Rapid and Serial Quantification of Adhesion Forces of Yeast and Mammalian Cells

Abstract

Cell adhesion to surfaces represents the basis for niche colonization and survival. Here we establish serial quantification of adhesion forces of different cell types using a single probe. The pace of single-cell force-spectroscopy was accelerated to up to 200 yeast and 20 mammalian cells per probe when replacing the conventional cell trapping cantilever chemistry of atomic force microscopy by underpressure immobilization with fluidic force microscopy (FluidFM). In consequence, statistically relevant data could be recorded in a rapid manner, the spectrum of examinable cells was enlarged, and the cell physiology preserved until approached for force spectroscopy. Adhesion forces of Candida albicans increased from below 4 up to 16 nN at 37°C on hydrophobic surfaces, whereas a Δhgc1-mutant showed forces consistently below 4 nN. Monitoring adhesion of mammalian cells revealed mean adhesion forces of 600 nN of HeLa cells on fibronectin and were one order of magnitude higher than those observed for HEK cells.

Isolation of Optically Targeted Single Bacteria by Application of Fluidic Force Microscopy to Aerobic Anoxygenic Phototrophs from the Phyllosphere

“…To explore and establish FluidFM for single-bacterium isolation, different parameters were tested and optimized to ensure efficient isolation of a wide range of randomly chosen bacteria from environmental samples. Cantilevers with an aperture diameter of 8 m were used; however, instead of cantilevers with a default channel height of 1 m, as used in previous studies (36,37,51), cantilevers with a channel height of only 0.5 m were used, because they ensured that the targeted bacteria remained confined at the aperture, where they could be easily spotted, and were not sucked into the channel of the probe. Plasma cleaning and coating the cantilever with PLL-g-PEG reduced the chance that a bacterium would irreversibly bind to the cantilever (38).…”

“…FluidFM experiments were carried out using the FluidFM system, which consists of an AFM head, a hollow cantilever, a drilled probe holder, and a pressure controller (Cytosurge AG, Zurich, Switzerland, and Nanosurf AG, Liestal, Switzerland) as described by Potthoff et al (37). The tipless hollow cantilevers (Cytosurge AG, Zurich, Switzerland) were made of silicon nitride (channel dimensions: length, 150 m; height, 0.5 m; width, 24 m; diameter of circular aperture, 8 m).…”

“…The tipless hollow cantilevers (Cytosurge AG, Zurich, Switzerland) were made of silicon nitride (channel dimensions: length, 150 m; height, 0.5 m; width, 24 m; diameter of circular aperture, 8 m). The cantilever was subjected to plasma cleaning (plasma cleaner PDC-32G; Harrick Plasma, Ithaca, NY) for 2 min prior to use and were subsequently coated with 0.1 mg/ml of the grafter copolymer poly(L-lysine)-g-poly(ethylene glycol) [PLL (20)g(3.5)-PEG(2)] (Surface Solutions, Zurich, Switzerland) in 100 mM phosphate buffer for 1 h, as described previously (37,38).…”

Adhesion kinetics of human primary monocytes, dendritic cells, and macrophages: Dynamic cell adhesion measurements with a label-free optical biosensor and their comparison with end-point assays

“…When it comes to measuring the kinetics of cell adhesion, nor the techniques based on direct measurements of the adhesion force (e.g., variants of atomic force microscopy, 31,32 automated micropipette, 24 and traction force microscopy 33,34 ), neither optical microscopy for the visualization of cells or their adhesion-associated molecular structures (e.g., wide-field, confocal, total internal reflection microscopies 35 ) can compete with cell-based label-free biosensors which enable the high temporal-resolution monitoring of the activity of surface-adhered cells. Evanescent field-based optical biosensors, including surface plasmon resonance (SPR), 36,37 optical waveguide lightmode spectroscopy (OWLS), 28,[38][39][40] photonic crystal biosensors, 41 grating coupling interferometry, 42,43 and resonant waveguide grating (commonly recognized as Epic) 44,45 biosensors, are considered to be especially straightforward means to monitor surface adhesion.…”

Microencapsulation of Baker’s Yeast in Gellan Gum Beads Used in Repeated Cycles of Glucose Fermentation

“…This type of yeast was selected due to the fact that it represents a cell biomass of the top fermenting yeast and is composed of living cells capable of producing fermentation of sugars without requiring a culture medium. These cells absorb the easiest hexoses (glucose) and then sucrose and maltose [43][44][45][46][47]. Glucose monohydrate was supplied by S.C. Chemical Company S.A., Ias,i, Romania.…”