Humidity-dependent open-circuit photovoltage from a bacteriorhodopsin/indium tin oxide bioelectronic heterostructure

Crittenden, Scott; Howell, Stephen W.; Reifenberger, R.; Hillebrecht, Jason R.; Birge, Robert R.

doi:10.1088/0957-4484/14/5/315

Cited by 14 publications

(16 citation statements)

References 32 publications

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“…The photoelectric signals generated from reconstituted bR films as observed by a variety of independent research groups have proved that photochemical properties of bR can be maintained in its solid phase because of the unusual stability of purple membrane (PM) sheets (Váró and Keszthelyi, 1983;Kononenko et al, 1987;He et al, 1998;Crittenden et al, 2003). However, the photocycle and proton transfer kinetics of dried bR film dramatically differ from those of the more commonly studied wet bR samples due to the influence of dehydration.…”

Section: Introductionmentioning

confidence: 99%

Photoelectric properties of a detector based on dried bacteriorhodopsin film

Wang

Knopf

Bassi

2006

Biosensors and Bioelectronics

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Section: Introductionmentioning

confidence: 99%

Photoelectric properties of a detector based on dried bacteriorhodopsin film

Wang

Knopf

Bassi

2006

Biosensors and Bioelectronics

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“…Because of its long-term stability against thermal, chemical, and photochemical degradation and its desirable photoelectric and photochromic properties, bR has attracted much interest as a material for biooptics and bioelectronics (5). Most of these efforts focused on multilayers and their photovoltage͞photocurrent generation (6)(7)(8) and photoconduction (9).…”

mentioning

confidence: 99%

Bacteriorhodopsin (bR) as an electronic conduction medium: Current transport through bR-containing monolayers

Jin

Friedman²,

Sheves³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

157

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Studying electron transport (ET) through proteins is hampered by achieving reproducible experimental configurations, particularly electronic contacts to the proteins. The transmembrane protein bacteriorhodopsin (bR), a natural light-activated proton pump in purple membranes of Halobacterium salinarum, is well studied for biomolecular electronics because of its sturdiness over a wide range of conditions. To date, related studies of dry bR systems focused on photovoltage generation and photoconduction with multilayers, rather than on the ET ability of bR, which is understandable because ET across 5-nm-thick, apparently insulating membranes is not obvious. Here we show that electronic current passes through bR-containing artificial lipid bilayers in solid ''electrode-bilayer-electrode'' structures and that the current through the protein is more than four orders of magnitude higher than would be estimated for direct tunneling through 5-nm, water-free peptides. We find that ET occurs only if retinal or a close analogue is present in the protein. As long as the retinal can isomerize after light absorption, there is a photo-ET effect. The contribution of light-driven proton pumping to the steady-state photocurrents is negligible. Possible implications in view of the suggested early evolutionary origin of halobacteria are noted. molecular electronics ͉ vesicles ͉ bioelectronics B acteriorhodopsin (bR) is a protein-chromophore complex that serves as a light-driven proton pump in the purple membrane (PM) of Halobacterium salinarum (1). It has been shown that the protein is composed of seven transmembrane helices with a retinal chromophore covalently bound in the central region via a protonated Schiff base to a lysine residue (Fig. 1A). The PM is organized in a 2D hexagonal crystal lattice with a unit cell dimension of Ϸ6.2 nm. Electron crystallography has indicated that bR is organized into trimers in which lipids mediate intertrimer contact (2). Light absorption by bR initiates a multistep reaction cycle with several distinct spectroscopic intermediates: J 625 , K 590 , L 550 , M 412 , N 560 , and O 640 . More details on the molecular alterations that occur during the photocycle were recently obtained from x-ray diffraction studies (see ref. 3 for a recent review). The light-adapted form of bR contains only all-trans retinal, whereas the dark-adapted form contains a 1:1 mixture of 13-cis and all-trans (4). Because of its long-term stability against thermal, chemical, and photochemical degradation and its desirable photoelectric and photochromic properties, bR has attracted much interest as a material for biooptics and bioelectronics (5). Most of these efforts focused on multilayers and their photovoltage͞photocurrent generation (6-8) and photoconduction (9).In principle, PM patches (Ϸ5 nm thick, a few m in size; see Fig. 1B) can serve as a model protein material that is important for both planar junction fabrication and current transport measurements, because the 5-nm membrane is well beyond the thickness over which tu...

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“…In contrast, the photoelectric response of BR, which depends on a net charge separation (voltage) across the lipid membrane, necessitates the fabrication of films in which PM fragments are uniformly oriented in order to facilitate unidirectional proton transport. Several approaches, involving layer by layer deposition, [13][14][15] Langmuir-Blodgett deposition, [16][17][18][19] electrophoretic sedimentation, [20,21] antibody recognition [22] and chemiadsorption selfassembly [23] have been developed to achieve this objective.The films are generally soft and brittle, and the photoelectric response sensitive to changes in environmental conditions such as pH, temperature and relative humidity. In this paper, we describe a novel approach for preparing BR-based mesolamellar nanocomposites comprising uniformly oriented sheets of intact PM lipid bilayers intercalated between nanometre-thick layers of amorphous silica (Fig.…”

mentioning

confidence: 99%

Bio‐Functional Mesolamellar Nanocomposites Based on Inorganic/Polymer Intercalation in Purple Membrane (Bacteriorhodopsin) Films

Bromley¹,

Patil²,

Seddon³

et al. 2007

Advanced Materials

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Fabrication of self-assembled structures using multiple building blocks with diverse functionalities such as biomolecules, polymers and inorganic nanoparticles has attracted considerable interest due to the potential applications of hybrid constructs in biotechnology and bio-electronic devices. [1,2] A principal candidate biomolecule for incorporation into multi-functional devices is the photoactive protein-retinal complex, bacteriorhodopsin (BR), [3] which acts as a light-activated proton pump in the purple membrane (PM) of halophilic bacteria. Extracted PM fragments exhibit photoelectric, photochromic and photo-induced proton transport properties, and have been investigated as potential materials for holography, non-linear optics, and optical information processing. [3,4] PM films are only stable over a limited range of pH, humidity and temperature conditions, and are fragile and difficult to manipulate, which severely limit their application in photoelectric devices. PM fragments can be readily extracted from halophilic bacteria such as Halobacterium salinarum in the form of micronsized, 5 nm-thick lipid bilayer sheets that consist of a 2D protein/lipid crystalline array of unidirectionally oriented BR molecules. Proton transport from the cytoplasmic to extracellular side of the PM is initiated by light-activated isomerisation of the BR-bound retinal chromophore, and coupled with a thermally activated photocycle involving a series of spectroscopic intermediates (J, K, L, M, N, and O states) associated with deprotonation/protonation of the Schiff-base retinal linkage. A significant blue shift occurs between the protonated ground state (B 568 ) and stable unprotonated intermediate (M 412 ) that gives rise to photochromism and the possibility of using PM patches in imaging and recording devices such as photochromic inks, holographic interferometry and volumetric memories.[4] The response to steady state illumination is extremely sensitive and the photocycle can be cycled many times more than for synthetic materials, as well as enhanced in efficiency by increasing the M lifetime by site-directed mutagenesis (notably replacing Asp96 by Asn96). [4,5] Previous research has been undertaken on the incorporation of PM flakes into polymer gels [6,7] and sol-gel derived glasses [8][9][10][11][12] in order to produce bulk composite materials for potential photochromic applications. In contrast, the photoelectric response of BR, which depends on a net charge separation (voltage) across the lipid membrane, necessitates the fabrication of films in which PM fragments are uniformly oriented in order to facilitate unidirectional proton transport. Several approaches, involving layer by layer deposition, [13][14][15] Langmuir-Blodgett deposition, [16][17][18][19] electrophoretic sedimentation, [20,21] antibody recognition [22] and chemiadsorption selfassembly [23] have been developed to achieve this objective.The films are generally soft and brittle, and the photoelectric response sensitive to changes in environmental conditions...

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Humidity-dependent open-circuit photovoltage from a bacteriorhodopsin/indium tin oxide bioelectronic heterostructure

Cited by 14 publications

References 32 publications

Photoelectric properties of a detector based on dried bacteriorhodopsin film

Photoelectric properties of a detector based on dried bacteriorhodopsin film

Bacteriorhodopsin (bR) as an electronic conduction medium: Current transport through bR-containing monolayers

Bio‐Functional Mesolamellar Nanocomposites Based on Inorganic/Polymer Intercalation in Purple Membrane (Bacteriorhodopsin) Films

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