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The current COVID-19 pandemic urges the extremely sensitive and prompt detection of SARS-CoV-2 virus. Here, we present a Human Angiotensin-converting-enzyme 2 (ACE2)-functionalized gold “virus traps” nanostructure as an extremely sensitive SERS biosensor, to selectively capture and rapidly detect S-protein expressed coronavirus, such as the current SARS-CoV-2 in the contaminated water, down to the single-virus level. Such a SERS sensor features extraordinary 106-fold virus enrichment originating from high-affinity of ACE2 with S protein as well as “virus-traps” composed of oblique gold nanoneedles, and 109-fold enhancement of Raman signals originating from multi-component SERS effects. Furthermore, the identification standard of virus signals is established by machine-learning and identification techniques, resulting in an especially low detection limit of 80 copies mL−1 for the simulated contaminated water by SARS-CoV-2 virus with complex circumstance as short as 5 min, which is of great significance for achieving real-time monitoring and early warning of coronavirus. Moreover, here-developed method can be used to establish the identification standard for future unknown coronavirus, and immediately enable extremely sensitive and rapid detection of novel virus.

Here we propose a scheme utilizing the double plasmon modes of gold nanorod (GNR) to efficiently enhance the fluorescence of surrounding emitters. The transversal and longitudinal surface plasmon resonance (TSPR and LSPR, respectively) modes of GNR are simultaneously utilized to enhance the excitation and emission efficiency, respectively. To demonstrate the idea, GNRs coated with an Oxazine-725 dye molecule-doped silica shell are employed. For comparison, gold nanospheres with the same shell are also studied, of which the single plasmon resonance mode matches only with the excitation wavelength of Oxazine-725. The experimental results, in agreement with theoretical simulations using the discrete dipole approximation method, successfully demonstrate the efficient excitation and emission enhancement of fluorescence assisted by the double SPRs of GNRs.

Inorganic chemistry Z 0100 Gold Nanocages: Engineering Their Structure for Biomedical Applications -[≈30 refs.]. -(CHEN, J.; WILEY, B.; LI, Z.-Y.; CAMPBELL, D.; SAEKI, F.; CANG, H.; AU, L.; LEE, J.; LI, X.; XIA*, Y.; Adv. Mater. (Weinheim, Ger.) 17 (2005) 18, 2255-2261; Dep. Chem., Univ. Wash., Seattle, WA 98195, USA; Eng.) -Schramke 45-229