Mechanically activated rupture of single covalent bonds: evidence of force induced bond hydrolysis

作者：Schmidt Sebastian W; Kersch Alfred; Beyer Martin K^*; Clausen Schaumann Hauke

来源：Physical Chemistry Chemical Physics, 2011, 13(13): 5994-5999.

DOI：10.1039/c0cp02827d

We have used temperature-dependent single molecule force spectroscopy to stretch covalently anchored carboxymethylated amylose (CMA) polymers attached to an amino-functionalized AFM cantilever. Using an Arrhenius kinetics model based on a Morse potential as a one-dimensional representation of covalent bonds, we have extracted kinetic and structural parameters of the bond rupture process. With 35.5 kJ mol(-1), we found a significantly smaller dissociation energy and with 9.0 X 10(2) s(-1) to 3.6 X 10(3) s(-1) also smaller Arrhenius pre-factors than expected for homolytic bond scission. One possible explanation for the severely reduced dissociation energy and Arrhenius pre-factors is the mechanically activated hydrolysis of covalent bonds. Both the carboxylic acid amide and the siloxane bond in the amino-silane surface linker are in principle prone to bond hydrolysis. Scattering, slope and curvature of the scattered data plots indicate that in fact two competing rupture mechanisms are observed.