title: Electrochemical biosensor for pesticides based on acetylcholinesterase immobilized on polyaniline deposited on vertically assembled carbon nanotubes wrapped with ssDNA.
abstract: An electrochemical biosensor for the determination of pesticides: methyl parathion and chlorpyrifos, two of the most commonly used organophosphorous insecticides in vegetable crops, is described. The self-assembled monolayers (SAMs) of single walled carbon nanotubes (SWCNT) wrapped by thiol terminated single strand oligonucleotide (ssDNA) on gold was utilized to prepare nano size polyaniline matrix for acetylcholinesterase (AChE) enzyme immobilization. The key step of this biosensor was AChE-acetylcholine enzymatic reaction which causes the small changes of local pH in the vicinity of an electrode surface. The pesticides were determined through inhibition of enzyme reaction. The dynamic range for the determination of methyl parathion and chlorpyrifos was found to be in between 1.0x10(-11) and 1.0x10(-6) M (0.6<SD<3.5) with good reproducibility and stability. The detection limit of the biosensor for both pesticides was found to be 1x10(-12) M. The biosensor has been applied for the determination of methyl parathion and chlorpyrifos in spiked river water samples.
authors.affiliation: Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Tuwima 10, 10-747 Olsztyn, Poland.
authors.forename: Subramanian
authors.initials: S
authors.lastname: Viswanathan
authors.forename: Hanna
authors.initials: H
authors.lastname: Radecka
authors.forename: Jerzy
authors.initials: J
authors.lastname: Radecki
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism*; D000814:Aniline Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D002138:Calibration; D004390:Chlorpyrifos / Q000032:analysis* / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods; D004791:Enzyme Inhibitors / Q000032:analysis / Q000378:metabolism; D004800:Enzymes, Immobilized / Q000378:metabolism; D008743:Methyl Parathion / Q000032:analysis* / Q000378:metabolism; D018625:Microscopy, Atomic Force; D037742:Nanotubes, Carbon / Q000737:chemistry*
chemical_list: D000814:Aniline Compounds; D004277:DNA, Single-Stranded; D004791:Enzyme Inhibitors; D004800:Enzymes, Immobilized; D037742:Nanotubes, Carbon; C416807:polyaniline; D008743:Methyl Parathion; D000110:Acetylcholinesterase; D004390:Chlorpyrifos