Carbon Nanostructure-Based DNA Sensor Used for Quickly Detecting Breast Cancer-Associated Genes

The early diagnosis of breast cancer highly relies on the detection of mutant DNA at low concentrations. Förster resonance energy transfer (FRET) quenching may offer a solution to quickly detect a small amount of single-strand DNA (ssDNA) through the combination of nanomaterials with special luminescence and unique structures of DNA double helix structure. Here, carbon quantum dots (CDs) modified with Capture ssDNA act as the FRET donor which interact with the two-dimensional fluorescence quencher, i.e., graphene oxide nanosheets (GO), to detect breast cancer-associated Target ssDNA at a low concentration. CDs bioconjugated with the designed Capture ssDNA (named CDs-Capture ssDNA) have the maximum fluorescence intensity (I_max) at the emission (λ_em) = 510 nm. The fluorescence of CDs-Capture ssDNA is quenched, while they interact with GO due to the π-π* interaction between ssDNA and GO. In the presence of Target ssDNA, the I_max is restored because of the stronger interaction between Target ssDNA and CDs-Capture ssDNA through the hydrogen bond. The restored fluorescence intensity of CDs has a linear relationship with the concentration of Target ssDNA from 0.25 to 2.5 μM with a detection limit around 0.24 μM. The selectivity of the sensing system has been further evaluated by testing the 3-base mismatched and non-base matched in which efficient restoration of photoluminescence of the sensing system cannot be observed. This carbon nanostructure-based DNA sensing system offers a user-friendly and quick detection of single-strand DNA at lower concentration.