Nanofiber protein adsorption affected by electrospinning physical processing parameters

Proteins as a mediator in the interfacial interactions between cell and substrates play an important role in the regulation of cell functions. In this study, polycaprolactone (PCL) nanofibers were prepared using electrospinning apparatus to obtain substrates with various physical characteristics and the same chemistry. Electrospin processing parameters were designed by Taguchi method and their effects on PCL fiber properties evaluated. Scanning electron microscopy was used for visual observation of fiber diameter, size distribution and bead formation. Mechanical properties of each specimen including tensile strength and elongation at break were assessed by means of standard mechanical test machine and correlated to the spinning parameters. In addition, adsorption of serum protein to each sample was quantified by Bradford method. SDS-PAGE analysis confirmed these results and revealed a significant difference between protein adsorption (up to 250 %) for the fibers with the same chemical composition. Additional experiments confirmed that the degree of protein adsorption is improved on increasing the quantity of beads in the structures. It was also verified that with increasing the time of exposure from 1 to 24 h, higher amount of proteins were adsorbed. The selected sample with the average diameter of 274 nm without any bead exhibited the highest tensile strength (7.6 MPa) and the lowest amount of adsorption. The results indicated that electrospinning processing parameters change the physical characteristics of the fibers (diameter and bead) and also their biological performance such as protein adsorption as well as cell attachment and cell spreading.