Figure 1.

Principle of Centrifugation-assisted Immiscible Fluid Filtration (CIFF). (A) CIFF comprises of two immiscible liquid phases, an aqueous phase (d: 1 g/mL) and a hydrophobic phase that is denser than the aqueous phase (FC-3283 fluorinated oil, d: 1.82 g/mL) underlying the bottom of the aqueous sample. Functionalized glass microbeads (d: 2.48 g/mL) are mixed with the aqueous sample to bind analytes of interest, then loaded into a reservoir (here we used a 0.2 mL PCR tube for demonstration). Due to the hydrophilicity of the glass microbeads, they remain trapped inside the aqueous phase even after vigorous mixing (B). Under centrifugation however, the increased centrifugal force allows the glass microbeads to overcome the lipophobic resistance between the glass beads and oil phase and partition according to their density into the bottom oil phase, which effectively removes non-target molecules behind in the aqueous phase (C). (D) Parallel CIFF processes can be performed using conventional multi-well PCR plates.