A novel cartridge for nucleic acid extraction, amplification and detection of infectious disease pathogens with the help of magnetic nanoparticles

Nucleic acid detection (NAD) based on real-time polymerase chain reaction (real-time PCR) is gold standard for infectious disease detection. Magnetic nanoparticles (MNPs) are widely used for nucleic acid extraction (NAE) because of their excellent properties. Microfluidic technology makes automated NAD possible. However, most of the NAD microfluidic chips are too complex to be applied to point-of-care (POC) testing. In this paper, a simple-structure cartridge was developed for POC detection of infectious diseases. This self-contained cartridge can be divided into a magnetic-controlled NAE part, a valve-piston combined fluidic control part and a PCR chip, which is able to extract nucleic acid from up to 500 µL of liquid samples by MNPs and finish the detection process from "sample in" to "answer out" automatically. Performance tests of the cartridges show that it met the demands of automated NAD. Results of on-cartridge detection of hepatitis B virus (HBV) demonstrated that this system has good uniformity and no cross-contamination between different cartridges, and the limit of detection (LOD) of this system for HBV in serum is 50 IU/mL. Multiplex detections of severe acute respiratory syndrome coronaviruses 2 (SARS-CoV-2) with a concentration of 500 copies/mL were carried out on the system and 100% positive detection rate was achieved.