AFM images and height profiles of lysozyme nanoarrays. (A) Lateral force image of a 8 Ám by 8 Ám square lattice of MHA dots deposited onto an Au substrate. The array was imaged with an uncoated tip at 42% relative humidity (scan rate = 4 Hz). (B) Topography image (contact mode) and height profile of the nanoarray after Lysozyme adsorption. A tip-substrate contact force of 0.2 nN was used to avoid damaging the protein patterns with the tip. (C) A tapping mode image (silicon cantilever, spring contant = ~40 N/m) and height profile of a hexagonal Lysozyme nanoarray. The image was taken at 0.5 Hz scan rate to obtain high resolution. (D) Three-dimensional topographic image of a lysozyme nanoarray, consisting of a line grid and dots with intentionally varied feature dimensions. Imaging was done in contact mode as described in (B).