We performed several experiments to quantify the brightness of SWNTs in the presence of reductants. On the ensemble level, the fluorescence intensity of DNA-wrapped SWNTs is weaker than that of SWNTs coated with some other surfactants, like sodium dodecylbenzenesulfonate (SDBS) and sodium deoxycholate;(19) thus, one concern was that the reductants simply restored individual SWNT fluorescence intensities to typical values. First, using identical experimental conditions, we compared the fluorescence intensity of individual DNA-wrapped SWNTs (after reductant addition) to individual SDBS-wrapped SWNTs deposited onto a surfactant-functionalized coverslip (Figure 3a and b). On average, the DNA-wrapped SWNTs (after reductant addition) were four times brighter than SWNTs wrapped in SDBS, indicating that fluorescence intensities from DNA-wrapped SWNTs surpassed typical values. It is important to note that this comparison was performed on the single molecule level, where only the brightest SWNTs in the distribution were observed. Second, a direct side-by-side comparison of fluorescence intensity counts between DNA-wrapped SWNTs (after addition of reductants) and highly fluorescent commercial CdTe/ZnS nanocrystals (QDot 805 from Invitrogen, QY ∼ 70%) shows that, again, when observed under identical experimental conditions, they are essentially equally bright (Figure 3c and d). Images in Figure 3c and d are shown using the same intensity scale; however, SWNTs emit at 990 nm (CCD quantum efficiency = 40%), and QDs emit at 805 nm (CCD quantum efficiency = 98%). For this reason, although SWNTs and QDs display comparable fluorescence intensities in Figure 3c and d, the SWNTs acutally emitted approximately twice as many photons as were detected (Table S2, Supporting Information).