Fluorogenic nanocrystals for highly sensitive detection of C-reactive protein

• Published in: IEE proceedings. Nanobiotechnology Vol. 153; no. 3; p. 54
• Main Authors: Sin, K-K, Chan, C P-Y, Leung, W-M, Seydack, M, Renneberg, R
• Format: Journal Article
• Language: English
• Published: England 01.06.2006
• Subjects: Aged; Biomarkers - blood; C-Reactive Protein - analysis; C-Reactive Protein - immunology; Female; Fluoresceins; Fluoroimmunoassay - methods; Heart Diseases - blood; Heart Diseases - diagnosis; Humans; Immunoglobulin G - analysis; Male; Middle Aged; Nanostructures; Risk Assessment; Sensitivity and Specificity
• ISSN: 1478-1581; 1740-9748
• DOI: 10.1049/ip-nbt:20050048

A solid-phase sandwich fluorescence immunoassay using nanocrystals of a fluorogenic precursor, fluorescein diacetate (FDA), conjugated with monoclonal antibodies for the detection of C-reactive protein (CRP), is described. FDA nanocrystals were coated with distearoylglycerophosphoethanolamine (DSPE), modified with amino(poly(ethylene glycol))(PEG(2000)-Amine) as an interface for coupling biomolecules. CRP was chosen as a model analyte because of its widely accepted role as a marker for acute inflammation and prospective heart failure. A low limit of detection (1.10 microg l(-1)) and high precision (CV = 2.72-9.48%) were achieved. Following the immunoreaction, the monoclonal anti-CRP conjugated nanocrystals were released by hydrolysis and dissolution instigated by the addition of a large volume of organic solvent-sodium hydroxide mixture. Using human serum samples from 66 patients with high heart attack risk and 19 healthy blood donors, this CRP fluorescence immunoassay showed a good correlation to the commercially available, turbidimetric immunoassay for CRP. This result was corroborated by the Bland-Altman plot that showed a mean difference between the two methods of only 0.36+/-1.46 mg l(-1). The study demonstrates that the organic fluorogenic FDA nanocrystals can be applied for the detection of CRP, which is a clinically interesting plasma protein with a low limit of detection.