Fast Electrochemical miRNAs Determination in Cancer Cells and Tumor Tissues with Antibody-Functionalized Magnetic Microcarriers

Microribonucleic acids (miRNAs) have been linked with various regulatory functions and diseases and constitute important targets in future medical diagnostics and prognostics. We report here a novel sensitive and rapid bioelectrochemical strategy for miRNA determination. This strategy involves the development of a sensing approach making use of magnetic beads (MBs) modified with a specific DNA-RNA antibody as capture bioreceptor and amperometric detection implying the H2O2/hydroquinone (HQ) system at disposable screen-printed carbon electrodes (SPCEs). The developed biosensor exhibits a dynamic range from 8.2 to 250 pM and a detection limit of 2.4 pM (60 amol) of a synthetic target without any amplification step in 2 h. The usefulness of the approach was evaluated by analyzing total RNA (RNA,) extracted from metastatic cancer cell lines and human tumor tissues, which demonstrated its potential to perform determination of mature miRNAs in these complex samples. Moreover, the feasibility of the developed methodology to detect simultaneously the expression of two different miRNAs at dual SPCEs (SPdCEs) in one single experiment was also explored. The feasibility to capture and release target miRNAs make the developed methodology also an attractive tool to isolate, purify, and determine target miRNAs with great applicability in the clinical field.