Functionalized Nanoporous Gold Leaf Electrode Films for the Immobilization of Photosystem I

Abstract

Plants and some types of bacteria demonstrate an elegant means to capitalize on the superabundance of solar energy that reaches our planet with their energy conversion process called photosynthesis. Seeking to harness Nature's optimization of this process, we have devised a biomimetic photonic energy conversion system that makes use of the photoactive protein complex Photosystem I, immobilized on the surface of nanoporous gold leaf (NPGL) electrodes, to drive a photoinduced electric current through an electrochemical cell. The intent of this study is to further the understanding of how the useful functionality of these naturally mass-produced, biological light-harvesting complexes can be integrated with nonbiological materials. Here, we show that the protein complexes retain their photonic energy conversion functionality after attachment to the nanoporous electrode surface and, further, that the additional PSI/electrode interfacial area provided by the NPGL allows for an increase in PSI-mediated electron transfer with respect to an analogous 2D system if the pores are sufficiently enlarged by dealloying. This increase of interfacial area is pertinent for other applications involving electron transfer between phases; thus, we also report on the widely accessible and scalable method by which the NPGL electrode films used in this study are fabricated and attached to glass and Au/Si supports and demonstrate their adaptability by modification with various self-assembled monolayers. Finally, we demonstrate that the magnitude of the PSI-catalyzed photocurrents provided by the NPGL electrode films is dependent upon the intensity of the light used to irradiate the electrodes.

Spatial modulation of light transmission through a single microcavity by coupling of photosynthetic complex excitations to surface plasmons

“…The PS I used in this study, derived from cyanobacterial membrane, is a nanosize protein-chlorophyll complex, which integrates 96 chlorophyll and 22 carotenoid pigment molecules in a helical protein membrane complex. It harvests photons with a quantum efficiency of B1, and was found to be stable and photoactive when adsorbed in a dry environment 19,[26][27][28] . Selfassembled mono and multilayers of PS I were fabricated by formation of a direct sulfide bond between unique cysteine mutants in PS I and the patterned Au surface (see Fig.…”

Nanoporous Gold Electrodes and Their Applications in Analytical Chemistry

“…The underpotential deposition (UPD) of metal (Pb 2+ , Cu 2+ , Ag + ), whereby the charge from the formation or stripping of the UPD monolayer is measured via chronoamperometry or CV, has been used [50,64,65,98]. In this case, the charge measured of a UPD monolayer is directly proportional to the surface area of the electrode [98].…”

“…12 K white gold leaf (Monarch brand), for example, is a ∼50 : 50 wt% gold alloy with a thickness of ∼100-200 nm [9,15,65]. The gold leaf has primarily been used for decorative purposes and can be purchased from a number of suppliers.…”

“…These SAMs can act as simple modifiers [68] or be used as linkers to attach various molecules to its surface such as proteins, enzymes, antibodies, or photosystem I [65,66,90,[106][107][108][109]. Because of the very high surface areas of nanoporous gold, a significantly larger amount of the modifier can be immobilized on its surface relative to a planar gold electrode.…”

Photosynthetic Energy Conversion: Recent Advances and Future Perspective

“…7 PSI complexes have been immobilized using several different strategies such as gold nanoparticle (GNP) modified electrode, 8 functionalized nano-porous gold leaf electrodes, 9 PSI-GNP hybrid electrode modified with 3-mercapto-1-propanesulfonic acid, 10 and via self-assembly onto zinc oxide nanomaterials. 11 The immobilization strategy is instrumental in dictating the orientation of biocatalyst on the surface as well as its proximity to the electrode.…”