Size and shape based chromosome separation in the inertial focusing device.

In this paper, we use a spiral channel inertial focusing device for isolation and purification of chromosomes, which are highly asymmetric. The method developed is proposed as a sample preparation process for transchromosomic research. The proposed microfluidics-based chromosome separation approach enables rapid, label-free isolation of bioactive chromosomes and is compatible with chromosome buffer. As part of this work, particle force analysis during the separation process is performed utilizing mathematic models to estimate the expected behavior of chromosomes in the channel and the model validated with experiments employing fluorescent beads. The chromosome sample is further divided into subtypes utilizing fluorescent activated cell sorting , including small condensed chromosomes, single chromosomes, and groups of two chromosomes (four sister chromatids). The separation of chromosome subtypes is realized based on their shape differences in the spiral channel device under high flow rate conditions. When chromosomes become aligned in the shear flow, the balance between the inertial focusing force and the Dean flow drag force is determined by the chromosome projection area and aspect ratio, or shape difference, leading to different focusing locations in the channel. The achieved results indicate a new separation regime in inertial microfluidics that can be used for the separation of non-spherical particles based on particle aspect ratios, which could potentially be applied in fields such as bacteria subtype separation and chromosome karyotyping.