Coronavirus disease 2019 (COVID-19) has been a life-threatening pandemic caused by SARS-CoV-2 [1, 2]. It consists of four structural proteins and a single-stranded RNA as the genetic materials . The rapid transmission of the virus among human beings has caused wide threats to the public health [4- 8]. Up to August 23, 2020, the disease has spread to more than 200 countries, infected over 23.2 million people, and resulted in at least 800,000 deaths . There is an urgent need on techniques for rapid and accurate detection of SARS-CoV-2 to inhibit its further spreading. Point-of-care testing(POCT) platforms with advantages of low-cost, easy operation, and high sensitivity/specificity are broadly applicable to daily life [10, 11].
The symptoms of the patients with the infection of COVID-19 are nonspecific, so various diagnostic methods have been developed accordingly [12-17]. To rapidly screen the subject infected with COVID-19, nucleic acid testing(NAT) based on the reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is now applied as a clinical-acceptable standard [18, 19]. Till now, RT-qPCR has been proved to be highly sensitive and specific [20, 21]. However, its dependence on expensive thermocycler and read-out systems limits the application, especially in some scenarios where the exponential increase of the infected