Continuous‐flow separation of nanoparticles by electrostatic sieving at a micro‐nanofluidic interface

Abstract

Continuous-flow separation of nanoparticles (NPs) (15 and 39 nm) is demonstrated based on electrostatic sieving at a micro-nanofluidic interface. The interface is realized in a poly(dimethylsiloxane) device with a nanoslit of 525 nm laterally spanning the microfluidic channel (aspect ratio of 540:1). Within this nanoslit, the Debye layers overlap and generate an electrostatic sieve. This was exploited to selectively deflect and sort NPs with a sorting purity of up to 97%. Because of the continuous-flow operation, the sample is continuously fed into the device, immediately separated, and the parameters can be adapted in real time. For bioanalytical purposes, we also demonstrate the deflection of proteins (longest axis 6.8 nm). The continuous operation mode and the general applicability of this separation concept make this method a valuable addition to the current Lab-on-a-Chip devices for continuous sorting of NPs and macromolecules.

Fundamental Studies of Nanofluidics: Nanopores, Nanochannels, and Nanopipets

“…A sieving structure composed of a nanoslit formed between a bowed ridge and a coverslip is used for fast and continuous separation of nanoparticles 217 and DNA complexes. 218 Small analyte molecules pass through the nanoslit unhindered, whereas larger molecules are trapped at the ridge and must find alternative pathways.…”

Nanofluidic devices for dielectrophoretic mobility shift assays by soft lithography

“…This is equivalent to larger polarizabilities of the DNA-complexes, also shown in [29]. Although manipulation and separation by dielectrophoresis of cells or DNA was presented earlier [7,25,26], only the miniaturization toward nanoslits allowed determination between pure DNA and DNA-complexes as demonstrated with the DEMSA. In figure 5, the corresponding EMSA experiments are depicted.…”

Permeability and selectivity analysis for affinity‐based nanoparticle separation through nanochannels

“…Figure 5B shows that the permeability decreases with decreasing W. This finding is generally consistent with the electrostatic sieving of nanoparticles. 61 The decrease in W with a constant W 0 lowers the cross-sectional area available for diffusion and, consequently, the permeability. Consistent with Figure 4B,…”