Simultaneous amplification of DNA in a multiplex circular array shaped continuous flow PCR microfluidic chip for...

Based on time to place conversion, continuous flow polymerase chain reaction (CF-PCR) can realize a rapid amplification of DNA by running the PCR reagent in a serpentine microchannel but a larger space is required for each sample, which greatly reduces the efficiency of the CF-PCR. Herein, we propose a multiplex circular array shaped CF-PCR microfluidic chip for on-site detection of bacteria. There were 12 serpentine microchannels which were distributed on the disc in an annular form, and each microchannel consisted of an inlet for sample injection, and an outlet for the detection of the PCR products based on fluorescence. Samples could be simultaneously driven into each inlet by a one-to-twelve diverter through a syringe. Moreover, the method of adding fluorescent dyes at the end of the microchannel can solve the inhibition effect of excessive fluorescent dyes on the PCR reaction. The process finished with simultaneous amplification of 12 different target genes from Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Escherichia coli, and on-site detection of their corresponding positives within 23 min. The fastest detectable PCR reaction time was 5.38 ± 0.2 min at a flow rate of 1 mL h^-1. For E. coli, the minimum detectable concentration was 2.5 × 10^-3 ng μL^-1 in this microfluidic system. Such a system can increase the throughput of CF-PCR for point-of-care testing of pathogens.