title: Langmuir and Langmuir-Blodgett films of organophosphorus acid anhydrolase.
abstract: In this paper, we describe the preparation and characterization of Langmuir and Langmuir-Blodgett (LB) monolayers of the enzyme organophosphorus acid anhydrolase (OPAA). Langmuir films of OPAA were characterized on different subphases, such as phosphate, ammonium carbonate, and bis-tris-propane buffers. Monolayers at the air-water interface were characterized by measuring the surface pressure and surface potential-area isotherms. In situ UV-vis absorption spectra were also recorded from the Langmuir monolayers. The enzyme activity at the air-water interface was tested by the addition of diisopropylfluorophosphate (DFP) to the subphase. LB films of OPAA were transferred to mica substrates to be studied by atomic force microscopy. Finally, a one-layer LB film of OPAA labeled with a fluorescent probe, fluorescein isothiocyanate (FITC), was deposited onto a quartz slide to be tested as sensor for DFP. The clear, pronounced response and the stability of the LB film as a DFP sensor show the potential of this system as a biosensor.
authors.affiliation: Department of Chemistry, University of Miami, Coral Gables, Florida 33146, USA.
authors.forename: Sarita V
authors.initials: SV
authors.lastname: Mello
authors.forename: Mustapha
authors.initials: M
authors.lastname: Mabrouki
authors.forename: Xihui
authors.initials: X
authors.lastname: Cao
authors.forename: Roger M
authors.initials: RM
authors.lastname: Leblanc
authors.forename: Tu-Chen
authors.initials: TC
authors.lastname: Cheng
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: DeFrank
mesh_terms: D043303:Aryldialkylphosphatase / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D015374:Biosensing Techniques / Q000379:methods; D002021:Buffers; D004795:Enzyme Stability; D018625:Microscopy, Atomic Force; D010261:Paraoxon / Q000378:metabolism; D010710:Phosphates / Q000737:chemistry; D011312:Pressure; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013499:Surface Properties; D014325:Tromethamine / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D002021:Buffers; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D014325:Tromethamine; C034249:1,3-bis(tris(hydroxymethyl)methylamino)propane; D043303:Aryldialkylphosphatase; D010261:Paraoxon