Highly Uniform Self-Assembly of Gold Nanoparticles by Butanol-Induced Dehydration and Its SERS Applications in SARS-CoV-2 Detection

Abstract

Wereport the development of a reproducible and highly sensitivesurface-enhanced Raman scattering (SERS) substrate using a butanol-inducedself-assembly of gold nanoparticles (AuNPs) and its application asa rapid diagnostic platform for severe acute respiratory syndromecoronavirus 2 (SARS-CoV-2). The butanol-induced self-assembly processwas used to generate a uniform assembly of AuNPs, with multiple hotspots,to achieve high reproducibility. When an aqueous droplet containingAuNPs and target DNAs was dropped onto a butanol droplet, butanol-induceddehydration occurred, enriching the target DNAs around the AuNPs andincreasing the loading density of the DNAs on the AuNP surface. TheSERS substrate was evaluated by using Raman spectroscopy, which showedstrong electromagnetic enhancement of the Raman signals. The substratewas then tested for the detection of SARS-CoV-2 using SERS, and avery low limit of detection (LoD) of 3.1 x 10(-15) M was obtained. This provides sufficient sensitivity for the SARS-CoV-2screening assay, and the diagnostic time is significantly reducedas no thermocycling steps are required. This study demonstrates amethod for the butanol-induced self-assembly of AuNPs and its applicationas a highly sensitive and reproducible SERS substrate for the rapiddetection of SARS-CoV-2. The results suggest the potential of thisapproach for developing rapid diagnostic platforms for other biomoleculesand infectious diseases.