Two pillared-helical-layer frameworks based on spiral chainlike metavanadate and [M(btx)]²⁺ complexes

<div><p>Two new isomorphous oxovanadium composite solids, [Zn(btx)V₂O₆] (<b>1</b>) and [Cu(btx)V₂O₆] (<b>2</b>) (btx = 1,4-bis(triazol-1-ylmethyl)benzene), have been synthesized and characterized by elemental analysis, IR, TGA, and single-crystal X-ray diffraction. The structures of <b>1</b> and <b>2</b> are composed of {MV₂O₆} (M = Zn or Cu) bimetallic oxide layers, linked through {MO₂N₂} building blocks and btx ligands into 3-D architectures. The two compounds consist of infinite spiral chains and all helical chains are meso-helices, which lead to racemic solid-state compounds. The electrochemical properties of the two compounds have been studied.</p></div

Nanoparticles show antitumor activity in a time and dose dependent manner.

<p>Cytotoxicity analysis of POM@SiO₂ nanoparticles on MCF-7 cells by MTT at different doses. The POM concentration was calculated by the encapsulate efficency of the nanoparticles. Data are presented as the mean ± SD of three independent experiments. *<i>P</i> < 0.05 for the nanoparticles at different doses <i>vs</i>. control.</p

Synthesis, cytotoxicity and antitumour mechanism investigations of polyoxometalate doped silica nanospheres on breast cancer MCF-7 cells

<div><p>Polyoxometalates (POMs) have shown the potential anti-bacterial, anti-viral and anti-tumor activities. In order to improve their physiological stability and antitumour activity for medical application, K₂Na[As^<b>III</b>Mo₆O₂₁(O₂CCH₂NH₃)₃]·6H₂O doped silica nanospheres (POM@SiO₂) with diameters of ~40 nm have been synthesized by the water-in-oil microemulsion method in this study. The obtained spheres were morphologically uniform nanosized and nearly monodispersed in solution. The nanoparticles had high entrapment efficiency, which was upto 46.2% by the inductively coupled plasma mass spectrometry (ICP-MS) analysis and POMs slowly released from the nanospheres both in the PH 7.4 and 5.5 phosphate buffer saline (PBS) solutions in 60 h. The <i>in vitro</i> MTT assays of particles on MCF-7 cell line (a human breast adenocarcinoma cell line) exhibited enhanced antitumor activity compared to that of plain polyoxometalate. The IC₅₀ value of the POM@SiO₂ nanoparticles was 40.0 μg/mL at 24 h calculated by the encapsulated POM concentration, which was much lower comparing to that of 2.0 × 10⁴ μg/mL according to the pure POM. And the SiO₂ shells showed low inhibitory effect at the corresponding concentration. Confocal images further indicated the cell morphology changes and necrosis. Flow cytometric analysis showed nanoparticles induced the apoptosis by arresting the cells in S phase and western blot analysis indicated they promoted apoptosis by inhibiting the Bcl-2 protein. Moreover, the study of interactions between human serum albumin (HSA) and the nanoparticles indicated the fluorescence quenching was static, and the nanoparticles were likely to bind to HSA and changed its conformation.</p></div

Characterization and release efficiency of the POM@SiO₂ nanoparticles.

<p><b>(a)</b> TEM images of AsMo₆@SiO₂ nanoparticles. The scale bar is 100 nm. <b>(b)</b> DLS measurement image of the nanoparticles. <b>(c)</b> FT-IR spectra of AsMo₆ (dash line) and nanoparticles (solid line). <b>(d)</b> The release efficiency of nanoparticles at pH 7.4 and 5.5. Results represent the mean ± SD from three independent experiments.</p

Schematic of the synthesis of POM@SiO₂ nanoparticles using in the antitumour procedure.

<p>Schematic of the synthesis of POM@SiO₂ nanoparticles using in the antitumour procedure.</p

Effect of nanocomposites on the absorption spectra of HSA.

<p><b>(a)</b> UV-vis spectra of 2.5 μM HSA, <b>(b)</b> POM@SiO₂ nanoparticles (4 mg/mL) and <b>(c)</b> nanoparticles-HSA complex.</p

Cell cycle arrest effect of nanoparticles on MCF-7 cells.

<p><b>(a)</b> Cells were treated with POM@SiO₂ nanoparticles (corresponding POM concentration of 20, 40, 80 μg/mL) for 24 h. The distribution of cell cycle was detected by FCM with PI staining. The percentages of G₁, S, G₂ phase were calculated using ModFit LT software. <b>(b)</b> Statistical results of S phase cells. Results represent the mean ± SD from three independent experiments. *<i>P</i> < 0.05 for G₁ phase <i>vs</i>. control. **<i>P</i> < 0.01 for S phase <i>vs</i>. control.</p

Effect of POM@SiO₂ on the expressions of β-actin, Bcl-2, and cleaved caspase 3 proteins.

<p>The MCF-7 cells were treated with different concentrations of POM@SiO₂ nanoparticles (corresponding POM concentration of 20, 40, 80 μg/mL) for 24 h. The nanoparticles induced apoptosis by inhibiting the Bcl-2 protein.</p

Annexin V-FITC/PI analysis of apoptosis in MCF-7 cancer cells induced by POM@SiO₂ nanoparticles.

<p>The corresponding POM concentration is 80 μg/mL. Cells were incubated with nanoparticles for 24 h. The lower-right panel presents early apoptotic cells, whereas the upper-right panel displays late apoptotic cells. <b>(a)</b>The control group. <b>(b)</b> The POM@ SiO₂ treated group.</p

Hoechst 33342/PI dye shows the normal and dead cells.

<p>MCF-7 cells treated with POM@SiO₂ nanoparticles (corresponding POM concentration of 80 μg/mL) at 24 h and stained with Hoechst 33342/PI dye. Scale bar is 60 μm (Original magnification 20 ×).</p