Single-cell adhesion force kinetics of cell populations from combined label-free optical biosensor and robotic fluidic force microscopy

Abstract

Single-cell adhesion force plays a crucial role in biological sciences, however its in-depth investigation is hindered by the extremely low throughput and the lack of temporal resolution of present techniques. While atomic force microcopy (AFM) based methods are capable of directly measuring the detachment force values between individual cells and a substrate, their throughput is limited to few cells per day, and cannot provide the kinetic evaluation of the adhesion force over the timescale of several hours. In this study a high spatial and temporal resolution resonant waveguide grating based label-free optical biosensor was combined with robotic fluidic force microscopy to monitor the adhesion of living cancer cells. In contrast to traditional fluidic force microscopy methods with a manipulation range in the order of 300-400 micrometers, the robotic device employed here can address single cells over mm-cm scale areas. This feature significantly increased measurement throughput, and opened the way to combine the technology with the employed microplate-based, large area biosensor. After calibrating the biosensor signals with the direct force measuring technology on 30 individual cells, the kinetic evaluation of the adhesion force and energy of large cell populations was performed for the first time. We concluded that the distribution of the single-cell adhesion force and energy can be fitted by lognormal functions as cells are spreading on the surface and revealed the dynamic changes in these distributions. The present methodology opens the way for the quantitative assessment of the kinetics of single-cell adhesion force and energy with an unprecedented throughput and time resolution, in a completely non-invasive manner.

Glycocalyx regulates the strength and kinetics of cancer cell adhesion revealed by biophysical models based on high resolution label-free optical data

“…Importantly, cell adhesion motifs displaying engineered surfaces with tunable biological properties have opened the way to control cell adhesion in both basic and application oriented researches 5 , 11 – 15 . Especially, in surface sensitive biosensors these synthetic coatings were found to be useful for controlling cell adhesion in a straightforward manner and to monitor cellular changes due to external stimuli 5 , 11 , 16 – 20 . Cells encounter surrounding surfaces first through their glycocalyx and therefore it may substantially contribute to crucial physiological and pathophysiological processes.…”

“…Cell adhesion can be well characterized by the force received by separating the cell from the substrate or from another cell 16 , 36 . However, force measuring technologies are typically low throughput methods 16 , 36 , 37 . Geometrically, cell adhesion on a flat surface is the transformation of a cell from a spherical object to a flattened, adherent form by maintaining the volume.…”

“…Contrarily, the resonance waveguide grating (RWG) technology 5 , 18 , 39 , 43 – 46 is available as a high-throughput device with outstanding surface sensitivity and time resolution. Importantly, this technology can measure even single cells and its signal was recently calibrated to adhesion force using fluidic force microscopy 16 . Membrane movements and cell mass redistributions at the nanometer scale are perfectly detectable by the RWG technology 5 , 44 .…”

Grating-coupled interferometry reveals binding kinetics and affinities of Ni ions to genetically engineered protein layers

“…In the last few decades, label-free optical biosensors have proven their unique capabilities in a wide range of applications from biomolecular interaction analysis (BIA) [1][2][3][4] to whole-cell monitoring [5][6][7][8][9] . Screening the interactions of various analyte-ligand pairs has become essential in drug discovery [10][11][12][13] , assay and sensor development 14,15 as well as for understanding molecular mechanisms in biochemistry and biophysics [16][17][18][19] .…”

Human primary endothelial label-free biochip assay reveals unpredicted functions of plasma serine proteases

“…The detection is typically limited to a probing depth of ~150 nm due to the exponentially decaying electromagnetic evanescent field of the sensing waveguide mode 3,4 . The technology is commercially available and was successfully employed previously to monitor the kinetics of cell-surface and cell membrane receptor-ligand interactions 3,[5][6][7] , binding affinity 8 , cellular signaling 9,10 , cytotoxicity 11 , nanoparticles 12 and the functional state of surface-adhered cells down to the single cell level 13 . The output of the sensor is an integrated signal of dynamic mass redistribution (DMR) taking place in the sensing depth above the bottom of each well 14 .…”