Ferredoxin molecular thin film with intrinsic switching mechanism for biomemory application

A biomemory device consisting of cysteine modified ferredoxin molecules which possess a memory effect via a charge transfer mechanism was developed. For achieving an efficient bioelectronic device, cysteine modified ferredoxin was developed by embodying cysteine residues in ferredoxin by site--directed mutagenesis method to directly coordinate with the gold (Au) surface without use of any additional linkers. The thin film formation of ferredoxin molecules on Au electrode is confirmed by surface plasmon resonance (SPR) spectroscopy and scanning tunneling microscope (STM). Cyclic voltammetry (CV) and open circuit potential amperometry (OCPA) methods were used to verify the memory switching characteristics of the fabricated device. The charge transfer between ferredoxin protein molecules and Au electrode enables a bi-stable electrical conductivity allowing the system to be used as a digital memory device. Data storage is achieved by applying redox voltages which are within the range of -500 mV. These results suggest that the proposed device has a function of memory and can be used for the construction of a nano-scale bioelectronic device.