title: Competitive Upconversion-Linked Immunosorbent Assay for the Sensitive Detection of Diclofenac.
abstract: Photon-upconverting nanoparticles (UCNPs) emit light of shorter wavelength under near-infrared excitation and thus avoid optical background interference. We have exploited this unique photophysical feature to establish a sensitive competitive immunoassay for the detection of the pharmaceutical micropollutant diclofenac (DCF) in water. The so-called upconversion-linked immunosorbent assay (ULISA) was critically dependent on the design of the upconversion luminescent detection label. Silica-coated UCNPs (50 nm in diameter) exposing carboxyl groups on the surface were conjugated to a secondary anti-IgG antibody. We investigated the structure and monodispersity of the nanoconjugates in detail. Using a highly affine anti-DCF primary antibody, the optimized ULISA reached a detection limit of 0.05 ng DCF per mL. This performance came close to a conventional enzyme-linked immunosorbent assay (ELISA) without the need for an enzyme-mediated signal amplification step. The ULISA was further employed for analyzing drinking and surface water samples. The results were consistent with a conventional ELISA as well as liquid chromatography-mass spectrometry (LC-MS).
authors.affiliation: Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg , 93040 Regensburg, Germany.|CEITEC-Central European Institute of Technology, Masaryk University , Brno 625 00, Czech Republic.|Institute of Analytical Chemistry AS CR, v. v. i. , Brno 602 00, Czech Republic.
authors.forename: Antonín
authors.initials: A
authors.lastname: Hlaváček
authors.affiliation: Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg , 93040 Regensburg, Germany.|CEITEC-Central European Institute of Technology, Masaryk University , Brno 625 00, Czech Republic.
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Farka
authors.affiliation: Chair of Analytical Chemistry and Institute of Hydrochemistry, Technical University of Munich , 81377 Munich, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Hübner
authors.affiliation: CEITEC-Central European Institute of Technology, Masaryk University , Brno 625 00, Czech Republic.
authors.forename: Veronika
authors.initials: V
authors.lastname: Horňáková
authors.affiliation: CEITEC-Central European Institute of Technology, Masaryk University , Brno 625 00, Czech Republic.
authors.forename: Daniel
authors.initials: D
authors.lastname: Němeček
authors.affiliation: Chair of Analytical Chemistry and Institute of Hydrochemistry, Technical University of Munich , 81377 Munich, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Niessner
authors.affiliation: CEITEC-Central European Institute of Technology, Masaryk University , Brno 625 00, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Skládal
authors.affiliation: Chair of Analytical Chemistry and Institute of Hydrochemistry, Technical University of Munich , 81377 Munich, Germany.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Knopp
authors.affiliation: Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg , 93040 Regensburg, Germany.
authors.forename: Hans H
authors.initials: HH
authors.lastname: Gorris
mesh_terms: D004008:Diclofenac / Q000032:analysis*; D060766:Drinking Water / Q000737:chemistry; D007118:Immunoassay / Q000379:methods*; D007164:Immunosorbents / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D060766:Drinking Water; D007164:Immunosorbents; D014874:Water Pollutants, Chemical; D004008:Diclofenac; D012822:Silicon Dioxide