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Streszczenie:
Biological interaction between cells and scaffolds is mediated through events at surfaces. Proteins present in the culture medium adsorb on substrates, generating a protein adlayer that triggers further downstream events governing cell adhesion. Polymer blends often combine the properties of the individual components, for example, can provide mechanical as well as surface properties in one fibre. Therefore, mixtures of synthetic polycaprolactone and gelatin as a denatured form of collagen were electrospun at selected conditions and polymer weight ratios. Fibre morphologies and chemical properties of the surfaces were analysed. These scaffolds were seeded with human mesenchymal stromal cells and their viability was studied. Gelatin addition to polycaprolactone leads to a reduction in fibre diameter. A linear increase in gelatin at the fibre surface was observed in function of the weighed polymers, except for polycaprolactone/gelatin fibres incorporating equal weight ratios. Thereby, a depletion of gelatin at the fibre surface is stated for equally mixed polymers. The depletion of gelatin at the fibre surface is most probably due to hydrophobic interactions between hydrophobic segments of polycaprolactone and gelatin, affecting the spinning mechanism and thus fibre structure. Furthermore, polycaprolactone/gelatin blends show enhanced wettability properties compared to pure gelatin, at least partly due to molecular segregation. Results of in vitro studies reveal an increase in cellular viability and proliferation for cells cultivated on nanofibres containing gelatin, caused by the cell-attractive surface composition as well as the hydrophilic nature of the scaffolds. Contact guidance of cells seeded on parallelised fibres is observed, and DNA tests show evidently enhanced cell numbers on nanofibres containing 20 wt% of gelatin.

Słowa kluczowe:
Mesenchymal stromal cells, electrospinning, surface, blends, biocompatibility, polymers, bioactivity

Streszczenie:
The effect of electrospinning parameters on morphology, molecular, and supermolecular structure of polycaprolactone (PCL) fibers was analyzed, with respect to tissue engineering applications. Fibers morphology and structure are mainly determined by solution concentration and collector type. Applied voltage does not significantly influence supermolecular structure (crystallinity) and mechanical stiffness. There is correlation between changes in structure and proliferation of 3T3 cells as evidenced by in vitro study. Processing window of optimal scaffolds is relatively wide, however, variation of electrospinning parameters do not significantly affect their biological functionality.

Słowa kluczowe:
3T3 cells, crystallinity, electrospinning, molecular orientation, polycaprolactone, porosity, tissue engineering

Streszczenie:
Blends of polycaprolactone (PCL) and gelatine (Ge), being effective materials for tissue engineering strategies, were electrospun at various conditions and polymer weight ratios. The morphology, the supermolecular structure as well as the mechanical properties of resulting submicron sized fibres have been analyzed in relation to electrospinning conditions and PCL/Ge weight ratio. Compared to pure PCL, Ge addition leads to large reduction of fibre diameter and finally to changes of fibre morphology. For parallelised fibres collected on a rotating drum, preferred molecular orientation of PCL crystals is found. With increasing Ge content a general reduction of molecular orientation is observed. In addition, there is peculiar dependence of polycaprolactone crystallinity on the content of Ge, showing maximum at low Ge concentration (20%) as determined by differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS). Such a trend can be explained by hydrophobic interactions in the system containing PCL, gelatine and water, being additional driving forces for crystallization of nonpolar PCL molecules. The presence of water within investigated blend systems has been evidenced experimentally using thermal gravimetric analysis (TGA). Young’s modulus of nonwovens, as determined by uniaxial tensile testing, indicates the effect of additivity of the stiffness of both polymers as well as the influence of preferred molecular orientation. Additional experiments were performed using collagen (Col) as a biopolymeric alternative to Ge. WAXS results show evidently amorphous structure of Col within the blended fibres, indicating strong tendency for denaturation of collagen into gelatine under the influence of hexafluoroisopropanol as a solvent.

Słowa kluczowe:
Electrospinning, Nanofibres, Blend, Gelatine polycaprolactone, Molecular structure