Direct Determination of miR‐21 in Total RNA Extracted from Breast Cancer Samples Using Magnetosensing Platforms and the p19 Viral Protein as Detector Bioreceptor

A novel magnetobiosensing approach for the rapid, sensitive and selective miR‐21 detection is reported involving the use of a specific RNA probe (antimiR‐21), streptavidin‐magnetic beads (Strep‐MBs), the siRNA Binding Protein p19 as detector bioreceptor, and amperometric detection with the H 2 O 2 /hydroquinone (HQ) system at disposable screen‐printed carbon electrodes. The magnetosensor exhibited a dynamic range from 1.4 to 10 nM and a detection limit of 4.2 fmol of synthetic target miR‐21 without any amplification step in 75 min. The usefulness of the approach was evaluated by analyzing total RNA (RNA t ) extracted from metastatic breast cancer cell lines, human tissues and breast cytologies.