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BioMed Research International
Volume 2017 (2017), Article ID 6385628, 13 pages
Research Article

Nonuniform Internal Structure of Fibrin Fibers: Protein Density and Bond Density Strongly Decrease with Increasing Diameter

1Department of Physics, Wake Forest University, Winston-Salem, NC 27109, USA
2Leeds Institute of Cardiovascular & Metabolic Medicine, The LIGHT Laboratories, University of Leeds, Clarendon Way, Leeds LS2 9NL, UK
3Department of Physics, University of Richmond, Richmond, VA 23173, USA
4Centre of Excellence for Nutrition, North-West University, Potchefstroom, South Africa
5Department of Health & Exercise Science, Wake Forest University, Winston-Salem, NC 27109, USA
6NanoMedica, LLC, Biotech Place, 575 Patterson Ave, Winston-Salem, NC 27101, USA

Correspondence should be addressed to Martin Guthold

Received 22 February 2017; Revised 5 May 2017; Accepted 22 August 2017; Published 10 October 2017

Academic Editor: Jeroen Rouwkema

Copyright © 2017 Wei Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The major structural component of a blood clot is a meshwork of fibrin fibers. It has long been thought that the internal structure of fibrin fibers is homogeneous; that is, the protein density and the bond density between protofibrils are uniform and do not depend on fiber diameter. We performed experiments to investigate the internal structure of fibrin fibers. We formed fibrin fibers with fluorescently labeled fibrinogen and determined the light intensity of a fiber, , as a function of fiber diameter, . The intensity and, thus, the total number of fibrin molecules in a cross-section scaled as . This means that the protein density (fibrin per cross-sectional area), , is not homogeneous but instead strongly decreases with fiber diameter as . Thinner fibers are denser than thicker fibers. We also determined Young’s modulus, , as a function of fiber diameter. decreased strongly with increasing ; scaled as . This implies that the bond density, , also scales as . Thinner fibers are stiffer than thicker fibers. Our data suggest that fibrin fibers have a dense, well-connected core and a sparse, loosely connected periphery. In contrast, electrospun fibrinogen fibers, used as a control, have a homogeneous cross-section.