title: Kinetic analysis of the hydrolysis of methyl parathion using citrate-stabilized 10 nm gold nanoparticles.
abstract: "Ligand-free" citrate-stabilized 10 nm gold nanoparticles (AuNPs) promote the hydrolysis of the thiophosphate ester methyl parathion (MeP) on the surface of gold as a function of pH and two temperature values. At 50 °C, the active surface gold atoms show catalytic turnover ∼4 times after 8 h and little turnover of gold surface atoms at 25 °C with only 40% of the total atoms being active. From Michaelis-Menten analysis, k(cat) increases between pH 8 and 9 and decreases above pH 9. A global analysis of the spectral changes confirmed the stoichiometric reaction at 25 °C and the catalytic reaction at 50 °C and mass spectrometry confirmed the identity of p-nitrophenolate (PNP) product. Additional decomposition pathways involving oxidation and hydrolysis independent of the formation of PNP were also seen at 50 °C for both catalyzed and un-catalyzed reactions. This work represents the first kinetic analysis of ligand-free AuNP catalyzed hydrolysis of a thiophosphate ester.
authors.affiliation: Chemistry Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901, USA.
authors.forename: Rafaela
authors.initials: R
authors.lastname: Nita
authors.affiliation: Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Trammell
authors.affiliation: National Academy of Sciences, National Research Council, Postdoctoral Research Associate, Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, USA.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Ellis
authors.affiliation: Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, USA.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Moore
authors.affiliation: Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, USA.
authors.forename: Carissa M
authors.initials: CM
authors.lastname: Soto
authors.affiliation: Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, USA.
authors.forename: Dagmar H
authors.initials: DH
authors.lastname: Leary
authors.affiliation: Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, USA.
authors.forename: Jake
authors.initials: J
authors.lastname: Fontana
authors.affiliation: Chemistry Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901, USA.
authors.forename: Somayeh F
authors.initials: SF
authors.lastname: Talebzadeh
authors.affiliation: Chemistry Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901, USA. Electronic address: aknight@fit.edu.
authors.forename: D Andrew
authors.initials: DA
authors.lastname: Knight
mesh_terms: D002384:Catalysis; D019343:Citric Acid / Q000737:chemistry*; D004785:Environmental Pollutants / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D008743:Methyl Parathion / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D013696:Temperature
chemical_list: D004785:Environmental Pollutants; D019343:Citric Acid; D008743:Methyl Parathion; D006046:Gold
keywords: Catalysis; Degradation; Gold nanoparticles; Methyl parathion