Eva Kostakova

Analysis and three-dimensional visualization of collagen in artificial scaffolds using nonlinear microscopy techniques

Extracellularly distributed collagen and chondrocytes seeded in gelatine and poly-ɛ-caprolactone scaffolds are visualized by two-photon excitation microscopy (TPEM) and second-harmonic generation (SHG) imaging in both forward and backward nondescanned modes. Joint application of TPEM and SHG imaging in combination with stereological measurements of collagen enables us not only to take high-resolution 3-D images, but also to quantitatively analyze the collagen volume and a spatial arrangement of cell-collagen-scaffold systems, which was previously impossible. This novel approach represents a powerful tool for the analysis of collagen-containing scaffolds with applications in cartilage tissue engineering.

Crystallinity of Electrospun and Centrifugal Spun Polycaprolactone Fibers: A Comparative Study

Crystalline properties of semicrystalline polymers are very important parameters that can influence the application area. The internal structure, like the mentioned crystalline properties, of polymers can be influenced by the production technology itself and by changing technology parameters. The present work is devoted to testing of electrospun and centrifugal spun fibrous and nanofibrous materials and compare them to foils and granules made from the same raw polymer. The test setup reveals the structural differences caused by the production technology. Effects of average molecular weight are also exhibited. The applied biodegradable and biocompatible polymer is polycaprolactone (PCL) as it is a widespread material for medical purposes. The crystallinity of PCL has significant effect on rate of degradation that is an important parameter for a biodegradable material and determines the applicability. The results of differential scanning calorimetry (DSC) showed that, at the degree of crystallinity, there is a minor difference between the electrospun and centrifugal spun fibrous materials. However, the significant influence of polymer molecular weight was exhibited. The morphology of the fibrous materials, represented by fiber diameter, also did not demonstrate any connection to final measured crystallinity degree of the tested materials.

Nanofibrous Composite Materials Integrating Nano/Micro Particlesbetween the Fibres

This article deals with the continual incorporation of particles by the ultrasonic dispersion in situ into a nanofibrous matrix produced by the electrospinning process. The new technology is based on the use of the needleless electrospinning method in combination with the ultrasound-enhanced dispersion of sub-micro or micro particles, which are deposited between nanofibres onto the support material. The main advantage of this technology is the independence of particle-incorporation of the electrospinning process. The particles are trapped between the fibres and they remain uncovered by polymer, thus maintaining all their active properties. Such materials can be cut with scissors without the particles being released. In this paper the authors present figures from scans of the electron microscopy of the newly-designed nanocomposite material and its morphological analysis, such as the particle distribution. The material was used as a sorbent of bis(2-chlorethyl) sulfide (mustard gas) with a sorption time greater than 240 minutes. Such material has been developed to be used for protection against chemical warfare agents; yet, it can be employed for several other applications depending on the powder material dispersed onto the nanofibrous layer.