Novel Application of Nanofluidic Chip Digital PCR for Detection of African Swine Fever Virus

African swine fever virus (ASFV) gives rise to a grievous transboundary and infectious disease, African swine fever (ASF), which has caused a great economic loss in the swine industry. To prevent and control ASF, once suspicious symptoms have presented, the movement of animal and pork products should be stopped, and then, laboratory testing should be adopted to diagnose ASF. A method for ASFV DNA quantification is presented in this research, which utilizes the next-generation PCR platform, nanofluidic chip digital PCR (cdPCR). The cdPCR detection showed good linearity and repeatability. The limit of detection for cdPCR is 30.1995 copies per reaction, whereas no non-specific amplification curve was found with other swine viruses. In the detection of 69 clinical samples, the cdPCR showed significant consistency [91.30% (63/69)] to the Office International des Epizooties-approved quantitative PCR. Compared with the commercial quantitative PCR kit, the sensitivity of the cdPCR assay was 86.27% (44/50), and the specificity was 94.44% (17/18). The positive coincidence rate of the cdPCR assay was 88% (44/50). The total coincidence rate of the cdPCR and kit was 89.86% (62/69), and the kappa value reached 0.800 (P < 0.0001). This is the first time that cdPCR has been applied to detecting ASFV successfully.

Nanofluidic devices prepared by an atomic force microscopy-based single-scratch approach

A nanofluidic chip was prepared based on a commercial AFM system. Effects on ion transport and enzymatic reaction specificity were demonstrated.

Alignment System and Application for a Micro/Nanofluidic Chip

In this paper, a direct pre-bonding technology after alignment of the chip is presented to avoid the post-misalignment problem caused by the transferring process from an alignment platform to a heating oven. An alignment system with a high integration level including a microscope device, a vacuum device, and an alignment device is investigated. To align the chip, a method of ‘fixing a chip with microchannels and moving a chip with nanochannels’ is adopted based on the alignment system. With the alignment system and the assembly method, the micro/nanofluidic chip was manufactured with little time and low cost. Furthermore, to verify the performance of the chip and then confirm the practicability of the device, an ion enrichment experiment is carried out. The results demonstrate that the concentration of fluorescein isothiocyanate (FITC) reaches an enrichment value of around 5 μM and the highest enrichment factor is about 500-fold. Compared with other devices, an alignment system presented in this paper has the advantages of direct pre-bonding and high integration level.