Colorimetric detection of Helicobacter pylori DNA using isothermal helicase-dependent amplification and gold nanoparticle probes

This study describes a nanodiagnostic method using thermophilic helicase-dependent isothermal amplification (tHDA) and gold nanoparticle probes for colorimetric detection of Helicobacter pylori DNA. The pruners targeting ureC gene were used for the amplification of bacterial DNA by the isothermal tHDA reaction, resulting in the accumulation of DNA amplicons. The amplicons were hybridized with specific gold nanoparticle probes. The hybrids were colorimetrically detected by the assembly of gold nanoparticles. Using this method, we detected as little as 10 CFU mL(-1) of H. pylori within less than I h. Results obtained from the gastric biopsy samples showed 92.5% and 95.4% of sensitivity and specificity, respectively, in comparison with culture results, and 100% and 98.8% of sensitivity and specificity, respectively, in comparison with those of the histologic studies. Owing to its ease of operation, this assay significantly reduces the time and cost needed for the molecular diagnosis of H. pylori and has the potential to facilitate early detection of this pathogen. (C) 2008 Elsevier Inc. All rights reserved.