Ordered Nanoparticle Assemblies Research Articles

Dynamic Interface-Assisted Rapid Self-Assembly of DNA Origami-Framed Anisotropic Nanoparticles.

The ordered arrangement of nanoparticles can generate unique physicochemical properties, rendering it a pivotal direction in the field of nanotechnology. DNA-based chemical encoding has emerged as an unparalleled strategy for orchestrating precise and controlled nanoparticle assemblies. Nonetheless, it is often time-consuming and has limited assembly efficiency. In this study, we developed a strategy for the rapid and ordered assembly of DNA origami-framed nanoparticles assisted by dynamic interfaces. By assembling Au nanoparticles (AuNPs) onto DNA origami with different sticky ends in various directions, we endowed them with anisotropic specific affinities. After assembling DNA origami-framed AuNPs onto supported lipid bilayers with freely diffusing single-stranded DNA via DNA hybridization, we found that DNA origami-framed AuNPs could form larger ordered assemblies than those in 3D solution within equivalent time frames. Furthermore, we also achieved rapid and ordered assembly of liposome nanoparticles by employing the aforementioned strategy. Our work provides a novel avenue for efficient and rapid assembly of nanoparticles across two-dimensional interfaces, which is expected to promote the application of ordered nanoparticle assemblies in sensor and biomimetic system construction.

Structural Characterization of Nanoparticle-Supported Lipid Bilayer Arrays by Grazing Incidence X-ray and Neutron Scattering

Arrays of nanoparticle-supported lipid bilayers (nanoSLB) are lipid-coated nanopatterned interfaces that provide a platform to study curved model biological membranes using surface-sensitive techniques. We combined scattering techniques with direct imaging, to gain access to sub-nanometer scale structural information on stable nanoparticle monolayers assembled on silicon crystals in a noncovalent manner using a Langmuir-Schaefer deposition. The structure of supported lipid bilayers formed on the nanoparticle arrays via vesicle fusion was investigated using a combination of grazing incidence X-ray and neutron scattering techniques complemented by fluorescence microscopy imaging. Ordered nanoparticle assemblies were shown to be suitable and stable substrates for the formation of curved and fluid lipid bilayers that retained lateral mobility, as shown by fluorescence recovery after photobleaching and quartz crystal microbalance measurements. Neutron reflectometry revealed the formation of high-coverage lipid bilayers around the spherical particles together with a flat lipid bilayer on the substrate below the nanoparticles. The presence of coexisting flat and curved supported lipid bilayers on the same substrate, combined with the sub-nanometer accuracy and isotopic sensitivity of grazing incidence neutron scattering, provides a promising novel approach to investigate curvature-dependent membrane phenomena on supported lipid bilayers.

Building ordered nanoparticle assemblies inspired by atomic epitaxy.

Self-assembly of inorganic nanoparticles into mesoscopic or macroscopic nanoparticle assemblies is an efficient strategy to fabricate advanced devices with emergent nanoscale functionalities. Furthermore, assembly of nanoparticles onto substrates may enable the fabrication of substrate-integrated devices, akin to atomic crystal growth on a substrate. Recent progress in nanoparticle assembly suggests that ordered nanoparticle assemblies could be well produced on a selected substrate, referred to as soft epitaxial growth. Herein, recent advances in soft epitaxial growth of a nanoparticle assembly are presented, including the assembly strategies, the choice of substrate and the epitaxial modes. Perspectives are also discussed for the material design based on substrate-integrated soft epitaxial growth.

Assembly of Protein Stacks With in Situ Synthesized Nanoparticle Cargo.

The ability of proteins to form hierarchical structures through self-assembly provides an opportunity to synthesize and organize nanoparticles. Ordered nanoparticle assemblies are a subject of widespread interest due to the potential to harness their emergent functions. In this work, the toroidal-shaped form of the protein peroxiredoxin, which has a pore size of 7 nm, was used to organize iron oxyhydroxide nanoparticles. Iron in the form of Fe2+ was sequestered into the central cavity of the toroid ring using metal-binding sites engineered there and then hydrolyzed to form iron oxyhydroxide particles bound into the protein pore. By precise manipulation of the pH, the mineralized toroids were organized into stacks confining one-dimensional nanoparticle assemblies. We report the formation and the procedures leading to the formation of such nanostructures and their characterization by chromatography and microscopy. Electrostatic force microscopy clearly revealed the formation of iron-containing nanorods as a result of the self-assembly of the iron-loaded protein. This research bodes well for the use of peroxiredoxin as a template with which to form nanowires and structures for electronic and magnetic applications.

Application of ordered nanoparticle self-assemblies in surface-enhanced spectroscopy

In this review, we focused on the mechanisms of ordered nanoparticle assemblies and the strategies and applications of ordered assemblies for surface-enhanced spectroscopy.

Optical response and SERS properties of individual large scale supracrystals made of small silver nanocrystals

There is a considerable interest in producing and understanding the optical and spectroscopic properties of ordered nanoparticle assemblies. Herein, we describe and interpret the optical absorbance and Raman properties of 5.9 nm ± 0.3 nm diameter silver nanocrystals coated with dodecanethiol and organized in highly ordered 3D superlattices of different heights. Each superlattice was studied individually, which allowed to elaborate a model based on Maxwell-Garnett theory to reproduce qualitatively the height and wavelength dependence of the absorbance. Importantly, because of their small size compared to that of traditional nanoparticles used in Surface Enhanced Raman Spectroscopy (SERS), the large 3D distribution of hot spots generated by the silver superlattices allowed to easily obtain SERS spectra of the surrounding ligands despite their intrinsic low Raman cross section. Accordingly, traces of thiophenol could be detected very easily.

ChemInform Abstract: Self‐Assembly of Superparamagnetic Nanoparticles

AbstractReview: 65 refs.

Self-assembly of superparamagnetic nanoparticles

Abstract

Two-dimensional nanoparticle organization using block copolymer thin films as templates

The creation of ordered nanoparticle assemblies is one of the main prerequisites for the utilization of nanoparticles in advanced device applications. However, while considerable progress has been made in the precision synthesis of high quality, uniform nanoparticles of different compositions, sizes and shapes, our ability to organize them into ordered structures still faces major challenges. This Feature Article focuses on a facile approach developed in recent years for the fabrication of two-dimensionally organized nanoparticle assemblies, which is based on patterning as a simple and straightforward assembly mechanism and on block copolymer films as easily created templates.

Photonics and lasing in liquid crystal materials

Owing to fundamental reasons of symmetry, liquid crystals are soft materials. This softness allows long length-scales, large susceptibilities and the existence of modulated phases, which respond readily to external fields. Liquid crystals with such phases are tunable, self-assembled, photonic band gap materials; they offer exciting opportunities both in basic science and in technology. Since the density of photon states is suppressed in the stop band and is enhanced at the band edges, these materials may be used as switchable filters or as mirrorless lasers. Disordered periodic liquid crystal structures can show random lasing. We highlight recent advances in this rapidly growing area, and discuss future prospects in emerging liquid crystal materials. Liquid crystal elastomers and orientationally ordered nanoparticle assemblies are of particular interest.

Site-Selective Assemblies of Gold Nanoparticles on an AFM Tip-Defined Silicon Template

This paper provides a convenient method for fabricating highly controlled arrays of gold nanoparticles on silicon by combining AFM nanolithography and self-assembly techniques. Our main methodology is to fabricate nanopatterns on silicon, covered with amino group and methyl group terminated self-assembled monolayers (SAMs), at different surface locations. These nanopatterns were then used to guide the assembly of gold nanoparticles according to their different affinities for amino and methyl groups. AFM was employed to induce a localized degradation of the methyl SAM on the silicon and therefore to control the amino SAM-covering area for nanoparticle adsorption, where the amino SAM was formed on the degraded regions by the conventional self-assembly technique. Gold nanoparticles (15 nm in diameter) selectively assembled at the AFM tip-defined amino regions, forming precisely positioned nanoparticle arrays. Such kinds of highly ordered nanoparticle assemblies are believed to contribute to the studies of na...