For this purpose, (GT)10-ssDNA functionalized SWCNTs were exposed to RB and light in aqueous phosphate buffered saline (PBS). The reaction solution was next dialyzed against PBS to remove residual RB. The complete removal of the chromophore RB from the sample was verified by absorption spectroscopy . In agreement with the literature , defect introduction caused a bathochromic shift and broadened the E11 NIR fluorescence feature (Figure ). DNA-SWCNTs illuminated in presence of higher RB concentrations had higher defect densities and hence stronger bathochromic shifts and peak-broadening. Next, we wanted to know if the amount of DNA, which is only loosely bound and can be removed from the SWCNTs changes for this covalent chemistry. Therefore, the product of the reaction was washed by spin filtration and the DNA amount in the washing solution was measured by absorption spectroscopy . First, PBS buffer was used to remove free DNA from the solution. It is expected, that adsorbed DNA will not be affected by this process. Surface adsorbed DNA was removed from the SWCNTs in a second step by washing with the surfactant sodium cholate (SC), which occupies the SWCNT surface and removes non-covalently bound DNA . For PBS washing steps, the amount of removable DNA decreased with increasing defect density. For washing with SC no significant difference was visible for different defect densities (Figure ). Therefore, for G d -SWCNTs more DNAmolecules are strongly bound than for pristine SWCNTs. To test the influence of the covalent character of surface functionalization on analyte recognition, 100 µM dopamine (DA) or riboflavin were added to G d -SWCNTs of different defect densities (Figure ). To compare defect densities between sensors, the position of the E11 peak was compared. All sensors showed a strong