Europium Nanoparticles and Time-resolved Fluorescence for Ultrasensitive Detection of Prostate-specific Antigen

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 47; no. 3; pp. 561 - 568
• Main Authors: Harma, Harri, Soukka, Tero, Lovgren, Timo
• Format: Journal Article
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01-03-2001; American Association for Clinical Chemistry
• Subjects: Biological and medical sciences; Biotinylation; Chelating Agents; Europium; Fluorescent Dyes; Fluoroimmunoassay; Host-tumor relations. Immunology. Biological markers; Image Enhancement; Indicators and Reagents; Medical sciences; Microscopy, Electron; Microscopy, Fluorescence; Particle Size; Prostate-Specific Antigen - analysis; Streptavidin; Tumors; Human; Urinary system disease; Biochemical analysis; Prostate disease; EC 3.4.21.77; Nanoparticle; Exploration; Tumoral marker; Fluorescence spectrometry; Prostate specific antigen; Time resolution; Clinical biology; Europium III; Detection threshold; Tumor; Male genital diseases; Prostate; Quantitative analysis
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/47.3.561

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.
Streptavidin was covalently coated on 107-nm nanoparticles containing >30 000 europium molecules entrapped with beta-diketones. In a model assay system, these nanoparticles were used to trace biotinylated prostate-specific antigen (PSA) in a microtiter plate format.
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.
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.