Electrochemistry of self-assembled monolayers of the blue copper protein Pseudomonas aeruginosa azurin on Au(111)

Chi, Qijin; Zhang, Jingdong; Friis, Esben P.; Andersen, Jens Enevold Thaulov; Ulstrup, Jens

doi:10.1016/s1388-2481(99)00012-0

Cited by 86 publications

(124 citation statements)

References 42 publications

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“…The Au(111) electrodes used in both electrochemical and scanning tunneling microscopy (STM) experiments were homemade from polycrystalline gold wires (Ն99.99% in purity, Goodfellow, Cambridge, England) by using a hydrogen flame as described in ref. 35. The quality of the electrodes was checked regularly by voltammetry and͞or STM imaging.…”

Section: Methodsmentioning

confidence: 99%

“…All measurements were carried out by using an Autolab system (Eco Chemie, Utrecht, The Netherlands) controlled by the general purpose electrochemical system software at room temperature (22 Ϯ 2°C). A three-electrode system consisting of a platinum coiled wire as counter electrode, a reversible hydrogen electrode (RHE) as reference electrode, and a Au(111)-based working electrode (WE) was used with the WE in a hanging-meniscus configuration (35). The RHE was checked regularly against a saturated calomel electrode (SCE) after each measurement.…”

Section: Methodsmentioning

confidence: 99%

“…Two structural features (a surface disulfide Cys 3 Cys 26 group and a hydrophobic patch around the copper center located at the two opposite ends) can be exploited to confine azurin molecules on Au(111) surfaces with well controlled orientations. Direct self-assembly through the disulfide group orients the protein molecules with the copper center opposite to the electrode surface, with a 26-Å distance between the copper center and the electrode surface (35,36). An interfacial ET rate constant of Ϸ30 s Ϫ1 was observed, largely consistent with intramolecular ET between the copper center and the Cys 3 Cys 26 site measured by pulse radiolysis in homogeneous solution (44 s Ϫ1 ) (29).…”

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confidence: 99%

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Long-range protein electron transfer observed at the single-molecule level: In situ mapping of redox-gated tunneling resonance

Chi

Farver

Ulstrup

2005

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

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173

220

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A biomimetic long-range electron transfer (ET) system consisting of the blue copper protein azurin, a tunneling barrier bridge, and a gold single-crystal electrode was designed on the basis of molecular wiring self-assembly principles. This system is sufficiently stable and sensitive in a quasi-biological environment, suitable for detailed observations of long-range protein interfacial ET at the nanoscale and single-molecule levels. Because azurin is located at clearly identifiable fixed sites in well controlled orientation, the ET configuration parallels biological ET. The ET is nonadiabatic, and the rate constants display tunneling features with distance-decay factors of 0.83 and 0.91 Å ؊1 in H2O and D2O, respectively. Redoxgated tunneling resonance is observed in situ at the single-molecule level by using electrochemical scanning tunneling microscopy, exhibiting an asymmetric dependence on the redox potential. Maximum resonance appears around the equilibrium redox potential of azurin with an on͞off current ratio of Ϸ9. Simulation analyses, based on a two-step interfacial ET model for the scanning tunneling microscopy redox process, were performed and provide quantitative information for rational understanding of the ET mechanism.blue copper protein ͉ scanning tunneling microscopy ͉ nanoscale bioelectronics ͉ bioelectrochemistry C harge transfer plays key roles in many chemical and biological processes as well as in molecular electronics (1-5). For example, long-range protein electron transfer (ET) is central in aerobic respiration and photosynthesis. The importance of longrange ET is illustrated by a recent special issue of PNAS on this topic (6-12). Several articles reflect broadly the current status of this subject. However, one of the major objectives in nanoscale science and technology is to fabricate molecular electronic devices with specified functions. Molecular electronics is rooted in the concept of molecular charge transfer (particularly, molecular conductivity) (13,14). Two essential steps involved in bottom-up manipulations are (i) organizing molecules into nanoscale structures and (ii) interfacing such nanostructures with macroscopically addressable components (e.g., metal and semiconductor electrodes). Molecular electronic device function thus rests fundamentally on charge transfer through organic and͞or biological molecules and across the interface between molecules and macroscopic electrodes (15, 16). Understanding of charge transfer mechanisms has mostly been based on average results of macroscopic measurements. The advent of scanning probe microscopies, along with other supersensitive techniques, has made it possible to characterize or directly observe charge transfer through organic molecules down to the nanoscale and single-molecule levels, as illustrated by measurements of singlemolecule conductivity (17-21) and probing of molecular switching and resonant tunneling (22,23). This, however, remains a daunting challenge for proteins, with difficulties arising from the assembly of suitable st...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Long-range protein electron transfer observed at the single-molecule level: In situ mapping of redox-gated tunneling resonance

Chi

Farver

Ulstrup

2005

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

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173

220

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“…The decay of the characteristic acetate adsorption/ desorption peak at 0.3 V at a given concentration of thiol reflects formation of SAMs, from which the required concentration of thiol can be found qualitatively. 97 Such information is important for the preparation of SAMs as well as for monitoring the formation process of SAMs by in situ STM.…”

Section: This Journal Is C the Owner Societies 2011mentioning

confidence: 99%

“…Cystine dimer thus needs 2.5-10 times higher concentration than cysteine, suggesting that breaking of the disulfide bridge in cystine is a slow process compared with the formation of cysteine SAMs. 97 …”

Section: Effects Of Terminal Groups In Target Moleculesmentioning

confidence: 99%

Electrochemically controlled self-assembled monolayers characterized with molecular and sub-molecular resolution

Zhang

Welinder

Chi

et al. 2011

Phys. Chem. Chem. Phys.

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Self-assembled organization of functional molecules on solid surfaces has developed into a powerful and sophisticated tool for surface chemistry and nanotechnology. A number of reviews on the topic have been available since the mid 1990s. This perspective article aims to focus on recent development in the investigations of electronic structures and assembling dynamics of electrochemically controlled self-assembled monolayers (SAMs) of thiol containing molecules on gold surfaces. A brief introduction is first given and particularly illustrated by a Table summarizing the molecules studied, the surface lattice structures and the experimental operating conditions. This is followed by discussion of two major high-resolution experimental methods, scanning tunnelling microscopy (STM) and single-crystal electrochemistry. In Section 3, we briefly address choice of supporting electrolytes and substrate surfaces, and their effects on the SAM structures. Section 4 constitutes the major body of the article by offering some details of recent studies for the selected cases, including in situ monitoring of assembling dynamics, molecular electronic structures, and the key external factors determining the SAM packing. In Section 5, we give examples of what can be offered by theoretical computations for the detailed understanding of the SAM electronic structures revealed by STM images. A brief summary of the current applications of SAMs in wiring metalloproteins, design and fabrication of sensors, and single-molecule electronics is described in Section 6. In the final two sections (7 and 8), we discuss the current status in understanding of electronic structures and properties of SAMs in electrochemical environments and what could be expected for future perspectives.

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Electrical “Wiring” of Enzymes

Polsky

Brozik

Xiao

et al. 2013

Wiley Encyclopedia of Electrical and Electronics Engineering

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Direct communication with the redox active center of many enzymes can be extremely beneficial for many applications ranging from basic research to the construction of sensors and biofuel cells. Unfortunately, most enzymes have evolved such that they naturally protect their active sites, which are shielded within their protein shell, to work more effectively in native environments. Therefore, much activity has taken place to try and artificially connect external electrode transducers to enzyme redox centers in what is termed electrical “wiring” of enzymes. This review gives a general overview of enzyme wiring including background, methods, and applications.

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Electrochemistry of self-assembled monolayers of the blue copper protein Pseudomonas aeruginosa azurin on Au(111)

Cited by 86 publications

References 42 publications

Long-range protein electron transfer observed at the single-molecule level: In situ mapping of redox-gated tunneling resonance

Long-range protein electron transfer observed at the single-molecule level: In situ mapping of redox-gated tunneling resonance

Electrochemically controlled self-assembled monolayers characterized with molecular and sub-molecular resolution

Electrical “Wiring” of Enzymes

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