Sensor dye-doped nanofibers could be spun successfully froma 15 wt% polystyrene solution in 2-butanone; adding 0.46 mg/mlof the cationic surfactant hexadecyl-trimethyl ammoniumbromide(HDAB) decreases the surface tension and increases the conduc-tivity of the polymer solution. Those two parameters have a highimpact on the spinability and therefore further enhance the spin-ning process, leading to defect-free nanofibers with no detectablebeats or droplets. As expected, the addition of the oxygen-sensitivedye platinum-tetra(pentafluorophenyl) porphyrine (PtTFPP) hadno impact on the electrospinning process. Fig. 2 shows SEM picturesof the electrospun fibers. The fibers exhibit a bank-like structurewith an eight-shaped cross-section with a rather homogeneousbroadness of 620 nm and a thickness of 100 nm at the thinnestposition in the middle of the fiber. Furthermore, the fiber surfacereveals a kind of “nanoporous” substructure which might addi-tionally accelerate diffusion and mass transport in the fibers. Aluminescent microscope image (excitation wavelength: 505 nm,emission cut-off filter at 610 nm) of the polystyrene nanofiberscontaining the luminescent dye PtTFPP is shown