title: Rapid and quantitative detection of C-reactive protein using quantum dots and immunochromatographic test strips.
abstract: BACKGROUND
  Rapid immunochromatographic tests can detect disease markers in 10-15 minutes, which facilitates clinical diagnosis and treatment programs. However, most immunochromatographic tests employ gold nanoparticles as reporters, and these have only moderate sensitivity and act as qualitative methods for analyzing high biomarker concentrations.
  
  
  METHODS
  In this study, we introduce quantum dots (QDs) as fluorescent probes and immunochromatographic strips to develop quantitative fluorescence point-of-care tests (QF-POCT) to analyze C-reactive protein (CRP) levels. Goat anti-rabbit IgG and rabbit IgG were used as control antibodies, and mouse monoclonal CRP antibody pairs were used for disease marker detection. One monoclonal CRP antibody was conjugated with QDs and served as a signal antibody, and the other monoclonal CRP antibody was dispensed onto the nitrocellulose membrane and served as a capturing antibody. In the presence of CRP, the fluorescence intensity of the monoclonal antibody-CRP-monoclonal antibody sandwich complex captured on the nitrocellulose membrane was determined using the fluorescence strip reader.
  
  
  RESULTS
  QF-POCT assays could quantitatively analyze the concentration of CRP in 15 minutes had a detection limit of 0.25 mg/L, and had a wide detection linearity range (0.5-300 mg/L). The intra-assay and interassay coefficients of variation were 8.95% and 9.86% at 0.5 mg/L, 6.47% and 8.66% at 10 mg/L, and 6.81% and 9.10% at 60 mg/L, respectively. In a comparison between clinical samples, the results of this QD-based assay of CRP levels were significantly correlated with those of an Immulite 2000 assay (R=0.993, P<0.001).
  
  
  CONCLUSIONS
  Our results demonstrated that the QD-based immunochromatographic test is a rapid, sensitive, accurate, and quantitative method for the detection of disease biomarkers.
authors.affiliation: Department of Laboratory Medicine, First Affiliated Hospital of Yangtze University, Jingzhou, Hubei, People's Republic of China.
authors.forename: Xianglin
authors.initials: X
authors.lastname: Cheng
authors.affiliation: Department of Laboratory Medicine, RenMin Hospital of Wuhan University, Wuhan, Hubei, People's Republic of China.
authors.forename: Xu
authors.initials: X
authors.lastname: Pu
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, People's Republic of China.
authors.forename: Pen
authors.initials: P
authors.lastname: Jun
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, People's Republic of China.
authors.forename: XiaoBo
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA.
authors.forename: Di
authors.initials: D
authors.lastname: Zhu
authors.affiliation: Department of Laboratory Medicine, First Affiliated Hospital of Yangtze University, Jingzhou, Hubei, People's Republic of China.
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002097:C-Reactive Protein / Q000032:analysis*; D002846:Chromatography, Affinity / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D045663:Quantum Dots / Q000737:chemistry*; D055815:Young Adult
chemical_list: D002097:C-Reactive Protein
keywords: C-reactive protein; fluorescence point-of-care test; immunochromatographic test; quantum dots