posted on 2022-01-18, 20:06authored byZhicheng Jin, Justin Yeung, Jiajing Zhou, Yong Cheng, Yi Li, Yash Mantri, Tengyu He, Wonjun Yim, Ming Xu, Zhuohong Wu, Pavla Fajtova, Matthew N. Creyer, Colman Moore, Lei Fu, William F. Penny, Anthony J. O’Donoghue, Jesse V. Jokerst
There
is a need for surveillance of COVID-19 to identify individuals
infected with SARS-CoV-2 coronavirus. Although specific, nucleic acid
testing has limitations in terms of point-of-care testing. One potential
alternative is the nonstructural protease (nsp5, also known as Mpro/3CLpro) implicated in SARS-CoV-2 viral replication
but not incorporated into virions. Here, we report a divalent substrate
with a novel design, (Cys)2–(AA)x–(Asp)3, to interface gold colloids in the
specific presence of Mpro leading to a rapid and colorimetric
readout. Citrate- and tris(2-carboxyethyl)phosphine (TCEP)-AuNPs were
identified as the best reporter out of the 17 ligated nanoparticles.
Furthermore, we empirically determined the effects of varying cysteine
valence and biological media on the sensor specificity and sensitivity.
The divalent peptide was specific to Mpro, that is, there
was no response when tested with other proteins or enzymes. Furthermore,
the Mpro detection limits in Tris buffer and exhaled breath
matrices are 12.2 and 18.9 nM, respectively, which are comparable
to other reported methods (i.e., at low nanomolar concentrations)
yet with a rapid and visual readout. These results from our work would
provide informative rationales to design a practical and noninvasive
alternative for COVID-19 diagnostic testingthe presence of
viral proteases in biofluids is validated.