The electrogenerated chemiluminescence detection of IS6110 of Mycobacterium tuberculosis based on a luminol functionalized gold nanoprobe

Abstract

A novel electrogenerated chemiluminescence (ECL) DNA sensor was developed for a fast test for Mycobacterium tuberculosis (MTB) without using the polymerase chain reaction amplification, and was based on luminol functionalized gold nanoprobes with excellent signal amplification functionality. This nanoprobe was formed by the conjugation of luminol functionalized gold nanoparticles (lum–AuNPs) with signal DNA probes. An 81bp segment derived from the Mycobacterium tuberculosis specific insertion sequence IS6110 was chosen as the target strand and corresponding probes were designed to specifically hybridize with it. Biotinylated capture probes can be effectively immobilized directly on a streptavidin coated AuNP modified indium tin oxide electrode. After catching the TB target strand, signal probes tagged with lum–AuNPs were attached to the assembled electrode surface to form a sandwich-type TB sensor. Treating the resulting electrode surface with a carbonate buffer solution containing 1.0 mmol L⁻¹ of H₂O₂ and applying a double-step potential to the electrode, the ECL response was generated which realized the detection of the TB target strand. The detection limit was estimated to be 6.7 × 10⁻¹⁵ mol L⁻¹ (equal to approximately 1.7 × 10⁻¹⁰ g L⁻¹) of the synthetic TB target strand, which is superior to other genetic methodologies for TB tests based on gold nanoprobes. Genomic DNA from other pathogenic bacterias (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) had a negligible effect on its detection, which guaranteed the good selectivity of the TB sensor. The efficacy of the TB sensor was also evaluated for genomic DNA extracted from cultured M. tuberculosis. The TB sensor is sensitive, highly selective, convenient and cost-effective. The simplicity of the assay and the lack of a requirement for sophisticated equipment render the TB sensor a promising candidate as a rapid molecular test for the detection ofM. tuberculosis.