Rechendorff, KristianWitz, GuillaumeAdamcik, JozefDietler, Giovanni2009-09-072009-09-072009-09-07200910.1063/1.3216111https://infoscience.epfl.ch/handle/20.500.14299/42468WOS:000269625400034We have characterized the polymer physics of single-stranded DNA (ssDNA) using atomic force microscopy. The persistence length l(p) of circular ssDNA adsorbed on a modified graphite surface was determined independently of secondary structure. At a very low ionic strength we obtained l(p)=9.1 nm from the bond correlation function. Increasing the salt concentration lead to a decrease in l(p); at 1 mM NaCl we found l(p)=6.7 nm, while at 10 mM NaCl a value l(p)=4.6 nm was obtained. The persistence length was also extracted from the root-mean-square end-to-end distance and the end-to-end distance distribution function. Finally, we have investigated the scaling behavior using the two latter quantities, and found that on long length scales ssDNA behaves as a two-dimensional self-avoiding walk.adsorptionatomic force microscopybiological techniquesDNAgraphitemolecular biophysicsATOMIC-FORCE MICROSCOPYRADIAL-DISTRIBUTION FUNCTIONSELF-AVOIDING WALKPOLYMER-CHAIN2 DIMENSIONSMICA SURFACEMOLECULESFLEXIBILITYADSORPTIONPOLYELECTROLYTEStext::journal::journal article::research article