| Abstract: | A specific and sensitive electrochemical biosensor with human monoamine oxidase B (hMAO B) as biological receptor and a MnO2 modified nanomaterial based transducer system has been developed and optimised. Best results for the biosensor were achieved when using enzyme immobilisation with a dialysis membrane (regenerated cellulose, molecular weight cut‐off 14000) and a 20 % (m/m) MnO2 modified multi‐walled carbon nanotubes (MWCNTs, ratio of fluid to solid compounds of 1 : 0.7 (m/m)) paste electrode smoothed with a glassy carbon paste (GCP, ratio 1 : 3.6 (m/m)) containing the same mediator concentration. The biosensor was operated in a flow injection analysis (FIA) system with Sørensen phosphate buffer (33 mM, pH 7.5) and amperometric detection at a fixed potential of +400 mV vs. Ag/AgCl. The developed sensor underwent validation using phenylethylamine (PEA) as standard substrate showing linearity between 5.0 and 400 µM PEA and limits of detection and quantification of 1.5 and 5.0 µM PEA, respectively. The sensor was successfully tested for the determination of total monoamines in rat brain calculated as PEA equivalents showing a result of 1.2 µg/g brain tissue (n=3, relative standard deviation 4.4 %). |
