Abstract

Here, we report the development of a novel photoactive biomolecular nanoarchitecture based on the genetically engineered extremophilic photosystem I (PSI) biophotocatalyst interfaced with a single layer graphene via pyrene-nitrilotriacetic acid self-assembled monolayer (SAM). For the oriented and stable immobilization of the PSI biophotocatalyst, an His6-tag was genetically engineered at the N-terminus of the stromal PsaD subunit of PSI, allowing for the preferential binding of this photoactive complex with its reducing side towards the graphene monolayer. This approach yielded a novel robust and ordered nanoarchitecture designed to generate an efficient direct electron transfer pathway between graphene, the metal redox center in the organic SAM and the photo-oxidized PSI biocatalyst. The nanosystem yielded an overall current output of 16.5 µA·cm−2 for the nickel- and 17.3 µA·cm−2 for the cobalt-based nanoassemblies, and was stable for at least 1 h of continuous standard illumination. The novel green nanosystem described in this work carries the high potential for future applications due to its robustness, highly ordered and simple architecture characterized by the high biophotocatalyst loading as well as simplicity of manufacturing.

Highlights

  • The photosystem I (PSI) biophotocatalyst was genetically modified at the N-terminus of the extrinsic

  • The PSI immobilization occurred via the organic conductive interface based on the pyrene-nitrilotriacetic acid (pyr-NTA) self-assembled monolayer (SAM) into which two distinct metal redox centers were incorporated (Ni or Co) as a rational strategy to improve direct electron transfer (DET) (Scheme 1)

  • His6 -PsaD-PSI biophotocatalyst, captured within the conductive organic SAM, on the graphene monolayer (SLG). This approach yielded the homogeneous and dense single layer graphene (SLG) coverage with the PSI biophotocatalyst leading to a significantly improved overall photocurrent output in conjunction with an enhanced stability of photocurrent generation compared to the abiotic fluorine-doped tin oxide (FTO)/SLG material

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Summary

Introduction

Photosynthesis is one of the most fundamental processes carried out by phototrophic organisms to convert photons into chemical energy [1]. This process evolved on earth over 3.5 billion years ago [2] and is directly responsible for the production of atmospheric oxygen, allowing the biosphere as we know to prosper, but it has provided all the fossil fuels that drive the present-day economies. To ameliorate climate change and to meet the ever-growing energy demand of humankind, the race is on to provide alternative viable technologies to produce sustainable fuels in a circular economy model. The biomimicry of the natural photosynthesis process offers an attractive technological option for solar-to-chemical conversion

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