title: Blocked Enzymatic Etching of Gold Nanorods: Application to Colorimetric Detection of Acetylcholinesterase Activity and Its Inhibitors.
abstract: The anisotropic morphology of gold nanorods (AuNRs) has been shown to lead to nonuniform ligand distribution and preferential etching through their tips. We have recently demonstrated that this effect can be achieved by biocatalytic oxidation with hydrogen peroxide, catalyzed by the enzyme horseradish peroxidase (HRP). We report here that modification of AuNRs with thiol-containing organic molecules such as glutathione and thiocholine hinders enzymatic AuNR etching. Higher concentrations of thiol-containing molecules in the reaction mixture gradually decrease the rate of enzymatic etching, which can be monitored by UV-vis spectroscopy through changes in the AuNR longitudinal plasmon band. This effect can be applied to develop novel optical assays for acetylcholinesterase (AChE) activity. The biocatalytic hydrolysis of acetylthiocholine by AChE yields thiocholine, which prevents enzymatic AuNR etching in the presence of HRP. Additionally, the same bioassay can be used for the detection of nanomolar concentrations of AChE inhibitors such as paraoxon and galanthamine.
authors.affiliation: CIC biomaGUNE , Paseo de Miramón 182, 20009 Donostia-San Sebastián, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Saa
authors.affiliation: CIC biomaGUNE , Paseo de Miramón 182, 20009 Donostia-San Sebastián, Spain.
authors.forename: Ruta
authors.initials: R
authors.lastname: Grinyte
authors.affiliation: CIC biomaGUNE , Paseo de Miramón 182, 20009 Donostia-San Sebastián, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Sánchez-Iglesias
authors.affiliation: CIC biomaGUNE , Paseo de Miramón 182, 20009 Donostia-San Sebastián, Spain.|Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain.|Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine, Ciber-BBN, Spain.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Liz-Marzán
authors.affiliation: CIC biomaGUNE , Paseo de Miramón 182, 20009 Donostia-San Sebastián, Spain.
authors.forename: Valeri
authors.initials: V
authors.lastname: Pavlov
mesh_terms: D000110:Acetylcholinesterase; D015374:Biosensing Techniques; D002800:Cholinesterase Inhibitors; D003124:Colorimetry; D006046:Gold; D043942:Nanotubes
chemical_list: D002800:Cholinesterase Inhibitors; D006046:Gold; D000110:Acetylcholinesterase
keywords: acetylcholinesterase; enzymatic biosensing; etching; gold nanorods; nerve gases