning process and the properties of nanofibers, as well as highlighting the enormous potential of nanofibers as drug-delivery systems and tissue scaffolds.
COBISS.SI-ID: 3380081