Evaluation of the CO₂ reduction capacity of rhodobacter sphaeroides immobilized on phthalocyanine based photosensitizers

Metallic phthalocyanines have been widely studied as sensitizers for photodynamic therapy. These studies look at photoinduced electron transfer in donor-acceptormolecules for covalently linked dyes in solution as a model system of natural photosynthesis to efficiently harvest solar energy. In the present study, an immobilization of Rhodobacter sphaeroides on zinc and copper phthalocyanines has been observed to improve electron transport. The electrode reaction of cell bound metallic phthalocyanines has been confirmed by cyclic voltammetry measurements. R. sphaeroides bound zinc phthalocyanines in water and copper phthalocyanine in sodium dodecyl sulphate shows the occurrence of active electrode reactions. These have been correlated to the concentration of cell bound metallic phthalocyanines. In addition, cell bound metallic phthalocyanines were used for CO₂ reduction by R. sphaeroides cultured under light or dark conditions. The electron donating properties of metallic phthalocyanines bound with R. sphaeroides can be exploited for improving the reducing efficiency of CO₂.