AFM/TIRFM study of individual fibrin fibers

Tuesday, October 09, 2012 — Poster Session I
1:00 p.m. – 3:00 p.m	Natcher Conference Center, Building 45	NIBIB	BIOPHY-6

Authors

• A L Popescu (Hategan)
• E K Dimitriadis

Abstract

Colocalized imaging of individual fibrin fibers by combined atomic force microscopy (AFM) and total internal reflection fluorescence microscopy (TIRFM) was used to gain insights into the structure and the effects of the degree of hydration. Under the conditions of AFM imaging in buffer fibers appear flattened, with heights one order of magnitude smaller (tens of nm) than diameters (hundreds of nm), with thicker fibers more flattened. All fibers presented thickness variations along their length, of up to 3 nm in diameter per 10 nm length of fiber. Branching of fibers, at angles between 0-900 was also observed. High resolution imaging reveals the periodic structure of fibers, with a periodicity of 23 nm corresponding to half-staggering of protofibrils. TIRFM imaging of the same fibers showed that fibers fluorescence correlated with the topographical features imaged by AFM, suggesting that labeled protein is uniformly distributed throughout the fibers. Single-molecule TIRFM imaging of fibrinogen molecules, basic constituents of fibers, allows for a molecular calibration that determines the number of molecules in individual fibers; correlated with AFM topographical data informs to the degree of hydration of the fibers – a major question in the fibrin fiber structure.

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