Applications of gold nanoparticles in virus detection

Draz, Mohamed Shehata; Shafiee, Hadi

HBV detection through AuNP-based scanometric assays mainly relies on the well-described AuNP-promoted silver-staining protocol, in which AuNP probes are applied to facilitate the reduction of silver ions into metallic silver that is deposited as visible black spots, indicating the presence of HBV. Following this protocol, AuNPs modified with staphylococcal protein A (SPA) [88] or specific DNA probes [50, 80] have been utilized in multiple chip-based assays to permit the detection of different HBV antibodies and DNA (Fig. 6 ). In addition, Wang et al. combined this AuNP-promoted silver-staining protocol integrated with a bio-barcode-amplification (BCA) technique to allow an enhanced scanometric detection of HBV DNA [85] . This BCA-based scanometric assay employs two different sets of DNA conjugates to capture and detect a specific HBV sequence. The first set is a group of AuNPs modified with the short dsDNA of a signal amplification DNA strand (barcode DNA) partially complemented with a detection probe strand, while the second set is a group of magnetic microparticles (MMPs) modified with ssDNA specific to the target HBV DNA. The presence of the complementary target sequences of DNA guides the assembly of AuNP/DNA/MMP sandwich hybrids. Subsequently, the sandwiched hybrids are magnetically isolated and washed, and the barcode DNA is eventually released from the AuNPs. The barcode DNA is then added to the surface of a chip modified with specific DNA-capturing probes and directly labeled with AuNP-DNA conjugates, followed by silver staining to further amplify the detection signal (Fig. 10) .