Mechanical Properties of Electrospun Single Fibers by Nanoindentation

초록

Nanoindentation using atomic force microscopy (AFM) is a technique that has been used to determine the mechanical properties of materials on a sub-micron scale.1 The use of this technique to measure the mechanical properties of nanofibers is relatively new.2 During AFM nanoindentation, the AFM probe tip is first lowered into contact with the sample, then indented into the sample surface, and finally lifted off the sample surface. The speed of indentation can be varied. Tip deflection is measured as a function of the vertical motion of the scanner, resulting in a curve that can be analyzed to provide information about local mechanical response. The objective in the present study was to assess the mechanical properties of electrospun silk fibers using the AFM nanoindentation technique. Furthermore, the goal was to assess changes in the mechanical properties associated with the various steps utilized in the processing of the electrospun fibers. To conduct these studies, first the morphology and microstructure of electrospun Bombyx mori silk/poly(ethylene oxide) (PEO) fibers were assessed, before and after methanol treatment and after extraction with water (Fig. 1).3,4 Then the mechanical properties of these fibers prepared at different stages in the processing were determined by AFM nanoindentation.5 Native B. mori silk fiber was also investigated for comparison.