A modular atomic force microscopy approach reveals a large range of hydrophobic adhesion forces among bacterial members of the leaf microbiota

Mittelviefhaus, Maximilian; Müller, Daniel B.; Zambelli, Tomaso; Vorholt, Julia A.

doi:10.1038/s41396-019-0404-1

Cited by 35 publications

(40 citation statements)

References 31 publications

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“…These findings are in agreement with those of previous studies [46,47]. Surface hydrophobicity can promote irreversible bacterial adhesion [48]. Although the presence of surface grooves increases the surface area for bacterial adhesion, the increase of hydrophilicity due to the presence of grooves likely reduced bacterial adhesion [49].…”

Section: Discussionsupporting

confidence: 92%

Biofunctionalization of Microgroove Surfaces with Antibacterial Nanocoatings

Lai¹,

Chen

et al. 2020

BioMed Research International

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Objectives. To investigate the physical properties of the modified microgroove (MG) and antibacterial nanocoated surfaces. In addition, the biological interactions of the modified surfaces with human gingival fibroblasts (HGFs) and the antibacterial activity of the surfaces against Porphyromonas gingivalis were studied. Methods. The titanium nitride (TiN) and silver (Ag) coatings were deposited onto the smooth and MG surfaces using magnetron sputtering. A smooth titanium surface (Ti-S) was used as the control. The physicochemical properties including surface morphology, roughness, and hydrophilicity were characterized using scanning electron microscopy, atomic force microscopy, and an optical contact angle analyzer. The “contact guidance” morphology was assessed using confocal laser scanning microscopy. Cell proliferation was analyzed using the Cell Counting Kit-8 assay. The expression level of the main focal adhesion-related structural protein vinculin was compared using quantitative reverse transcription PCR and Western blotting. The antibacterial activity against P. gingivalis was evaluated using the LIVE/DEAD BacLight™ Bacterial Viability Kit. Results. The Ag and TiN antibacterial nanocoatings were successfully deposited onto the smooth and MG surfaces using magnetron sputtering technology. TiN coating on a grooved surface (TiN-MG) resulted in less nanoroughness and greater surface hydrophilicity than Ag coating on a smooth surface (Ag-S), which was more hydrophobic. Cell proliferation and expression of vinculin were higher on the TiN-MG surface than on the Ag-coated surfaces. Ag-coated surfaces showed the strongest antibacterial activity, followed by TiN-coated surfaces. Conclusion. Nano-Ag coating resulted in good antimicrobial activity; however, the biocompatibility was questionable. TiN nanocoating on an MG surface showed antibacterial properties with an optimal biocompatibility and maintained the “contact guidance” effects for HGFs.

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Section: Discussionsupporting

confidence: 92%

Biofunctionalization of Microgroove Surfaces with Antibacterial Nanocoatings

Lai¹,

Chen

et al. 2020

BioMed Research International

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“…The FluidFM has been used to study the elasticity and adhesion of several cell types [15][16][17][18]. Studies addressing specifically the adhesion of bacterial cells include the work of Potthoff et al [19], Sprecher et al [20] and Mittelviefhaus et al [21]. Potthoff et al further showed that bacteria still divided after SCFS measurements using the FluidFM and thus had survived the measurement.…”

Section: Introductionmentioning

confidence: 99%

FluidFM as a tool to study adhesion forces of bacteria - Optimization of parameters and comparison to conventional bacterial probe Scanning Force Spectroscopy

2020

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The FluidFM enables the immobilization of single cells on a hollow cantilever using relative underpressure. In this study, we systematically optimize versatile measurement parameters (setpoint, z-speed, z-length, pause time, and relative underpressure) to improve the quality of force-distance curves recorded with a FluidFM. Using single bacterial cells (here the gram negative seawater bacterium Paracoccus seriniphilus and the gram positive bacterium Lactococcus lactis), we show that Single Cell Force Spectroscopy experiments with the FluidFM lead to comparable results to a conventional Single Cell Force Spectroscopy approach using polydopamine for chemical fixation of a bacterial cell on a tipless cantilever. Even for the bacterium Lactococcus lactis, which is difficult to immobilze chemically (like seen in an earlier study), immobilization and the measurement of force-distance curves are possible by using the FluidFM technology.

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“…More than 700 FD-curves were recorded, the highest force values are around 50 nN of the members from Gammaproteobacteria.The nominal spring constant value for micropipette cantilevers was used as 0.2 Nm −1 . InvOLS was recalibrated after each bead exchange, but exact values are not given. 33 Force evaluation of different particle sizes grabbed by FluidFM micropipette and nanopipette cantilevers. Silica particles with diameters of 0.5 µm, 1 µm and 4.3 µm were used.The nominal spring constant values were used for micropipette (0.3 and 2 Nm −1 ) and nanopipette (0.6 Nm −1 ) cantilevers.…”

Section: Introductionmentioning

confidence: 99%

Spring constant and sensitivity calibration of FluidFM micropipette cantilevers for force spectroscopy measurements

Nagy

Kámán

Horváth

et al. 2019

Sci Rep

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The fluidic force microscope (FluidFM) can be considered as the nanofluidic extension of the atomic force microscope (AFM). This novel instrument facilitates the experimental procedure and data acquisition of force spectroscopy (FS) and is also used for the determination of single-cell adhesion forces (SCFS) and elasticity. FluidFM uses special probes with an integrated nanochannel inside the cantilevers supported by parallel rows of pillars. However, little is known about how the properties of these hollow cantilevers affect the most important parameters which directly scale the obtained spectroscopic data: the inverse optical lever sensitivity (InvOLS) and the spring constant ( k ). The precise determination of these parameters during calibration is essential in order to gain reliable, comparable and consistent results with SCFS. Demonstrated by our literature survey, the standard error of previously published SCFS results obtained with FluidFM ranges from 11.8% to 50%. The question arises whether this can be accounted for biological diversity or may be the consequence of improper calibration. Thus the aim of our work was to investigate the calibration accuracy of these parameters and their dependence on: (1) the aperture size (2, 4 and 8 µm) of the hollow micropipette type cantilever; (2) the position of the laser spot on the back of the cantilever; (3) the substrate used for calibration (silicon or polystyrene). It was found that both the obtained InvOLS and spring constant values depend significantly on the position of the laser spot. Apart from the theoretically expectable monotonous increase in InvOLS (from the tip to the base of the cantilever, as functions of the laser spot’s position), we discerned a well-defined and reproducible fluctuation, which can be as high as ±30%, regardless of the used aperture size or substrate. The calibration of spring constant also showed an error in the range of −13/+20%, measured at the first 40 µm of the cantilever. Based on our results a calibration strategy is proposed and the optimal laser position which yields the most reliable spring constant values was determined and found to be on the first pair of pillars. Our proposed method helps in reducing the error introduced via improper calibration and thus increases the reliability of subsequent cell adhesion force or elasticity measurements with FluidFM.

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A modular atomic force microscopy approach reveals a large range of hydrophobic adhesion forces among bacterial members of the leaf microbiota

Cited by 35 publications

References 31 publications

Biofunctionalization of Microgroove Surfaces with Antibacterial Nanocoatings

Biofunctionalization of Microgroove Surfaces with Antibacterial Nanocoatings

FluidFM as a tool to study adhesion forces of bacteria - Optimization of parameters and comparison to conventional bacterial probe Scanning Force Spectroscopy

Spring constant and sensitivity calibration of FluidFM micropipette cantilevers for force spectroscopy measurements

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