Authors: del Cano, R; Garcia-Mendiola, T; Garcia-Nieto, D; Alvaro, R; Luna, M; Iniesta, HA; Coloma, R; Diaz, CR; Milan-Rois, P; Castellanos, M; Abreu, M; Canton, R; Galan, JC; Pineda, T; Pariente, F; Miranda, R; Somoza, A; Lorenzo, E
Article.
Microchim. Acta. vol: 189. page: 0026-3672.
Date: APR. 2022.
Doi: 10.1007/s00604-022-05272-y.
Abstract:
Gold nanotriangles (AuNTs) functionalized with dithiolated oligonucleotides have been employed to develop an amplification-free electrochemical biosensor for SARS-CoV-2 in patient samples. Gold nanotriangles, prepared through a seed-mediated growth method and exhaustively characterized by different techniques, serve as an improved electrochemical platform and for DNA probe immobilization. Azure A is used as an electrochemical indicator of the hybridization event. The biosensor detects either single stranded DNA or RNA sequences of SARS-CoV-2 of different lengths, with a low detection limit of 22.2 fM. In addition, it allows to detect point mutations in SARS-CoV-2 genome with the aim to detect more infective SARS-CoV-2 variants such as Alpha, Beta, Gamma, Delta, and Omicron. Results obtained with the biosensor in nasopharyngeal swab samples from COVID-19 patients show the possibility to clearly discriminate between non-infected and infected patient samples as well as patient samples with different viral load. Furthermore, the results correlate well with those obtained by the gold standard technique RT-qPCR, with the advantage of avoiding the amplification process and the need of sophisticated equipment..
