Supporting Information Individual Single-Wall Carbon Nanohorns Separated From Aggregates Minfang Zhang 1 *, Takashi Yamaguchi 2 , Sumio Iijima 1, 2 , Masako Yudasaka 1 * 1 National Institute of Advanced Industrial Science and Technology, Higashi 1-1-1, Tsukuba, 305-8565, Japan. 2 Nagoya University, Chiikusa-ku, Nagoya, 464-8601, Japan Corresponding authors: m-zhang@aist.go.jp , m-yudasaka@aist.go.jp 1. Effect of oxidation conditions on the isolation of the small aggregates of SWNHs or individual SWNHs. We found that the oxidation conditions affected the quantities of individual single- wall carbon nanohorns (SWNHin) and small aggregates (SWNHsm) obtained in the top layer of the sucrose gradient (Zone I, Figure 1b) following sucrose density gradient centrifugation. The oxidized SWNHs (ox-SWNHs) prepared by slow combustion (temperature increase from ~20 o C to a final temperature (T(end)) at a rate of 1 o C/min followed by natural cooling) 1 with different T(end) between 350 and 550 o C) were treated by sucrose gradient centrifugation(SGC). The SGC was also performed on ox- SWNH prepared by light-assisted oxidation with hydrogen peroxide (LAOx). 2 After SGC, we estimated concentrations of ox-SWNH in the top SGC-layers from optical absorbances at 700 nm using a calibration curve. Here, the calibration curve (Figure SI- 1a) was obtained by measuring UV-Vis-NIR absorption spectra of ox-SWNHag dispersed in aqueous solutions of sodium cholate. The concentration of ox-SWNHs in the top layer decreased with the increase of T(end) (Figure SI-1b). We also observed ox-SWNHs in the top layers by transmission electron microscopy (TEM). For ox-SWNHs obtained by slow combustion with T(end) at 400 o C, ox- SWNHin was a minor component, but the large-sized ox-SWNHag and ox-SWNHsm were the dominant forms(Figure SI-1c). The SGC top layers for ox-SWNHag obtained at high T(end) or by LAOx also contained a small number of SWNHin. From the quantity estimation and TEM observations described above, we concluded that the optimum oxidation condition for obtaining the maximum number of SWNHin was the slow combustion method with T(end) at 450 or 500 o C.