The final mat thickness was 60 μm. Doping process: Stock solutions were prepared by dissolving Protoporphyrin IX (STREM chemicals) and chlorophyll (Spectrum, a mixture of chlorophyll a and b) in 1 mL dimethyl sulfoxide (DMSO) (Carlo-Erba) for a final concentration of 3.2 mM. These stock solutions were then diluted with 1 ml DMSO and 5 mL physiological buffered saline (PBS) buffer to yield doping solutions having a concentration of 0.1 mM. The mats were then placed in the doping solutions on a stirring plate without light exposure for around 24 h.