[en] The majority of in vitro studies characterizing the impact of engineered nanoparticles (NPs) on cells that line the respiratory tract were conducted in cells exposed to NPs in suspension. This approach introduces processes that are unlikely to occur during inhaled NP exposures in vivo, such as the shedding of toxic doses of dissolved ions. ZnO NPs are used extensively and pose significant sources for human exposure. Exposures to airborne ZnO NPs can induce adverse effects, but the relevance of the dissolved Zn2+ to the observed effects in vivo is still unclear. Our goal was to mimic in vivo exposures to airborne NPs and decipher the contribution of the intact NP from the contribution of the dissolved ions to airborne ZnO NP toxicity. We established the exposure of alveolar type II epithelial cells to aerosolized NPs at the air-liquid interface (ALI), and compared the impact of aerosolized ZnO NPs and NPs in suspension at the same cellular doses, measured as the number of particles per cell. By evaluating membrane integrity and cell viability 6 and 24 hours post exposure we found that aerosolized NPs induced toxicity at the ALI at doses that were in the same order of magnitude as doses required to induce toxicity in submersed cultures. In addition, distinct patterns of oxidative stress were observed in the two exposure systems. These observations unravel the ability of airborne ZnO NPs to induce toxicity without the contribution of dissolved Zn2+ and suggest distinct mechanisms at the ALI and in submersed cultures.

[en] As a first step toward improving the treatment of stroke, we are developing a magnetic carrier system to target tissue plasminogen activator (tPA) to a thrombosis. We report the characterization of biodegradable microspheres containing tPA and magnetic iron oxide. The resultant microspheres were superparamagnetic with a magnetization of 6.9-8.7emu/g. We encapsulated 5% tPA by mass which eluted from the microspheres to produce a solution concentration of 5.3-19.6μg/mL in tPA, which exceeds the theoretical thrombolysis concentration. Although smaller microspheres will be necessary for in vivo experiments, we have shown that sufficient tPA can be encapsulated and released in a magnetic matrix

[en] In this study, the simulant biotoxin (biotinylated horseradish peroxidase) was efficiently removed from simple electrolyte solutions and blood using a highly selective complexation reaction (biotin-avidin). Sequestration of the biotoxin is realized with streptavidin-functionalized magnetic nanoparticles that selectively capture the biotoxin. Quantitative removal of the model toxin is achieved using an external magnetic field to trap the toxin-bound particles