Δf-ΔD plots from the QCM-D data of (a) 10 μM N1 or (b) N2 binding to POPC/POPS (2:1) bilayers, or binding to (c and d) POPC/POPG (2:1) bilayers. The data shown is from the 3rd (black), 5th (red), 7th (green), 9th (blue), 11th (magenta), and 13th (cyan) overtones. To see this figure in color, go online.