Highly sensitive detection of HER2 DNA based on enzyme-free target-triggered biped DNA walker combined with ARGET ATRP.

Breast cancer (BC) is one of the most common cancers in women and a major global health challenge. Human epidermal growth factor receptor 2 (HER2) an important biomarker of BC, and its early detection is of great significance for the early diagnosis and treatment of BC patients. Here, a bipedal DNA walker was synthesized using an enzyme-free target-triggered catalytic hairpin assembly (CHA) strategy that is straightforward. And then an electrochemical DNA nanobiosensor for the ultrasensitive detection of HER2 was constructed based on the bipedal DNA walker and activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP), an electron-transfer regeneration catalyst with signal-amplifying effects. While moving, DNA walker operates without enzymatic involvement, consequently escaping enzymatic degradation in unfavorable environmental settings. The ARGET ATRP reaction introduces a large number of polymers into the sensing system, thus amplifying the signal. Notably, the method has a low detection limit of 0.04 pM and a wide detection range of 10 pM to 10 nM. In addition, the biped DNA walker biosensor showed high selectivity and good reproducibility. More importantly, this strategy can be used for the detection of HER2 in human serum, proving its high practical value in biological analysis.