DNA‐Mediated Stabilization of Self‐Assembling Bead Monolayers for Microfluidic Applications

Abstract

Forming ordered 2D or 3D arrays of colloidal particles on the micro‐ or nanometer scale in a bottom‐up process is a challenging task. In previous works by various groups, hybridization between DNA strands localized on the particle surface is used to create crystalline arrays. However, this method requires an annealing process with a duration of one day or more and usually yields agglomerates of only a few dozen particles. In this work, a method for the rapid formation of highly‐ordered 2D agglomerates of superparamagnetic microparticles (beads) is presented. Dipolar coupling between the beads under the influence of a rotating magnetic field leads to the formation of a dense monolayer. The monolayer is then stabilized through DNA hybridization between DNA strands immobilized on the bead surface and a linker strand in solution. The whole self‐assembly process requires less than an hour and is therefore significantly faster than comparable methods.

A review on self-assembly in microfluidic devices

“…Surfactants can, at one hand, lower interfacial tension to lower droplet formation energy; and on the other hand, self-assemble at the interface to stabilize it. Nanoparticles [13] and biomolecules with similar properties, like peptides [40] and DNAs [41], could also self-assemble to functional structures at interfaces. Figure 3(B) showed the competitive adsorption of cholic acid (CA) at the droplet interface of aqueous solution and the sodium dodecyl sulfate (SDS)-laden 4-cyano-4′-penthlbiphenyl (5CB) [42].…”

“…Different from the self-assembly in bulk solution or macroscale system, the precise controlling in a microfluidic device is not only in microstructures, but also in fluidic flow; therefore, railing and guiding objects to specific directions could be realized. Structures formed by self-assembled proteins [45], peptide microparticles [40], Janus particles [46], magnetic microbeads [41,47,48] or cell aggregates [49] have been obtained by using microfluidic induced assembly process, which can be potentially applied in various fields, such as catalyst, sensors, displays and drug delivery.…”

“…Chains/clusters of magnetic microbeads. Magnetic microbeads were reported to self-assemble into chains or clusters in microfluidic medium induced by magnetic fields [41]. These assembled structures increased the active contact between analysts and magnetic beads; and therefore being beneficial for sensing applications.…”