A copper based enzyme-free fluorescence ELISA for HER2 detection.

We reported an enzyme-free ELISA to detect breast cancer biomarker human epidermal growth factor receptor 2 (HER2) in human serum samples. Instead of enzymes (such as horseradish peroxidase) used in traditional ELISA, CuO nanoparticles were utilized as the signal probe. Compared to traditional enzymes, CuO nanoparticles have the advantages of low cost and good stability. After dissolving CuO nanoparticles with acid, the Cu (II) ions generated catalyzed the reaction of o-phenylenediamine with ascorbic acid to produce fluorescent quinoxaline derivative molecules. The immunoassay displays high sensitivity and good selectivity towards HER2 with detection limit as low as 9.65pg·mL-1. The assay was successfully applied to the analysis of HER2 in serum of breast cancer patients. The analysis results demonstrated the HER2 level in the serum samples determined by our assay were in good agreement with those determined by commercial HER2 ELISA kit. This enzyme-free ELISA assay can be easily adapted to the detection of other analytes. With these merits, the simple, sensitive and cost effective fluorescence immunoassay shows great potential for clinical applications.