Ratiometric porphyrin-based layers and nanoparticles for measuring oxygen in biosamples

Oxygen-sensitive polystyrene layers and nanoparticles have been developed for measuring oxygen in biosamples. Polymer layers were prepared via spin-coating on glass plates while the nanoparticles were synthesized by microemulsion polymerization. Platinum(II)meso-tetra(pentafluorophenyl)porphine (PtTFPP) was used as an oxygen sensor whereas N,N′-bis(1-hexylheptyl)perylene-3,4:9,10-bis-(dicarboximide) (S13) was used as a reference dye. For both, layers and nanoparticles, the sensor response was assessed in aqueous solution as well as in yeast culture. Quenching of porphyrin phosphorescence by oxygen was observed whereas fluorescence of the reference dye remained essentially unaffected. By using the signal of the reference dye fluctuations in the intensity of the excitation light or the nanosensor concentration can be easily corrected. Both sensor systems were compared with respect to their spectral response and their sensitivity.