Guanine defects were created by mixing 10 nM DNA-functionalized SWCNTs with the respective concentrations of RB (Merck, product no. 198250) to a total volume of 2 ml and irradiation at 561 nm under stirring for 15 min in a custom build light chamber. After defect introduction, the sample was dialyzed against 500 ml 1 x PBS for at least four days a 300 kDa dialysis bag (Spectra/Por, product no. 131450) and daily buffer exchange. Concentration was determined by absorption spectroscopy as mentioned above. The success of defect reactions could be followed by bathochromic shifts of the E11 absorption maximum and increased FWHM. Residual RB could be detected (if present) at around 560 nm in the absorption spectrum.