Fig. 3.

XP spectra and SEM images of SAP surface and reference materials, [amphiphilic Janus pillars with pillar size w = 10 μm, h = 22 μm, and a surface fraction of 19.6% and with trichloro(1H,1H,2H,2H-perfluorooctyl)silane fluorinated flat silica coated silicon wafer], all incubated for 2 h in a solution of BSA in phosphate buffer (1 mg/ml): The emission centered near 402 eV observed for the pillar structure and the fluorinated flat surface is related to nitrogen groups within BSA adsorbed to the surfaces.