Abstract
Anisotropic assembly of nanoparticles (NPs) has attracted extensive attention because of the potential applications in materials science, biology, and medicine. However, assembly control (e.g., the number of assembled NPs) has not been adequately studied. Here, the growth of anisotropic gold NP assemblies on a liposome surface is reported. Citrate-coated gold NPs adsorbed on liposome surfaces were assembled in one dimension at temperatures above the phase transition temperature of the lipid bilayer. Growth of the anisotropic assemblies depended on the heating time. Absorption spectroscopy and transmission electron microscopy revealed that the gradual growth was attributed to liposome fusion, which was strongly affected by the size of the gold NPs. This method enabled us to precisely control the number of NPs in each anisotropic assembly. These results will enable the fabrication of functional materials based on NP assemblies and enable investigations of cell functions and disease causality.
Highlights
When light interacts with a metal nanoparticle (NP), a unique surface plasmon resonance (SPR)frequency is observed [1]
Growth of Anisotropic cAuNP14 Assemblies on Liposome Surfaces cAuNPs with average diameters of 14 nm (cAuNP14, as determined by transmission electronic microscopy (TEM) (JEOL Ltd., Tokyo, Japan) were prepared by a modified method reported by Frens [24,25]
The DPPC liposomes and the cAuNP14 s were mixed at the ratio
Summary
When light interacts with a metal nanoparticle (NP), a unique surface plasmon resonance (SPR). The SPR strongly depends on the NP size and shape [1,2,3,4], its composition [3], and the nature of the dialectic materials surrounding the NPs [5,6,7]. Anisotropic cAuNP self-assembly on sphere-shaped vesicles of phospholipid bilayers (liposomes) was recently reported [23]. CAuNPs adsorbed on liposome surfaces were initially fixed and did not self-assemble below the phospholipid. Anisotropic cAuNP self-assembly did occur when the phospholipids became fluid above Tm. The decomposition of the citrate layer on the AuNP surface might have induced dipolar interactions between AuNPs, and enabled anisotropic assembly. The growth of anisotropic cAuNP assemblies by liposome fusion is reported. Control of the number of cAuNPs in each assembly via regulation of liposome fusion was demonstrated
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