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March 7th 2011
HYBRID MATERIALS 2011: Second International Conference on Multifunctional, Hybrid and Nanomaterials; 6-10 March 2011 Strasbourg (France).
Sabine Crunaire (1), Thu-Hoa Tran-Thi (1), Khanh-Quyen Ngo (1), Pierre R. Marcoux (2), Jean-Pierre Moy (2) and Frédéric Mallard (3)
1 Laboratoire Francis Perrin, CEA/DSM/IRAMIS/SPAM – CNRS URA 2453, Gif-sur-Yvette, France.
2 Commissariat à l'Energie Atomique (CEA), LETI, MINATEC, Grenoble, France.
3 bioMérieux, Grenoble, France.
There is a well-established and growing interest in the detection and identification of microorganisms by measuring their release of volatile organic compounds (VOCs). Indeed, the measurement of the VOCs emitted by in vitro or in vivo bacterial culture could be used as a characteristic fingerprint for detection and identification. To be of greatest diagnostic value, real-time non-invasive measurements of breath or headspaces above urine, feces, blood, or sputum would replace time-consuming culture techniques.
Our study deals with the detection of microbial VOCs with functionalised nanoporous materials. These sol-gel materials include a probe molecule. This probe is chosen in order to react specifically with a target VOC, in liquid or gas phase, so as to produce an absorbent and/or fluorescent molecule within pores. This transduction pathway is called direct optical transduction.
We will focus on the detection of indole. This volatile metabolite comes out of the degradation of the amino acid tryptophan and its presence is tested in numerous identification schemes, especially to presumptively identify Escherichia coli, the gram-negative bacillus most encountered in diagnostic bacteriology.
We have prepared hybrid materials showing high-surface area (~600 m2/g), using the sol-gel chemistry. They are doped either with DMACA (dimethylaminocinnamaldehyde) or DMABA (dimethylaminobenzaldehyde), two probes reacting with indole in a complete and fast way. Therefore, we can measure indole concentration in a few minutes, by following the absorption kinetics at a chosen wavelength. Indole production of model strains of E. coli and H. alvei has also been monitored with our detectors, in liquid as well as in gas phase. We have proved the ability of these detectors to discriminate indole-producing bacteria from the others.