Ultrasensitive Magnetogenoassay for Detection of microRNA for Diagnosis of Metastatic Lymph Nodes in Head and Neck Cancer Using Disposable Electrodes

Abstract A fast and simple magnetogenoassay is proposed for diagnosis of metastatic lymph nodes in patients with head and neck squamous cell carcinoma (HNSCC). The developed method involved the construction of a low-cost disposable electrochemical sensor (DES) for the detection of microRNA-203 (miRNA-203) as a biomarker in lymph node samples from patients with HNSCC. A hairpin DNA designed for selectively binding the miRNA-203 was immobilized in magnetic particles (MPs) and used to capture and separate the biomarker from the sample solution. Gold nanoparticles (AuNPs) decorated with single-stranded DNA with a sequence complementary to the hairpin terminal section were prepared and used for biomarker detection. The miRNA-203 magneto-bioconjugate obtained was added to the DES and the biomarker was quantitatively determined by means of the redox properties of the gold present in the AuNPs, using square-wave voltammetry in 0.2 mol L-1 HCl. The proposed method presented a linear range from 1.0 to 500.0 fmol L−1, with a limit of detection of 0.52 fmol L−1. The magnetogenoassay was able to detect the miRNA-203 in 90 min, showing similar results when compared with qRT-PCR for the discrimination of positive and negative metastatic lymph nodes from HNSCC patients. The proposed molecular test requires no amplification steps, offering an effective, simple, and fast alternative for the detection of microRNAs as biomarkers for cancer diagnosis.