Two-step acoustofluidic cancer cell enrichment

We have previously proposed and evaluated acoustophoresis for the enrichment of circulating tumor cells (CTC) and clusters thereof from the blood of patients with prostate cancer [1]. In that protocol, the cells were fixed and preserved in paraformaldehyde before processing and were thus non-viable. To enable future enrichment of also viable CTCs from patients, we have in this study investigated the ability to discriminate cancer cell line cells from sub-groups of viable white blood cells (WBC). We found that acoustophoresis alone has poorer performance for viable cells than for fixed cells. Therefore, we added a second step of acoustic gradient separation wherein cells migrate into a medium of increasing acoustic impedance. The resulting separation results in >80% of cancer cells reaching the target outlet while 99.8% of all WBCs are removed.