Development of a biosensor for endocrine disrupting compounds based on tyrosinase entrapped within a poly(thionine) film.
Preparation of semiconducting films by electropolymerisation of a monomer which is itself a redox mediator is an attractive and simple method for biosensor fabrication. A polymeric film of the redox dye thionine (phenothiazine) enables the stable immobilisation of polyphenol oxidase (tyrosinase) while acting as mediator for the enzymatic process. The immobilisation method is based on an inner crosslinked tyrosinase layer which contains thionine with an electropolymerised film of poly(thionine) on top. This method gave the most stable redox couple for poly(thionine) and exhibited the greatest response stability. The sensor was tested using a range of synthetic oestrogens and phenolic compounds, which are suspected endocrine disruptors/oestrogen mimics. The device responded well to all compounds tested with limits of detection ranging from 1 to 23 microM (based on three times S/N ratio). The tyrosinase/poly(thionine) electrode response to phenol was 3 orders of magnitude greater than the unmediated response in the absence of poly(thionine).
Department of Applied Science, Electrochemical Technology Research Centre, Institute of Technology Tallaght, Dublin 24, Ireland. eithne.dempsey@it-tallaght.ie
Eithne
E
Dempsey
Dermot
D
Diamond
Avril
A
Collier
D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004566:Electrodes; D004703:Endocrine System / Q000187:drug effects*; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis* / Q000633:toxicity*; D004800:Enzymes, Immobilized / Q000032:analysis / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008567:Membranes, Artificial; D014442:Monophenol Monooxygenase / Q000032:analysis / Q000737:chemistry*; D010640:Phenothiazines / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D020099:Coated Materials, Biocompatible; D004785:Environmental Pollutants; D004800:Enzymes, Immobilized; D008567:Membranes, Artificial; D010640:Phenothiazines; D014442:Monophenol Monooxygenase; C009469:thionine