Interactive effects of ZnO nanoparticles and temperature on molecular and cellular stress responses of the blue mussel Mytilus edulis

Temperature is an important abiotic factor that modulates all aspects of ectotherm physiology, including sensitivity to pollutants. Nanoparticles are emerging pollutants in coastal environments, and their potential to cause toxicity in marine organisms is a cause for concern. Here we studied the interactive effects of temperature (including seasonal and experimental warming) on sublethal toxicity of ZnO nanoparticles (nano-ZnO) in a model marine bivalve, the blue mussel Mytilus edulis. Molecular markers were used to assess the pollutant-induced cellular stress responses in the gills and the digestive gland of mussels exposed for 21 days to 10 μg l^-1 and 100 μg l^-1 of nano-ZnO or dissolved Zn under different temperature regimes including ambient temperature (10 °C and 15 °C in winter and summer, respectively) or experimental warming (+5 °C). Exposure to high concentration (100 μg l^-1) of nano-ZnO caused oxidative injury to proteins and lipids and induced a marked apoptotic response indicated by increased transcript levels of apoptosis-related genes p53, caspase 3 and the MAPK pathway (JNK and p38) and decreased mRNA expression of anti-apoptotic Bcl-2. No significant induction of inflammatory cytokine-related response (TGF-β and NF-κB) of tissues was observed in nano-ZnO exposed-mussels. Furthermore, the oxidative injury and apoptotic response could differentiate the effects of nano-ZnO from those of dissolved Zn in the mussels. This study revealed that oxidative stress and stress-related transcriptional responses to nano-ZnO were strongly modified by warming and season in the mussels. No single biomarker could be shown to consistently respond to nano-ZnO in all experimental groups, which implies that multiple biomarkers are needed to assess nano-ZnO toxicity to marine organisms under the variable environmental conditions of coastal habitats.

Agglomeration-Free Preparation of Modified Silica Nanoparticles for Emulsion Polymerization-A Well Scalable Process

To prepare modified silica nanospheres for emulsion polymerization, a new agglomeration-free change of dispersion media has been developed. Nanosized silica spheres were synthesized by the Stöber method and directly modified with a silane coupling agent. To prepare these particles for subsequent polymerization, the dispersion medium was changed in a two-step process from ethanol to water without agglomeration of the particles. The emulsion polymerization leads to hemispherical single-core-structured silica-polystyrene composite particles. The thickness of the polymer shell can be altered by varying the amount of styrene. The developed change of dispersion media provides nonagglomerated modified silica particles for the encapsulation with polystyrene and enables the synthesis of narrowly distributed single-core composite particles. The developed process is a promising approach for the preparation of nanoparticles for subsequent polymerization and can be scaled-up for industrial applications.

Novel carbon nitride composites with improved visible light absorption synthesized in ZnCl2-based salt melts

The outcome of the ionothermal condensation of melamine in ZnCl₂-containing salt melts can be directed to poly(triazine imides), MOF-like hybrid materials or zinc cyanamide/C₃N₄ composites by careful selection of reaction conditions.

Enhanced dielectric properties of sol–gel-BaTiO3/P(VDF-HFP) composite films without surface functionalization

BaTiO₃–P(VDF-HFP) composite films without surface functionalization show a tenfold increase of the relative permittivity compared to the pure polymer.

Improving carbon nitride photocatalysis by supramolecular preorganization of monomers

Here we report a new and simple synthetic pathway to form ordered, hollow carbon nitride structures, using a cyanuric acid-melamine (CM) complex in ethanol as a starting product. A detailed analysis of the optical and photocatalytic properties shows that optimum hollow carbon nitride structures are formed after 8 h of condensation. For this condensation time, we find a significantly reduced fluorescence intensity and lifetime, indicating the formation of new, nonradiative deactivation pathways, probably involving charge-transfer processes. Enhanced charge transfer is seen as well from a drastic increase of the photocatalytic activity in the degradation of rhodamine B dye, which is shown to proceed via photoinduced hole transfer. Moreover, we show that various CM morphologies can be obtained using different solvents, which leads to diverse ordered carbon nitride architectures. In all cases, the CM-C3N4 structures exhibited superior photocatalytic activity compared to the bulk material. The utilization of CM hydrogen-bonded complexes opens new opportunities for the significant improvement of carbon nitride synthesis, structure, and optical properties toward an efficient photoactive material for catalysis.