Immobilization of l-lysine α-oxidase on gold-mercaptopropionic acid self-assembled monolayer: Preparation and electrochemical characterization

In Silico Study of a Bacteriorhodopsin/TiO2 Hybrid System at the Molecular Level

Bacteriorhodopsin (bR) is a light-harvesting membrane protein that represents a promising sensitizer of TiO2 for photovoltaic and photoelectrochemical devices. However, despite numerous experimental studies, the molecular-level understanding of the bR/TiO2 hybrid system is still unsatisfactory. In this contribution, we report the construction and analysis of an atomistic model of such a system. To do so, both steered molecular dynamics-molecular dynamics and quantum mechanics/molecular mechanics computations are applied to four different bR orientations on the anatase TiO2 surface. The resulting bR/TiO2 models are then used to compute the light absorption maxima changes relative to those of bR. We show that all four models reproduce the experimentally observed blue-shift value induced by bR binding on TiO2 and could be used to study the binding and binding-induced protein modifications. We conclude that the constructed models could provide a basis for future studies aiming to simulate the complex long-range electron transfer mechanism in bR/TiO2-based solar energy conversion devices as well as in engineering bR to achieve enhanced efficiencies.

Gold-deferrioxamine nanometric interface for selective recognition of Fe(III) using square wave voltammetry and electrochemical impedance spectroscopy methods

Deferrioxamine, a bacterial hydroxamic siderophore having high binding affinity for Fe(III), is used in its immobilized form, as self-assembled monolayer on Au, for accumulation and recognition of Fe(III) from the solution phase. The accumulated Fe(III) is detected via both active mode based on faradaic reduction current of Fe(III), and inactive mode based on impedimetric effect of accumulated Fe(III) against redox reaction of a suitable probe. Appropriate electrochemical techniques, square wave voltammetry and electrochemical impedance spectroscopy, are used for the transduction of analytical signals obtained by this sensor. Then, the parameters influencing the sensor response are optimized. In the best conditions, a linear response, from 1.0×10(-10) to 1.0×10(-7)M Fe(III) in logarithmic scale with a detection limit of 2.0×10(-11)M, and mean relative standard deviation of 1.7% for n=4 is observed. The results show that the sensor can be used for determination of Fe(III) in the presence of various inorganic ions and biological species. Validity of the method and applicability of the sensor are successfully tested by determination of Fe(III) in various real samples including plant tissue (corn leaves), industrial alloy (Ferrotitanium), and pharmaceutical samples (Venofer(®) ampoule, Ironorm(®) capsule, and V.M. Protein(®) powder).