The size and shape of semiconductor nanocrystals govern their optical and electronic properties. Liquid cell transmission electron microscopy (LCTEM) is an emerging tool that can directly visualize nanoscale chemical transformations and therefore inform the precise synthesis of nanostructures with desired functions. However, it remains difficult to controllably investigate the reactions of semiconductor nanocrystals with LCTEM, because of the highly reactive environment formed by radiolysis of liquid. Here, we harness the radiolysis processes and report the single-particle etching trajectories of prototypical semiconductor nanomaterials with well-defined crystalline facets. Lead selenide nanocubes represent an isotropic structure that retains the cubic shape during etching via a layer-by-layer mechanism. The anisotropic arrow-shaped cadmium selenide nanorods have polar facets terminated by either cadmium or selenium atoms, and the transformation trajectory is driven by etching the selenium-terminated facets. LCTEM trajectories reveal how nanoscale shape transformations of semiconductors are governed by the reactivity of specific facets in liquid environments.

Background. Xuanwei City in Yunnan province has been one of the towns with highest lung cancer mortality in China. The high content of amorphous silica in the bituminous coal from Xuanwei of Yunnan is mainly present as irregular and spherical silica nanoparticles (SiNPs). It has been reported that silica nanoparticles in bituminous coal correlated with the high incidence of lung cancer in Xuanwei. To explore the role and mechanism of SiNPs in the tumorigenesis of lung cancer in Xuanwei, human mononuclear cells (THP-1) and human bronchial epithelial cells (BEAS-2B) were cocultured in a transwell chamber. Combined with Benzo[a]pyrene-7, 8-dihydrodiol-9, and 10-epoxide (BPDE), SiNPs could significantly promote the proliferation and Epithelial-Mesenchymal Transition (EMT) and inhibit apoptosis of BEAS-2B cells and induce the release of TGF-α from THP-1 cells. After neutralizing TGF-α with antibody, the proliferation and EMT were decreased and enhanced apoptosis of BEAS-2B cells. Furthermore, the results showed that TGF-α in the sera of patients with lung adenocarcinoma in Xuanwei were significantly higher than in patients with benign pulmonary lesions in Xuanwei and those with lung adenocarcinoma in outside of Xuanwei of Yunnan. Taken together, our study found that SiNPs promoted the proliferation and EMT of BEAS-2B cells by inducing the release of TGF-α from THP-1 cells.

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Objective This study aimed to examine the role of spherical silica nanoparticles (SiNPs) on human bronchial epithelial (BEAS-2B) cells through inflammation. Methods Human mononuclear (THP-1) cells and BEAS-2B cells were co-cultured in transwell chambers and treated with 800 mmol/L benzo[ a]pyrene-7, 8-dihydrodiol-9, 10-epoxide (BPDE) and 12.5 µg/mL SiNPs for 24 hours. For controls, cells were treated with BPDE alone. Subcutaneous tumorigenicity and epithelial-mesenchymal transition (EMT) of BEAS-2B cells were measured. The cells were blocked with a stromal cell-derived factor-1α (SDF-1α)-specific antibody. EMT was analyzed in cells treated with 800 mmol/L BPDE and 12.5 µg/mL SiNPs relative to matched control cells and xenografts in vivo. Serum SDF-1α levels were measured in 23 patients with lung adenocarcinoma in Xuanwei, in 25 with lung adenocarcinoma outside Xuanwei, and in 22 with benign pulmonary lesions in Xuanwei. Results SiNPs significantly promoted tumorigenesis and EMT, induced the release of SDF-1α, and activated AKT (ser473) in BEAS-2B cells. EMT and phosphorylated AKT (ser473) and glycogen synthase kinase-3β levels were decreased when blocked by SDF-1α antibody in BEAS-2B cells. SDF-1α was mainly secreted by THP-1 cells. Conclusion SiNPs combined with BPDE promote EMT of BEAS-2B cells via the AKT pathway by inducing release of SDF-1α from THP-1 cells.

Layered hybrid perovskites have attracted much attention in recent years due to their emergent physical properties and exceptional functional performances, but the coexistence of lattice order and structural disorder severely hinders our understanding of these materials. One unsolved problem regards how the lattice dynamics are affected