title: Electronic nose screening of ethanol release during sol-gel encapsulation. A novel non-invasive method to test silica polymerisation.
abstract: Porous silica matrices prepared by sol-gel process yield biocompatible materials adequate for encapsulation of biomolecules or drugs. The procedure is simple and fast, but when alkoxyde precursors like tetraethoxysilane (TEOS) are used the polymerisation reaction leads to the formation of alcohol as a by-product, which can produce undesirable effects on the activity of entrapped enzymes or modify a drug release kinetic. Therefore, it is critical to determine that no remnant ethanol is left prior using or storing the obtained biomaterial. In this regard, the technique used in the alcohol determination should be non-invasive and non-destructive to preserve the encapsulation device intact and ready to use. In this work we have successfully used a portable electronic nose (e-nose) for the screening of silica polymerisation process during theophylline encapsulation. TEOS reaction was "smelt" since precursor pre-hydrolysis until the end of ethanol release, sensed directly at the headspace of matrices slabs. Measurements showed that ethanol was negligible since 10th day in polymeric slabs of 10 mm width and 2 cm diameter. This first use of e-nose following a polymerisation reaction opens a wide number of putative applications in pharmaceutical and biochemical fields.
authors.affiliation: Instituto de Química Física de los Materiales, Ambiente y Energía, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, Argentina.
authors.forename: Magalí
authors.initials: M
authors.lastname: Lovino
authors.forename: M Fernanda
authors.initials: MF
authors.lastname: Cardinal
authors.forename: Diana B V
authors.initials: DB
authors.lastname: Zubiri
authors.forename: Delia L
authors.initials: DL
authors.lastname: Bernik
mesh_terms: D032701:Biomimetics / Q000295:instrumentation / Q000379:methods; D020099:Coated Materials, Biocompatible / Q000032:analysis / Q000737:chemistry; D004058:Diffusion; D004337:Drug Carriers / Q000032:analysis / Q000737:chemistry*; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D000431:Ethanol / Q000032:analysis / Q000737:chemistry*; D005740:Gases / Q000032:analysis* / Q000737:chemistry; D008422:Materials Testing / Q000379:methods*; D044367:Phase Transition; D016062:Porosity; D012821:Silanes / Q000032:analysis / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D012903:Smell; D014159:Transducers
chemical_list: D020099:Coated Materials, Biocompatible; D004337:Drug Carriers; D005740:Gases; D012821:Silanes; D000431:Ethanol; C040733:tetraethoxysilane; D012822:Silicon Dioxide