Biomimetic synthesis of photoactive α-Fe₂O₃ templated by the hyperthermophilic ferritin from Pyrococus furiosus

Utilizing a biomimetic approach toward materials synthesis a ferritin protein cage, from the hyperthermophilic archeaon Pyrococcus furiosus, was utilized to first tempate the formation of a largely amorphous ferrihydrite iron oxide and then bring about its transformation to hematite (α-Fe₂O₃). This was achieved under boiling aqueous conditions by refluxing the ferritin protein cage/ferrihydrite composite. The resultant material showed diffraction indicative of hematite, a visible band gap semiconductor, and photocurrents were measured under visible illumination. The resultant protein/mineral composite was also studied via dynamic light scattering, transmission electron microscopy, and size exclusion chromatography.