Proof of Concept for a Quick and Highly Sensitive On-Site Detection of SARS-CoV-2 by Plasmonic Optical Fibers and Molecularly Imprinted Polymers

Abstract

The rapid spread of the Coronavirus Disease 2019 (COVID-19) pandemic, caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pathogen has generated a huge international public health emergency. Currently the reference diagnostic technique for virus determination is Reverse Transcription Polymerase Chain Reaction (RT-PCR) real time analysis that requires specialized equipment, reagents and facilities and typically 3–4 h to perform. Thus, the realization of simple, low-cost, small-size, rapid and point-of-care diagnostics tests has become a global priority. In response to the current need for quick, highly sensitive and on-site detection of the SARS-CoV-2 virus in several aqueous solutions, a specific molecularly imprinted polymer (MIP) receptor has been designed, realized, and combined with an optical sensor. More specifically, the proof of concept of a SARS-CoV-2 sensor has been demonstrated by exploiting a plasmonic plastic optical fiber sensor coupled with a novel kind of synthetic MIP nano-layer, especially designed for the specific recognition of Subunit 1 of the SARS-CoV-2 Spike protein. First, we have tested the effectiveness of the developed MIP receptor to bind the Subunit 1 of the SARS-CoV-2 spike protein, then the results of preliminary tests on SARS-CoV-2 virions, performed on samples of nasopharyngeal (NP) swabs in universal transport medium (UTM) and physiological solution (0.9% NaCl), were compared with those obtained with RT-PCR. According to these preliminary results, the sensitivity of the proposed optical-chemical sensor proved to be higher than the RT-PCR one. Furthermore, a relatively fast response time (about 10 min) to the virus was obtained without the use of additional reagents.

A Nanoplasmonic-Based Biosensing Approach for Wide-Range and Highly Sensitive Detection of Chemicals

“…In addition, the longitudinal configuration has also denoted a red-shift resonance, ascribable to an SPR phenomenon, sensitive to higher BSA concentrations. In the latter case, exploiting the SPR phenomenon, we obtained an LOD (≅0.57 µM) similar to the one obtained with an SPR-POF reference sensor functionalized with the same receptor [ 44 ]. Standing this, the more evident advantage of the proposed sensing approach is the feasibility of monitoring a wide range of analyte concentrations (from pM to µM) by a single plasmonic platform (longitudinal configuration).…”

“…At low concentration, which means c much lower than K , Equation (1) can be approximated to a linear function, where the slope (Δλ max /K) is called “sensitivity at low concentration”. It is essential to underline that, to compare the limit of detection (LOD) with other SPR POF-based sensor configurations, we used the same LOD definition adopted in [ 39 , 44 ]. So, by considering the linear behavior at low BSA concentration, the latter is used to calculate the LOD defined as: where represents the standard error relative to the blank solution, that is, the standard error relative to λ 0 reported in Table 1 .…”

“…Finally, a comparative analysis relative to the BSA detection was reported in Table 3 regarding the LOD and the detection range. We compared these results with the ones reported in [ 39 , 44 ], where the same MIP receptor was used.…”

“…In this study, a synthetic receptor was grown on the Au surface in nanometric film. In particular, a recently developed molecular imprinted polymer synthesis strategy for proteins, under non-denaturing conditions, is used [ 44 ]. The preparation is reported below.…”

(INVITED)Quantitative detection of SARS-CoV-2 virions in aqueous mediums by IoT optical fiber sensors

“…In response to the current need for simple and fast approaches to detect SARS-CoV-2 virions, we have proposed two different SPR-POF sensors. Both the SARS-CoV-2 SPR-POF sensors can be monitored exploiting the same experimental setup ( Cennamo et al, 2021 , Cennamo et al, 2021 ). These sensors have been realized by covering the same gold nano-film of the SPR-POF platform with two different kinds of receptors specific to detect the SARS-CoV-2 spike protein: an aptamer ( Cennamo et al, 2021 ) and an MIP ( Cennamo et al, 2021 ).…”