Response of the Intertidal Microbial Community Structure and Metabolic Profiles to Zinc Oxide Nanoparticle Exposure.

The toxicity of nanomaterials to microorganisms is related to their dose and environmental factors. The aim of this study was to investigate the shifts in the microbial community structure and metabolic profiles and to evaluate the environmental factors in a laboratory scale intertidal wetland system exposed to zinc oxide nanoparticles (ZnO NPs). Microbial assemblages were determined using 16S rRNA high-throughput sequencing. Community-level physiological profiles were determined using Biolog-ECO technology. Results showed Proteobacteria was the predominant (42.6%-55.8%) phylum across all the sediments, followed by Bacteroidetes (18.9%-29.0%). The genera Azoarcus, Maribacter, and Thauera were most frequently detected. At the studied concentrations (40 mg·L-1, 80 mg·L-1, 120 mg·L-1), ZnO NPs had obvious impacts on the activity of Proteobacteria. Adverse effects were particularly evident in sulfur and nitrogen cycling bacteria such as Sulfitobacter, unidentified_Nitrospiraceae, Thauera, and Azoarcus. The alpha diversity index of microbial community did not reflect stronger biological toxicity in the groups with high NP concentrations (80 mg·L-1, 120 mg·L-1) than the group with low NP concentration (40 mg·L-1). The average well color development (AWCD) values of periodically submersed groups were higher than those of long-term submersed groups. The group with NP concentration (40 mg·L-1) had the lowest AWCD value; those of the groups with high NP concentrations (80 mg·L-1, 120 mg·L-1) were slightly lower than that of the control group. The beta diversity showed that tidal activity shaped the similar microbial community among the periodically submerged groups, as well as the long-term submerged groups. The groups with high DO concentrations had higher diversity of the microbial community, better metabolic ability, and stronger resistance to ZnO NPs than the groups with a low DO concentration.

Applications of polymeric nanocapsules in field of drug delivery systems.

Drug-loaded polymeric nanocapsules have exhibited potential applications in the field of drug delivery systems in recent years. This article entails the biodegradable polymers generally used for preparing nanocapsules, which include both natural polymers and synthetic polymers. Furthermore, the article presents a general review of the different preparation methods: nanoprecipitation method, emulsion-diffusion method, double emulsification method, emulsion-coacervation method, layer-by-layer assembly method. In addition, the analysis methods of nanocapsule characteristics, such as mean size, morphology, surface characteristics, shell thickness, encapsulation efficiency, active substance release, dispersion stability, are mentioned. Also, the applications of nanocapsules as carriers for use in drug delivery systems are reviewed, which primarily involve targeting drug delivery, controlled/sustained release drug delivery systems, transdermal drug delivery systems and improving stability and bioavailability of drugs. Nanocapsules, prepared with different biodegradable polymers, have received more and more attention and have been regarded as one of the most promising drug delivery systems.

Nanosuspensions of poorly soluble drugs: preparation and development by wet milling.

Nanosizing techniques are important tools for improving the bioavailability of water insoluble drugs. Here, a rapid wet milling method was employed to prepare nanosuspensions: 4 types of stabilizers at 4 different concentrations were tested on 2 structurally different drug compounds: indomethacin and itraconazole. Photon correlation spectroscopy (PCS) results showed that the finest nanosuspensions were obtained when 80 wt% (to drug amount) pluronic F68 was the stabilizer for indomethacin and 60 wt% pluronic F127 for itraconazole. Compared to physical mixtures, dissolution rates of the nanosuspensions showed significant increases. The morphology of nanoparticles was observed by transmission electron microscopy (TEM). Crystalline state of the drugs before and after milling was confirmed using differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD). The physical and chemical stabilities of the nanosuspensions after storage for 2 months at room temperature and at 4°C were investigated using PCS, TEM and HPLC. No obvious changes in particle size and morphology and no chemical degradation of the drug ingredients were seen.