The mechanical properties of individual, electrospun fibrinogen fibers

Abstract

We used a combined atomic force microscopic (AFM)/fluorescence microscopic 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 17.5 × 106 Pa and the relaxed elastic modulus was 7.2 × 106 Pa. When held at constant strain, electrospun fibrinogen fibers showed a fast and slow stress relaxation time of 3 and 55 s. Our fibers were spun from the typically used 90% 1,1,1,3,3,3-hexafluoro-2-propanol (90-HFP) electrospinning solution and re-suspended in aqueous buffer. Circular dichroism spectra indicate that α-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 Use of Natural Polymers in Tissue Engineering: A Focus on Electrospun Extracellular Matrix Analogues

“…Similarities were observed in the extensibilities of the individual fibers and the mats. However, both the peak stress and the modulus of elasticity of the mats were approximately an order of magnitude lower than the single fibers, suggesting that amongst other factors, the mechanical properties of the mats are a complex combination of the mechanical properties of the individual fibers making up the mats [103].…”

“…As such, it was demonstrated that scaffold remodeling and collagen matrix production were inversely related to the aprotinin concentration, with nearly complete remodeling taking place after 14 days in even the highest aprotinin concentrations (Figure 7). The mechanical properties of individual, electrospun fibrinogen fibers have been evaluated [103] and compared to the mechanical properties of wet, non-woven mats made from randomly oriented electrospun fibrinogen fibers [104]. Similarities were observed in the extensibilities of the individual fibers and the mats.…”

Actuating individual electrospun hydrogel nanofibres

“…Recently, a method using an atomic force microscope (AFM) has been described that allows tensile testing of individual nanofibres to high strains with sub nN force resolution. 20,21 The method is applicable to soft, elastomeric materials and allows the samples to be immersed in a fluid. The technique is ideally suited for actuation testing of individual hydrogel nanofibres.…”

“…The fibres were stretched by lateral movement of the fully-immersed AFM cantilever, using the method similar to that described previously 20,21 and illustrated in Fig. 1a.…”

Fibrinogen and fibrin based micro and nano scaffolds incorporated with drugs, proteins, cells and genes for therapeutic biomedical applications

“…45 Carlisle et al analyzed the mechanical properties of a single electrospun Fbg nanofiber, using a combined atomic force/fluorescence microscopic technique, and the result indicated that Fbg nanofiber had a high extensibility. 46 High-extensibility fiber scaffolds have been found to be more widely applicable for in vitro and in vivo tissue engineering due to their flexibility. Electrospun Fbg nanofibers that Abbreviations: Fbg, fibrinogen; SEM, scanning electron microscope.…”