Ultra-sensitive and fast optical detection of the spike protein of the SARS-CoV-2 using AgNPs/SiNWs nanohybrid based sensors

Abstract

Severe acute respiratory syndrome SARS-CoV-2 virus led to notable challenges amongst researchers in view of development of new and fast detecting techniques. In this regard, surface-enhanced Raman spectroscopy (SERS) technique, providing a fingerprint characteristic for each material, would be an interesting approach. The current study encompasses the fabrication of a SERS sensor to study the SARS-CoV-2 S1 (RBD) spike protein of the SARS-CoV-2 virus family. The SERS sensor consists of a silicon nanowires (SiNWs) substrate decorated with plasmonic silver nanoparticles (AgNPs). Both SiNWs fabrication and AgNPs decoration were achieved by a relatively simple wet chemical processing method. The study deliberately projects the factors that influence the growth of silicon nanowires, uniform decoration of AgNPs onto the SiNWs matrix along with detection of Rhodamine-6G (R6G) to optimize the best conditions for enhanced sensing of the spike protein. Increasing the time period of etching process resulted in enhanced SiNWs’ length from 0.55 to 7.34 µm. Furthermore, the variation of the immersion time in the decoration process of AgNPs onto SiNWs ensued the optimum time period for the enhancement in the sensitivity of detection. Tremendous increase in sensitivity of R6G detection was perceived on SiNWs etched for 2 min (length=0.90 µm), followed by 30s of immersion time for their optimal decoration by AgNPs. These SiNWs/AgNPs SERS-based sensors were able to detect the spike protein at a concentration down to 9.3 × 10 −12 M. Strong and dominant peaks at 1280, 1404, 1495, 1541 and 1609 cm −1 were spotted at a fraction of a minute. Moreover, direct, ultra-fast, facile, and affordable optoelectronic SiNWs/AgNPs sensors tuned to function as a biosensor for detecting the spike protein even at a trace level (pico molar concentration). The current findings hold great promise for the utilization of SERS as an innovative approach in the diagnosis domain of infections at very early stages.

Lateral Flow Immunoassay of SARS-CoV-2 Antigen with SERS-Based Registration: Development and Comparison with Traditional Immunoassays

“…To date, rapid diagnostics of COVID-19 to determine the antigen and the presence of IgG/IgM antibodies to SARS-CoV-2 to prevent the spread of the virus is carried out using lateral flow tests [ 43 , 44 ]. In parallel, other methods of virus identification are being developed, including electrochemical sensors, colorimetric tests, and SERS sensors [ 45 , 46 , 47 ]. The latter has limitations associated with complex procedures for preparing the metal substrate, and in the case of direct SERS detection, with the difficulty of obtaining an intrinsic spectrum of the target analyte.…”

A Framework for Biosensors Assisted by Multiphoton Effects and Machine Learning

“…Coronavirus disease (COVID-19) outbreaks in several communities have compelled governments worldwide to enact stringent controls such as blockades, border closures, and widespread screening [ 43 ]. The SARS-CoV-2 virus is compatible with the coronavirus family with single-stranded gene RNA and surface proteins such as membranes, envelopes, nucleocapsids, and spikes [ 44 ]. Cryo-electron microscopy was utilized to establish the structure of the SARS-CoV-2 spike glycoprotein, which was then used for the creation of cell-specific vaccinations [ 45 ].…”

Study of the morphological, optical, structural and electrical properties of silicon nanowires at varying concentrations of the catalyst precursor

“…A similar trend was observed in previous studies by other researchers viz., Doudi et al 35 and Gaidi et al 36 With the increase in etching time, the topology of the nanowires also changed. As the length of the nanowires increase, they become more flexible and bending takes place.…”