We constructed a novel and universal biosensing platform based on polymerase-nicking enzyme synergetic isothermal quadratic DNA machine (ESQM). It tactfully integrates two signal amplification modules including strand displacement amplification (SDA) and nicking enzyme signal amplification (NESA) into a one-step biosensing system via a bifunctional DNA probe with stem-loop structure. ESQM can be activated to afford a high amplified signal in the presence of target. The ultrasensitive detection of Pb2+ (30 fM) even in real water sample was achieved within 40 min, and the practicability of ESQM in DNA methyltransferase activity analysis demonstrated the universality of this biosensing platform.
- Yongxi Zhao
- Feng Chen
- Chunhai Fan
