Silver nanoparticle labeled immunoresonance scattering spectral assay for trace fibrinogen

Silver nanoparticles in size of 8.0 nm was prepared by the trisodium citrate and used to label goat anti-human fibrinogen. In the pH 5.8 Na2HPO4-NaH2O4 buffer solution (PBS) and in the presence of polyethylene glycol (PEG) and KCI, the immune reaction between silver-labeled goat anti-human fibrinogen and fibrinogen took place and led the resonance scattering intensity at 465 nm (I-465) to decreasing. The I-465 decreased intensity was linear to the fibrinogen concentration in the range from 0.067 to 1.67 mu g/mL, with a detection limit of 0.024 mu g/mL. This method was applied to determination of fibrinogen in human plasma, with satisfactory results.