Label-free fluorescent biosensor based on the target recycling and Thioflavin T-induced quadruplex formation for short DNA species of c-erbB-2 detection

Non-invasive early diagnosis of breast cancer is the most effective way to improve the survival rate and increase more chances of breast-conserving. In this paper, we developed a label-free fluorescent biosensor based on nuclease assisted target recycling and Thioflavin T-induced quadruplex formation for short DNA species of c-erbB-2 detection in saliva. By employing the strategy, the sensor can detect as low as 20 fM target DNA with high discrimination ability even against single-base mismatch sequence. To the best of our knowledge, the proposed sensor is the first attempt to apply Thioflavin T that possesses outstanding structural selectivity for G-quadruplex in DNA amplification techniques, which may represent a promising path toward direct breast cancer detection in saliva at the point of care.