Competitive Upconversion-Linked Immunosorbent Assay for the Sensitive Detection of Diclofenac

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• 作者：Antonín Hlaváček ; Zdeněk Farka ; Maria Hübner ; Veronika Horňáková ; Daniel Němeček ; Reinhard Niessner ; Petr Skládal ; Dietmar Knopp ; Hans H. Gorris
• 刊名：Analytical Chemistry
• 出版年：2016
• 出版时间：June 7, 2016
• 年：2016
• 卷：88
• 期：11
• 页码：6011-6017
• 全文大小：331K
• 年卷期：0
• ISSN：1520-6882

文摘

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).