In vitro selection of a single-strand DNA aptamer targeting the receptor-binding domain of SARS-CoV-2 spike protein

Nucleic acid aptamers are developed from a pool of random oligonucleotide libraries with an in vitro selection through systematic evolution of ligands via exponential enrichment (SELEX) process, which are capable of specific and high-affinity molecular binding against targets. The receptor-binding domain (RBD) of spike protein from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is involved in the early stages of viral infection, is a promising target for aptamer selection. Currently, there are no effective approaches to prevent virus from spreading. In this study, a new ssDNA aptamer RBD/S-A1 binding to the RBD of spike protein from SARS-CoV-2 with high affinity (Kd=1.74 ± 0.2 nM) and low cross-binding activity was selected and evaluated. Although aptamers targeting the RBD of spike protein from SARS-CoV-2 have been described in a handful of previous studies, the RBD/S-A1 aptamer identified in this work may be considered as a potential supplementation for the current diagnosis and research of coronavirus SARS-CoV-2.