The synthesis of AgNPs using the ferritin photochemical system. Kinetic trace (a) of AgNPs formation and spectra (b) of the samples before (△) and after (▲) illumination. Upon illumination, the absorbance increases at 420 nm due to the formation of AgNPs. This absorbance is due to the surface plasmon resonance properties of AgNPs. (c) The color of the solution changes from almost colorless before (top) to amber after (bottom) illumination.