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

Background: Several 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.

Methods: Three ING-RSS probes for hCG were prepared, using nanogold in size of 8, 10, 13 nm to label rabbit hCG antiserum (anti-hCG).

Results: In citric acid-Na(2)HPO(4) 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 DeltaI(RS) 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.

Conclusion: This assay has simplicity, sensitivity and good selectivity for quantitative determination of hCG.