Impedimetric gene assay for BCR/ABL transcripts in plasmids of patients with chronic myeloid leukemia

A label-free impedimetric biosensor was developed for determination of BCR/ABL transcripts. Specific DNA primers were covalently immobilized on a gold electrode modified with carboxylated multiwalled carbon nanotubes (cMWCNTs) and zinc oxide nanoparticles (ZnO-NPs). Aggregation of the ZnO-NPs is prevented by the introduction of an amino-modified silica coating, which also allows a subsequent covalent linkage to cMWCNTs. The impedimetric biosensor was typically operated at a working voltage of +10 mV vs. Ag/AgCl, in a frequency range from 100 mHz to 100 kHz. Studies on the surface morphology and electrochemical properties of the electrode demonstrated improved bioactivity. Amperometric currents and impedimetric parameters, such as charge transfer resistance, varied significantly throughout the construction of the biosensor. The hybridization process was also evidenced by changes in the topography of the surface after exposure to samples containing BCR/ABL. The gene sensor has a linear concentration range for the target gene of 6.94 aM to 694 fM with a limit of detection as low as 0.039 aM. Also, the biosensor is selective and reproducible with a standard deviation of 4.1%. Three replicates for each experimental condition were used. Hence, it is perceived to be a viable tool for early-stage diagnosis of the BCR/ABL fusion gene and monitoring of major molecular remission in clinical samples. Graphical abstract Schematic of a highly sensitive hybridization assay for the BCR/ABL fusion gene. It is based on ZnO nanoparticle functionalized with 3-(aminopropyl)triethoxysilane.