High-sensitive Detection Of BCR/ABL Fusion Gene Based On Well-regulated DNA Walker-induced Isothermal Amplification Strategy

Chronic myeloid leukemia（CML）is a malignant proliferative disease originating from marrow multifunctional hematopoietic stem cells.BCR/ABL fusion gene is the characteristic biomarker of CML,which forms by the translocation of BCR gene on chromosome 22 and the ABL gene on chromosome 9.To date,various useful and efficient clinical diagnostic techniques,including fluorescence in situ hybridization（FISH）,reverse transcription-quantitative polymerase chain reaction（RT-PCR）and flow cytometry（FCM）have been established to recognize BCR/ABL fusion gene.But there are still limitations of these methods,in terms of time consumption,poor precision,need for high technology instrumentations and expensiveness.On all accounts,the development of assays with rapidity,simplicity and high sensitivity for BCR/ABL fusion gene early detection is still in urgent need.Here,utilizing the well-regulated tracks-based DNA walker as efficient signal amplification and Au@g-C₃N₄ NHs as excellent luminophores and nanocarriers,an ultrasensitive“off-on”ECL biosensor has been successfully fabricated for the BCR/ABL fusion gene detection.The well-regulated DNA tracks were constructed via supersandwich hybridization chain reaction of two DNA strands（L₁ and L₂）to generate periodic linear ds DNA concatemers where exposed L₁ domain closed with blocking strands（BS）.The prepared DNA tracks were further assembled onto the surface of the Au nanoparticles functionalized g-C₃N₄ nanohybrids（Au@g-C₃N₄NHs）modified electrode,achieving well-regulated interfacial tracks for DNA walker.On this state,folic acid-labelled BS（FA-BS）were close to Au@g-C₃N₄NHs,performing a quenched ECL emission.With existence of the BCR/ABL fusion gene,target combined two walking DNA strands（WD₁,WD₂）to form the bipedal DNA walkers,which walked on the well-regulated interfacial DNA tracks and replaced the FA-BS to light up the ECL emission,realizing DNA walker-based signal amplification.Comparing to randomly constructed DNA tracks,the well-regulated DNA tracks reduced the kinetics barrier and fitted the step size of DNA walker,thus promoting the DNA walking efficiency and decreasing the risk of interruption in walking process.As a result,the designed DNA walker presented higher efficiency and capacity in signal amplification.Benefiting from this efficient DNA walker strategy,this ECL biosensing technology realizes the rapid and sensitive detection of BCR/ABL fusion gene,and is expected to provide strong support for early diagnosis,early treatment and prognosis judgment of clinical CML.