Capteurs chimiques à base de matrices synthétisées par voie sol-gel et à transduction optique pour la détection de composés organiques volatils microbiens (mCOV)

Abstract : Microbial contamination of food and biological samples is a big issue in the industry as much as in the medical field. In that context, the present thesis brings innovative solutions. A first explored way is the identification of Salmonella by detecting and measuring the specific metabolomics volatile organic compounds (mVOC) released, H2S and cadaverine. Another new concept is the use of osmogenic substrates able to release mVOC under the action of specific enzyme of Escherichia coli.A first colorimetric sensor able to discriminate H2S from CH3SH was produced, using a nanoporous silicate matrix doped with N,N-dimethyl-p-phenylenediamine and Fe3+ ions. A very acidic medium is needed to stabilize the “key” intermediate of the reaction, the quinonediimine species (QD), which gives with H2S and CH3SH a green and red-brown product, respectively. The fluorimetric sensor of cadaverine is based on the formation of a fluorescent complex between AS-BI demethylated Naphthol and cadaverine and can detect 250 ppb of cadaverine. A proof of concept of osmogenic substrates is given with the detection of p-nitrophenol (pNP) et de β-naphthylamine (β-NA) released under the action of Escherichia coli enzymes, β-D-glucuronidase et L-alanine- β-naphthylamidase. Various nanoporous sensors are produced with tailored pore size, which can detect 100 ppm of the yellow pNP, 100 ppm of the fluorescent β-NA and 100 ppm of the red product issued from the derivation of β-NA with dimethyl-p-aminocinnamaldehyde. In biological media, water remains the major interfering agent.
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Laure Hélène Guillemot. Capteurs chimiques à base de matrices synthétisées par voie sol-gel et à transduction optique pour la détection de composés organiques volatils microbiens (mCOV). Autre. Université Paris Sud - Paris XI, 2012. Français. ⟨NNT : 2012PA112243⟩. ⟨tel-00769955⟩

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