Fluorometric determination of the breast cancer 1 gene based on the target-induced conformational change of a DNA template for copper nanoclusters

The breast cancer 1 (BRCA1) gene is a tumor suppressor gene, whose mutation is closely related to breast cancer. Therefore, the sensitive detection of the BRCA1 gene is extremely important for human health, particularly for women. In this study, a label-free fluorescent method based on hairpin DNA-templated copper nanoclusters (CuNCs) was for the first time developed for the detection of the BRCA1 gene. In the absence of target DNA, the detection system showed a strong red emission and produced a high emission peak. However, in the presence of the BRCA1 gene, the DNA probe hybridized with the BRCA1 gene and conformation of the DNA probe changed. As a result, the amount of produced CuNCs decreased and a low emission peak was obtained. The fluorescence intensity of the detection system was linearly correlated with the concentration of the BRCA1 gene ranging from 2 nM to 600 nM. The detectable limit was 2 nM for the BRCA1 gene assay, which was comparable with those reported by other non-amplifying sensors. Moreover, the developed method showed satisfactory recoveries for the BRCA1 gene assay in the bovine serum. The DNA-templated CuNC-based fluorescent assay thus offered a promising platform for the diagnosis of a breast cancer biomarker.