Plasmon‐Enhanced Photocurrent of Photosynthetic Pigment Proteins on Nanoporous Silver

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms AbstractIn a quest to fabricate novel solar energy materials, the high quantum efficiency and long charge separated states of photosynthetic pigment-proteins are being exploited through their direct incorporation in bioelectronic devices. In this work, photocurrent generation by bacterial reaction center-light harvesting 1 (RC-LH1) complexes self-assembled on a nanostructured silver substrate yielded a peak photocurrent of 166 µA cm -2 under 1 sun illumination, and a maximum of over 400 µA cm -2 under 4 suns, the highest reported to date.A 2.5-fold plasmonic enhancement of light absorption per RC-LH1 complex was measured on the rough silver substrate. This plasmonic interaction was assessed using confocal fluorescence microscopy, revealing an increase of fluorescence yield and radiative rate of the RC-LH1 complexes. Nano-structuring of the silver substrate also enhanced the stability of the protein under continuous illumination by almost an order of magnitude relative to a nonstructured bulk silver control. Due to its ease of construction, increased protein loading capacity, stability and more efficient use of light, this hybrid material is an excellent candidate for further development of plasmon enhanced biosensors and bio-photovoltaic devices.3

Functional Nanohybrid Materials from Photosynthetic Reaction Center Proteins

“…When photosynthetic systems (light-harvesting antenna complexes or RCs) are bound to metal nanoparticles or to specific metal surfaces (like silver or gold), an additional effect is observed which offers exceptional, unique, and sophisticated application in nanoelectronics [74][75][76][77]. If proper geometric conditions are fulfilled, the electric field of 1.E-09…”

“…Antenna-plasmon interaction enhanced fluorescence [76], and photocurrent generation using bacterial RC:LH1 complex assembled on nanostructured silver [77] was demonstrated (LH1, light-harvesting complex 1 of purple bacteria). Furthermore, surface plasmon resonance equipment was designed for successful detection of the herbicide atrazine, which is used in agriculture and blocks PS II electron transfer between Q A and Q B [65].…”

On the mechanism of ubiquinone mediated photocurrent generation by a reaction center based photocathode

“…This provides sufficient time for diffusional processes to remove electrons from the "negative terminal" of the RC and donate electrons to the "positive terminal", resetting the RC for the next turnover. Developments in our understanding of RC mechanism have influenced the design of new synthetic materials for solar energy conversion, and there is interest in the hybridization of both natural and engineered RC proteins with man-made materials for applications in photovoltaics [4][5][6][7][8][9], biosensing [10,11] and molecular electronics [12,13].…”

“…Particular attention has been paid to the Photosystem I complex from oxygenic phototrophs [15][16][17] and both the RC and RC/light harvesting complexes from anoxygenic purple photosynthetic bacteria such as Rhodobacter (Rba.) sphaeroides [4][5][6][7][8]10,[18][19][20][21][22][23]. Major preoccupations of this work have been the development of strategies for effective interfacing of the positive and negative terminals of the photovoltaic protein to the working and counter electrode, either through direct binding or the use of diffusional mediators [4][5][6][7][8][16][17][18][19][20][21][22][23][24][25][26][27].…”

“…sphaeroides [4][5][6][7][8]10,[18][19][20][21][22][23]. Major preoccupations of this work have been the development of strategies for effective interfacing of the positive and negative terminals of the photovoltaic protein to the working and counter electrode, either through direct binding or the use of diffusional mediators [4][5][6][7][8][16][17][18][19][20][21][22][23][24][25][26][27]. In the case of RC's from purple bacteria a particularly effective strategy has been to use analogues of the natural electron donor and electron acceptor, cytochrome (cyt) c2 and ubiquinone-10 (UQ10), to connect the photovoltaic protein to the two electrodes [18,20,22,[27][28][29].…”