Singlet Oxygen Generation from Polymer Nanoparticles–Photosensitizer Conjugates Using FRET Cascade

Abstract

Herein, we demonstrate π-conjugated polymer nanoparticles–photosensitizer conjugates for singlet oxygen generation via FRET cascade, which would be useful for photodynamic therapy. Rose Bengal (RB) molecules are attached on the surface of coumarin 153 (C153)-dye-doped poly­[<i>N</i>-vinyl carbazole] (PVK) polymer nanoparticles, where polymer nanoparticles act as efficient light-absorbing antenna materials. The energy funneling from C153 to RB at the excitation of the PVK host (340 nm) is confirmed by shortening of decay time of C153 and disappearing of its rise time. Again, it is evident that the efficient multistep energy transfer occurs from host PVK to RB dye molecules through C153 dye molecules to generate singlet oxygen (¹O₂) in solution. In addition, photo-oxidation of 2-chlorophenol provides quantitative evidence of singlet oxygen generation in different systems indirectly. The estimated singlet oxygen quantum yield for RB-attached C153-dye-doped PVK polymer nanoparticles is 21%. The present investigations should pave the way for future development of different photodynamic and theranostic devices