Preparation of chlorine e6-conjugated single-wall carbon nanotube for photodynamic therapy

We fabricated single-wall carbon nanotubes (SWNTs) modified with chlorine e6 (as a photosensitizing drug: Ce6) and poly(ethylene glycol) (PEG, as a polymeric stabilizer) were fabricated to develop a light-sensitive nanovehicle for tumor treatment. The carboxyl group of Ce6 and poly(ethylene glycol) (PEG) was coupled with aminated SWNT via N,N'-dicyclohexyl carbodiimide (DCC)- and N-hydroxysuccinimide (NHS)-mediated amide formation. During light irradiation, singlet oxygen generation from Ce6 coupled to the SWNTs was reduced due to the quenching effect of SWNTs for Ce6. Unlike free Ce6, Ce6 coupled to the SWNTs accumulated to a significant degree in the tumor site, reflecting its pharmaceutical potential under in vivo conditions. This might become a potential carrier system for improving photodynamic therapy.