Label-Free Separation of Circulating Tumor Cells and Clusters by Alternating Frequency Acoustic Field in a Microfluidic Chip

Abstract

Circulating tumor cells (CTCs) play an important role in the prognosis and efficacy evaluation of metastatic tumors. Since CTCs are present in very low concentrations in the blood and the phenotype is dynamically changing, it is a great challenge to achieve efficient separation while maintaining their viability. In this work, we designed an acoustofluidic microdevice for CTCs separation based on the differences in cell physical properties of size and compressibility. Efficient separation can be achieved with only one piece of piezoceramic working on alternating frequency mode. The separation principle was simulated by numerical calculation. Cancer cells from different tumor types were separated from peripheral blood mononuclear cells (PBMCs), with capture efficiency higher than 94% and a contamination rate of about 1% was obtained. Furthermore, this method was validated to have no negative effect on the viability of the separated cells. Finally, blood samples from patients with different cancer types and stages were tested, with measured concentrations of 36-166 CTCs per milliliter. Effective separation was achieved even when the size of CTCs is similar to that of PBMCs, which has the prospect of clinical application in cancer diagnosis and efficacy evaluation.

Design and Application of Microfluidic Capture Device for Physical–Magnetic Isolation of MCF-7 Circulating Tumor Cells

“…The physical methods include using the physical properties (such as their larger size, larger mass and different shape) of CTCs to isolate them [ 12 ]. These techniques include hydrodynamic flow focusing, entrapment using micro/nanostructures, dielectrophoresis (DEP) and acoustic isolation [ 13 , 14 , 15 ]. Immunological/bio-affinity methods involve utilizing the CTC membrane’s entities, such as molecules (such as the epithelial cell adhesion molecule (EpCAM)), proteins, receptors and antigens, to chemically interact with functionalized nanoparticles and chip surfaces to trap them [ 11 ].…”