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Détection de molécules d'ADN sur transistors à effet de champ

Abstract : This work presents a new approach for the electronic detection of charged biopolymers at a solid/liquid
interface using field effect transistors arrays. In our experiments, we use arrays of EOSFET. This type
of semiconductor transistor is operating with a reference electrode and consists in a gate structure of
electrolyte-oxide-semiconductor interfaces. Micro- or macro-droplets containing charged biopolymers solution
are locally spotted on the transistors arrays. The localised deposits induce sizeable variations in
the dc current-voltage characteristics of the transistors exposed to the molecular charges. The variations
of the dc characteristics due to the adsorption of two opposite charged biopolymers (polylysine and DNA)
showed opposite effects and can thus be correlated to a contribution of positive charges for polylysine
and negative charges for DNA. Experiments on the effect of the variation in the concentration of biopolymers
allowed us to identify a dynamical detection zone. In this zone the electronic signals increases with
the biopolymers spotting concentration until a saturation corresponding to the maximum biopolymers
quantity being able to be adsorbed on the surface. Interfering signals observed on the buffers used for
dilutions limit the detection of low biopolymers concentration. Sensibilities of 10^7 lysine monomers/FET and 4x10^8 bases of ADN/FET have been estimated. A modeling of the interface charge screening by the electrolyte may account for the reductions in the electronic signals observed when the electrolyte salt molarity is gradually increased. The electronic detection of DNA was shown in a reproducible way for short
ssDNA (oligonucleotides) as well as for dsDNA molecules synthesized by PCR. Using Cy5-modified DNA
the electronic signals are compared with local fluorescence measurements. By combining the electronic
approach with an allele specific PCR, we demonstrated the detection of a single base pair mutation.
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Submitted on : Friday, October 27, 2006 - 2:36:34 PM
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  • HAL Id : tel-00110318, version 1

Citation

François Pouthas. Détection de molécules d'ADN sur transistors à effet de champ. Biophysique [physics.bio-ph]. Université Pierre et Marie Curie - Paris VI, 2004. Français. ⟨tel-00110318⟩

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