An immunonanogold resonance scattering spectral probe for rapid assay of human chorionic gonadotrophin

BackgroundSeveral assays for human chorionic gonadotrophin (hCG) such as radioimmunoassay and fluorescence immunoassays were reported. So far, there was no report about the immunonanogold resonance scattering spectral (ING-RSS) assay based on the immunoreaction and resonance scattering (RS) effect.MethodsThree ING-RSS probes for hCG were prepared, using nanogold in size of 8, 10, 13 nm to label rabbit hCG antiserum (anti-hCG).ResultsIn citric acid–Na2HPO4 buffer solution and in the presence of polyethylene glycol (PEG)6000, the immunoreaction between hCG and nanogold-labeled anti-hCG took place, the immunonanogold-complex was formed and deposited. The decreased intensity ΔIRS for the nanogold in sizes of 8, 10, 13 nm was proportional to hCG concentration in the ranges of 40–10000, 40–10000 and 40–8000 mIU/ml, with the detection limits of 19.4, 15.1 and 13.6 mIU/ml, respectively. The hCG in urine samples were assayed by the ING-RSS assay, and by immunospectrophotometry. The results of both assays showed a close correlation.ConclusionThis assay has simplicity, sensitivity and good selectivity for quantitative determination of hCG.