Figure 3.
Tapping mode phase contrast AFM images of layers (top layers indicated) in sensor fabrication and use: (A) Nafion on freshly cleaved mica; (B) Nafion/FeO(OH)-FeOCl bilayer; (C) SWNT forests on Nafion/ FeO(OH)-FeOCl bilayer; (D) after covalent linkage of primary anti-PSA antibody (Ab1) followed by washing with 0.05% Tween-20, PBS buffer and water; (E) after addition of 2% BSA in 0.05% Tween-20 PBS buffer onto antibody layer and washing with 0.05% Tween-20, PBS buffer and water; (F) after addition of 40 ng mL−1 PSA in calf serum and washing with 0.05% Tween-20, PBS buffer and water; (G) after addition of 4 pmol mL−1 Ab2-HRP in PBS buffer containing 0.05% Tween-20 followed by washing with buffer solutions and water.