Periplasmic bacterial biomineralization of copper sulfide nanoparticles

Metal sulfides are a common group of extracellular bacterial biominerals. Only few cases of intracellular biomineralization have been reported in this group, mostly limited to greigite (Fe3S4) in magnetotactic bacteria. Here, we report the intracellular but periplasmic biomineralization of copper sulfide by the magnetotactic bacterium Desulfamplus magnetovallimortis (strain BW-1) that is known to mineralize greigite and magnetite (Fe3O4) in the cytoplasm. BW-1 produces hundreds of spherical nanoparticles, composed of 1-2 nm substructures of a poorly crystalline hexagonal copper sulfide that remains in a thermodynamically unstable state. Differential proteomics suggests that periplasmic proteins, such as a DegP-like protein and a heavy metal-binding protein, could be involved in this process. The unexpected periplasmic formation of copper sulfide nanoparticles in BW-1 reveals previously unknown possibilities for intracellular biomineralization.

Porphyrin tripod as a monomeric building block for guest-induced reversible supramolecular polymerisation

Reversible supramolecular polymerisation and depolymerisation of biomacromolecules are common and fundamental phenomena in biological systems, which can be controlled by the selective modification of biomacromolecules through molecular recognition. Herein, a porphyrin tripod (DPZnT) connected through a triazole bridge was prepared as a monomeric building block for guest-induced supramolecular polymerisation. Although the lone pair electrons in triazolic nitrogen potentially bind to the zinc porphyrin units through axial ligation, the intrinsic steric hindrance suppressed the coordination of the triazole bridge to the porphyrin unit in DPZnT. Therefore, DPZnT formed spherical nanoparticles through π-π interactions. The addition of 1,3,5-tris(pyridine-4-yl)benzene (Py3B) caused the guest-induced fibrous supramolecular polymerisation of DPZnT by forming a 1:1 host-guest complex, which was further assembled into a fibrous polymer. Furthermore, addition of Cl− to DPZnT induced the transformation of spherical nanoparticles to fibrous supramolecular polymers. The fibrous supramolecular polymers of DPZnT obtained by adding Py3B or Cl− were depolymerised to their original spherical particles after adding Cu(ClO4)2 or AgNO3, respectively.

M13 Phages Uptake of Gold Nanoparticles for Radio- and Thermal-Therapy and Contrast Imaging Improvement

The presented work deals with the uptake of gold nanoparticles (Au NPs) by M13 phages in solutions. In particular, the Au NPs uptake modalities and their localization in the filamentous phages are evaluated and measured. Gold spherical nanoparticles (with an average diameter of the order of 10 nm) are obtained by laser ablation in water with a sodium citrated surfactant. The interest of such application comes from the possibility to employ living biological structures to transport heavy metallic nanoparticles inside cells of tumoral tissues. Indeed, phages have the capability to introduce Au NPs in the proximity to the cell nucleus, increasing the efficiency of DNA destruction in the tumoral cells by employing low doses of ionizing radiation during radiotherapy and hyperthermia treatments. Several analyses and microscopy characterizations of the prepared phages samples embedding gold nanoparticles are presented, demonstrating that the presence of Au NPs increases the phages imaging contrast.

Blending Ratio Effect of ZnPc/ZnO Hybrid Nanocomposite on Surface Morphology and Structural Properties

Recently, organic/inorganic hybrid nanocomposites being the future in electronic applications. In this paper, we have investigated hybrid nanocomposite zinc phthalocyanine (ZnPc)/zinc oxide nanoparticles (ZnO). ZnPc/ZnO hybrid nanocomposites were prepared with different ratios (wt/wt) (1/0), (0/1), (0.75/0.25), (0.5/0.5), (0.25/0.75), and, deposited on glass substrates by spin coating technique. X-Ray diffraction investigate the structural of ZnPc/ZnO thin films and studied the morphological properties using field emission scan electron microscopy, the surface of ZnPc/ZnO hybrid nanocomposites shows the presence of nanorod-like structures represented the organic material (ZnPc) and spherical nanoparticles for (ZnO), that is depending on the ratio of the blend. In ratio (0.5/0.5) we get the preferred homogeneous surface between like-nanorod and spherical shapes were show various properties from pure compounds which used to prepare the blend. The distribution of ZnO nanoparticles on ZnPc particles nanorods led to the disappearance feature of ZnO morphological characterize and ZnPc decorated was dominated on the hybrid nanocomposite structure.

Using high refractive index nanoparticles to inhibition of spontaneous emission

The article discusses the issues of inhibition of spontaneous emission of molecules by using silicon spherical nanoparticles and dimers made from them. It is shown that at different wavelengths of the visible spectral range, the value of the total spontaneous transitions rate in a molecule located at an optimal distance with respect to the structure with silicon nanospheres and at an optimal size of the structure can be up to 5–10 times lower than the transition rate in the case when the nanoparticles are absent.

Tungsten disulfide nanoparticles produced by femtosecond laser ablation in water for nanophotonic applications

We demonstrate nearly spherical nanoparticles of tungsten disulfide (WS2) produced by femtosecond pulsed laser ablation of bulk target in deionized water. Structural and optical analysis reveals that produced nanospheres preserve the crystalline structure, high refractive index and support strong excitons and Mie resonances in the spectral range 400-700 nm, resulting in enhanced photothermal response probed by Raman spectroscopy.

The Size and Shape Effects on the Melting Point of Nanoparticles Based on the Lennard-Jones Potential Function

A model is proposed to calculate the melting points of nanoparticles based on the Lennard-Jones (L-J) potential function. The effects of the size, the shape, and the atomic volume and surface packing of the nanoparticles are considered in the model. The model, based on the L-J potential function for spherical nanoparticles, agrees with the experimental values of gold (Au) and lead (Pb) nanoparticles. The model, based on the L-J potential function, is consistent with Qi and Wang’s model that predicts the Gibbs-Thompson relation. Moreover, the model based on the non-integer L-J potential function can be used to predict the melting points of nanoparticles.