We used a combined atomic force microscope (AFM)/fluorescence microscope technique to study the mechanical properties of individual, electrospun fibrinogen fibers in aqueous buffer. Fibers (average diameter 208 nm) were suspended over 12 μm-wide grooves in a striated, transparent substrate. The AFM, situated above the sample, was used to laterally stretch the fibers and to measure the applied force. The fluorescence microscope, situated below the sample, was used to visualize the stretching process. The fibers could be stretched to 2.3 times their original length before breaking; the breaking stress was 22·106 Pa. We collected incremental stress-strain curves to determine the viscoelastic behavior of these fibers. The total stretch modulus was 16·106 Pa and the relaxed, elastic modulus was 6.7·106 Pa. When held at constant strain, electrospun fibrinogen fibers showed a fast and slow stress relaxation time of 3 and 56 seconds.
Our fibers were spun from the typically used 90% 1,1,1,3,3,3-hexafluoro-2-propanol (90-HFP) electrospinning solution and resuspended in aqueous buffer. Circular dichroism spectra indicate that alpha-helical content of fibrinogen is ~70% higher in 90-HFP than in aqueous solution.
These data are needed to understand the mechanical behavior of electrospun fibrinogen structures. Our technique is also applicable to study other, nanoscopic fibers.
The definitive version is available at: http://www.sciencedirect.com/science/article/pii/S0142961208008806#
Carlisle, Christine R., Corentin Coulais, Manoj Namboothiry, David L. Carroll, Roy R. Hantgan, and Martin Guthold. "The Mechanical Properties of Individual, Electrospun Fibrinogen Fibers." Biomaterials 30, no. 6 (February 2009): 1205-213. doi:10.1016/j.biomaterials.2008.11.006.
Helms, Christine C.; Coulais, Corentin; Namboothiry, Manoj; Carroll, David L.; Hantgan, Roy R.; and Guthold, Martin, "The Mechanical Properties of Individual, Electrospun Fibrinogen Fibers" (2009). Physics Faculty Publications. 98.