Magnetic-Particle-Encapsulated Alginate Beads for Aqueous-Based Bacteria Culturing and Manipulation

Active sorting of bacteria has shown great potential in revealing the huge biodiversity of various microbial communities. Droplet microfluidics offer a powerful tool for bacteria culturing and sorting. However, most traditional sorting methods fail to work in all-aqueous droplet microfluidic systems, due to the similar dielectric constants between aqueous solutions. This drawback hinders the application of droplet microfluidic in bacteria screening. Magnetic manipulation is a good candidate to overcome this hurdle, since it can provide relatively long-range, non-contact force regardless of the dielectric properties of the solutions. In this article, Fe
₃
O
₄
magnetic nanoparticles (Fe
₃
O
₄
MNPs) encapsulated alginate beads containing bacteria were generated. The capsules can be manipulated using an external magnetic field, making it possible for effective sorting after culturing. The generation of the alginate capsules under different conditions was systematically studied. The experiments showed that the bacteria-laden capsules can be manipulated using magnetic field. Bacteria culturing demonstrated that bacteria can be raised inside the alginate beads, verifying the feasibility of the proposed technique.