Detection of antibodies against SARS-CoV-2 spike protein by gold nanospikes in an opto-microfluidic chip

• Published in: Biosensors & bioelectronics Vol. 169; p. 112578
• Main Authors: Funari, Riccardo, Chu, Kang-Yu, Shen, Amy Q.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01-12-2020
• Subjects: Antibodies, Viral - blood; Antibodies, Viral - immunology; Antibody; Betacoronavirus - immunology; Coronavirus Infections - blood; Coronavirus Infections - immunology; Coronavirus Infections - virology; COVID-19; Equipment Design; Gold - chemistry; Gold electrodeposition; Humans; Lab-On-A-Chip Devices; Limit of Detection; LSPR; Microfluidics; Nanostructures - chemistry; Nanostructures - ultrastructure; Pandemics; Pneumonia, Viral - blood; Pneumonia, Viral - immunology; Pneumonia, Viral - virology; SARS-CoV-2; Spike Glycoprotein, Coronavirus - immunology; Surface Plasmon Resonance - instrumentation; COVID-19; SARS-CoV-2; Gold electrodeposition; LSPR; Antibody; Microfluidics
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2020.112578

The ongoing global pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to active research in its associated diagnostics and medical treatments. While quantitative reverse transcription polymerase chain reaction (qRT-PCR) is the most reliable method to detect viral genes of SARS-CoV-2, serological tests for specific antiviral antibodies are also important as they identify false negative qRT-PCR responses, track how effectively the patient’s immune system is fighting the infection, and are potentially helpful for plasma transfusion therapies. In this work, based on the principle of localized surface plasmon resonance (LSPR), we develop an opto-microfluidic sensing platform with gold nanospikes, fabricated by electrodeposition, to detect the presence and amount of antibodies specific to the SARS-CoV-2 spike protein in 1μL of human plasma diluted in 1mL of buffer solution, within ∼30min. The target antibody concentration can be correlated with the LSPR wavelength peak shift of gold nanospikes caused by the local refractive index change due to the antigen–antibody binding. This label-free microfluidic platform achieves a limit of detection of ∼0.08ng/mL (∼0.5pM), falling under the clinical relevant concentration range. We demonstrate that our opto-microfluidic platform offers a promising point-of-care testing tool to complement standard serological assays and make SARS-CoV-2 quantitative diagnostics easier, cheaper, and faster.
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•Opto-microfluidic sensing platform is developed to rapidly detect antibodies against the SARS-CoV-2 spike protein in diluted human plasma with high sensitivity.•The sensing platform achieves the limit of detection of ∼0.5 pM (0.08 ng/mL) and takes up to 30 mins to complete the sample analysis.•The sensing principle is based on localized surface plasmon resonance (LSPR) involving gold nanospikes (fabricated by electrodeposition) in a microfluidic device, coupled with an optical probe.•The diagnostic platform demonstrates potential to complement existing serological assays and improve COVID-19 diagnosis.