Figure 3. The correlation between the amount of added NaCl in the gap and the measured adhesion force between two mica surfaces.

(a) After DNA adsorption in 10 mM CoCl₂ (), an equivalent amount of 10 mM NaCl was added into the surface gap. Then, the gap buffer was completely replaced with 10 mM NaCl (). (b) The measured adhesion force decreased with an increase in the amount of 10 mM NaCl in a buffer solution, followed by a recovery to ¾ of the original magnitude when the buffer is returned to 10 mM CoCl₂.