Charge transport in bacteriorhodopsin monolayers: The contribution of conformational change to current-voltage characteristics

Alfinito, Eleonora; Reggiani, L.

doi:10.1209/0295-5075/85/68002

Cited by 24 publications

(37 citation statements)

References 21 publications

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“…The trend evidenced by experiments is reproduced when considering an interacting radius of 6 Å and a single energy barrier between neighboring amino acids of 59 meV [14,15]. The agreement with experiments is improved when using a Gaussian distribution of barrier heights with average value of 69 meV and a standard deviation of 44 meV [14,15]. …”

Section: Reviewmentioning

confidence: 93%

“…By implementing an impedance network protein analogue (INPA), the theoretical model is henceforth called INPA model. To this scope, we further included in the model a sequential tunneling mechanism [14-16] able to account for the superlinear I-V characteristics experimentally evidenced in bR and similar proteins at increasing applied voltages. Then, the model is validated on available experiments and its predictability discussed in the perspective of further experimental confirmations.…”

Section: Reviewmentioning

confidence: 99%

“…Accordingly, the best agreement between structure and function was obtained with values of R C in the range 5 to 70 Å [12,13]. To determine nonlinear I-V characteristics, the model was implemented to include a sequential tunneling mechanism of charge transfer by means of a stochastic selection of low resistive links ruled by the voltage-dependent probability [14,15]: …”

Section: Reviewmentioning

confidence: 99%

“…( b ) - The same as Figure 3 with calculations carried out with an average Φ = 69 meV Gaussian distributed with a variance σ = 44 meV. All the calculated currents are normalized to the experimental value of current in dark at 1 V [14]. …”

Section: Reviewmentioning

confidence: 99%

“…Interestingly enough, the microscopic interpretation is obtained with a length-independent electron effective mass, contrary to the case of [8,9] where, to fit experiments, the carrier effective mass should increase over one order of magnitude at increasing the tip indentation. Both these features are consequences of the sequential tunneling mechanism [14-16] that replaces the single tunneling mechanisms of the metal-insulator-metal model previously used [8,9]. …”

Section: Reviewmentioning

confidence: 99%

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Microscopic modeling of charge transport in sensing proteins

2012

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Sensing proteins (receptors) are nanostructures that exhibit very complex behaviors (ions pumping, conformational change, reaction catalysis, etc). They are constituted by a specific sequence of amino acids within a codified spatial organization. The functioning of these macromolecules is intrinsically connected with their spatial structure, which modifications are normally associated with their biological function. With the advance of nanotechnology, the investigation of the electrical properties of receptors has emerged as a demanding issue. Beside the fundamental interest, the possibility to exploit the electrical properties for the development of bioelectronic devices of new generations has attracted major interest. From the experimental side, we investigate three complementary kinds of measurements: (1) current-voltage (I-V) measurements in nanometric layers sandwiched between macroscopic contacts, (2) I-V measurements within an AFM environment in nanometric monolayers deposited on a conducting substrate, and (3) electrochemical impedance spectroscopy measurements on appropriate monolayers of self-assembled samples. From the theoretical side, a microscopic interpretation of these experiments is still a challenging issue. This paper reviews recent theoretical results carried out within the European project, Bioelectronic Olfactory Neuron Device, which provides a first quantitative interpretation of charge transport experiments exploiting static and dynamic electrical properties of several receptors. To this purpose, we have developed an impedance network protein analogue (INPA) which considers the interaction between neighboring amino acids within a given radius as responsible of charge transfer throughout the protein. The conformational change, due to the sensing action produced by the capture of the ligand (photon, odour), induces a modification of the spatial structure and, thus, of the electrical properties of the receptor. By a scaling procedure, the electrical change of the receptor when passing from the native to the active state is used to interpret the macroscopic measurement obtained within different methods. The developed INPA model is found to be very promising for a better understanding of the role of receptor topology in the mechanism responsible of charge transfer. Present results point favorably to the development of a new generation of nano-biosensors within the lab-on-chip strategy.

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Section: Reviewmentioning

confidence: 93%

Section: Reviewmentioning

confidence: 99%

Section: Reviewmentioning

confidence: 99%

Section: Reviewmentioning

confidence: 99%

Section: Reviewmentioning

confidence: 99%

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Microscopic modeling of charge transport in sensing proteins

2012

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The Electrical Properties of Olfactory Receptors in the Development of Biological Smell Sensors

Alfinito

Pousset

Reggiani

2013

Methods in Molecular Biology

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We present here the results of the investigation of the electrical properties of two olfactory receptors (ORs): rat, OR I7, and human, OR 17-40, which are of interest in the creation of smell nanobiosensors. Described here is our investigation comparing the results from experiments using electrochemical impedance spectroscopy with the theoretical predictions obtained from a recently developed impedance network protein analog. The changes in the OR response following excitation correlated with the protein conformational change. The satisfactory agreement between theory and experiment points to a promising development of a new class of nanobiosensors based on the electrical properties of sensing proteins.

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