Sliding contact dynamic force spectroscopy method for interrogating slowly forming polymer cross-links

Kate A. Bowman, Olav Andreas Aarstad, Bjørn Torger Stokke, Gudmund Skjåk-Bræk, Andrew N. Round

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)
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Dynamic Single Molecule Force Spectroscopy (SMFS), conducted most commonly using AFM, has become a widespread and valuable tool for understanding the kinetics and thermodynamics of fundamental molecular processes such as ligand-receptor interactions and protein unfolding. Where slowly forming bonds are responsible for the primary characteristics of a material, as is the case in crosslinks in some polymer gels, care must be taken to ensure that a fully equilibrated bond has first formed before its rupture can be interpreted. Here we introduce a method, sliding contact force spectroscopy (SCFS), which effectively eliminates the kinetics of bond formation from the measurement of bond rupture. In addition it permits bond rupture measurements in systems where one of the binding partners may be introduced into solution prior to binding without tethering to a surface. Taking as an exemplar of a slowly forming bond the ‘eggbox’ junction crosslinks between oligoguluronic acid chains (oligoGs) in the commercially important polysaccharide alginate, we show that SCFS measures accurately the equilibrated bond strength of the crosslink when one chain is introduced into the sample solution without tethering to a surface. The results validate the SCFS technique for performing single molecule force spectroscopy experiments, and show that it has advantages in cases where the bond to be studied forms slowly and where tethering of one of the binding partners is impractical.
Original languageEnglish
Pages (from-to)12814–12822
Number of pages9
Issue number48
Early online date4 Nov 2016
Publication statusPublished - 6 Dec 2016

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