4th EucheMs chemistry congress

Monday, 27-Aug 2012
s595
chem. Listy 106, s587–s1425 (2012)
Analytical chemistry Electrochemistry, Analysis, sample manipulation
Electroanalytical methods - ii
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MAteriALS StrAteGieS for eLeCtroAnALytiCAL
SenSorS And BioSenSorS
C. M. A. Brett 1
1 University of Coimbra, Department of Chemistry, Coimbra,
Portugal
The development of efficient and reliable electroanalytical
sensors and biosensors, with fast response, depends primarily on
the materials used for their construction. Appropriate materials
can confer enhanced selectivity and stability whilst, at the same
time, increasing electrocatalytic effects for the desired species
which can contribute to reducing interference problems.
Nanostructured materials are essential for this purpose and can
include metals, different forms of carbon, redox and conducting
polymers. Their use can enhance performance and the reduction
of response times by improving diffusion or reducing diffusion
lengths Sensors and biosensors will be illustrated, prepared using
such approaches and which are useful in the clinical, food and
environmental areas.
Recent research has included using metal hexacyanoferrates
and polyazine layers as electrode modifier materials and for redox
mediators in biosensors. [1] The incorporation of carbon nanotubes
in these assemblies has been investigated, also including
nitrogen-doped carbon nanotubes. Electrocatalytic and synergistic
effects are found, for example in the detection of hydrogen
peroxide for oxidase-based biosensors. [2] The immobilization of
functionalized carbon nanotubes by reticulation and covalent
bonding in chitosan or dihexadecylphosphate film matrices has
been studied, [3] giving evidence for unmediated electron transfer
in biosensors. Stability is enhanced, sensitivities are higher, with
comparable or lower detection limits and linear ranges.
A layer-by-layer approach using self-assembly to create
multilayer modified electrodes for biosensors will also be
described, particularly concerning the hyaluronic acid/myoglobin
system and the minimum number of bilayers necessary to achieve
efficient sensor/biosensor operation. [4]
references:
1. R. Pauliukaite, M.E. Ghica, M.M. Barsan, C.M.A. Brett,
Anal. Lett. 43 (2010) 1588.
2. R.C. Pena, M. Bertotti, C.M.A. Brett, Electroanalysis 23
(2011) 2290.
3. B.C. Janegitz, R. Pauliukaite, M.E. Ghica, C.M.A. Brett,
O. Fatibello-Filho, Sens. Actuat. B 158 (2011) 411.
4. M.M. Barsan, E.M. Pinto, C.M.A. Brett, Phys. Chem.
Chem. Phys. 13 (2011) 5462.
Keywords: Electrochemistry; Sensors; Biosensors;
Voltammetry; Materials science;
Electroanalytical methods - ii
4 th EucheMs chemistry congress
o - 0 0 6
An oriGinAL Method to ProduCe JAnuS
MiCro- And nAnoPArtiCLeS in the BuLK PhASe
d. ziGAh 1 , C. KuMSAPAyA 1 , G. LoGet 1 ,
L. Bouffier 1 , C. wArAKuLwit 2 , J. LiMtrAKuL 2 ,
A. Kuhn 1
1 ISM - Institut des Sciences Moléculaires-UMR 5255 CNRS,
University of Bordeaux, Talence, France
2 Center of Nanotechnology and Chemistry Department,
Kasetsart University, Bangkok, Thailand
Janus particles are asymmetric particles. This type of
particles has a lot of applications in different areas from molecular
electronics, to targeted drug delivery. In order to break the
symmetry and produce Janus particles, most of the technics are
based on using interfaces. Just a few bulk procedures are known
to produce these particles. We propose an original method to
obtain Janus particles in bulk phase, based on bipolar
electrochemistry. Bipolar electrochemistry is a technique which
allows to perform electrochemistry at a conductive objet exposed
in solution to an electric field. The electric field polarizes the
object and when the potential difference is big enough, oxidation
and reduction reactions can take place on the two opposite sides
of the object. This technique is already used in the nanoscience
field and to build analytical devices. In this contribution we use
this concept to make electrodeposition. This approach allows us
to produce a large variety of asymmetric compounds with
characteristic features in the micro- or nanometer range. It is
possible to modify either anisotropic or isotropic objects and to
deposit metals, semiconductors, polymer and organic layers with
a high spatial control. Due to its versatility and because these
modifications are carried out in the bulk phase, this process might
become a major technology for the production of Janus particles,
also at an industrial scale.
Keywords: Electrochemistry; Diazo compounds; Fluorescent
probes; Nanoparticles; Polymerization;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc