Enhanced cancer cell sorting using lab-on-a-disk pattern design with magnetic and centrifugal forces

Abstract

Using microfluidic flow for biological detection is a non-invasive method that can replace traditional invasive testing methods to achieve fast and accurate results. The design of the detection device and lab-on-a-disk (LoaD) can impact performance in accurately identifying biological features. Therefore, we created a novel device to extract cancer cells from a heterogeneous cell population by centrifugal-force-driven microfluidic flow and magnetic labeling. Two-stage centrifugal force and a specially designed LoaD were used to drive microfluidic flow and control its movement to designated areas. The purpose was to allow the CD44 antibody-magnetic bead complex (CD44 beads), which specifically binds to the abundantly present CD44 receptors on identifiable cancer cells, to flow into the reservoir well, while the biological mixture containing the cancer cells is retained in the capture well. Fluorescence imaging as well as flow cytometric analysis revealed the successful retention of the microbead-bound cancer cells in the magnetic area, while the remaining biological mixture was retained in the reservoir area. The entire separation process took less than 2 h.

Keywords: cell sorting; lab-on-a-disk; microfluidic flow; non-invasive method; rapid detection.

FIGURE 1

(a) DC motor system. (b) Servomotor system.

FIGURE 2

Pattern design of the LoaD (Lin Y. T. et al., 2021).

FIGURE 3

Inverted fluorescence microscopy. A. light source; B. condenser lens; C. eyepiece; D. observation sample; E. objective lens; F. imaging lens.

FIGURE 4

Stability test of the LoaD at higher rotational speed. The LoaD was mounted onto a motor shaft driven by either (a) a DC motor or (b) a servomotor at a designated speed for 30 s.

FIGURE 5

Stability test of LoaD at lower rotational speed. The LoaD was allowed to rotate on a motor shaft driven by either (a) a DC motor or (b) a servomotor at a designated speed for 30 s.

FIGURE 6

Performance of microfluidic flow in the pattern of the LoaD. (a) Coomassie Brilliant Blue R-250 of microfluids in the buffer well. (b) Microfluid flow to the reaction area from the buffer well by the first rotating mode of the centrifugal device. (c) Microfluid flow to the reservoir area from the reaction area by the second rotating mode of the centrifugal device.

FIGURE 7

Purification of human breast cancer cells MDA-MB-231 from a cell mixture. The day before the purification experiment, HEK293 cells were stained with Mitotracker Green, and MDA-MB-231 cells were stained with Mitotracker Red. (a–f) A total of 2 × 10⁴ cells that consisted of specified ratios of HEK293 cells and MDA-MB-231 cells were mixed in the same cell culture media at the final volume 120 µL. After the centrifugation steps, fluorescence images of the cells retained at either the reservoir area or the capture well were taken (scale bar, 100 µm). Subsequently, cells were removed and subjected to flow cytometric analysis. The number of Mitotracker Green stained HEK293 cells (green) and Mitotracker Red stained MDA-MB-231 cells (red) detected in either the reservoir area or the capture well (N = 4).