Applications of gold nanoparticles in virus detection

Draz, Mohamed Shehata; Shafiee, Hadi

AuNPs have been preferentially employed to perform numerous optical signal transduction functions in virus detection, such as resonance light scattering [49] [50] [51] [52] [53] , color amplification [54] [55] [56] [57] [58] [59] , and fluorescence quenching or enhancing [60] [61] [62] [63] [64] [65] (Fig. 2) . Resonance light-scattering-based detections usually involve measuring the amount of light scattered by different light spectroscopy techniques, including localized surface plasmon resonance (LSPR) [52] , Raman spectroscopy [49, 50] and dynamic light scattering (DLS) [51, 53] . The colorimetric detection of viruses using AuNPs usually relies on two main techniques: 1) a color amplification technique in which AuNPs are applied to act as direct coloring labels with their characteristic, intense red color [55, 58, 59, 66] ; and 2) color change technique in which a color change from red to purple occurs in response to particle aggregation. AuNP aggregation can be noncrosslinked aggregation caused by the target-triggered removal of stabilizing ligands from the surfaces of AuNPs [54, 56] or interparticle-crosslinked aggregation caused by the binding of ligands on modified AuNPs with target analytes [57, 67] . Analogous to FRET, AuNP-based fluorescence quenching is a distance-dependent process in which AuNPs act to reduce the radiative rate of fluorophores in their proximity. Thus, as efficient acceptors, AuNPs have been paired with dyeand QD-based fluorophores in different analyte-induced donor-acceptor crosslinking and coupling protocols [60-62, 64, 65] .