Figure 3

Measuring the specific binding forces of individual adhesins. (a) Schematics of the surface chemistry used to functionalize the AFM tip and substrate with HBHA and heparin. Recombinant histidine-tagged HBHA were attached onto an AFM tip terminated with Ni⁺⁺-nitrilotriacetate (NTA) groups while biotinylated heparin was bound to a gold surface via streptavidin and biotinylated bovine serum albumin (BBSA) layers. (b) Representative force curves and adhesion force histogram obtained in PBS between a HBHA tip and a heparin surface. The adhesion force histogram revealed a bimodal distribution reflecting the binding strength of one and two adhesins. (c) Same experiment in the presence of free heparin (50 μg/ml) demonstrating a dramatic reduction of adhesion frequency due to the blocking of the HBHA adhesion sites. Reprinted with permission from ref. [39]