T-Shaped Aptamer-Based LSPR Biosensor Using Ω-Shaped Fiber Optic for Rapid Detection of SARS-CoV-2

Abstract

SARS-CoV-2, especially the variant strains, is rapidly spreading around the world. Rapid detection methods for the virus are crucial for controlling the COVID-19 epidemic. Herein, a localized surface plasmonic resonance (LSPR) biosensor based on Ω-shaped fiber optic (Ω-FO) was developed for dual assays of SARS-CoV-2 monitoring. Due to its strong ability to control the orientation and density, a new T-shaped aptamer exhibits enhanced binding affinity toward N proteins. After being combined on the fiber optic surface, the T-shaped aptamer sensitively captured N proteins of SARS-CoV-2 for a direct assay. Further, core–shell structured gold/silver nanoparticles functionalized with a T-shaped aptamer (apt-Ag@AuNPs) can amplify the signal of N protein detection for a sandwich assay. The real-time analytical feature of the dual assays endows time-dependent sensitivity enhancement behavior, which provides a guideline to save analytical time. With those characteristics, the LSPR biosensor has been successfully used to rapidly identify 39 healthy volunteers and 39 COVID-19 patients infected with the ancestral or variant SARS-CoV-2. With the help of simple pretreatment, we obtain a true negative rate of 100% and a true positive rate of 92.3% with a short analysis time of 45 min using the direct assay. Further, the LSPR biosensor could also broaden the detection application range to the surface of cold-chain foods using a sandwich assay. Thus, the LSPR biosensor based on Ω-FO was demonstrated to have broad application potential to detect SARS-CoV-2 rapidly.

Detection of SARS-CoV-2 in saliva by a low-cost LSPR-based sensor

“…Other LSPR sensors were developed for SARS-CoV-2 detection. However, some were developed for serum, 57,58 plasma, 59,60 nasopharyngeal swabs 61 or not tested in a body fluid or comparative media. 62,63 Other relies on more complex construction ( e.g.…”

Aptamers and Nanobodies as New Bioprobes for SARS-CoV-2 Diagnostic and Therapeutic System Applications

“…Localized SPR (LSPR) using nanoparticles was employed to also achieve ultra-sensitivity while using the SPR aptasensor. LSPR-based aptasensors had much higher sensitivities with an LOD of 0.26 nM for the S protein subunit 1 (S1) [ 84 ] and an LOD of 9.2 pM for the N protein [ 85 ].…”

“…Biosensors 2024, 14, x FOR PEER REVIEW 11 of 37 SPR aptasensor. LSPR-based aptasensors had much higher sensitivities with an LOD of 0.26 nM for the S protein subunit 1 (S1) [84] and an LOD of 9.2 pM for the N protein [85].…”

The Sensitivity of a Hexagonal Au Nanohole Array under Different Incident Angles

“…Surface plasmon resonance (SPR) supported by noble metal nanostructures can concentrate optical fields into nanoscale space and significantly enhance the near-field intensity [ 1 , 2 , 3 ], bringing in sensitive response to the refractive index change of the surrounding environment [ 4 , 5 , 6 , 7 ]. Because of this characteristic, SPR sensors have been widely used in the fields of medical diagnosis, food safety regulation and environmental monitoring in the past few decades [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. The sensing performance of an SPR sensor can be evaluated by sensitivity, which is defined as the spectral shift of the sensor per refractive index unit (RIU) [ 17 ].…”