INVESTIGADORES
BATTAGLINI Fernando
congresos y reuniones científicas
Título:
A versatil matrix for the construction of sensors
Autor/es:
GRACIELA A. GONZALEZ; M.L. CORTEZ; FERNANDO BATTAGLINI
Lugar:
Gijón, España
Reunión:
Congreso; 13 International Conference on Electroanalysis; 2010
Institución organizadora:
International Society of Electroanalysis
Resumen:
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The modification of electrode
surfaces with carbon nanotubes and surfactants has widely been explored in the
last years [1-6]. An important characteristic of these materials is the
capacity to facilitate the electron transfer process when interactions with the
electrode surface is involved in the redox reaction. In this work we present
the construction of a stable and versatile matrix using a polylectrolyte
(polyallylamine, PAA) and a tensioactive (sodium dodecyl sulfate, DS)
combination, that are easily handled and chemically modifiable. In this matrix
a redox mediator could be assembled for its use as an amperometric sensor. The
amino grorup present in PAA was modified
with a polypyridyl osmium complex (OsPAA) that, in the presence of DS precipitates, generating a product that is
soluble in organic solvent (DMF or methanol). This organic solution is applied
on graphite surfaces.The evaporation of these solutions generates an extremely
stable and resistant film showing an quasi-reversible electrochemical behavior.
Onto this film, glucose oxidase was efficiently adsorbed, where a catalytic
current of 250 mA cm-2 can be obtained in saturated conditions. This
system, compared to others built by self-assembled, present the following
advantages, it can be applied on any conducting surface (graphite, gold, etc)
without the need of an anchor molecule (thiols, diazonium salts), it presents
excellent electron transfer properties through the film and with other
molecules, it is able to be modified covalently through the amino groups or by
self-assembled interactions and is highly stable in time.
Simultaneously
the amperometric response was modeled solving using a finite-element software
to obtain the cyclic voltammetric responses and the concentration profiles. The
space dimension was set to 2D and the boundary condition was as an infinite
plane electrode; the generated current is calculated by Butler-Volmer equation.
Kinetic constants referred to catalysis and enzyme regeneration from [7] were
used. Kinetic constant referred to the enzyme saturation in this environment
and wired enzyme concentration arise from adjustment of the model to
experimental cyclic voltammetries. The agreement between experimental and numerical
results from several experiments presents three outcomes. First, the wired
enzyme concentration is related to the film thickness. Second, in this system
the enzyme is saturated at a substrate concentration higher than in
self-assembles without DS or solution. Finally, the relevance of numerical
model to analysis this kind of system is shown.