Unmodified gold nanoparticles for direct and rapid detection of Mycobacterium tuberculosis complex

Abstract

Objectives: This work aims to develop rapid nano-gold assay prototypes for specific detection of Mycobacterium tuberculosis complex (MTBC).

Design and methods: Spherical gold nanoparticles (AuNPs, 14nm) were synthesized by citrate reduction method and characterized by spectrophotometry and SEM. MTB 16s rDNA regions were amplified by PCR and amplicons were detected using genus- and species-specific oligotargeters and AuNPs. In a second prototype, MTBC unamplified genomic DNA was directly detected using species-specific oligo-targeters and AuNPs.

Results: Detection limits were 1ng for PCR product and 40ng for genomic DNA. The nano-gold prototype detected 45 positive genomic DNA samples which were also positive with automated liquid culture system (BACTEC™ MGIT™) and semi-nested PCR (100% concordance). Following DNA extraction, using standard procedures, the TB nano-gold prototype turnaround time is about 1h.

Conclusions: We have developed nano-gold assay prototype for direct and inexpensive detection of MTBC. The developed prototypes are simple, sensitive, rapid and can substitute PCR-based detection. The developed assay may show potential in the clinical diagnosis of TB especially in developing countries.