title: Extended lifetime of reagentless detector for multiple inhibitors of acetylcholinesterase.
abstract: Competitive inhibitors of acetylcholinesterase (AChE) are detected using an evanescent wave technique to monitor changes in the absorbance spectrum of an AChE-monosulfonate tetraphenyl porphyrin (TPPS(1)) complex immobilized on the surface of a glass slide. In this technique, porphyrin is displaced from the AChE active site by the inhibitor. The loss in absorbance intensity of the characteristic absorbance peak for the AChE-TPPS(1) complex at 446 nm is linearly dependent on the log of the inhibitor concentration. This technique yields detection limits at 3:1 S/N of 37 ppt for eserine, 50 ppt for galanthamine, 100 ppt for scopolamine, 250 ppt for tetracaine, 45 ppt for diazinon, and 83 ppb for Triton X-100. When stored under vacuum, the enzymatic lifetime of the immobilized AChE surface is greater than 73 days while the responsive lifetime of the immobilized AChE-TPPS(1) surface is currently 49 days.
authors.affiliation: Department of Physics, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Brandy J
authors.initials: BJ
authors.lastname: White
authors.forename: J Andrew
authors.initials: JA
authors.lastname: Legako
authors.forename: H James
authors.initials: HJ
authors.lastname: Harmon
mesh_terms: D000110:Acetylcholinesterase / Q000737:chemistry*; D001667:Binding, Competitive; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002800:Cholinesterase Inhibitors / Q000032:analysis* / Q000737:chemistry; D003976:Diazinon / Q000032:analysis / Q000737:chemistry; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017743:Equipment Reuse; D005702:Galantamine / Q000032:analysis / Q000737:chemistry; D007202:Indicators and Reagents; D017830:Octoxynol / Q000032:analysis / Q000737:chemistry; D010830:Physostigmine / Q000032:analysis / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry*; D011786:Quality Control; D015203:Reproducibility of Results; D012601:Scopolamine / Q000032:analysis / Q000737:chemistry; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods; D013748:Tetracaine / Q000032:analysis / Q000737:chemistry
chemical_list: D002800:Cholinesterase Inhibitors; D004800:Enzymes, Immobilized; D007202:Indicators and Reagents; D011166:Porphyrins; D013748:Tetracaine; D005702:Galantamine; C016136:tetraphenylporphine sulfonate; D017830:Octoxynol; D010830:Physostigmine; D012601:Scopolamine; D000110:Acetylcholinesterase; D003976:Diazinon