title: Bioelectronic detector with monoamine oxidase for halitosis monitoring.
abstract: Methyl mercaptan (MM) is known as one of the major chemicals of halitosis (bad breath). In this study, a bioelectronic gas sensor (bio-detector) for gaseous MM was developed and was applied to measure halitosis in breath. The bio-detector consisted of a Clark-type dissolved oxygen electrode, a monoamine oxidase type-A (MAO-A) immobilized membrane and a reaction unit that had liquid and gaseous compartments separated by a hydrophobic porous polytetrafluoroethylene (PTFE) diaphragm membrane. The tip of the electrode covered with MAO-A membrane was placed into the liquid compartment as touching to the PTFE diaphragm membrane. In order to amplify the bio-detector output, a substrate regeneration cycle caused by coupling the monooxygenase with l-ascorbic acid as reducing reaction with reagent system, was applied. The results of MM vapor measurements showed the calibration range of the bio-detector for MM vapor was from 0.087 to 11.5 ppm (correlation coefficient: 0.993) and included the human sense of smell level 5 (0.2 ppm). The bio-detector had good selectivity being attributed to enzyme specificity was obtained for several substances (trimethyl amine, ammonia, dimethyl sulfide, etc.). The bio-detector was applied for halitosis measurement. Expired gases in five subjects were sampled every hour and the concentrations of MM in the expired gases were monitored. The output of bio-detector showed behaviour of halitosis level changes in a day such as increasing with passage of time and decreasing after eating.
authors.affiliation: Graduate School of Engineering, Tokai University, Hiratsuka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Minamide
authors.forename: K
authors.initials: K
authors.lastname: Mitsubayashi
authors.forename: N
authors.initials: N
authors.lastname: Jaffrezic-Renault
authors.forename: K
authors.initials: K
authors.lastname: Hibi
authors.forename: H
authors.initials: H
authors.lastname: Endo
authors.forename: H
authors.initials: H
authors.lastname: Saito
mesh_terms: D015374:Biosensing Techniques; D001944:Breath Tests / Q000295:instrumentation / Q000379:methods; D004566:Electrodes; D006209:Halitosis / Q000175:diagnosis*; D006801:Humans; D008995:Monoamine Oxidase / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000032:analysis*
chemical_list: D013438:Sulfhydryl Compounds; C005231:methylmercaptan; D008995:Monoamine Oxidase