Competitive Upconversion-Linked Immunosorbent Assay for the Sensitive Detection of Diclofenac
| Authors | |
|---|---|
| Year of publication | 2016 |
| Type | Article in Periodical |
| Magazine / Source | Analytical Chemistry |
| MU Faculty or unit | |
| Citation | |
| Web | http://pubs.acs.org/doi/abs/10.1021/acs.analchem.6b01083 |
| Doi | http://dx.doi.org/10.1021/acs.analchem.6b01083 |
| Field | Analytic chemistry |
| Keywords | antibody; bioconjugation; diclofenac; immunoassay; pharmaceutical micropollutant; photon-upconversion |
| Description | 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). |
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