The singlet oxygen dose is adjusted by the SWCNT/RB ratio in the reaction solution, as the RB reaction is irreversible . In contrast to sp 3 defects, guanine defects (g-defects) are considered to create sp 2 hybridized carbons . The wave functions of the defects overlap as a consequence of spatial proximity between g-defects and create more shallow exciton traps. Unlike sp 3 defect SWCNTs, guanine defect functionalized SWCNTs (G d -SWCNTs) only have a single NIR emission feature, which is redshifted and broadened compared to pristine SWCNTs. This surface chemistry enables also well-defined and periodic DNA structures around SWCNTs . So far it is not understood if covalent binding of DNA to the SWCNT surface affects the sensing mechanism in DNA-SWCNT-based biosensors. SWCNTs are versatile sensors, which are frequently used in biological environments in vitro and in vivo. The interaction of a SWCNT with a cellular membrane and therefore the transportation process across the membrane depends on the SWCNT´s surface properties such as size or charge.