M. tuberculosis strain H37Rv electrochemical sensor mediated by aptamer and AuNPs-DNA.

The accurate and rapid detection of Mycobacterium tuberculosis (M. tuberculosis) is essential for the effective treatment of tuberculosis. In this article, we propose an electrochemical sensor to detect M. tuberculosis reference strain H37Rv. The sen-sor contains an H37Rv aptamer and oligonucleotides modified with gold nanoparticles (AuNPs-DNA). An H37Rv aptamer screened by our laboratory was used as the recognition probe. The change in frequency shift mediated by AuNPs-DNA in the presence of H37Rv was detected using a multichannel series piezoelectric quartz crystal (MSPQC) system. Three oligonucleo-tides modified with gold nanoparticles were designed. These oligonucleotides contained 12, 12, and 13 bases that hybridized with the 37-nt H37Rv aptamer. H37Rv aptamer was immobilized on the gold electrode surface by Au-S bonds. A conductive-layer was then formed by sequential hybridization of the aptamer with the three designed AuNPs-DNAs. When H37Rv was present, it specifically bound to the aptamer, resulting in the detachment of AuNPs-DNA from the electrode. The conductive layer was thereby replaced by a non-conductive complex of aptamer and bacteria. These changes were monitored by the MSPQC system. The proposed sensor is rapid, specific and sensitive, the detection time was 2 h. The limit of detection limit was 100 cfu/mL. This sensor would be of great benefit for the early clinical diagnosis of tuberculosis.