Ultrasensitive electrochemical immunoassay for BRCA1 using BMIM·BF₄-coated SBA-15 as labels and functionalized graphene as enhancer

Abstract

BRCAl is an anti-oncogene in women, who are genetically predisposed to breast and ovary cancer. The detection of BRCA1 can offer an opportunity to characterize the function of genetic features in breast and ovarian cancer and to screen breast or ovarian cancer patients. In this study, we designed a new label and fabricated a novel sandwich-type electrochemical immunoassay for the ultrasensitive detection of BRCAl. Horseradish peroxidase (HRP) was entrapped in the pores of amino-group functionalized SBA-15 and the secondary antibody (Ab₂) combined with SBA-15 by covalent bond. Ionic liquid (IL) was added into the mixed solution of SBA-15/HRP/Ab₂ and application of IL increased the electrochemical activity of HRP and promoted electron transport. The synergistic effect between IL, SBA-15, Ab₂ and HRP could retain the bioactivity of HRP and Ab₂. The sensitivity of the sandwich-type immunosensor using SBA-15/HRP/Ab₂/BMIM·BF₄ as labels for BRCA1 detection was much higher than that using either SBA-15/HRP/Ab₂ or SBA-15/Ab₂ as labels. Under optimal conditions, the electrochemical immunoassay exhibited a wide working range from 0.01 to 15 ng/mL with a detection limit of 4.86 pg/mL BRCA1. The precision, reproducibility, and stability of the immunoassay were acceptable.