An ensemble of aptamers and antibodies for multivalent capture of cancer cells

Abstract

We developed an optimized ensemble of aptamers and antibodies that functions as a multivalent adhesive domain for the capture and isolation of cancer cells. When incorporated into a microfluidic device, the ensemble showed not only high capture efficiency, but also superior capture selectivity at a high shear stress (or high flow rate).

Fig. 1

Schematic showing an ensemble of antibodies and aptamers: multiple receptors on the cell membrane can bind strongly via cooperative, multivalent interactions to the channel surfaces immobilized with aptamers and antibodies. The drawing is not to scale.

Fig. 2

(a, b) Representative images of the target CEM cells (green) and control Ramos cells (red) captured using (a) an antibody–aptamer ensemble or (b) anti-PTK7 alone. The effects of antibody-to-aptamer ratio (c) and the flow rate (d) on the cell capture efficiency.

Fig. 3

Comparison of the antibody–aptamer ensemble with antibody or aptamer alone for cell capture: (a) capture efficiency of 10³ mL⁻¹ CEM cells (target) and 10⁶ mL⁻¹ Ramos cells (negative control) in PBS buffer; (b) capture purity under the same conditions. Error bars represent one standard deviation (n = 3).

Fig. 4

Calibration plot of cancer cell capture from whole blood and a buffer solution containing different cell concentrations (flow rate at 2.0 μL s⁻¹); solid lines represent linear fitting. Error bars represent one standard deviation (n = 3). The inset is a representative image of captured CEM cells (DiI+, DAPI+) from whole blood; the DAPI+ cells (blue only) are non-specifically captured white blood cells.