Search

In this study, bioactive glass (BG) and copper metal nanoparticles (Cu NPs)-doped poly(Ɛ-caprolactone) (PCL) nanofiber membranes were produced by electrospinning method. Box–Behnken design was used to evaluate the effect of formulation variables including PCL concentration, Cu NPs ratio and BG ratio on nanofiber diameter, and cytotoxicity studies on mouse fibroblasts (L-929) were performed to evaluate the formulation suitable for tissue engineering applications. Membranes containing BG showed enhanced cytocompatibility. It was determined that the toxic properties of the membranes increased with the increase of the Cu NPs ratio. In light of these studies, it was determined that 10% w/v PCL concentration, 15% w/w BG ratio and 0.025% w/w Cu NPs ratio were biocompatible with L929 fibroblast cells. The stability and mineralization ability of the obtained membrane in simulated body fluid were determined by scanning electron microscope and X-ray diffraction analysis. This proved the osteogenic potential of the obtained membrane. Copper ions release from the nanofiber mat was detected by inductively coupled plasma-optical emission spectrometry, and it was found that this membrane had an angiogenic potential. Therefore, this study provides an overview of the effect of formulation variables to fabricate PCL nanofiber scaffolds with BG and Cu NPs for tissue engineering applications.

The rheological characterizations of concentrated suspensions are generally carried out assuming “well-mixed” suspensions. However, the variation of the concentration distributions of the ingredients of the formulation, i.e., the “goodness of mixing”, the size and shape distributions of the particle clusters and the rheological behavior of the suspension all depend on the thermo-mechanical history that the suspension is exposed to during the mixing process. Here, various experimental tools are used for the characterization of the degree of mixedness (concentration distributions) of various ingredients along with the characterization of rheological material functions, wall slip behavior and the maximum packing fraction of a graphite/elastomer suspension. The degree of mixedness values of the ingredients of the suspensions processed using batch and continuous processes and under differing operating conditions were characterized quantitatively using wide-angle X-ray diffraction and thermo gravimetric analysis and were elucidated under the light of the electrical properties of the suspension as affected by the mixing process. Upon achieving better homogeneity of the graphite particles and the binder and decreases in the size and breadth of the size distributions of particle clusters (as inferred from electrical measurements and maximum packing fraction values), the elasticity (storage modulus) and the shear viscosity (magnitude of the complex viscosity from small-amplitude oscillatory shear and shear viscosity from steady torsional and capillary rheometry) of the suspension decreased significantly and the wall slip velocity values increased. These findings demonstrate the intimate relationships that exist between the rheological behavior of concentrated suspensions and the thermo-mechanical history that they are exposed to during the processing stage and suggest that the preparation conditions for suspensions should be carefully selected and well documented to achieve reproducible characterization of rheological material functions.