title: Gold-labeled nanoparticle-based immunoresonance scattering spectral assay for trace apolipoprotein AI and apolipoprotein B.
abstract: BACKGROUND
  Apolipoprotein AI (ApoAI) and ApoB are risk indicators of cardiovascular disease. We describe the use of immunoresonance scattering to measure the ApoAI and ApoB in serum.
  
  
  METHODS
  We used a trisodium citrate method to prepare 9.0-nm gold nanoparticles labeled with goat anti-human ApoAI and ApoB antibodies. The immune reaction between gold-labeled antibodies and antigens took place in Na2HPO4-NaH2PO4 buffer solution (pH 6.4 for ApoAI and pH 6.0 for ApoB) in the presence of 75 g/L polyethylene glycol (PEG). We used a transmission electron microscope to observe the shape of the gold nanoparticles. Results were compared with those obtained by immunoturbidimetric methods. Twenty-five human serum samples were assayed by the immunoresonance scattering assay preset with the data indicated and by an immunoturbidimetric assay.
  
  
  RESULTS
  The presence of PEG greatly enhanced the intensity of resonance-scattering peaks at 560 nm. The intensity (DeltaI) was proportional to concentration at 0.00833-0.3333 mg/L ApoAI and 0.00197-0.1972 mg/L ApoB. The detection limits were 2.04 and 0.96 microg/L for ApoAI and ApoB, respectively. The results for human serum samples were in agreement with those obtained with an immunoturbidimetric method. Linear regression analysis revealed a correlation coefficient, slope, and intercept of 0.915, 0.966, and 68.53 mg/L, respectively, for ApoAI and 0.919, 0.996, and 15.46 mg/L for ApoB.
  
  
  CONCLUSIONS
  This method showed high sensitivity and good selectivity for quantitative determination of ApoAI and ApoB in human serum, with satisfactory results.
authors.affiliation: Department of Resource and Environmental Science, Guangxi Normal University, Guilin, China.
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Jiang
authors.forename: Shuangjiao
authors.initials: S
authors.lastname: Sun
authors.forename: Aihui
authors.initials: A
authors.lastname: Liang
authors.forename: Wenxin
authors.initials: W
authors.lastname: Huang
authors.forename: Aimiao
authors.initials: A
authors.lastname: Qin
mesh_terms: D016632:Apolipoprotein A-I / Q000097:blood*; D001055:Apolipoproteins B / Q000097:blood*; D005453:Fluorescence; D017979:Gold Colloid; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008854:Microscopy, Electron; D049329:Nanostructures; D009391:Nephelometry and Turbidimetry; D012542:Scattering, Radiation
chemical_list: D016632:Apolipoprotein A-I; D001055:Apolipoproteins B; D017979:Gold Colloid