Rectified photocurrent in a protein based molecular photo-diode consisting of a cytochrome b₅₆₂-green fluorescent protein chimera self-assembled monolayer

We fabricated a self-assembled monolayer (SAM) of a chimeric protein created as a novel model protein for an artificial light-harvesting complex (LHC) composed of two proteins, cytochrome b₅₆₂ (cytb₅₆₂) mutated for SAM fabrication (cytb₅₆₂, N22C, G82C) and enhanced green fluorescent protein (EGFP). The SAM formation of chimeric protein on a single-crystalline Au(111) substrate was confirmed by atomic force microscopy (AFM) measurement. The rectified photocurrent of the chimeric protein SAM on a gold substrate was detected by light-illumination scanning tunneling microscopy (LI-STM) co-operated with a lock-in technique. The photocurrent generation of the chimeric protein SAM was wavelength-specific to the light-illumination (488nm), which indicated that the EGFP part of the chimera plays a role as a sensitizer in the photo-induced electron transfer process.