The X-ray computed tomography (CT) to accurately image the morphology of tumor blood vessels with contrast agents is of significant importance to clarify the mechanisms underlying tumor progression and evaluate the efficacy of drugs. In this study, we attempted to visualize morphological changes in identical tumor blood vessels over time by micro X-ray CT imaging using new X-ray contrast agents. First, glutathione-supported single nanometer-sized gold nanoparticles (sAu/GSH) (diameter, ~2.2 nm) were fabricated using tetrakis (hydroxymethyl) phosphonium chloride as a reducing agent. The sAu/GSHs were intravenously injected into mice, remained in vessels for a few minutes, and were then excreted by the kidneys after 24 h. Next, the sAu/GSH and lactoferrin complex (sAu/GSHLF) (diameter, ~17 nm) was produced by using amide bonds. On intravenously administering the sAu/GSH-LF to mice, the blood retention time was longer than that observed with sAu/GSH. Additionally, we succeeded in imaging and analysis morphological changes in identical tumor vessels for several days using micro X-ray CT with sAu/ GSH-LF.
Metal nanoclusters (NCs) show size- and structure-specific physicochemical properties. Photoluminescence (PL) is one of the most interesting characteristics of silver (Ag) NCs. Therefore, it is important to investigate the relationship between the structure and PL of Ag NCs at the atomic level. In this study, we synthesized a Ag79 cluster (SO4@Ag79S15( i PrS)28( i PrSO3)15(CF3CO2)4), which has a very similar geometrical structure to the reported Ag78 cluster (SO4@Ag78S15(CpS)27(CF3CO2)19), by using tridentate sulfonate ligand. The shell layers of Ag79 cluster have an extra Ag atom compared with Ag78 cluster, although the core and middle layers have the same geometrical structure. Ag79 exhibits a bright red emission with a PL quantum yield (PLQY) 70-fold higher than that of Ag78 cluster. We found that the difference in PLQY is attributable to the increase of radiative rate constant and decrease of non-radiative rate constant in Ag79 cluster.
Assemblies of inorganic nanoparticle building blocks exhibit properties that cannot be exhibited from individual nanoparticles or corresponding bulk counterparts. Since the arrangement of nanoparticles is crucial in the collective properties, development of a procedure to control the assembly manner of nanoparticle constituents is important. Herein, we demonstrate direct synthesis of nickel phosphide nanoparticle “superlattices” with tunable crystallinity via van der Waals attractive force-driven spontaneous self-assembly of nanoparticles in a general one-pot colloidal synthesis. The quantity of size-regulating reagent, tri-n-octylphosphine, modulates the assembly of nanoparticles from ordered close-packed to a disordered configuration. In situ small-angle X-ray scattering using synchrotron X-ray source revealed that the size distribution of the nanoparticles before assembly determines the crystallinity of superlattices, indicating the importance of regulating the growth kinetics of nanoparticles. This work will be useful for universal scalable preparation of three-dimensional superlattices, from a variety of materials and structures, with tunable concerted properties.
Single-particle analysis technology plays a crucial role in examining biological entities like viruses and extracellular vesicles (EVs). Its significance resonates deeply within both the realms of life science and medical research. Specifically, swiftly delving into the physical attributes of biological particles, such as size, shape, and stiffness, is important. This paper unveils the cutting-edge advancements in single-particle analysis technology, employing the prowess of nanopore devices. It elaborates on studies wherein these devices have been effectively utilized to measure biological particles. Furthermore, the potential and forthcoming prospects of nanopore devices are also contemplated upon.