A study of the decomposition behaviour for Ammonium Perchlorate(AP) was carried out by differential thermal analysis and the two decomposition peaks were observed. The high temperature peak was found to shift to lower temperatures, but the corresponding shift in the low temperature peak was smaller due to the effect of nanometer metal powders. Results shows that Cu and NiCu nanopowders decreased both the high and low decomposition temperature, while Ni and Al nanopowders just decreased the high decomposition temperature and increased the low decomposition temperature. Metal micron‐sized powders show catalytic effects on the thermal decomposition of AP, but their effects are less than that of nanometer metal powders. With the increase in content, nanometer metal powders enhanced their catalytic effect on the high temperature decomposition of AP, however their effect was weakened on the low temperature decomposition.

Pulmonary surfactant (PS) is a lipid-protein complex that adsorbs to the air-water surface of the lung as a thin film. Previous studies have suggested that the adsorbed PS film is composed of an interfacial monolayer, plus a functionally attached vesicular complex, called the surface-associated surfactant reservoir. However, direct visualization of the lateral structure and morphology of adsorbed PS films using atomic force microscopy (AFM) has been proven to be technically challenging. To date, all AFM studies of the PS film have relied on the model of Langmuir monolayers. Here, we showed the first, to our knowledge, AFM imaging of adsorbed PS films under physiologically relevant conditions using a novel, to our knowledge, experimental methodology called constrained drop surfactometry. In conjunction with a series of methodological innovations, including subphase replacement, in situ Langmuir-Blodgett transfer, and real-time surface tension control using closed-loop axisymmetric drop shape analysis, constrained drop surfactometry allowed the study of lateral structure and topography of animal-derived natural PS films at physiologically relevant low surface tensions. Our data suggested that a nucleation-growth model is responsible for the adsorption-induced squeeze-out of the PS film, which likely results in an interfacial monolayer enriched in dipalmitoylphosphatidylcholine with the attached multilayered surface-associated surfactant reservoir. These findings were further supported by frequency-dependent measurements of surface dilational rheology. Our study provides novel, to our knowledge, biophysical insights into the understanding of the mechanisms by which the PS film attains low surface tensions and stabilizes the alveolar surface.

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With the rapid development of nanotechnology and an increasing use of nanoenabled consumer products, there is an urgent need to develop precautionary tools to evaluate acute lung toxicity of engineered nanomaterials (ENMs). As natural pulmonary surfactant (PS) film represents the initial barrier of nano–bio interactions in the lungs, a novel in vitro experimental method, called constrained drop surfactometry (CDS), is developed to quantitatively evaluate PS inhibition caused by ENMs. The results show that at a very low concentration, four representative ENMs, including carbon nanotubes, graphene oxide, zinc oxide, and silver nanoparticles, all increase in vitro minimum surface tension of a modified natural PS, Infasurf. These in vitro results are related to the extensive alveolar collapse and inflammation observed in vivo in mice exposed to these ENMs in an intratracheal instillation model. Thus, there may be a direct correlation between in vitro surface tension increase due to PS inhibition by ENMs and in vivo lung toxicity revealed by alveolar collapse and inflammation. Compared to commonly used animal models, CDS holds great promise for the development of an animal‐free, easy‐to‐use, and low‐cost precautionary assay for the prediction of acute lung toxicity of inhaled ENMs.

Environmental exposure and health risk upon engineered nanomaterials are increasingly concerned. The family of mesoporous carbon nanomaterials (MCNs) is a rising star in nanotechnology for multidisciplinary research with versatile applications in electronics, energy and gas storage, and biomedicine. Meanwhile, there is mounting concern on their environmental health risks due to the growing production and usage of MCNs. The lung is the primary site for particle invasion under environmental exposure to nanomaterials. Here, we studied the comprehensive toxicological profile of MCNs in the lung under the scenario of moderate environmental exposure. It was found that at a low concentration of 10μg/mL MCNs induced biophysical inhibition of natural pulmonary surfactant. Moreover, MCNs at similar concentrations reduced viability of J774A.1 macrophages and lung epithelial A549 cells. Incubating with nature pulmonary surfactant effectively reduced the cytotoxicity of MCNs. Regarding the pro-inflammatory responses, MCNs activated macrophages in vitro, and stimulated lung inflammation in mice after inhalation exposure, associated with lung fibrosis. Moreover, we found that the size of MCNs played a significant role in regulating cytotoxicity and pro-inflammatory potential of this nanomaterial. In general, larger MCNs induced more pronounced cytotoxic and pro-inflammatory effects than their smaller counterparts. Our results provided valuable information on the toxicological profile and environmental health risks of MCNs, and suggested that fine-tuning the size of MCNs could be a practical precautionary design strategy to increase safety and biocompatibility of this nanomaterial.

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Metal-based nanomaterials (MNMs) represent a large category of the engineered nanomaterials, and have been extensively used to enhance the electrical, optical, and magnetic properties of nanoenabled consumer products. Inhaled MNMs can penetrate deeply into the peripheral lung at which they first interact with the pulmonary surfactant (PS) lining of alveoli. Here we studied the biophysical inhibitory potential of representative MNMs on a modified natural PS, Infasurf, using a novel in vitro experimental methodology called the constrained drop surfactometry (CDS). It was found that the biophysical inhibitory potential of six MNMs on Infasurf ranks in the order CeO > ZnO > TiO > Ag > FeO > ZrO-CeO. This rank of in vitro biophysical inhibition is in general agreement with the in vitro and in vivo toxicity of these MNMs. Directly imaging the lateral structure and molecular conformation of the PS film using atomic force microscopy revealed that there exists a correlation between biophysical inhibition of the PS film by the MNMs and their aggregation state at the PS film. Taken together, our study suggests that the nano-bio interactions at the PS film are determined by multiple physicochemical properties of the MNMs, including not only well-studied properties such as their chemical composition and particle size, but also properties such as hydrophobicity, dissolution rate, and aggregation state at the PS film found here. Our study provides novel insight into the understanding of nanotoxicology and metallomics of MNMs.