Direct detection of unamplified hepatitis C virus RNA using unmodified gold nanoparticles

Department of Chemistry & Yousef Jameel Science & Technology Research Center, the American University in Cairo, PO Box 74 New Cairo 11835, Egypt.
Clinical biochemistry (Impact Factor: 2.28). 09/2010; 43(13-14):1163-8. DOI: 10.1016/j.clinbiochem.2010.07.001
Source: PubMed


Gold nanoparticles (AuNPs) exhibit a unique phenomenon known as Surface Plasmon Resonance, which is responsible for their intense red color. This color changes to blue upon aggregation of AuNPs.
This work aims to develop a rapid, simple and cheap assay for direct detection of unamplified HCV RNA extracted from clinical samples using unmodified AuNPs.
Serum samples were collected from healthy volunteers (n=45) and chronic HCV patients (n=30). Extracted RNA, hybridization buffer containing PBS, and a primer targeting the 5'UTR of HCV were mixed. The mixture was denatured, annealed, and then cooled to room temperature for 10 min followed by addition of AuNPs.
Salt, primer, AuNPs concentrations and annealing temperature and time were all optimized. In HCV positive specimens, the color of the solution changed from red to blue within 1 min. The assay has a sensitivity of 92%, a specificity of 88.9%, and a detection limit of 50 copies/reaction.
To our knowledge, this is the first assay that allows the detection of unamplified HCV RNA in clinical specimens using unmodified AuNPs. The developed assay is highly sensitive, has a turnaround time of 30 min, and eliminates the need for thermal cycling and detection instruments.

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Available from: Sherif M Shawky, Feb 24, 2014
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    • "In contrast, AuNP-probe solution without complementary DNA containing aggregated AuNPs is purple with a shift in surface plasmon resonance from 520 to 550 nm. Nowadays such biosensors are used to recognize E. coli [48], Mycobacterium [49], Pseudomonas syringae [32], HBV [51] and HCV [52] "
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    • "The adsorption of ss-DNA on the surface of AuNPs increases the overall negative charge and electrostatic repulsion between AuNPs and thus allows them to resist salt-induced aggregation (Li and Rothberg 2004). This concept has been successfully employed for detection of hepatitis C virus in serum (Shawky et al. 2010) and detection of Mycobacterium tuberculosis isolated from clinical specimens (Hussain et al. 2013). In this study, a nanoparticle-based assay prototype was developed for detection of clinically isolated Ac. baumannii strains. "
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