Biosensor for arsenite using arsenite oxidase and multiwalled carbon nanotube modified electrodes.
A biosensor for arsenite has been developed using molybdenum-containing arsenite oxidase, prepared from the chemolithoautotroph NT-26 that oxidizes arsenite to arsenate. The enzyme was galvanostatically deposited for 10 min at 10 microA onto the active surface of a multiwalled carbon nanotube modified glassy carbon electrode. The resulting biosensor enabled direct electron transfer, i.e., effecting reduction and then reoxidization of the enzyme without an artificial electron-transfer mediator. Arsenite was detected within 10 s at an applied potential of 0.3 V with linearity up to 500 ppb and a detection limit of 1 ppb. The biosensor exhibited excellent reproducibility, 2% at 95% confidence interval for 12 repeated analyses of 25 ppb arsenite. Copper, a severe interfering species commonly found in groundwater, did not interfere, and the biosensor was applicable for repeated analysis of spiked arsenite in tap water, river water, and a commercial mineral water.
Male
Keith B
KB
Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, Canada H4P 2R2.
Hrapovic
Sabahudin
S
Santini
Joanne M
JM
Luong
John H T
JH
D018053:Arsenites / Q000032:analysis* / Q000378:metabolism*; D015374:Biosensing Techniques / Q000379:methods*; D002138:Calibration; D002849:Chromatography, Gas; D003300:Copper; D004563:Electrochemistry; D004566:Electrodes; D004583:Electrons; D008855:Microscopy, Electron, Scanning; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D010088:Oxidoreductases / Q000378:metabolism*; D012231:Rhizobium / Q000378:metabolism; D014867:Water
D018053:Arsenites; D037742:Nanotubes, Carbon; D014867:Water; D003300:Copper; D010088:Oxidoreductases; C078179:arsenite oxidase; C015001:arsenite