Next, we investigated whether oxidized catechol products could be detected when these compounds were exposed to ssDNA-SWCNT conjugates, as suggested by the correlations presented in the foregoing analysis. We first used an enzyme-linked immunosorbent assay (ELISA) that can sensitively quantify concentration of dopamine at picomolar concentrations but is otherwise insensitive to quinones, the oxidative product of catechols (fig. ). Oxidation of dopamine with sodium periodate induced rapid depletion of the starting material, which we verified with the ELISA assay (Fig. ). We then quantified the level of oxidation of dopamine in solutions that had been exposed to ssDNA-SWCNT conjugates for various durations and excitation laser intensities. Surprisingly, no oxidation product was detected using this assay, indicating minimal oxidation of dopamine in the starting material (Fig. ). Similarly, highperformance liquid chromatography (HPLC) detection of quinones showed depletion of starting material in periodate controls (Fig. , dopaquinone (DQ)) but not in experimental solutions (Fig. , DA/SWCNT/Excited, DA/SWCNT/ Not Excited).