SARS-CoV-2 spike protein detection through a plasmonic D-shaped plastic optical fiber aptasensor

A specific aptameric sequence has been immobilized on short polyethyleneglycol (PEG) interface on gold nano-film deposited on a D-shaped plastic optical fiber (POFs) probe, and the protein binding has been monitored exploiting the very sensitive surface plasmon resonance (SPR) phenomenon. The receptor-binding domain (RBD) of the SARS-CoV-2 spike glycoprotein has been specifically used to develop an aptasensor. Surface analysis techniques coupled to fluorescence microscopy and plasmonic analysis have been utilized to characterize the biointerface. Spanning a wide protein range (25 divided by 1000 nM), the SARS-Cov-2 spike protein was detected with a Limit of Detection (LoD) of about 37 nM. Different interferents (BSA, AH1N1 hemagglutinin protein and MERS spike protein) have been tested confirming the specificity of our aptasensor. Finally, a preliminary test in diluted human serum encouraged its application in a point-of-care device, since POF-based aptasensor represent a potentially low-cost compact biosensor, characterized by a rapid response, a small size and could be an ideal laboratory portable diagnostic tool.

Automated summary

A specific aptameric sequence has been immobilized on a gold nano-film deposited on a D-shaped plastic optical fiber, allowing the monitoring of protein binding through the surface plasmon resonance phenomenon. The aptasensor specifically developed using the receptor-binding domain of the SARS-CoV-2 spike glycoprotein showed a high sensitivity in detecting the spike protein in a range of 25 to 1000 nM, with a Limit of Detection of about 37 nM. Various interferents were tested to confirm the specificity of the aptasensor, indicating its potential application as a point-of-care device.