title: Gold nanoparticle-catalyzed uranine reduction for signal amplification in fluorescent assays for melamine and aflatoxin B1.
abstract: A multifunctional fluorescence platform has been constructed based on gold nanoparticle (AuNP)-catalyzed uranine reduction. The catalytic reduction of uranine was conducted in aqueous solution using AuNPs as nanocatalyst and sodium borohydride as reducing reagent, which was monitored by fluorescence and UV-vis spectroscopy. The reaction rate was highly dependent on the concentration, size and dispersion state of AuNPs. When AuNPs aggregated, their catalytic ability decreased, and thereby a label-free fluorescent assay was developed for the detection of melamine, which can be used for melamine determination in milk. In addition, a fluorescent immunoassay for aflatoxin B1 (AFB1) was established using the catalytic reaction for signal amplification based on target-induced concentration change of AuNPs, where AFB1-BSA-coated magnetic beads and anti-AFB1 antibody-conjugated AuNPs were employed as capture and signal probe, respectively. The detection can be accomplished in 1 h and acceptable recoveries in spiked maize samples were achieved. The developed fluorescence system is simple, sensitive and specific, which could be used for the detection of a wide range of analytes.
authors.affiliation: Institute of Hydrochemistry, Chair for Analytical Chemistry, Technische Universität München, Marchioninistr. 17, D-81377 München, Germany. dietmar.knopp@ch.tum.de.
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.forename: Jutta
authors.initials: J
authors.lastname: Pauli
authors.forename: Reinhard
authors.initials: R
authors.lastname: Niessner
authors.forename: Ute
authors.initials: U
authors.lastname: Resch-Genger
authors.forename: Dietmar
authors.initials: D
authors.lastname: Knopp
mesh_terms: D016604:Aflatoxin B1 / Q000737:chemistry*; D000818:Animals; D001894:Borohydrides / Q000737:chemistry; D002384:Catalysis; D004583:Electrons; D019793:Fluorescein / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D005504:Food Analysis / Q000379:methods; D005506:Food Contamination / Q000032:analysis; D006046:Gold / Q000737:chemistry*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D008892:Milk / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D019163:Reducing Agents / Q000737:chemistry; D014227:Triazines / Q000737:chemistry*; D014466:Ultraviolet Rays; D003313:Zea mays / Q000378:metabolism
chemical_list: D001894:Borohydrides; D005456:Fluorescent Dyes; D019163:Reducing Agents; D014227:Triazines; D006046:Gold; C025364:sodium borohydride; D016604:Aflatoxin B1; C011907:melamine; D019793:Fluorescein