Interrogation of Single Synthetic Polymer Chains and Polysaccharides by AFM‐Based Force Spectroscopy

Abstract

This contribution reviews selected mechanical experiments on individual flexible macromolecules using single-molecule force spectroscopy (SMFS) based on atomic force microscopy. Focus is placed on the analysis of elasticity and conformational changes in single polymer chains upon variation of the external environment, as well as on conformational changes induced by the mechanical stress applied to individual macromolecular chains. Various experimental strategies regarding single-molecule manipulation and SMFS testing are discussed, as is theoretical analysis through single-chain elasticity models derived from statistical mechanics. Moreover, a complete record, reported to date, of the parameters obtained when applying the models to fit experimental results on synthetic polymers and polysaccharides is presented.

Atomic force microscopy of the morphology and mechanical behaviour of barnacle cyprid footprint proteins at the nanoscale

“…Polymer elasticity was described by the WLC model (Giannotti & Vancso 2007). The WLC model describes the relationship between the chain extension x and entropic force F(x) generated in the form:…”

Nanoscale Structural and Mechanical Properties of Nontypeable Haemophilus influenzae Biofilms

“…Statistical analysis of unbinding events was performed by first identifying local minima in force-versus-distance curves and then evaluating unbinding forces as described previously (3,9). When unbinding events in a force-extension curve were identified, each event of the curve was fitted to the extended freely jointed chain (m-FJC) model (32,43,45,(48)(49)(50)62) to analyze the elasticity of the possible LOS molecule(s) being extended by the AFM tip. In the m-FJC model, the extension (z) of the polymer is related to the force (F) applied by the cantilever…”

“…A value of k s ϭ 2.2 N/m was found suitable for the analyzed force-extension curves after allowing it to vary between 1 and 100 N/m in several fitting attempts. Values of k s have been reported to vary greatly for different polysccharides, depending on the specific polysaccharide and solvent used (32). To discard events unlikely to originate from the extension of LOS molecules, only Kuhn and contour lengths with L k Ͼ 0.09 nm and L c Ͼ 10 nm were considered in the results summarized in the histograms.…”

Applications of Scanning Electrochemical Microscopy (SECM) Coupled to Atomic Force Microscopy with Sub-Micrometer Spatial Resolution to the Development and Discovery of Electrocatalysts

“…Since the invention and introduction of AFM in 1986 [13], AFM has been widely used to investigate the surface of polymers [24,25] and bio-materials [26] in singlestrain molecules with high resolution [27] and on the atomic scale [28]. For example, AFM has been employed to investigate single protein-DNA interactions ( Fig.…”