title: Formaldehyde assay by capacitance versus voltage and impedance measurements using bi-layer bio-recognition membrane.
abstract: A novel formaldehyde sensitive biosensor based on bacterial formaldehyde dehydrogenase (FDH) as a bio-recognition element has been developed. The bio-recognition membrane had bi-layer architecture and consisted of FDH, cross-linked with albumin, and of the cofactor NAD at a high concentration level (first layer). The second layer was a negatively charged Nafion membrane, which prevented a leakage of negatively charged NAD molecules from the bio-membrane. As transducers, gold electrodes SiO(2)/Si/SiO(2)/Ti/Au and electrolyte-insulator-semiconductor Si/SiO(2) (EIS) structures have been used. Changes in capacitance and impedance properties of the bio-recognition membrane have been used for monitoring formaldehyde concentration in a bulk solution. It has been shown that formaldehyde can be detected within a concentration range from 1 microM to 20mM depending on the type of transduction used, with a detection limit of 1 and 100 microM for gold-based and EIS-based transducers, respectively.
authors.affiliation: Institut Supérieur des Sciences, Appliquées et de Technologies, Cité Taffela-Sousse 4003, Tunisia. mounirbenali@yahoo.com
authors.forename: M
authors.initials: M
authors.lastname: Ben Ali
authors.forename: Y
authors.initials: Y
authors.lastname: Korpan
authors.forename: M
authors.initials: M
authors.lastname: Gonchar
authors.forename: A
authors.initials: A
authors.lastname: El'skaya
authors.forename: M A
authors.initials: MA
authors.lastname: Maaref
authors.forename: N
authors.initials: N
authors.lastname: Jaffrezic-Renault
authors.forename: C
authors.initials: C
authors.lastname: Martelet
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D025802:Electric Capacitance; D017097:Electric Impedance; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004574:Electromagnetic Fields; D004784:Environmental Monitoring / Q000379:methods; D004800:Enzymes, Immobilized / Q000737:chemistry; D005465:Fluorocarbon Polymers / Q000737:chemistry; D005557:Formaldehyde / Q000032:analysis*; D008422:Materials Testing; D008567:Membranes, Artificial; D009243:NAD / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D004800:Enzymes, Immobilized; D005465:Fluorocarbon Polymers; D008567:Membranes, Artificial; D014874:Water Pollutants, Chemical; D009243:NAD; D005557:Formaldehyde; C040402:perfluorosulfonic acid; D000445:Aldehyde Oxidoreductases; C087006:formaldehyde dehydrogenase, glutathione-independent