Persistence Lengths and Structure Factors of Wormlike Polymers under Confinement

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• 作者：Peter Cifra ; Zuzana Benkov&aacute ; Tom&aacute ; //pubs.acs.org/images/entities/scaron.gif" border="0"> Bleha
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：February 7, 2008
• 年：2008
• 卷：112
• 期：5
• 页码：1367 - 1375
• 全文大小：247K
• 年卷期：v.112,no.5(February 7, 2008)
• ISSN：1520-5207

文摘

The behavior of semiflexible chains modeling wormlike polymers such as DNA and actin in confined spaceswas explored by coarse-grained Monte Carlo simulations. The persistence length P, mean end-to-end distance<R²>, mean radius of gyration <R_g²>, and the size ratio <R²>/<R_g²> were computed for chains in slits, cylinders,and spheres. It was found that the intrinsic persistence length of a free chain undergoes on confinementsubstantial alteration into the apparent persistence length. The qualitative differences were found in trends ofthe apparent persistence lengths between slits and cylinders on one side and spheres on the other side. Thequantities P, <R²>, <R_g²>, and <R²>/<R_g²> display similar dependences upon squeezing the chains in nanopores.The above quantities change nonmonotonically with confinement in slits and cylinders, whereas they dropsmoothly with decreasing radius of a sphere. For elongation of a chain in a cylinder, two regimes correspondingto strong and moderate confinements were found and compared to experiments and predictions of the bloband Odijk theories. In a spherical cavity, the toroidal chain structure with a hole in the center was detectedunder strong confinements. The scattering form factor S(q) computed for semiflexible confined chains revealedthree regimes of behavior in a slit and a cylinder that matched up well with the scaling theory. The complexform of the function S(q) computed for a sphere was interpreted as a sign of the toroidal structure. A reasonableagreement was found between the simulations and measurements of DNA and actin filaments, confined innano- and microfluidic channels and spherical droplets, pertaining to the changes of the persistence lengths,chain elongation, and toroidal structure formation.