Nanocapsules of Magnetic Au Self-Assembly for DNA Migration and Secondary Self-Assembly

To endow valuable responsiveness to self-assemblies of Au nanoparticles (Au NPs), the magnetic Au nanoparticles (Au NPs)/C₁₆H₃₃(CH₃)₃N⁺[CeCl₃Br]^- (CTACe) mixtures were first prepared by using an emulsion self-assembly of a magnetic surfactant, C₁₆H₃₃(CH₃)₃N⁺[CeCl₃Br]^-. A versatile morphology of self-assemblies of Au NPs could be controlled by the counterions in surfactants including [CeCl₃Br]^-, [FeCl₃Br]^-, and Br^- as well as solvent. In particular, the magnetic counterion, [CeCl₃Br]^-, can induce self-growth of Au NPs in an emulsion self-assembly process due to the oxidability of [CeCl₃Br]^-. It enhances the rigidity of Au NPs/CTACe scaffolds template compared with Au NPs/hexadecyltrimethylammonium bromide. [CeCl₃Br]^- engaged Au NPs/CTACe with fascinating capability of conglutination and targeted migration of DNA (150 μmol/L) under a magnet field. The conglutination capability of the DNA molecules can increase to 39.8% by adopting the magnetic strategy when using Au NPs/CTACe as a magnetic booster. Au NPs/CTACe mixtures can ideally self-assemble to be scaffolds, providing abundant conjugation sites of surface charges. Magnetic Au NPs/CTACe can serve as a template scaffold to secondary self-assemble with DNA (40 mmol/L) outside, producing smooth-faced and hollow DNA nanocapsules. We believe that the creative Au NPs/CTACe/DNA nanocapsules will extend the biological application field of Au NPs assemblies.