At-Home COVID-19 Rapid Antigen Test Down to 0.03 pg mL -1 of Nucleocapsid Protein.

Rapid and ultra-sensitive detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is critical for early screening and management of COVID-19. Currently, the real-time reverse transcription polymerase chain reaction (rRT-PCR) is the primary laboratory method for diagnosing SARS-CoV-2. It is not suitable for at-home COVID-19 diagnostic test due to the long operating time, specific equipment, and professional procedures. Here an all-printed photonic crystal (PC) microarray with portable device for at-home COVID-19 rapid antigen test is reported. The fluorescence-enhanced effect of PC amplifies the fluorescence intensity of the labeled probe, achieving detection of nucleocapsid (N-) protein down to 0.03 pg mL -1 . A portable fluorescence intensity measurement instrument gives the result (negative or positive) by the color of the indicator within 5 s after inserting the reacted PC microarray test card. The N protein in inactivated virus samples (with cycle threshold values of 26.6-40.0) can be detected. The PC microarray provides a general and easy-to-use method for the timely monitoring and eventual control of the global coronavirus pandemic.