In this work, an integrated nucleic acid test, which includes cell lysing, nucleic acid extraction, amplification, and detection, was developed on a centrifugal platform. In the conventional approach, molecular diagnostic methods were often conducted manually by trained and experienced technicians and the task is usually labor-intensive and time-consuming. In addition, cross contamination often occurred during sample transferring between operations. Therefore, an integrated and automated nucleic acid testing system is desired.
In our platform, sample preparation procedures were integrated on a disk and the assay procedure were carried out by the coordination of the disk spinning control, microfluidic structures on the disk, and the magnetic module. Magnetic beads were used as the nucleic acid carriers and they were transported between various reagent reservoirs under a programmable spinning control. During the test, the cell sample was loaded into the disk and was lysed by the lysis buffer. The nucleic acid was released from the cell sample and was captured by the magnetic beads. To reduce the background signals, the magnetic beads were transferred through immiscible phases so that the unbounded materials were filtered at the immiscible interface. Then the magnetic beads were transferred to the elution buffer reservoir to elute the nucleic acid to the buffer. Then the nucleic acid was replicated by the recombinase polymerase amplification (RPA) process at a constant temperature.
To evaluate the performance of the nucleic acid test on the centrifugal platform, a commercial nucleic acid extraction kits was used and the test results between the two systems were compared. The test results from the centrifugal platform showed good consistency and is in good agreement with the commercial kit.