Versatility and performance for biology and life science

For success in life science research, scientists depend on professional tools that can readily provide the information needed, regardless of the tasks at hand. By combining key technologies and components, Nanosurf has made the FlexAFM system one of the most versatile and flexible AFM systems ever, allowing a large variety of biological and life science applications to be handled with ease. With the FlexAFM, you can combine the liquid AFM imaging, spectroscopy and nanomanipulation capacity of this system with the high-end optical techniques available for inverted microscopes.

Flexible system design for life science research

FlexAFM comes with manual and motorized stages for seamless integration on Zeiss, Olympus, Nikon and Leica inverted microscopes or with standalone stages. On the inverted microscope, optical and AFM data can be correlated, as shown here for internal limiting membrane (ILM) of the human retina.

The modular stage, cantilever holder, and software concept allows an easy upgrade of the system to access many new possibilities in life science and materials research. Flex-FPM for cell and nano-manipulation, for example, and Flex-ANA for automatic nanomechanical analysis. In addition, advanced modes like MFM and KPFM that were originally developed for the Flex-Axiom system, are also available for FlexAFM. For measurements that don’t need optical access from below, e.g. for the imaging and spectroscopy of samples like bacteriorhodopsin, a standalone stage makes the FlexAFM compatible with the Nanosurf Isostage and Acoustic Enclosure 300, and generally makes the system much more compact.

FlexAFM lifescience application examples

Imaging of type I collagen fibrils

Collagen is the most abundant protein in mammals and contributes to more than 25% of the whole-body protein content. It is the main structural protein of the extracellular matrix of connective tissues and provides e.g. tendons and bone with their tensile strength. Most of the collagen found in mammals is fibrillar type I collagen. Type I collagen fibrils show a typical periodic morphology, the so-called D-banding. D-bands result from staggered self-assembly of individual collagen molecules into larger fibrils with a periodicity of about 67 nm. Images of collagen fibrils from rat tendon were recorded in Prof. Snedeker’s research group at the ETH Zürich. One of the reasearch areas of Prof. Snedeker is tendon mechanics and biology.

The 3D representation of the AFM topography image nicely shows the typical periodic D-banding of type I collagen on all fibrils. The colloagen topography was recorded in static mode using a Nanosensors PPP-XYCONTR cantilever. AFM images were processed using Nanosurf Report Software. Preparation and imaging of collagen fibrils was performed by Massimo Bagnani, Prof. Snedeker research group, Uniklinik Balgrist, Institute for Biomechanics, ETH Zürich, Switzerland.

Measurements on living cultured cells

Mechanobiology is an emerging research area that deals with the effect of changing physical forces or changes in the mechanical properties of cells and tissues. Several diseases, such as fibrosis and atherosclerosis are associated with changes in tissue stiffness. Moreover, in cancer, the metastatic potential of cancer cells depends on their elastic modulus. Here, the elastic modulus of living cells from a human breast basal epithelial cell line was measured using a Nanosurf FlexAFM system with the Flex-ANA software.

The first image shows the elastic modulus (in kPa) recorded on living breast epithelial cells immersed in cell culture medium. Differences in the elastic modulus within the cell can be clearly observed. The dark area surrounding the cells originate from the much stiffer cell culture dish substrate. The second image shows the unperturbed cell topography extracted from the force mapping data. The topography is determined from the contact point of each force curve and thus shows the cell topography at zero applied force.

Mapping the elastic modulus data to the 3D topography allows relating the information of both channels. The 3D image was generated using Gwyddion software. The last image shows the distribution of the elastic moduli extracted from nanomechanical force mapping experiments. The peak at lower moduli corresponds to the stiffness of the cells. The peak at the right originates from the cell culture substrate and shows much higher elastic moduli. AFM data courtesy of Philipp Oertle, Biozentrum, University Basel.

Single molecule force spectroscopy of bacteriorhodopsin

The force-distance curve below reports the controlled C-terminal unfolding of a single bacteriorhodopsin (BR) membrane protein from its native environment, the purple membrane from Halobacterium salinarium. Solid and dashed orange lines represent the WLC curves corresponding to the major and minor unfolding peaks observed upon unfolding BR, respectively. The contour length of the stretched polypeptides of the major unfolding peaks is given in amino acids (aa).

This data was recorded using a FlexAFM scan head (10-µm; version 3) in combination with the C3000 controller and a cantilever with a nominal spring constant of 0.1 N/m (Uniqprobe, qp-CONT, Nanosensors).

FlexAFM image gallery

Cell-cell adhesion force studied with Flex-FPM

Nanomechanical analysis of alginate hydrogels

AFM imaging of type I collagen fibrils

AFM topography of a living HeLa cell

High resolution imaging of the cytoplasmic side of bacteriorhodopsin

Living Rat-2 cells

Imaging DNA with the AFM

Tissue samples

Dynamic mode AFM of human hair

AFM for dental implants

AFM image of butterfly wings

The most flexible atomic force microscope for materials research

For success in materials research studies, scientists depend on professional tools that can readily provide the information needed, regardless of the tasks at hand. By advancing key technologies and designs, Nanosurf has made the FlexAFM one of the most versatile and flexible AFMs ever, allowing a large variety of materials research applications to be handled with ease. In combination with the powerful C3000i controller, complex material characterizations are possible.

The precision and performance you need for your research

The FlexAFM uses an extremely linear electromagnetic scanner for XY movement. This scanner delivers an average linearity deviation of less than 0.1% over the full scan range, top-ranking on the AFM market. The Z-axis is piezo-driven, with a position sensor that enables closed-loop operation. A sensitive cantilever detection system can measure well into the MHz frequency range. The scan head is connected to the full-featured, 24-bit C3000i controller with digital feedback and 2 dual-channel lock-in amplifiers.

Topography of SrTiO₃ in dynamic mode

Strontium titanate (SrTiO₃, STO) is an oxide of titanium and strontium exhibiting a perovskite structure. It has interesting and partly unique material properties. It is used as substrate for growth of oxide-based thin films and high-temperature superconductors. STO forms surfaces that show a layered structure. The thickness of individual layers is in the range of a few Angstrom. Atomic force microscopy is an ideal tool to image and measure these structures.

The sample clearly shows the typical layer structure STO. Here, the layers are not perfectly smooth, but exhibit residual roughness of approx. 125 pm (RMS). This is caused by a non-ideal termination process during the preparation of this STO sample. The graph shows the profile of the image shown above along a line extending from the top left to the bottom right corner of the imaged area. The profile also clearly shows the layered structure of the sample and reveals step heights of approx. 4 Å. Similarly in the right panel, the height distribution histogram of the image above clearly shows approx. 4 Å-spaced peaks for the different layers of the sample.

Topography and KPFM of CVD grown molybdenum disulfide monolayers

In this application note, monolayer MoS₂ grown by chemical vapor deposition (CVD) was imaged with Kelvin probe force microscopy (KPFM) using a FlexAFM to study the contact potential difference variation on a single crystal. Monolayers of MoS₂ were grown on a silicon substrate by chemical vapor deposition (Sample courtesy: University of Illinois – Urbana-Champlain). Non-uniformity of the contact potential signal across the monolayer can inform about doping profiles and other surface defects.

Measurements using the FlexAFM show a step height of 0.6 nm for the MoS₂ monolayer. Concurrent KPFM measurements show a 650 mV contact potential difference between the monolayer and the SiO₂ substrate.

All measurements were performed using a FlexAFM system equipped with a ANSCM-PA cantilever from AppNano. Images were processed using MountainsMap SPM. For more information contact our application scientists

KPFM and MFM on stainless steel

In the experiment shown below, KPFM and topography data were recorded in a single run using a FlexAFM system. Also see the related MFM application.

FlexAFM image gallery

Magnetic force microscopy of thin permalloy film with stripe domains

Topography of SrTiO3 in dynamic mode

Magnetic force microscopy of digital backup tape

Topography on multilayer graphene

KPFM on multilayer graphene

Topography of MoS2 monolayer

MoS2 monolayer: 3D topography overlaid with KPFM signal

Topography of locally deposited charges on an insulating oxide surface

KPFM of locally deposited charges on an insulating oxide surface

Topography of an integrated circuit structure with multiple transistor contacts

Conductive AFM of an integrated circuit structure with multiple transistor contacts

Out of plane PFM on Lithium Niobate

Electrostatic force (EFM) measurements on aluminum dots deposited on gold

Topography of polished stainless steel

Magnetic force microscopy on polished stainless steel

KPFM on polished stainless steel

Nanomechanical analysis of alginate hydrogels

Electrochemical AFM with rod-like samples: Cu deposition on a commercial Pt electrode

Dynamic mode AFM of pyrene nanosheets

Dynamic mode AFM of polished sapphire

AFM force spectroscopy on a polymer blend

AFM phase image of a polymer blend

Topography analysis of ePTFE membrane using AFM

Airplane Wing Coating

Topography of solar cell layers

Screw dislocations in GaN

Dynamic mode AFM on pentacene film on TiO2

Morphology analysis of paper

Contact mode AFM of polished ceramic plate used in dentistry

MFM of bits on a harddisk

AFM for dental implants

Static force AFM of stainless steel