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Atomic Force Microscopy (AFM) is a type of high-resolution scanning probe microscopy that allows for imaging, manipulation and force measurement. Atomic Force Microscopy was first discovered in 1986 by Binning, Quate, and Gerber as a way with of overcoming the drawbacks of scanning tunneling microscopy (STM). It is used in a variety of different industries, including solid-state physics, semiconductor science, molecular engineering, polymer and surface chemistry, molecular biology, cell biology, and medicine.
How it Works
Scanning probe microscopy scans the surface of samples with a probe to measure fine surface shapes and properties and generate an image. Scanning probe microscopy measures properties such as height, friction, and magnetism. The main types of scanning probe microscopy include atomic force microscopy, scanning tunneling microscopy (STM) and near-field scanning optical microscopes (MSOM).
AFM has a fine silicon or silicon nitride probe which is attached to a cantilever. When the probe moves across the sample surface, it measures the surface morphology on the atomic scale. The force between the tip and the sample is measured during scanning by monitoring the deflection of the cantilever. The tip can be modified in various ways to investigate different surface properties
AFM applications include biochemical imaging of molecules, cells and tissues, chemistry, materials science, nanotechnology applications to image polymers and nanostructures, and physical and biophysical applications such as measuring forces between the AFM tip and the sample surface.
AFM has become a standard technique for surface imaging, but it is now also increasingly used in biological research to look at the properties of living cells. AFM is used to look at biological issues such as the characterization of organelles, DNA-protein interactions, cell adhesion forces and electromechanical properties of living cells can all be measured by AFM.
Changes in the mechanical properties of the cell membrane such as cell stiffness and viscoelasticity can be measured by AFM, as well as AFM having the ability to assess cell adhesion the rheological properties of cells. Samples can be directly analyzed in their natural environment, without the need for any sample preparation, saving a lot of research time.
Recent advances in AFM have enabled it to be used in cancer research and diagnosis.
The physicochemical properties of live cells change when their physiological conditions are altered. When cells undergo the process of carcinogenesis from external stimuli, their morphology, elasticity, and adhesion properties change. AFM surface imaging and ultrastructural observation of live cells can be done with atomic resolution under near-physiological conditions, collecting force spectroscopy information which allows for the study of the mechanical properties of cells.
AFM can detect the changes and differences between single cancerous and non-cancerous cells, which allows for early diagnosis and treatment of cancer. AFM can also study the structure and function of cancerous cells by looking at the mechanisms involved in their spreading, mechanisms of anti-cancer drugs and the interaction processes between cells.
The ability of AFM to scan the interaction between lipid bi-layers and drugs is a major advantage of AFM that can be used in the pharmaceutical industry.
AFM can test the interactions of drugs with receptors as well as testing the contact of the drug candidate with target cell membranes. Due to the non-destructive nature of AFM, it can be used to look at soft systems under controlled environmental conditions, which then serves as a unique foundation for the in vitro development of novel drug delivery systems. Enzyme hydrolysis visualization can also be done by the phase imaging mode of the AFM.
AFM is used for thorough qualitative and quantitative evaluation of pharmaceutical formulations. Surface properties can affect the final formulation characteristics so needs to be analyzed. AFM is currently the only available technique that is capable of measure interactions in the pN range.
Frictional determination by AFM in the past decade has mainly been focused on biochemical materials at the nanoscale. AFM has developed from the determination of frictional morphology to several mechanical parameters of friction value and process. Two aspects that determine dynamic and static properties can be achieved by multi-AFM modes. Frictional morphology, friction curve, and friction motion process can all be measured using AFM.
Oscillatory AFM techniques
The improvement to AFM instrumentation has decreased over the recent years, with a focus being on the accessories and microscopes themselves. One area of improvement has been the introduction of oscillatory AFM techniques.
Oscillatory AFM techniques such as amplitude and frequency modulation modes have allowed for a further expansion of the applications of AFM. The destructive lateral forces in the contact mode are practically eliminated, and AFM applications have been expanded to a broad range of soft biological samples and polymers.
High-speed Atomic Force Microscopy
High-speed AFM (HS-AFM) is a relatively new type of microscopy tool that was developed to overcome the current limitations of structural biology and light-based single-molecule biophysics. HS-AFM allows for the simultaneous assessment of the structure and dynamics of single protein molecules whilst in action at high spatiotemporal resolution.
HS-AFM has been successfully applied to a variety of proteins, including motor proteins, membrane proteins, antibodies, enzymes, and intrinsically disordered proteins.
Atomic Force Microscopy Global Market
According to the Statistics Marketing Research Council, the Global Atomic Force Microscopes Market is expected to grow at a CAGR of 6.8% from 2017-2026. The increased need for high-resolution microscopy and the use of AFM in biology and medicine are thought to be the driving factors for the market growth.
Researchers are increasingly using AFM for ultra-high-resolution studies of proteins and DNA, and this is a main factor for the market growth. The Asia Pacific market is anticipated to show an increased interest in AFM due to the rising popularity of smartphones, the adoption of advanced technologies and the growth of the semiconductor industry. The growth in North America is attributed to numerous technological advancements in this region.