Probing the topography and mechanical properties of biomaterials with atomic force microscopy
Authors: Mueller Torsten , Koernig André , Neumann Tanja 
Published: July 2020

&lt;p&gt;The composition, topography, adhesiveness and nanomechanical properties of biomaterials are all factors that affect biological processes, e.g. biofilm formation, cell differentiation, and morphogenesis [1-4]. Atomic Force Microscopy (AFM) is a highly versatile tool, ideal for the characterization of samples properties ranging from single molecules to complex biological systems, on the nm scale.&lt;/p&gt;
&lt;p&gt;JPK BioAFMs, like the NanoWizard&lt;sup&gt;&amp;#174;&lt;/sup&gt; ULTRA Speed 2, enable fast imaging of challenging biological samples and the visualization of dynamic processes with high spatio-temporal resolution under near physiological conditions, e.g. the kinetics of collagen type I fibrillogenesis was imaged in situ revealing the formation of the 67 nm D-banding hallmark.&lt;/p&gt;
&lt;p&gt;Our distinctive Quantitative Imaging mode (QI&amp;#8482;) measures various sample properties such as topography, nanomechanics and adhesion on the nanometer scale. Complex data like contact point, Young&amp;#180;s modulus or recognition images can also be extracted at the same resolution. To demonstrate the capability and flexibility of the QI&amp;#8482; mode, various biological samples like living cells have been investigated and their topographical and mechanical properties determined. QI&amp;#8482;, based on fast force mapping, can also be used to determine the mechanical properties of different bacterial strains. We will discuss the application of HighSpeed AFM for the characterisation of dynamic biofilms with high spatiotemporal resolution, information which can then be directly correlated with advanced optical microscopy for immuno-characterisation of the sample.&lt;/p&gt;
&lt;p&gt;Investigating large, sticky and rough samples such as tissues and hydrogels using AFM has always been a challenge due to the limited z-axis of the AFM. The HybridStage&amp;#8482;, equipped with an extended xyz scanner unit up to 300x300x300 &amp;#181;m&lt;sup&gt;3&lt;/sup&gt;, an additional motorized unit for large sample movements in the mm range and optical tiling, is ideal for investigating such samples. This combination enables multi-region AFM probing over a large, uneven sample area and provides additional correlative optical data sets.&lt;/p&gt;
&lt;p&gt;Adhesion dynamics between cells and biomaterials play a crucial role in, e.g. the applicability of potential implant materials. The AFM based Single Cell Force Spectroscopy platform enables quantitative measurement of the interactions between individual cells and any substrate.&lt;/p&gt;
&lt;p&gt;A number of important research topics in the field of biomedicine, relate directly to the increased antimicrobial resistance of various biofilms to commonly prescribed drugs, and have identified adhesion, as a leading factor in biofilm formation, colony progression, and pathogenesis of microbial agents. JPK BioAFM has developed novel techniques for studying single-molecule forces and adhesion profiles at the cell/cell or cell/substrate interface. We will provide an overview of how to functionalize various surface substrates for the attachment of bacteria.&lt;/p&gt;
&lt;p&gt;We will also provide information on working with AFM under Biosafety Level L2/L3 conditions.&lt;/p&gt;
&lt;p&gt;&amp;#160;&lt;/p&gt;
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