Figure 4.

Surface-tethered methylene blue. (A) We used maleimide chemistry to immobilize methylene blue to a gold surface via a six-carbon-linker dithiol chain with a 6-mercapto-1-hexanol monolayer covering the rest of the surface. We then measured square-wave voltammograms (full line traces) at a frequency of 100 Hz (see the other frequencies in Figure S6) and amplitudes of (B) 25, (C) 50, and (D) 75 mV. When we impose k⁰ = 1.5 ± 0.5 cm s⁻¹ $(k_{x=8\stackrel{\circ }{\mathrm{A}}}^0=5.0\pm 1.7\times {10}^4{\mathrm{s}}^{-1})$ and α = 0.37 ± 0.02 in our numerical model, we find that the resultant simulated voltammograms closely match the experimental voltammograms.