Rapid, Single Affinity Sensor for SARS-CoV-2 Detection

Description:
The SARS-CoV-2 pandemic has clearly illustrated the need for rapid, affordable diagnostics. A popular platform for fast, affordable, POC diagnostics is microfluidic paper-based analytical devices (µPADs). While µPADs have several advantages, they are often criticized for their lack of sensitivity and higher detection limits. One way to improve the sensitivity of these assays is by using an enzyme-substrate pair in an enzyme-linked immunosorbent assay (ELISA). ELISAs rely on a capture antibody to bind to its target of interest in the sample and an enzyme-labeled capture antibody for detection.
Here, a rapid diagnostic test for SARS-CoV-2 was developed that automates the reagent delivery and washing steps required for an ELISA. This device is made of inexpensive transparency film and double-sided adhesive that is patterned, cut, layered, and laminated to create hollow channels. After sample is added, sample, dried reagents, and washing steps are sequentially delivered to and washed from a nitrocellulose test strip, resulting in a visual readout in <20 minutes. An analytical limit of detection of 83 PFU/mL virus in buffer and 222 PFU/mL for virus-spiked nasal swabs was determined.
Although antibodies provide high selectivity, are a high-binding affinity ligand, and have been widely used in diagnostics over the past 20 years, they also have significant limitations, though reagents without said limits are and will be needed for future advances in the field. Aptamers are chemically synthesized and have sufficient surface areas to recognize and bind to their targets in a similar fashion to antibodies and can differentiate between isoforms and variants of a specific protein. Aptameric detection of SARS-CoV-2 is being conducted to study aptamer’s future in the point-of-care. This study hopes to illustrate the advantages and struggles of using aptamers compared to typical antibodies used throughout our system and show their viability for use in future diagnostic tests.

Speaker: Elijah Barstis - Colorado State University
Elijah Barstis is currently a PhD candidate in the Henry Research Group in the Department of Chemistry at Colorado State University. He got his B.A. in Chemistry (ACS certified) and Art from Hamilton College in 2019 and served as a Professional Specialist at Saint Mary's College, Notre Dame, IN before attending CSU. His research focuses on the development of a rapid, single-step affinity sensor for the point-of-care diagnostics focusing mainly on SARS-CoV-2. Recently he helped develop and optimize a Capillary-Driven Immunoassay for the detection of SARS-CoV-2 in non-invasive nasopharyngeal samples with high sensitivity and selectivity. Currently Elijah's main research goal is studying and optimizing the use of aptamers in the POC diagnostics.