Nanonewton scale adhesion force measurements on biotinylated microbeads with a robotic micropipette

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:602

Article

Ungai-Salanki, Rita^1,2  Csippa, Benjamin³  Gerecsei, Tamas^1,4  Peter, Beatrix⁴  Horvath, Robert⁴  Szabo, Balint^1,2 

[1] Eotvos Lorand Univ, Dept Biol Phys, Budapest, Hungary

[2] CellSorter Co Innovat, Erdoalja Ut 174, H-1037 Budapest, Hungary

[3] Budapest Univ Technol & Econ, Dept Hydrodynam Syst, Budapest, Hungary

[4] ELKH, Inst Tech Phys & Mat Sci, Nanobiosensor Lab, Ctr Energy Res, Budapest, Hungary

关键词: Adhesion force;    Binding force;    Microbead;    Micropipette;    Computational fluid dynamics;   

DOI  :  10.1016/j.jcis.2021.05.180

来源: Elsevier

【 摘 要 】

Binding force between biomolecules has a crucial role in most biological processes. Receptor-ligand interactions transmit physical forces and signals simultaneously. Previously, we employed a robotic micropipette both in live cell and microbead adhesion studies to explore the adhesion force of biomolecules such as cell surface receptors including specific integrins on immune cells. Here we apply standard computational fluid dynamics simulations to reveal the detailed physical background of the flow generated by the micropipette when probing microbead adhesion on functionalized surfaces. Measuring the aspiration pressure needed to pick up the biotinylated 10 um beads on avidin coated surfaces and converting it to a hydrodynamic lifting force on the basis of simulations, we found an unbinding force of 12 +/- 2 nN, when targeting the beads manually; robotic targeting resulted in 9 +/- 4 nN (mean +/- SD). We measured and simulated the effect of the targeting offset, when the microbead was out of the axis (off-axis)of the micropipette. According to the simulations, the higher offset resulted in a higher lifting force acting on the bead. Considering this effect, we could readily correct the impact of the targeting offset to renormalize the experimental data. Horizontal force and torque also appeared in simulations in case of a targeting offset. Surprisingly, simulations show that the lifting force acting on the bead reaches a maximum at a flow rate of similar to 5 mu l/s if the targeting offset is not very high (<5 mu m). Further increasing the flow rate decreases the lifting force. We attribute this effect to the spherical geometry of the bead. We predict that higher flow rates cannot increase the hydrodynamic lifting force acting on the precisely targeted microbead, setting a fundamental force limit (16 nN in our setup) for manipulating microbeads with a micropipette perpendicular to the supporting surface. In order to extend the force range, we propose the offset targeting of microbeads. (C) 2021 The Author(s). Published by Elsevier Inc.

【 授权许可】

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