Short-Time Preamplification-Assisted One-Pot CRISPR Nucleic Acid Detection Method with Portable Self-Heating...

Infectious diseases, especially respiratory infections, have been significant threats to human health. Therefore, it is essential to develop rapid, portable, and highly sensitive diagnostic methods for their control. Herein, a short-time preamplified, one-pot clustered regularly interspaced short palindromic repeats (CRISPR) nucleic acid detection method (SPOC) is developed by combining the rapid recombinase polymerase amplification (RPA) with CRISPR-Cas12a to reduce the mutual interference and achieve facile and rapid molecular diagnosis. SPOC can reduce the detection time and stably detect up to 1 copy/μL of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA without affecting the detection sensitivity. A highly sensitive one-pot assay integrated with reverse transcription RPA is achieved by wrapping paraffin with a specific melting point on the lyophilized CRISPR reagent surface. A self-heating pack is designed based on thermodynamic principles to melt the paraffin and release CRISPR reagents, enabling low-cost and time-saving detection. Notably, the designed system, coupled with RNA extraction-free technology, can achieve "sample-in-answer-out" detection of the SARS-CoV-2 Orf1ab gene within 22 min using smartphone imaging. The developed assay is validated on 12 clinical samples, and the results 100% correlate with real-time polymerase chain reaction. SPOC is time-saving, is easy to operate, and can eliminate centrifugal and complex hardware devices, satisfying the demand for point-of-care diagnostics in resource-constrained settings.