title: Effects of anions on nanostructuring of cationic amphiphilic peptides.
abstract: The effects of addition of a series of stoichiometric salts on the nanostructuring of cationic amphiphilic peptides have been investigated through the combination of atomic force microscopy (AFM), circular dichroism (CD), and turbidity measurements. The results revealed that anions had more pronounced effects than cations in tuning the nanostructures formed from these peptides. Addition of ClO(3)(-), NO(3)(-), and Br(-) could stabilize the primary nanostructures (nanostacks, nanospheres, or short nanorods) formed by A(9)K and I(3)K and effectively inhibit their growth into longer nanostructures (nanorods or nanotubes). In contrast, the anions of Cl(-), SO(4)(2-), HPO(4)(2-), PO(4)(3-), and C(6)H(5)O(7)(3-) (citrate) favored the axial growth of these peptides to form long intersecting nanofibrils and led to an increase in diameter and surface roughness, as well, clearly enhancing their propensity for nanostructuring. The efficiency of different anions in promoting the growth of peptide nanoaggregates into larger ones could be ordered as ClO(3)(-) < NO(3)(-) ≤ Br(-) < Cl(-) < SO(4)(2-) < HPO(4)(2-) < PO(4)(3-) < C(6)H(5)O(7)(3-), broadly consistent with the Hofmeister anion sequence. These observations were well rationalized by considering different aspects of direct interactions of the anions with the peptide molecules.
authors: Centre for Bioengineering and Biotechnology,  China University of Petroleum  (East China), 66 Changjiang West Road, Qingdao Economic Development Zone, Qingdao 266555, People's Republic of China.
authors: Meiwen
authors: M
authors: Cao
authors: Yuming
authors: Y
authors: Wang
authors: Xin
authors: X
authors: Ge
authors: Changhai
authors: C
authors: Cao
authors: Jing
authors: J
authors: Wang
authors: Hai
authors: H
authors: Xu
authors: Daohong
authors: D
authors: Xia
authors: Xiubo
authors: X
authors: Zhao
authors: Jian R
authors: JR
authors: Lu
mesh_terms: D000838:Anions / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D002942:Circular Dichroism; D018625:Microscopy, Atomic Force; D049329:Nanostructures / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*
chemical_list: D000838:Anions; D002412:Cations; D010455:Peptides