Illustration of (A) nanoplasmonic metasurface design and (B) functionalization, aptamer attachment, Raman spectra acquisition, and machine learning classification of spectra. (IMAGE)
Caption
(A) Genetic algorithm-driven computational screening and fabrication of the nanoplasmonic SERS aptasensor metasurfaces. Flowchart for genetic algorithm and computational screening of periodic gold nanostructures for maximizing the Raman cross-section of the metasurfaces, Scanning emission microscopy images of the e-beam lithography fabrication for optimized periodic gold nanopattern over 200-μm × 200-μm area. (B) Gold-nanopatterned metasurface is functionalized using a thiol-modified primary aptamer that is specific for SARS-CoV-2 spike glycoproteins. Unprocessed COVID-19 patient saliva or inactive SARS-CoV-2 sample is mixed with fluorescent secondary aptamer, resulting in virus–secondary aptamer complex. Sample is dropped onto the metasurface modified with the primary aptamer to form a sandwich structure (primary aptamer, SARS-CoV-2, and secondary aptamer). Aptamers capture the SARS-CoV-2 by binding to virus glycoproteins, forming a sandwich structure yielding strong plasmonic enhancement of the virus-specific fluorescent and Raman emissions. These Raman spectra are then used in the machine learning classifier model for viral presence, concentration, and variant type. a.n., arbitrary numbers.
Credit
Advanced Devices & Instrumentation
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