A split-type electrochemical biosensor using enzyme-linked DNA magnetic beads realizes the detection of BCR/ABLp210 fusion gene in clinical samples: Duplex ligation chain reaction coupled with OR logic gate design

Detection of BCR/ABLp210 transcript levels, allowing for the early diagnosis of chronic myelocytic leukemia (CML) and its minimal residual disease (MRD) monitoring, plays a decisive role in the cure of CML. Herein, to realize the sensitive detection of BCR/ABLp210 transcript by electrchemical DNA (E-DNA) sensors in clinical samples, a split-type strategy using enzyme-linked DNA magnetic beads (MBs) was intelligently provided. Specifically, the utilization of magnetic separation makes the target recognition event separate from electrochemical measurements, avoiding the interference of complex matrices on the sensing interface. Besides, the MBs adopted as dispersible electrodes could improve mass transfer of target compared to that of a planar electrode. Consequently, the proposed E-DNA sensor combined with the ligation chain reaction (LCR) could achieve an exceptional performance with a low detection limit of 1 aM, a broad linear concentration range, and a remarkable specificity with a single-base resolution. Also, K562 cells in up to a 1000-fold excess of NB4 cells could be successfully detected by this E-DNA sensor. Finally, the integration of duplex LCR and OR logic gate into the E-DNA sensor has enabled the detection of e13a2/e14a2/both isoforms of BCR/ABLp210 transcript in a single assay in both newly diagnosed CML patients and those undergoing or having undergone treatment by tyrosine kinase inhibitors. Therefore, this method offers an alternative for the early diagnosis of CML and its MRD monitoring, and holds a huge potential of clinical translation due to its advantage of low cost, ease of miniaturization and generalizability.