High-throughput microfluidic chip for magnetic enrichment and photothermal DNA extraction of foodborne bacteria

We have developed a high-throughput pretreatment microfluidic chip for enrichment of microorganisms in food using magnetic particles and extracting DNAs using photothermal effects of magnetic particles. Magnetic particles modified with Concanavalin A can capture a variety of pathogens in the sample. As magnetic particles and bacteria injected into the microfluidic chip at a high flow rate, they bound actively in the mixing channel. After passing through the mixing channel, the combined bacteria and magnetic particles complexes were captured and enriched by magnetic force at the chambers which rectangular neodymium magnets were assembled in the form of dozens of arrays. After the magnet arrays were removed, the elution buffer was injected at a slightly lower flow rate and the eluted particles were captured in a small lysis chamber. The laser with a wavelength of 532 nm was irradiated at the lysis chamber to dissolve the captured bacteria as strong heat generated by the photothermal effects of the magnetic particles. Finally, the extracted DNAs were detected by real-time PCR.