期刊
ELECTROANALYSIS
卷 29, 期 7, 页码 1741-1748出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/elan.201700111
关键词
amperometric choline biosensor; choline oxidase; electrochemical impedance spectroscopy; inhibition by lead ions; multiwalled carbon nanotubes
资金
- European Commission 7TH Framework Programme Marie Curie Actions People IRSES [294993 SMARTCANCERSENS]
- Fundacao para a Ciencia e a Tecnologia (FCT), Portugal [PTDC/QEQ-QAN/2201/2014]
- European Community Fund FEDER [3599-PPCDT, UID/EMS/00285/2013]
- FCT [SFRH/BPD/103103/2014]
The determination of lead ions by inhibition of choline oxidase enzyme has been evaluated for the first time using an amperometric choline biosensor. Choline oxidase (ChOx) was immobilized on a glassy carbon electrode (GCE) modified with multiwalled carbon nano-tubes (MWCNT) through cross-linking with glutaraldehyde. In the presence of ChOx, choline was enzymatically oxidized into betaine at -0.3V versus Ag/AgCl reference electrode, lead ion inhibition of enzyme activity causing a decrease in the choline oxidation current. The experimental conditions were optimised regarding applied potential, buffer pH, enzyme and substrate concentration and incubation time. Under the best conditions for measurement of the lowest concentrations of lead ions, the ChOx/MWCNT/GCE gave a linear response from 0.1 to 1.0 nM Pb2+ and a detection limit of 0.04 nM. The inhibition of ChOx by lead ions was also studied by electrochemical impedance spectroscopy, but had a narrower linear response range and low sensitivity. The inhibition biosensor exhibited high selectivity towards lead ions and was successfully applied to their determination in tap water samples.
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