Nanozyme-strip for rapid and ultrasensitive nucleic acid detection of SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic has created a huge demand for sensitive and rapid detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The current gold standard for SARS-CoV-2 detection is reverse transcription-polymerase chain reaction (RT-PCR)-based nucleic acid amplification. However, RT-PCR is time consuming and requires specialists and large instruments that are unattainable for point-of-care testing (POCT). To develop POCT for SARS-CoV-2, we combined recombinase polymerase amplification (RPA) and FeS₂ nanozyme strips to achieve facile nucleic acid amplification and subsequent colorimetric signal enhancement based on the high peroxidase-like activity of the FeS₂ nanozymes. This method showed a nucleic acid limit of detection (LOD) for SARS-CoV-2 of 200 copies/mL, close to that of RT-PCR. The unique catalytic properties of the FeS₂ nanozymes enabled the nanozyme-strip to amplify colorimetric signals via the nontoxic 3,3',5,5'-tetramethylbenzidine (TMB) substrate. Importantly, the detection of clinical samples of human papilloma virus type 16 (HPV-16) showed 100% agreement with previous RT-PCR results, highlighting the versatility and reliability of this method. Our findings suggest that nanozyme-based nucleic acid detection has great potential in the development of POCT diagnosis for COVID-19 and other viral infections.