Engineering Photosystem I Complexes with Metal Oxide Binding Peptides for Bioelectronic Applications

Abstract

Conventional dye-sensitized solar cells comprise semiconducting anodes sensitized with complex synthetic organometallic dyes, a platinum counter electrode, and a liquid electrolyte. This work focuses on replacing synthetic dyes with a naturally occurring biological pigment–protein complex known as Photosystem I (PSI). Specifically, ZnO binding peptides (ZOBiP)-fused PSI subunits (ZOBiP–PsaD and ZOBiP–PsaE) and TiO₂ binding peptides (TOBiP)-fused ferredoxin (TOBiP–Fd) have been produced recombinantly from Escherichia coli. The MOBiP-fused peptides have been characterized via western blotting, circular dichroism, MALDI-TOF, and cyclic voltammetry. ZOBiP–PSI subunits have been used to replace wild-type PsaD and PsaE, and TOBiP–Fd has been chemically cross-linked to the stromal hump of PSI. These MOBiP peptides and MOBiP–PSI complexes have been produced and incubated with various metal oxide nanoparticles, showing increased binding when compared to that of wild-type PSI complexes