摘要
The electrostatic interaction between of poly(amidoamine) (PAMAM) G9 dendrimer and an achiral surfactant, dodecylbenzenesulfonic acid (DBSA), leads to the formation of nucleosome-like structure, where the globular dendrimer molecule directs the DBSA cylindrical micelle to wrap around it spirally with a regular pitch length of 3.2 ∼ 4.3 nm. Molecular dynamics simulation demonstrates that the spherical micelles of DBSA in the aqueous solution first condense on the dendrimer surface via the electrostatic attraction. The micelles then merge with their neighbors to form cylinders bending around the dendrimer, which further connect with one another to form a spring-like helix wrapping around the dendrimer. The discovery of the helical supramolecular structure attests the universality of soft cylindrical building block such as DNA and micelle to twist and wrap helically around the oppositely charged particle such as histone protein and dendrimer for attaining the optimal charge matching at the expense of the bending energy of the cylinder.