A novel electrochemical method was developed for the detection of Type b3a2 (BCR/ABL gene) as a biomarker of Chronic Myelogenous Leukemia that is based on the use of locked nucleic acid incorporating LNA switching, Fe3O4 nanoparticles (NPS), and enzymatic signal amplification. The quality of the biosensor was proven by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy tests. The LNA probe was modified by NH2 and biotin at its 3-end and 5-end, respectively. After unfolding the loop-and-stem structure of the probe, it was hybridized with Type b3a2, which makes the biotin stay away from the surface of Fe3O4 NPS. Type b3a2 can be evaluated quantitatively using electrochemical detection of the benzoquinone enzymatic product with the presence of H2O2 and hydroquinone via the particular interaction between SA-HRP and biotin. Particular and selective Type b3a2 detection was obtained over an extensive concentration range from 50 femtometer (fM) to 5 micrometer (µM) in a low limit of detection of 17 fM via the biosensor. Manuscript profile