Detection of Singlet Oxygen Generation

3-Diphenylisobenzofuran (DPBF) is a common chemical probe to detect singlet oxygen generation. DPBF can combine with singlet oxygen to gradually lose its characteristic absorption peak at 415 nm. In a typical experiment, 20 μL of DPBF (1000 ppm in DMF) was added to 2 mL of PZD suspension in a quartz cuvette. The cuvette was kept in dark and irradiated with a 660 nm He-Ne laser at a power of 100 mW/cm², and the absorption spectrum was recorded at 0 s, 30 s, 60 s, 150 s and 300 s. The rate of singlet oxygen generation was determined by the reduction of DPBF absorbance over time. Irradiation of ZnPc in the absence of free polymersomes was also carried out and set as a positive control.