High-sensitivity immunoassay using a novel upconverting phosphor reporter

William H. Wright; Naheed A. Mufti; N. Troy Tagg; Robert R. Webb; Luke V. Schneider

doi:10.1117/12.274357

22 May 1997 High-sensitivity immunoassay using a novel upconverting phosphor reporter

William H. Wright, Naheed A. Mufti, N. Troy Tagg, Robert R. Webb, Luke V. Schneider

Proceedings Volume 2985, Ultrasensitive Biochemical Diagnostics II; (1997) https://doi.org/10.1117/12.274357
Event: BiOS '97, Part of Photonics West, 1997, San Jose, CA, United States

Abstract

A new class of reporter label, consisting of rare earth elements embedded in a crystalline particle, has been developed for in vitro diagnostic applications. These unique labels upconvert low energy (IR) radiation to high energy light by a multiphoton absorption process and subsequent phosphorescence emission. As a result, upconverting phosphors can be visualized with no biological background or autofluorescence signal. In addition, phosphors have narrow absorption and emission bands, making them ideal for simultaneous multianalyte test. The crystalline nature of the phosphors makes them insensitive to environmental conditions, with essentially infinite shelf life and no photobleaching at the irradiances used for excitation. We have covalently coupled (Y_0.86Yb_0.08Er_0.06)₆O₂S phosphor labels to antibody probes to create a reporter reagent that can be excited by 980 nm radiation from a diode laser and detected by a modified spectrofluorimeter. Target analyte sensitivities of approximately 10 ng/mL to Staphylococcal enterotoxin B have been demonstrated using a sandwich assay in a magnetic bead or capillary wick formats in a non-optimized assay system. These results are directly applicable to the development of assays that can be performed on microfabricated biochips or in microflow channels.

Citation Download Citation

William H. Wright, Naheed A. Mufti, N. Troy Tagg, Robert R. Webb, and Luke V. Schneider "High-sensitivity immunoassay using a novel upconverting phosphor reporter", Proc. SPIE 2985, Ultrasensitive Biochemical Diagnostics II, (22 May 1997); https://doi.org/10.1117/12.274357

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