Iron-related toxicity effects of single-walled carbon nanotubes in human placental cells (BeWo) investigated by X-ray fluorescence microscopy

As the prospect of human beings exposed to new nanomaterials increases, there are growing concerns about the foetal exposure and effects of such nanomaterials during pregnancy. Among others, due to their ample usage, it becomes urgent to address the vulnerability of the human placental barrier to carbon nanotubes (CNTs). Recently, by applying a combination of advanced synchrotron-based X-ray microscopy and X-ray fluorescence (XRF) techniques, we demonstrated that raw single-walled CNTs (SWCNTs) may cause an asbestos-like iron-related toxicity in mesothelial (MeT5A) cells. This work shows the results obtained with the same approach and experimental conditions in human choriocarcinoma (BeWo) cells as a placental model. XRF microscopy in mild and soft X-ray regimes was used to map the distribution of P, S, Ca, and Fe in exposed and control cells, whereas absorption and phase-contrast imaging (soft X-ray microscopy) provided simultaneous morphological information. The findings show that exposure to SWCNTs affects cell viability and causes a small increase in intracellular iron content, further confirmed by the stimulation of the ferritin protein. It is interesting to note that the iron changes are negligible when highly purified SWCNTs are used. In all tested conditions, including exposure to iron sulfate, the iron accumulation or ferritin increase was much lower in BeWo cells than in MeT5A ones, suggesting a different iron metabolism and possibly a lower vulnerability of the placental barrier to iron-rich nanomaterials.     

Theoretical and experimental investigation on the near-infrared and UV–vis spectral regions of a newly synthesized triarylamine electrochromic system

A new triarylamine derivative, N,N′-Bis(4-heptanoylamidophenyl)-N,N′-di(4-methoxyphenyl)-1,4-phenylenediamine, with stable electrochromism in near-infrared and visible light regions, has been synthesized and characterized at theoretical and experimental level. The detected and simulated spectra, with and without the presence of an external potential at different values, clearly show that this mixed-valence system undergoes ionization at a low value of the applied potential, and the formed radical cation absorbs in the near-infrared region with an intense peak located at 1,040 nm. Density functional computations give the geometrical structure and absorption properties in very good agreement with experiment, allowing assigning the electronic transition and contributing to an understanding of the electron-transfer process between the two redox centers.     

Electro‐optical Properties of Neutral and Radical Ion Thienosquaraines

Thienosquaraines are an interesting class of electroactive dyes that are useful for applications in organic electronics. Herein, the redox chemistry and electrochromic response of a few newly synthesized thienosquaraines are presented. These properties are compared to those of the commercial 2,4‐bis[4‐(N,N‐diisobutylamino)‐2,6‐dihydroxyphenyl]squaraine. The stability of the radical ions formed in electrochemical processes strongly affects these properties, as shown by cyclic voltammetry, in situ spectroelectrochemistry, and quantum chemical calculations. Furthermore, all of the dyes show aggregation tendency resulting in panchromatic absorption covering the whole UV/Vis spectral range.     

Hückel's Rule of Aromaticity Categorizes Aromatic closo Boron Hydride Clusters

A direct connection is established between three‐dimensional aromatic closo boron hydride clusters and planar aromatic [n]annulenes for medium and large boron clusters. In particular, the results prove the existence of a link between the two‐dimensional Hückel rule, as followed by aromatic [n]annulenes, and Wade–Mingos’ rule of three‐dimensional aromaticity, as applied to the aromatic [B_nH_n]^2? closo boron hydride clusters. The closo boron hydride clusters can be categorized into different series, according to the n value of the Hückel (4 n+2) π rule. The distinct categories studied in this work correspond to n=1, 2, and 3. Each category increases in geometrical difficulty but, more importantly, it is possible to associate each category with the number of pentagonal layers in the structure perpendicular to the main axis. Category 1 has one pentagonal layer, category 2 has two, and category 3 has three.