Fiber-optic label-free biosensor for SARS‐CoV‐2 spike protein detection using biofunctionalized long-period fiber grating

Abstract

With COVID-19 widespread worldwide, people are still struggling to develop faster and more accurate diagnostic methods. Here we demonstrated the label-free detection of SARS-CoV-2 spike protein by employing a SARS-CoV-2 spike antibody-conjugated phase-shifted long-period fiber grating (PS-LPFG) inscribed with a CO 2 laser. At a specific cladding mode, the wavelength separation ( λ D ) between the two split dips of a PS-LPFG varies with the external refractive index, although it is virtually insensitive to ambient temperature variations. To detect SARS-CoV-2 spike protein, SARS-CoV-2 spike antibodies were immobilized on the fiber surface of the fabricated PS-LPFG functionalized through chemical modification. When exposed to SARS-CoV-2 spike protein with different concentrations, the antibody-immobilized PS-LPFG exhibited the variation of λ D according to the protein concentration, which was caused by bioaffinity binding-induced local changes in the refractive index at its surface. In particular, we also confirmed the potential of our sensor for clinical application by detecting SARS-CoV-2 spike protein in virus transport medium. Moreover, our sensor could distinguish SARS-CoV-2 spike protein from those of MERS-CoV and offer efficient properties such as reusability and storage stability. Hence, we have successfully fabricated a promising optical transducer for the detection of SARS-CoV-2 spike protein, which can be unperturbed by external temperature disturbances.

Highly sensitive electrochemical aptasensor for SARS-CoV-2 antigen detection based on aptamer-binding induced multiple hairpin assembly signal amplification

“… Methods linear rang LOD Ref. Carbon magnetic beads-based electrochemical immunosensor 40 ngmL −1 –10 μgmL −1 14 ngmL −1 [ 15 ] Nanozyme-based chemiluminescence immunoassay 0.2 ngmL −1 –100 ngmL −1 0.1 ngmL −1 [ 16 ] Fiber-optic label-free biosensor 1 pgmL −1 –100 μgmL −1 _ [ 17 ] Field-effect transistor-based electrical immunosensor _ 100 fgmL −1 [ 18 ] Aptamer binding-induced multiple hairpin assembly-based electrochemical aptasensor 50 fg mL −1 ∼ 50 ng mL −1 9.79 fg mL −1 This work …”

Recent advances in the biosensors application for the detection of bacteria and viruses in wastewater

“…Additionally, the sensor has shown a linear detection range of 0–10 7 vp/mL. Moreover, fiber-optic biosensing platforms were utilized by Lee et al [86] . The optical transducer reported was based on SARS-CoV-2 spike antibodies (SSAs) integration with a phase-shifted long-fiber grating (PS-LPEGs), and variation in wavelength separation was used to determine the binding of antibodies to proteins.…”

Rapid and direct quantification of the SARS-CoV-2 virus with an ultrasensitive nanobody-based photonic nanosensor

“…7 For SARS-CoV-2, few studies have been recently published fully addressing the label-free optical biosensing of viral particles, [10][11][12] viral RNA, 13 or viral antigens. 14 Besides, photonic biosensors have been developed for serological assays through the detection and quantification of COVID-19 antibodies, although only a few have been clinically validated. 15,16 Nonetheless, the sensitivity levels achieved so far for the direct detection of SARS-CoV-2 infection have not reached yet the clinical standards set by PCR-based assays, or they involve costly and sophisticated instrumentation and bioreagents making them unsuitable for eventual implementation for POC mass testing.…”