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-ß 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.

Core-shell designs of photoluminescent nanodiamonds with porous silica coatings for bioimaging and drug delivery I: fabrication.

A multifunctional core-shell nanocomposite platform consisting of a photoluminescent nanodiamond (ND) core with uniform porous silica coatings is presented. This design intended for drug delivery applications allows simultaneous stable fluorescent imaging with high loading capacity of bioactive molecules. Despite irregularly shaped starting cores, well-dispersed and uniformly shaped nanocomposite particles can be produced. Moreover, after optimization of the silica source-to-diamond ratio, the thickness of the porous layer can be tuned by adjusting the ethanol amount, allowing rational nanoparticle size control. The ND key property, photoluminescence, is not quenched regardless of coating with thick silica layers. The high loading capacity for incorporation of active agents, provided by the introduced porous layer, is demonstrated by adsorption of a hydrophobic model drug to the composite particles. The loading degree, as compared to a pure ND, increased by two orders of magnitude from 1 wt% for the ND to >100 wt% for the composite particles. Combining these two material classes, which both have well-documented excellent performance especially in biomedical applications, for the NDs with emphasis, but not exclusively, on imaging and mesoporous silica (MSN) on drug delivery, the advantages of both are shown here to be synergistically integrated into one multifunctional nanocomposite platform.