FIG. 4.

Strategy for measuring the IsdA-loricrin interaction forces using AFM. (A) Schematics of the surface chemistry used to functionalize AFM tips and supports with IsdA and loricrin (see the text for details). (B and C) AFM images of the biologically modified supports in PBS confirming the presence of smooth, homogeneous IsdA (B) and loricrin (C) layers. To determine the thickness of the layers, small square areas first were scanned at large forces (>25 nN), followed by imaging 5- by 5-μm images of the same areas under smaller forces.