High-Throughput Generation, Manipulation, and Degradation of Magnetic Nanoparticle-Laden Alginate Core-Shell Beads...

Microbes could be found almost everywhere around us and have significant impacts on our human society. The treatment of microorganisms has long been seen as a complex problem. Till now, most of the genetic and phenotypic information regarding rare species is buried in the bulk microbial colony due to a lack of efficient tools to screen live bacteria. Droplet microfluidics offers a powerful approach to address this problem. However, the interactions among bacteria and their living environment are entirely restricted by the water/oil interfaces in conventional water/oil single emulsion-based microfluidic systems. Here, we demonstrate an oil-mediated all-aqueous microfluidic workflow that can overcome this drawback. In contrast to the previous works, our all-aqueous culturing environment allows cell-cell and cell-environment interactions, thus facilitating the growth of bacteria. Fe₃O₄ magnetic nanoparticles added into the alginate beads enables on-chip manipulation of the microcapsules. The core-shell structure separately encapsulates bacteria and magnetic particles in the core and shell to avoid contamination. We demonstrate the feasibility of this approach by single bacterium culturing in droplet-templated alginate beads. Finally, a new approach is proposed to degrade the alginate beads for post-treatment. This novel microfluidic workflow can create new opportunities for microbial applications, such as bacteria culturing and screening.