We herein developed a novel signal amplification strategy combining the DNA tetrahedron with magnetic microbeads, for the highly sensitive detection of BRCA1 DNA biomarker. In the present study, a “sandwich-like” biosensor was developed and a tetrahedron-structured reporter probe (TSRP) was designed (Figure 1), in which 3 vertices of the tetrahedron were labelled with digoxin (Dig) and the other one was labelled with a detection probe. TSRP here provided accurate enzyme loading and well-organized spatial arrangement for optimized signal amplification. Thus, the signal-to-noise ratio was significantly increased. The detection limit was as low as 10 fM, which is at least 4 orders of magnitude lower than single DNA probe (100 pM), and more convincingly, 2 orders of magnitude lower than a nanoprobe (10 pM) based on unspecific adsorption of HRP on the AuNPs. Our work for the first time demonstrated the fact that the optimization of the interfacial engineering for the reporter probe plays key role for the performance of the biosensor. By using this novel TSRP strategy, we can distinguish DNA sequences with only 1 base mismatch, and the practicability of our TSRP biosensor was proved to be equally good in both PCR product and real FCS sample as in buffer. Given the high sensitivity, practicability and operation convenience, we believe our sensor is a promising method for point-of-care testing.

Colorimetric BRCA1 detection based on a 3D DNA nanostructured reporter probe

256th National Meeting (2018)

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