title: Fluorogenic nanocrystals for highly sensitive detection of C-reactive protein.
abstract: 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.
authors.affiliation: Department of Chemistry, Kowloon, The Hong Kong University of Science &Technology, Clear Water Bay, Kowloon.
authors.forename: K-K
authors.initials: KK
authors.lastname: Sin
authors.forename: C P-Y
authors.initials: CP
authors.lastname: Chan
authors.forename: W-M
authors.initials: WM
authors.lastname: Leung
authors.forename: M
authors.initials: M
authors.lastname: Seydack
authors.forename: R
authors.initials: R
authors.lastname: Renneberg
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis* / Q000276:immunology; D005260:Female; D005452:Fluoresceins; D015200:Fluoroimmunoassay / Q000379:methods*; D006331:Heart Diseases / Q000097:blood / Q000175:diagnosis; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D008297:Male; D008875:Middle Aged; D049329:Nanostructures; D018570:Risk Assessment; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D005452:Fluoresceins; D007074:Immunoglobulin G; D002097:C-Reactive Protein; C018506:diacetylfluorescein