In situ Imaging of Single Polyelectrolyte Chains with the Atomic Force Microscope

This article discusses the possibilities offered by modern atomic force microscopes (AFMs) with ultra-small cantilevers to perform in situ imaging of single adsorbed polyelectrolytes in aqueous solutions. We demonstrate that such AFM techniques permit high quality images of single polyelectrolyte molecules to be obtained. These images can then be used to qualitatively address differences in the adsorbed conformations for different polyelectrolyte architectures. Moreover, such images can be also analyzed quantitatively. As an example, we discuss the determination of the persistence length of adsorbed polyelectrolytes.