| Autor: |
Hao X; Department of Chemistry and Biochemistry, School of Natural Sciences, University of California, Merced, California 95343, USA. tao.ye@ucmerced.edu.; School of Public Health and Jiangxi Provincial Key Laboratory of Disease Prevention and Public Health, Nanchang University, Nanchang, Jiangxi 330006, China., Gu Q; Materials and Biomaterials Science and Engineering, School of Engineering, University of California, Merced, California 95343, USA., Isborn C; Department of Chemistry and Biochemistry, School of Natural Sciences, University of California, Merced, California 95343, USA. tao.ye@ucmerced.edu., Vasquez JR; Department of Chemistry and Biochemistry, School of Natural Sciences, University of California, Merced, California 95343, USA. tao.ye@ucmerced.edu., Long MP; Department of Chemistry and Biochemistry, Creighton University, Omaha, Nebraska 68178, USA. makenzielong@creighton.edu., Ye T; Department of Chemistry and Biochemistry, School of Natural Sciences, University of California, Merced, California 95343, USA. tao.ye@ucmerced.edu.; Materials and Biomaterials Science and Engineering, School of Engineering, University of California, Merced, California 95343, USA. |
| Abstrakt: |
Anionic polyelectrolytes, such as DNA, are attracted to anionic surfaces in the presence of multivalent cations. A major barrier toward molecular-level understanding of these attractive interactions is the paucity of measurements of the binding strength. Here, atomic force microscopy-based single molecule force spectroscopy was used to quantify the binding free energy of double-stranded DNA to an anionic surface, with complementary density functional theory calculations of the binding energies of metal ion-ligand complexes. The results support both electrostatic attraction and ion-specific binding. Our study suggests that the correlated interactions between counterions are responsible for attraction between DNA and an anionic surface, but the strength of this attraction is modulated by the identity of the metal ion. We propose a mechanism in which the strength of metal-ligand binding, as well as the preference for particular binding sites, influence both the concentration dependence and the strength of the DNA-surface interactions. |
