CHANICHANI

ELECTROCHEMISTRY Study of solid-liquid interfaces

Research

The research directions of the CHANI's Electrochemistry group address a series of questions related to new analytical tools and electrified interfaces providing unique opportunities to obtain innovative electrochemical routes.

 Main topics :

 -        Adsorption at electrodes and functionnalisation for biosensing 

-          Environmental Electrochemistry

-          Electrochemistry in ionic liquids

  Adsorption at electrodes

The Brussels electrochemical group investigates since many years the thermodynamic and kinetics of adsorption and ordering of organic layers at well-defined electrodes. Such organized and controlled structures have wide technological applications dealing namely with the fabrication of sensors, corrosion protective layers, wear-resistant layers and electronic devices.


Most of the investigations is devoted to the physico-chemical characterisations of the modified electrodes by conventional and advanced electrochemical methods, complemented by optical and spectroscopic techniques, such as in situ infrared spectroscopy (SNIFTIRS or in situ-IRRAS), in situ quartz micro-balance and ellipsometry. Single-crystal electrodes are frequently used to gain a fundamental understanding of the interfacial phenomena (self-assembly process and electrochemical behaviour).


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Biosensing. 

 

More recently, self-assembled monolayers (SAMs) formed of thiolated molecules have been considered in order to tailor
surfaces for analytical purposes and in particular for sensing.

 

Electrochemical biosensors present many advantages in terms of rapidity, miniaturisation, liability and cost. Novel
methods of analysis and identification of proteins are essential not only for the advancement of knowledge in
genomics and proteomics but also for increasing the efficiency of diagnostic analysis in the biomedical field.
Starting from our experience on DNA sensors, we are now interested in extending this strategy to other targets,
especially proteins. The emergency of new types of compounds highly selective to proteins, peptides aptamers and
nucleic acid aptamers provide a new way to design highly performing sensors. Fundamental research is aimed at
evaluating the potentialities of this strategy for the electrochemical detection of proteins and at optimising conditions
for which probe-proteins specific interactions lead to better analytical performances of the sensors.

 

Present research project:  

 

New platforms, made of self-assembled monolayers of peptide aptamers, for the specific detection of proteins
(Promotor: Dr. Th. Doneux – Chargé de Recherches FNRS).

-          Study of the potentialities of aptamers – DNA sequences selected for their affinity for a target – as recognition probes
for the conception of a biosensor. (Aurore De Rache - PhD thesis in progress)

We are interested in the sequence-structure-activity relationships of a quadruplex aptamer immobilized on the electrode
surface for thrombin detection.

 

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The electrochemical studies are completed by spectroscopic measurements like circular dichroïsm in order to gain a better
insight in the structural characteristics of the bioprobe.

 

-          Study of the interfacial behavior of a peptide aptamer of p53 immobilized at the gold-electrolyte interface for the detection

of the protein Mdm2. (Eléonore Triffaux – PhD thesis in  progress)

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The transcriptional factor protein p53 regulates the cellular cycle, maintaining the cell integrity. Its activity is functionally
inactivated by the interaction with the protein Mdm2. The p53 probe selected in this work is composed of the amino acids
12 to 26 (P-P-L-S-Q-E-T-F-S-D-L-W-K-L-L) and is modified by a cysteine amino acid at the N-terminal to allow the formation
of a covalent bond between the sulfur and the gold surface.

The electrochemical studies are completed by fluorescence confocal microscopy measurements.

 

Environmental Electrochemistry: Electrocatalysis and Electromembranes

Preparation of electrode materials (metal single crystals, metal polycrystals, modified carbon electrodes …)  and the study
of their electroactivity for electrochemical reactions of importance for a sustainable development of our environment (oxygen
reduction, carbon dioxide, reduction, nitrate reduction…) Metal deposition and more specifically platinum deposition at the
submonolayer level leading to nanoparticles dispersion on electrodes (carbon or gold) or incorporated in an organic matrix
is investigated to evaluate their electroactivity.

-          Present  research projects : Chemical and electrochemical modification of carbon electrodes for oxygen reduction and
electrode-membrane assemblies (Medhi Dhaini- PhD thesis in progress)

 

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Study of ion exchange membranes and elaboration of selective membranes. Besides characterizing commercial membranes
by parameters such as the ion exchange capacity and hydrogen ion transport number, we also proceed to
measurements (potentio-amperometric or chronopotentiometric) leading to some micro-structural description of the membrane
on the basis of micro-heterogeneous model. Selectivity for monovalent cations was investigated after modification of
home-made cationic exchange membranes by a thin film of positively charged amines.

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Electrochemistry in ionic liquids

Room Temperature Ionic liquids (RTIL) have become recently an active subject of research because they are considered as
environmental friendly alternatives to conventional solvents.  Indeed they have attractive physicochemical properties such as
negligible vapour pressure and thermal stability. RTIL exhibit ionic conductivity because they consist exclusively or almost exclusively
of ions.
The intrinsic conductivity and the electrochemical stability of the RTIL allow their use in electrochemistry.

 In order to contribute to a better understanding of metal electrodeposition into ionic liquids we realise fundamental analyses of the
interface between the RTIL and a metal electrode. In absence of neutral solvent molecules the inner capacitance do not have physical
signification and the diluted media approximation used in the
Gouy-Chapmann theory is no longer valid thus the classical model of Stern
needs to be reconsidered. The description of the double layer and the expression of the capacity have to be different than those used in
aqueous solutions.

An important goal of our research is to generate fundamental knowledge on the electrical double layer formed at the electrode-room
temperature ionic liquid (RTIL) interface.
RTILs are fascinating and intriguing for electrochemists since the classical double layer
model is no longer valid.
The understanding of the double layer structure and properties is essential to allow electrochemists to establish
relationships between the characteristics of the electrochemical interface and its reactivity in RTILs. 

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- Present research project : Electrochemistry of coinable metals in ionic liquid
(Stéphanie Vanderaspoilden – PhD thesis in  progress)

 

OTHER PROJECT:

Due to its expertise in interfacial electrochemistry and adsorption phenomena, the group is also involved together with several
Belgian partners in the study of corrosion inhibition.  Self-healing coating is one solution considered to protect mild steel against
corrosion. The protection of mild steel may be assured by a combination of a barrier layer containing corrosion inhibitors to provide
the self-healing effect. To ensure a good protection of such systems it is fundamental to control the adhesion and consequently the
surface preparation prior to the treatment. Various inhibitors are tested to select the best for further incorporation in nanoreservoir.

 Present Project (FEDER- RW) : CLEARZINC                                                                 

(Fouad Atmani – PhD thesis in  progress - UMons – Promotor : MarjorieOlivier, Co-promotor : Claudine Buess-Herman)

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