posted on 2021-08-11, 20:43authored bySeunghyeon Kim, Emma Yee, Eric A. Miller, Yining Hao, Dousabel M. Y. Tay, Ki-Joo Sung, Huan Jia, Joseph M. Johnson, Mohsan Saeed, Charles R. Mace, Deniz Yüksel Yurt, Hadley D. Sikes
The
ongoing COVID-19 pandemic has clearly established how vital
rapid, widely accessible diagnostic tests are in controlling infectious
diseases and how difficult and slow it is to scale existing technologies.
Here, we demonstrate the use of the rapid affinity pair identification
via directed selection (RAPIDS) method to discover multiple affinity
pairs for SARS-CoV-2 nucleocapsid protein (N-protein), a biomarker
of COVID-19, from in vitro libraries in 10 weeks. The pair with the
highest biomarker sensitivity was then integrated into a 10 min, vertical-flow
cellulose paper test. Notably, the as-identified affinity proteins
were compatible with a roll-to-roll printing process for large-scale
manufacturing of tests. The test achieved 40 and 80 pM limits of detection
in 1× phosphate-buffered saline (mock swab) and saliva matrices
spiked with cell-culture-generated SARS-CoV-2 viruses and is also
capable of detection of N-protein from characterized clinical swab
samples. Hence, this work paves the way toward the mass production
of cellulose paper-based assays which can address the shortages faced
due to dependence on nitrocellulose and current manufacturing techniques.
Further, the results reported herein indicate the promise of RAPIDS
and engineered binder proteins for the timely and flexible development
of clinically relevant diagnostic tests in response to emerging infectious
diseases.