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1
Department of Biotechnology, University of Turku, Tykistökatu 6, FIN-20520 Turku, Finland.
a Author for correspondence. Fax 358-2-3338050; e-mail
harri.harma{at}utu.fi.
Background: Nanoparticle-based detection technologies have the potential to improve detection sensitivity in miniature as well as in conventional biochemical assays. We introduce a detection technology that relies on the use of europium(III) nanoparticles and time-resolved fluorometry to improve the detection limit of biochemical assays and to visualize individual molecules in a microtiter plate format.
Methods: Streptavidin was covalently coated on 107-nm nanoparticles containing >30 000 europium molecules entrapped with ß-diketones. In a model assay system, these nanoparticles were used to trace biotinylated prostate-specific antigen (PSA) in a microtiter plate format.
Results: The detection limit (mean + 3 SD of the zero calibrator) of biotinylated PSA was 0.38 ng/L, corresponding to 10 fmol/L or 60 zeptomoles (60 x 10-21 moles) of PSA. Moreover, single nanoparticles, representing individual PSA molecules, were visualized in the same microtiter wells with a time-resolved fluorescence microscope using a x10 objective. Single nanoparticles, possessing high specific activity, were also detected in solution by a standard time-resolved plate fluorometer.
Conclusions: The universal streptavidin-coated europium(III) nanoparticle label is suitable for detection of any biotinylated molecule either in solution or on a solid phase. The europium(III) nanoparticle labeling technology is applicable to many areas of modern biochemical analysis, such as immunochemical and multianalyte DNA-chip assays as well as histo- and cytochemistry to improve detection sensitivities.
The following articles in journals at HighWire Press have cited this article:
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G. Rundstrom, A. Jonsson, O. Martensson, I. Mendel-Hartvig, and P. Venge Lateral Flow Immunoassay Using Europium (III) Chelate Microparticles and Time-Resolved Fluorescence for Eosinophils and Neutrophils in Whole Blood Clin. Chem., February 1, 2007; 53(2): 342 - 348. [Abstract] [Full Text] [PDF]
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H. M.E. Azzazy, M. M.H. Mansour, and S. C. Kazmierczak Nanodiagnostics: A New Frontier for Clinical Laboratory Medicine Clin. Chem., July 1, 2006; 52(7): 1238 - 1246. [Abstract] [Full Text] [PDF]
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P. Huhtinen, A.-M. Pelkkikangas, S. Jaakohuhta, T. Lovgren, and H. Harma Quantitative, Rapid Europium(III) Nanoparticle-Label-Based All-in-One Dry-Reagent Immunoassay for Thyroid-Stimulating Hormone Clin. Chem., October 1, 2004; 50(10): 1935 - 1936. [Full Text] [PDF]
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D. S. Fran and M. W. Sundberg RE: Europium Nanoparticles and Time-resolved Fluorescence for Ultrasensitive Detection of Prostate-specific Antigen Clin. Chem., September 1, 2001; 47(9): 1743 - 1744. [Full Text] [PDF]
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T. Soukka, J. Paukkunen, H. Harma, S. Lonnberg, H. Lindroos, and T. Lovgren Supersensitive Time-resolved Immunofluorometric Assay of Free Prostate-specific Antigen with Nanoparticle Label Technology Clin. Chem., July 1, 2001; 47(7): 1269 - 1278. [Abstract] [Full Text] [PDF]
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E. P. Diamandis Signal Amplification in Time-resolved Fluorometry Clin. Chem., March 1, 2001; 47(3): 380 - 381. [Full Text] [PDF]
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