Atomic-force imaging of biological molecules using an enviromental cell with sample translation capability

Abstract

Atomic force microscope images of well-characterized biological macromolecules always appear wider and flatter than expected. These dimensional artifacts can be explained in part by tip convolution and tip compression as well as the relative strengths of the tip-sample and tipsubstrate interactions. The effects of tip convolution and tip compression can be manipulated by knowing the tip geometry and applied force, however the tip-sample interaction strength is highly dependent on the environment in which the specimen is scanned. In order to manipulate the environmental conditions under which images are obtained we have constructed an enviromental cell (Fig. 1.) that allows us to simultaneously image molecules in the topographic and lateral force modes in almost any gas or liquid at ambient temperatures and pressures. The design of the enviromental cell allows the sample to be translated in the x and y directions, and also allows the sample to be viewed optically at magnifications up to 400 times.