Gold nanoparticles biosensor of Brucella spp. genomic DNA: Visual and spectrophotometric detections

Introduction: The causative agents of brucellosis from genus Brucella can infect a variety of animal species and human. However, conventional methods for the detection of Brucella are time-consuming and the handling of microorganism is hazardous for laboratory personnel. In this study, a nanobiosensor based on gold nanoparticles (AuNPs) and oligonucleotide probe was designed for the visual detection of Brucella spp. Methods: A specific oligonucleotide probe from IS711 gene region was functionalized with AuNPs (AuNP-probe). Then, AuNP-probe was exposed to target (complementary) and non-target (non-complementary) DNA for the hybridization. Also, hybridization conditions were analyzed in the presence of Brucella genomic DNA and extracted DNA from clinical samples. Results: Upon acid addition, a red color for the samples containing complementary DNA was observed, whereas in the samples without complementary DNA, AuNP-probe turned blue-purple. The results were investigated visually and also by UV-vis spectroscopic measurements. This method detected up to 1.09 pg mu L-1 of unamplified Brucella genomic DNA. Since Brucella is a facultative intracellular bacteria, clinical samples were amplified by PCR, and calorimetric detections were performed. The results showed high sensitivity and selectivity for the amplified clinical samples. Conclusion: To the best of our knowledge, this developed assay is highly specific, and this is the first assay that can be used with low cost, and as a method of rapid, direct and visual detection of Brucella spp. (C) 2015 Elsevier B.V. All rights reserved.