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Electrodes poreuses pour applications (bio)analytiques, Porous electrodes for bioanalytical applications

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143 pages
Sous la direction de Alexander Kuhn, Karel Vytras
Thèse soutenue le 09 juin 2010: Bordeaux 1
Dans cette mémoire nous discutons l´élaboration d´électrodes poreuses par un processus de type “template” et leur application potentielle dans le domaine de l´analyse environnementale et neurobiologique. La première partie de ce travail est dédiée à l'élaboration d’électrodes poreuses de bismuth et d'antimoine. Ces électrodes montrent des limites de détection améliorées par rapport à des électrodes non poreuses, ouvrant ainsi des applications prometteuses dans le domaine de l'analyse de trace. La deuxième partie vise à surmonter des facteurs limitants de micro-électrodes dans le cadre de l'enregistrement de signaux extracellulaires et la stimulation de réseaux neuronaux en culture, qui peut donner des informations sur des interactions et des phénomènes synergétiques dans les systèmes nerveux.
-Electrodes poreuses
-Analyse de trace
-Stimulation de réseaux neuronaux
-Electrodes poreuses de bismuth
-Micro-électrodes
-Electrodes poreuses et d'antimone
-Analyse neurobiologique
-Analyse environnementale
-Enregistrement de signaux extracellulaires
In the present dissertation thesis the elaboration of porous electrodes via templating methods and their potential application in the field of environmental and neurobiological analysis are discussed. The electrodes of controlled porosity are characterized by an increased internal electroactive area and thus they can be used to enhance significantly the electrochemical performance. High surface area materials are promising for biosensing and more generally in electrochemical experiments. The first part of this work is focused on the elaboration of porous bismuth and antimony film electrodes. These porous electrodes show improved detection limits compared to non-porous one and thus open up promising applications in the field of trace analysis. The second part deals with overcoming limiting factors of microelectrode arrays in the context of extracellular recording and stimulating cellular neuronal networks or neural tissues in culture that can reveal information about interactions and synergetic features of nervous systems.
-Porous electrodes
-Porous bismuth
-Electrodes
-Porous antimony electrodes
-Trace analysis
-Environmental analysis
-Microelectrodes
-Neurobiological analysis
-Recording of extracellular signals
-Stimulation of neuronal network
Source: http://www.theses.fr/2010BOR14026/document
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N° d’ordre : 4026



THÈSE

PRÉSENTÉE A

L’UNIVERSITÉ BORDEAUX 1

ÉCOLE DOCTORALE DES SCIENCES CHIMIQUES

par Veronika URBANOVA

POUR OBTENIR LE GRADE DE

DOCTEUR
SPÉCIALITÉ : Chimie-analytique

L´ELECTRODES POREUSES POUR L´APPLICATIONS
(BIO)ANALYTIQUES

Thèse dirigée par M. Alexander KUHN, M. Karel VYTŘAS


Soutenue le : 9 juin 2010

Devant la commission d’examen formée de :
M. Ivan ŠVANCARA Professeur, Université de Pardubice president
M. Karel ŠTULÍK Profeseur, Charles Université Prague rapporteur
M. Paolo UGO Professeur, Université de Venise rapporteur
M. Blaise YVERT Chargé de la recherche, CNRS invité
M. Neso SOJIC Professeur, Université de Bordeaux invité
M. Alexander KUHN Professeur, Université de Bordeaux directeur de thèse
M. Karel VYTŘAS Professeur, Université de Pardubice directeur de thèse
RÉSUMÉ

Dans cette mémoire nous discutons l´élaboration d´électrodes poreuses par un processus de
‟template‟ et leur application potentielle dans le domaine de l´analyse environnmentale et
neurobiologique. Ces électrodes d´une porosité contrôlée sont caractérisées par une
augmentation significative de la surface électroactive qui permet d´augmenter de manière
significative leur performance électrochimique. Les matériaux d´une grande superficie sont
prometteurs tant que biocapteurs mais aussi de manière générale dans des applications
électrochimiques diverse allant de l’électrocatalyse jusqu’au stockage d’énergie. La première
partie de ce travail est dédiée à l'élaboration des électrodes poreuses de bismuth et d'antimone.
Ces électrodes poreuses montrent des limites de détection améliorées comparé avec des
électrodes non poreuses, ouvrant ainsi des applications prometteuses dans le domaine de
l'analyse de trace. La deuxième partie vise à surmonter des facteurs limitant de micro-électrode
dans le cadre de l'enregistrement de signaux extracellulaire et la stimulation de réseau neuronaux
dans la culture qui peut donner des informations sur des interactions et des phénomènes
synergétiques dans les systèmes nerveux.


Mots-clés
Électrodes poreuses, électrodes poreuses de bismuth et d'antimone, l´analyse de trace, l´analyse
environmentale, micro-électrodes, l´analyse neurobiologique, l'enregistrement de signaux
extracellulaire, la stimulation de réseaux neuronaux. SUMMARY

In the present dissertation thesis the elaboration of porous electrodes via templating methods and
their potential application in the field of environmental and neurobiological analysis are
discussed. The electrodes of controlled porosity are characterized by an increased internal
electroactive area and thus they can be used to enhance significantly the electrochemical
performance. High surface area materials are promising for biosensing and more generally in
electrochemical experiments. The first part of this work is focused on the elaboration of porous
bismuth and antimony film electrodes. These porous electrodes show improved detection limits
compared to non-porous one and thus open up promising applications in the field of trace
analysis. The second part deals with overcoming limiting factors of microelectrode arrays in the
context of extracellular recording and stimulating cellular neuronal networks or neural tissues in
culture that can reveal information about interactions and synergetic features of nervous systems.



Keywords
Porous electrodes, porous bismuth electrodes, porous antimony electrodes, trace analysis,
environmental analysis, microelectrodes, neurobiological analysis, recording of extracellular
signals, stimulation of neuronal network.





CONTENTS
INTRODUCTION ……………………………………………………………… 13
CHAPTER 1: Introduction to Colloidal Crystal Templating ………………… 17
1.1 Colloidal microspheres and their synthesis …………………………... 18
1.2 Colloidal crystals ................................................................................... 19
1.3 Self-assembly of colloidal particles ...................................................... 22
1.4 Infiltration ............................................................................................. 28
1.4.1. Soaking ...................................................................................... 28
1.4.2. Filtration ..................................................................................... 28
1.4.3. Chemical Vapour Deposition ..................................................... 28
1.4.4. Electrochemical deposition ........................................................ 28
1.5 Applications of colloidal crystals ........................................................... 31
1.5.1. Photonic crystals ........................................................................ 31
1.5.2. Surface Enhanced Raman Spectroscopy ................................... 32
1.5.3. Sensors and Actuators ............................................................... 32
References ............................................................................................................. 35
CHAPTER 2: Lyotropic Liquid Crystal Templating ....................................... 40
2.1 Liquid crystals ........................................................................................ 41
2.2 Thermodynamics .................................................................................... 42
2.3 Liquid crystal phases .............................................................................. 43
2.4 Surfactant templating ............................................................................. 45
2.4.1. Silica based mesoporous materials .............................................. 46
2.4.2. Mesoporous metals and alloys .................................................... 47
References .................................................................................................... 50
CHAPTER 3: Macroporous bismuth film electrodes for enhanced electrochemical
stripping analysis ………………………………………………….. 51
1. Introduction ............................................................................................. 52
1.1. Mercury-free electrodes ............................................. 55
1.2. Bismuth film electrodes .................................................................. 55
2. Macroporous bismuth film electrodes ............................... 63
2.1. Synthesis of macroporous bismuth films ........................................ 64
2.2. Stripping analysis of heavy metals ................................................. 74
References ............................................................................. 82


CHAPTER 4: Macroporous antimony film electrodes in stripping analysis ..... 86
1. Introduction ............................................................................................... 86
2. Elaboration of macroporous antimony films and their applications ……. 92
References ……………………………………………………………….… 100
CHAPTER 5: Porous modification of microelectrode arrays ………………… 101
1. Microelectrode arrays (MEAs) ………………………………………… 101
2. Microelectrode arrays in the context of neuroscience ………………… 103
2.1. Tissue recording with MEAs……………………………………… 104
2.2. Extracellular electrical stimulation with MEAs …………………… 105
2.3. Factors limiting the use of MEAs ……… 105
3. MEA covered with a highly porous metal overlayer …………………. 109
3.1. MEA modification by colloidal templates ……………………….. 110
3.1.1. Electrochemical characterization ………………………….. 114
3.1.2. Noise measurements ………………………………………. 115
3.2. Porous modification of MEA by lyotropic liquid crystal templating ... 119
3.2.1. Characterization of modified arrays ……………………… 122
3.2.2. Recording of action potentials ………………….………… 124
3.2.3. Porous modification of ESIEE arrays …………………….. 128
References ………………………………………………………………….. 131
GENERAL CONCLUSION AND PERSPECTIVES …………………………. 133
APPENDIX ………………………………………………………………………. 135
A. Apparatus and techniques ……………………………………………… 135
A1. Scanning electron microscopy ……………………………………. 135
A2. Electrochemical measurements …………………………………… 136
A3. Multi-electrode arrays ……………. 138
TM1. Ayanda MEA arrays ……………………………………….. 138
2. ESIEE arrays ………………………………………………….. 141
B. Synthesis ………………………………………………………………. 145
B1. Preparation of mixtures serving as template for lyotropic liquid crystal
templating …………………………………………………………. 145
C. Publications and conferences ………………………………………….. 146
C1. Publications ……………………………………………………….. 146
C2. Conferences participations ………………………………………... 146

List of abbreviations:
AdSV adsorptive stripping voltammetry
AG α-glucosidase
ASV anodic stripping voltammetry
Bi-CPE carbon paste modified by bismuth powder
BiFE bismuth film electrode
CE counter electrode
CMC critical micellar concentration
CNT carbon nanotube
CPD citrate-phosphate-dextrode
CV cyclic voltammetry
CVD Chemical Vapor Deposition
DPASV differential pulse anodic stripping voltammetry
DVLO Derjaguin-Landau-Verwey-Overbeek theory
fcc faced centred cubic
FEM field emission miscroscopy
GCE glassy carbon electrode
hcp hexagonal close packed
HMDE hanging mercury drop electrode
LC liquid crystal
LFP local field potential
LLC lyotropic liquid crystal
MEA microelectrode array, multielectrode array
MFE mercury film electrode
NADH nicotinamide adenine dinucleotide
PBG photonic band gap
PMMA poly(methyl methacrylate)
PNPGP 4-nitrophenyl- α-D-glucopyranoside
PSA potentiometric stripping analysis
PS polystyrene
RE reference electrode
Sb-CPE antimony coated carbon paste
SbFE antimony film electrode

SEM scanning electron microscopy
SERS surface enhanced raman spectroscopy
TEM transmission electron microscopy
WE working electrode


Introduction
In recent years, nanostructured metallic materials have generated considerable interest due to a
large number of the potential applications. Nanoscience is a fascinating field because it is on this
scale that atoms and molecules interact and assemble into the structures that possess size and
shape dependent unique properties. Among these properties are a specifically high surface to
volume ratio and a high surface area with a very ordered, uniform pore structure. These novel
types of materials have a very versatile and rich surface composition and surface properties,
which offer a wide range of potential applications in various fields, such as materials science,
electronics, optics, magnetism, energy storage or as electrochemical sensors.
Tailoring the surfaces of conventional electrodes by either depositing functional layers or
building micro- or nanostructures has resulted in the development of a wide range of new
electrochemical devices and open new fields for various applications. Such devices are notably
interesting in electroanalytical chemistry and biology as they may be used to enhance the
performance of many biomedical devices, including immunoisolation devices, dialysis, targeted
drug delivery systems, bioanalytical devices and biosensors.
In the past decades, many methods have been developed and applied to synthesize
nanostructured materials with controlled size, shape, dimensionality and structure. Among the
strategies from lithographic techniques to chemical methods, the template method is known as a
useful route to prepare porous nanomaterials with different morphologies such as spherical
particles, hollow nanostructures and two- or three-dimensional ordered arrays. It is obvious that
the most attractive feature of template-directed synthesis is its versatility for the transfer of
structures from templates to desired materials.
1,2The template synthesis for electrochemical applications was first explored by Martin . He
introduced membrane based synthesis by which the desired materials were prepared within the
pores of a nanoporous membrane called “template”. In general, the templates could be divided
into hard templates and soft templates. Hard templates usually include silica or polystyrene
microspheres, anodic aluminium oxide or mesoporous carbon. The soft templates have received
more attention over the last decade because they are more versatile and therefore more
advantageous than hard templates. The soft templates are composed of soft compounds such as
biomolecules, polymer gels, block-copolymers, fibres and emulsions.
_______________________________________
1C. R. Martin, Science, 1994, 266, 1961.
2C. R. Martin, Chem. Mater.,1996, 14, 1739.
8
The dissertation thesis deals with elaboration of porous electrodes via templating methods as
well as with their potential applications, mainly in the field of evironmental and neurobiological
analysis.
The manuscript starts with the theoretical part reviewing the two templating methods used in this
work. These two approaches are based on templating with colloidal crystals and lyotropic liquid
crystals. In these two first chapters, the theoretical aspects of each single step of the procedure
are discussed. Also recent progress and applications of templating methods are mentioned.
The second part is related to the elaboration of new electrochemical sensors – porous bismuth
and antimony film electrodes. Both types of electrodes have been currently suggested as
alternative electrode material to the formerly popular mercury electrodes which is more and
more replaced due to the high toxicity of mercury and many of its compounds. Porous electrodes
were elaborated via the colloidal crystal templating method. In the view of potential analytical
applications for the sensitive quantification of trace heavy metals, these electrodes have been
characterized with respect to calibration, reproducibility and detection limits in combination with
differential pulse anodic stripping voltammetry in model solutions. The attractive stripping
performance of the new porous bismuth film electrodes is indicated from the anodic stripping
analysis of Cd(II) and Pb(II). The electrodes display well defined, sharp and separated peaks
even for short deposition times. The obtained results indicate that the total internal surface area
can be easily increased depending on the thickness of the porous layer and this consequently
improves the sensitivity and the detection limits of porous bismuth film electrodes. The novel
porous antimony electrodes also exhibit an improved electrochemical performance and thus
present another interesting alternative to mercury electrodes in electrochemical stripping analysis
with sensitivities that are significantly higher than the one observed for flat antimony films.
Finally, in the last chapter, the elaboration of a highly porous metal overlayer on the
microelectrodes of microelectrode arrays (MEA) is reported. Microelectrode arrays have been
used by neuroscientists as a powerful tool to study the bioelectrical activity of neuronal networks
at a multi single cell level. Even if MEA provide advantages in simultaneous recording, there are
three main factors limiting their usage: (1) The thermal noise of the electrodes becomes high and
thus limits the recording sensitivity. (2) The current that can be injected without damaging the
electrode material or neural tissue is small and often not sufficient for stimulating the
surrounding neurons. (3) The sensitivity of detection remains poor due to the reduced size of the
electrodes. This work deals with overcoming these limiting factors using organized porous
electrodes because the noise, the charge injection efficiency and the sensitivity all can be
improved by increasing the active surface area of the electrodes. In order to generate the porous
9
structures both, colloidal crystal templating and also lyotropic liquid crystal templating methods
were used. The improved electrochemical properties of the modified arrays have lead to lower
noise content compared to non-modified ones. A modified MEA array was used for the
recording of activity of embryonic mouse spinal cord in order to show its application for real
measurements.

10