Prismatic Confinement Induces Tunable Orientation in Plasmonic Supercrystals.

Throughout history scientists have looked to Nature for inspiration and attempted to replicate intricate complex structures formed by self-assembly. In the context of synthetic supercrystals, achieving such complexity remains a challenge due to the highly symmetric nature of most nanoparticles (NPs). Previous works have shown intricate coupling between the self-assembly of NPs and confinement in templates, such as emulsion droplets (spherical confinement) or tubes (cylindrical confinement). This study focuses on the interplay between anisotropic NP shape and tunable "prismatic confinement" leading to the self-assembly of supercrystals in cavities featuring polygonal cross sections. A multiscale characterization strategy is employed to investigate the orientation and structure of the supercrystals locally and at the ensemble level. Our findings highlight the role of the mold interface in guiding the growth of distinct crystal domains: each side of the mold directs the formation of a monodomain that extends until it encounters another, leading to the creation of grain boundaries. Computer simulations in smaller prismatic cavities were conducted to predict the effect of an increased confinement. Comparison between prismatic and cylindrical confinements shows that flat interfaces are key to orienting the growth of supercrystals. This work shows a method of inducing orientation in plasmonic supercrystals and controlling their textural defects, thus offering insight into the design of functional metasurfaces and hierarchically structured devices.

Extracting the morphology of gold bipyramids from small-angle X-ray scattering experiments via form factor modelling.

Accurate shape description is a challenge in materials science. Small-angle X-ray scattering (SAXS) can provide the shape, size and polydispersity of nanoparticles by form factor modelling. However, simple geometric models such as the ellipsoid may not be enough to describe objects with complex shapes. This work shows that the form factor of gold nanobipyramids is accurately described by a truncated bicone model, which is validated by comparison with transmission electron microscopy (TEM) data for nine different synthesis batches; the average shape parameters (width, height and truncation) and the sample polydispersity are obtained. In contrast, the ellipsoid model yields worse fits of the SAXS data and exhibits systematic discrepancies with the TEM results.

[Research progress of Angelicae Sinensis Radix and predictive analysis on its quality markers].

Angelicae Sinensis Radix, as a medicinal and edible Chinese medicinal herb, is widely used in clinical practice. It is mainly cultivated in Minxian, Tanchang, Zhangxian and Weiyuan counties of Gansu province. In recent years, with the comprehensive and in-depth study of Angelicae Sinensis Radix in China and abroad, its chemical composition, pharmacological effects and application and development have attracted much attention. In this study, the chemical composition, traditional efficacy, and modern pharmacological effects of Angelicae Sinensis Radix were summarized. On this basis, combined with the core concept of quality markers(Q-markers), the Q-markers of Angelicae Sinensis Radix were discussed from the aspects of mass transfer and traceability and chemical composition specificity, availability, and measurability, which provided scientific basis for the quality evaluation of Angelicae Sinensis Radix.

Double-Lattice Packing of Pentagonal Gold Bipyramids in Supercrystals with Triclinic Symmetry.

Pentagonal packing is a long-standing issue and a rich mathematical topic, brought to the fore by recent progress in nanoparticle design. Gold pentagonal bipyramids combine fivefold symmetry and anisotropy and their section varies along the length. In this work, colloidal supercrystals of pentagonal gold bipyramids are obtained in a compact arrangement that generalizes the optimal packing of regular pentagons in the plane. Multimodal investigations reveal a two-particle unit cell with triclinic symmetry, a lower symmetry than that of the building blocks. Monte Carlo computer simulations show that this lattice achieves the densest possible packing. Going beyond pentagons, further simulations show an odd-even effect of the number of sides on the packing: odd-sided bipyramids are non-centrosymmetric and require the double-lattice arrangement to recover inversion symmetry. The supercrystals display a facet-dependent optical response that is promising for sensing, metamaterials applications, and for fundamental studies of self-assembly processes.

Real-Time In Situ Observations Reveal a Double Role for Ascorbic Acid in the Anisotropic Growth of Silver on Gold.

Rational nanoparticle design is one of the main goals of materials science, but it can only be achieved via a thorough understanding of the growth process and of the respective roles of the molecular species involved. We demonstrate that a combination of complementary techniques can yield novel information with respect to their individual contributions. We monitored the growth of long aspect ratio silver rods from gold pentatwinned seeds by three in situ techniques (small-angle X-ray scattering, optical extinction spectroscopy and liquid-cell transmission electron microscopy). Exploiting the difference in reaction speed between the bulk synthesis and the nanoparticle formation in the TEM cell, we show that the anisotropic growth is thermodynamically controlled (rather than kinetically) and that ascorbic acid, widely used for its mild reductive properties, plays a shape-directing role, by stabilizing the {100} facets of the silver cubic lattice, in synergy with the halide ions. This approach can easily be applied to a wide variety of synthesis strategies.

Determining the morphology and concentration of core-shell Au/Ag nanoparticles.

Accurately measuring the shape, structure and concentration of nanoparticles (NPs) is a crucial step towards understanding their formation and a prerequisite for any applications. While determining these parameters for single-metal NPs is by now rather routine, reliably characterizing bimetallic NPs is still a challenge. Using four complementary techniques: transmission electron microscopy (TEM), light absorbance spectroscopy (AS), small-angle X-ray scattering (SAXS) and inductively coupled plasma mass spectrometry (ICP-MS) we study bimetallic nanoparticles obtained by growing a silver shell on top of a gold seed. The initial quasi-spherical objects become faceted and grow into a rounded cube as the molar silver-to-gold ratio K increases. The shape evolution is well described by SAXS and TEM. The shell thickness, overall size polydispersity and number particle concentration obtained by the various methods are in good agreement, validating the use of non-invasive in situ techniques such as AS and SAXS for the study of bimetallic NPs.

Plasmonic Oligomers with Tunable Conductive Nanojunctions.

Engineering plasmonic hot spots is essential for applications of plasmonic nanoparticles. A particularly appealing route is to weld plasmonic nanoparticles together to form more complex structures sustaining plasmons with symmetries targeted to given applications. However, control of the welding and subsequent hot spot characteristics is still challenging. Herein, we demonstrate an original method that connects gold particles to their neighbors by another metal of choice. We first assemble gold bipyramids in a tip-to-tip configuration, yielding short chains of variable length, and grow metallic junctions in a second step. We follow the chain formation and the deposition of the second metal (i.e., silver or palladium) via UV/vis spectroscopy, and we map the plasmonic properties using electron energy loss spectroscopy. The formation of silver bridges leads to a huge red shift of the longitudinal plasmon modes into the mid-infrared region, while the addition of palladium results in a red shift accompanied by significant plasmon damping.

[Research progress on anti-inflammatory mechanism of natural sesquiterpenoids].

Sesquiterpenoid is a kind of compound widely distributed in nature, which has a wide range of biological activities, such as anti-inflammatory, anti-tumor and immunomodulatory activities. This paper would review the anti-inflammatory mechanism of sesquiterpenoid. The mechanism is mainly by inhibiting the activation of nuclear factor (NF-κB), mitogen-activated protein kinase (MAPKs) and signal transducers and activators of transcription (STAT) signaling pathways and down-regulating the inflammatory gene expression including tumor necrosis factor-α (TNF-α), prostaglandin E2 (PGE2), nitric oxide (NO), interleukin-1(IL-1), IL-6, IL-8 and other inflammatory factors. Thereby, the production and release of inflammatory cytokines are reduced to exert anti-inflammatory effect. This review is intended to provide reference for related research.