Issue 7, 2009

Biopolymerization-driven self-assembly of nanofiber air-bridges


Several proteins, including actin and fibrin, polymerize in vivo to form nanometre diameter fibers. These processes can be duplicated in vitro using only the essential enzyme and protein precursors. These same protein solutions are directed to self-assemble into oriented arrays of air-bridges using only the crude operation of hand brushing them over textured micron-scale surfaces. The creation of these suspended structures could be used as nanomechanical elements in various sensors and actuators, and their fabrication by this rapid directed self-assembly method would be useful, especially during the early phases of prototype device development. The fabrication method extends earlier studies (Harfenist et al., Nano Lett., 2004, 4, 1931) in which an organic polymer dissolved in a volatile solvent forms nanofiber air-bridges through a combination of capillary force driven thinning of liquid bridges and evaporation driven solidification of the polymer solution. However, in the current study polymerization is initiated when a monomeric solution of soluble protein is brushed over the micro-textured surface. When fibrinogen solutions are brushed over a thrombin primed surface, or monomeric actin over a KCl primed array, fiber air-bridges are formed, sometimes reaching diameters as small as 16 nm. The uniformity in diameter of one hand-brushed array of 358 parallel fibrin air-bridges was 36.4 nm (6.8 nm standard deviation), with no more than 3 broken fibers. The fibrin bridges are shown to be both highly elastomeric and adhesive through demonstration of the construction and stretching of a three point bridge using a micromanipulator. Also the brush-on method produced ordered arrays of suspended fibrin membranes, which sometimes were anchored perpendicular to the vertical sidewalls of the textured surface and other times were anchored parallel to the sidewalls. The demonstration of air-bridge formation by biopolymerization suggested that air-bridges might also be formed during initiated polymerization of organic monomers. Even though the monomer of norbornylene has a much smaller molecular weight than fibrinogen, hand brushing of norbornylene in toluene with Grubbs' catalyst resulted in the self-assembly of fiber air-bridges as small as 4 nm diameter over nearly 6 microns length.

Graphical abstract: Biopolymerization-driven self-assembly of nanofiber air-bridges

Supplementary files

Article information

Article type
09 Oct 2008
05 Dec 2008
First published
03 Feb 2009

Soft Matter, 2009,5, 1378-1385

Biopolymerization-driven self-assembly of nanofiber air-bridges

S. Pabba, M. M. Yazdanpanah, B. H. Fasciotto Totten, V. V. Dobrokhotov, J. M. Rathfon, G. N. Tew and R. W. Cohn, Soft Matter, 2009, 5, 1378 DOI: 10.1039/B817761A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity