2D Visualization of Mannose Distribution Using AFM Force Sensing with Probe Modified by Concanavalin A

It is very important to clarify the distribution of sugar chains on the surface of biological membranes for understanding physiological reactions in detail. However, there has been little information available on the two-dimensional distribution of sugar chains on biological surfaces on micro- to nanometer scale until now. Atomic force microscopy (AFM) has been widely used for the direct detection of specific interactions between biologically active molecules. Concanavalin A (ConA) is a well-known lectin with specific affinities for α-D-mannosyl and α-D-glucosyl residue. In this study, mannose (Man) and oligoethylene glycol (OEG) were locally immobilized on a substrate, and the two-dimensional distribution was visually mapped on micrometer scale using AFM force sensing with a ConA-modified tip. As a result, the distinct contrast between Man and OEG regions was observed based on the difference of the interaction with ConA. It is expected that distribution analysis of sugar chains on biological membranes will be realized by this method in the near future.