Mechanical Properties of Electrospun, Blended Fibrinogen: PCL Nanofibers.

Jacquelyn M Sharpe,Martin Guthold,Keith Bonin,Adam R Hall,Hyunsu Lee

doi:10.3390/nano10091843

Abstract

Electrospun nanofibers manufactured from biocompatible materials are used in numerous bioengineering applications, such as tissue engineering, creating organoids or dressings, and drug delivery. In many of these applications, the morphological and mechanical properties of the single fiber affect their function. We used a combined atomic force microscope (AFM)/optical microscope technique to determine the mechanical properties of nanofibers that were electrospun from a 50:50 fibrinogen:PCL (poly-ε-caprolactone) blend. Both of these materials are widely available and biocompatible. Fibers were spun onto a striated substrate with 6 μm wide grooves, anchored with epoxy on the ridges and pulled with the AFM probe. The fibers showed significant strain softening, as the modulus decreased from an initial value of 1700 MPa (5–10% strain) to 110 MPa (>40% strain). Despite this extreme strain softening, these fibers were very extensible, with a breaking strain of 100%. The fibers exhibited high energy loss (up to 70%) and strains larger than 5% permanently deformed the fibers. These fibers displayed the stress–strain curves of a ductile material. We provide a comparison of the mechanical properties of these blended fibers with other electrospun and natural nanofibers. This work expands a growing library of mechanically characterized, electrospun materials for biomedical applications.

Highlights

Electrospinning is a relatively straightforward method to make fibers with micrometer and sub-micrometer diameters from many different materials
With the knowledge of the mechanical properties of the pure, electrospun PCL and fibrinogen fibers, we created a new fiber type by combining these two materials into a 50:50 blend. This combination of natural and synthetic materials expands the library of fibers available to scientists. We studied these fibers using an atomic force microscope (AFM) technique, and determined the total and elastic modulus, maximum stress and strain, and energy loss
To create the 50:50 fibrinogen:PCL fibers, 1 mL of the PCL solution and 1 mL of the fibrinogen solution were mixed in a beaker with a stir bar until well blended

Summary

Introduction

Electrospinning is a relatively straightforward method to make fibers with micrometer and sub-micrometer diameters from many different materials. The technique of electrospinning was first reported and patented in the early 20th century [2,3]; initially it was only used in a few applications relating to textiles [4] and filtering [1]. This initial sparsity of applications has been attributed to a lack of tools to characterize and, understand these nanoscopic fibers [1]. Once a basic theoretical understanding of electrospinning was developed and fibers could be characterized, electrospinning saw an enormous increase in applications, especially over the last two decades. Significant research efforts in developing innovative applications, thorough fiber characterization, and improved theoretical understanding of fiber formation and properties are ongoing [1]

Methods

Results

Conclusion