AFM Mechanical Studies Of A Novel Form Of The Biopolymer Fibrin: Elastomeric Sheets

Abstract

Fibrin is a gel-forming biopolymer that constitutes the supporting fiber network structure of blood clots within the vasculature. The structure and mechanical properties of these fiber networks have been extensively studied for decades, inspired both by their unusual materials properties as well as their profound biomedical importance. We have recently observed a previously unreported alternate form of polymerized fibrin: two dimensional sheets of molecular thickness. Structural data revealing the sheet structure collected with atomic force microscopy (AFM), SEM and TEM will be presented. When prepared on micropatterened surfaces, the fibrin sheets spontaneously polymerized to span channels or holes in the underlying substrate. Using a combination fluorescence/AFM system, we have manipulated the suspended sheets and collected strain and force data. Our results show that fibrin sheets are a novel biological material: continuous elastomeric films capable of supporting reversible strains well in excess of 100% with an elastic modulus in the few MPa range.