A rapid and sensitive immunonanogold resonance scattering spectral probe for complement 3

Gold nanoparticles in size of about 10 nm was used to label goat anti-human complement 3 (anti-C3) to obtain a sensitive and selective immunoresonance scattering spectral probe for C3. It was based on the immune reaction between labeled anti-C3 and C3 in the pH 5.6 Na2HPO4-citric acid buffer solutions and in presence of polyethylene glycol (PEG). The resonance scattering (RS) intensity at 560 nm enhanced greatly with C3. Well linear relationships between the enhanced RS intensity (△IRS) and the C3 concentration in the range of 8.33-200 ng ml−1 were obtained, with a detection limit of 2.8 ng ml−1 and the limit of quantification 8.51 ng ml−1 for C3. The convenient and selective and sensitive assay was applied to quantification of C3 in human sera, with satisfactory results.