title: Layer-by-layer self-assembled chitosan/poly(thiophene-3-acetic acid) and organophosphorus hydrolase multilayers.
abstract: The aim of this study is to immobilize an enzyme, namely, organophosphorus hydrolase (OPH), and to detect the presence of paraoxon, which is an organophosphorus compound, using the layer-by-layer (LbL) deposition technique. To lift the OPH from the solid substrate, a pair of polyelectrolytes (positively charged chitosan (CS) and negatively charged poly(thiophene-3-acetic acid) (PTAA)) were combined. These species were made charged by altering the pH of the solutions. LbL involved alternate adsorption of the oppositely charged polyions from dilute aqueous solutions onto a hydrophilic quartz slide. This polyion cushion was held together by the electrostatic attraction between CS and PTAA. The growing process was monitored by fluorescence spectroscopy. OPH was then adsorbed onto the five-bilayer CS/PTAA system. This five-bilayer macromolecular structure compared to the solid substrate rendered stability to the enzyme by giving functional integrity in addition to the ability to react with paraoxon solutions. The ultimate goal is to use such a system to detect the presence of organophosphorus compounds with speed and sensitivity using the absorption and fluorescence detection methodologies.
authors.affiliation: Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida 33146, USA.
authors.forename: Celeste A
authors.initials: CA
authors.lastname: Constantine
authors.forename: Sarita V
authors.initials: SV
authors.lastname: Mello
authors.forename: Annie
authors.initials: A
authors.lastname: Dupont
authors.forename: Xihui
authors.initials: X
authors.lastname: Cao
authors.forename: David
authors.initials: D
authors.lastname: Santos
authors.forename: Osvaldo N
authors.initials: ON
authors.lastname: Oliveira
authors.forename: Francisco T
authors.initials: FT
authors.lastname: Strixino
authors.forename: Ernesto C
authors.initials: EC
authors.lastname: Pereira
authors.forename: Tu-Chen
authors.initials: TC
authors.lastname: Cheng
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Defrank
authors.forename: Roger M
authors.initials: RM
authors.lastname: Leblanc
mesh_terms: D000085:Acetates / Q000737:chemistry*; D000327:Adsorption; D043303:Aryldialkylphosphatase; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry*; D048271:Chitosan; D004573:Electrolytes / Q000737:chemistry; D004800:Enzymes, Immobilized / Q000737:chemistry*; D004950:Esterases / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D000085:Acetates; D004573:Electrolytes; D004800:Enzymes, Immobilized; D013876:Thiophenes; C472956:poly(thiophene-3-acetic acid); D002686:Chitin; D048271:Chitosan; D004950:Esterases; D043303:Aryldialkylphosphatase