Mesoporous carbon nanomaterials induced pulmonary surfactant inhibition,cytotoxicity,inflammation and lung fibrosis

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 10 μg/mL MCNs induced biophysical inhibition of natural pulmonary surfactant. Moreover, MCNs at similar concentrations reduced viability of J774 A.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.

Tricrystalline TiO_2 with enhanced photocatalytic activity and durability for removing volatile organic compounds from indoor air

It is important to develop efficient and economic techniques for removing volatile organic compounds（VOCs） in indoor air. Heterogeneous Ti O2-based semiconductors are a promising technology for achieving this goal. Anatase/brookite/rutile tricrystalline Ti O2 with mesoporous structure was synthesized by a low-temperature hydrothermal route in the presence of HNO3.The obtained samples were characterized by X-ray diffraction and N2 adsorption-desorption isotherm. The photocatalytic activity was evaluated by photocatalytic decomposition of toluene in air under UV light illumination. The results show that tricrystalline Ti O2 exhibited higher photocatalytic activity and durability toward gaseous toluene than bicrystalline Ti O2,due to the synergistic effects of high surface area, uniform mesoporous structure and junctions among mixed phases. The tricrystalline Ti O2 prepared at R HNO3= 0.8, containing80.7% anatase, 15.6% brookite and 3.7% rutile, exhibited the highest photocatalytic activity,about 3.85-fold higher than that of P25. The high activity did not significantly degrade even after five reuse cycles. In conclusion, it is expected that our study regarding gas-phase degradation of toluene over tricrystalline Ti O2 will enrich the chemistry of the Ti O2-based materials as photocatalysts for environmental remediation and stimulate further research interest on this intriguing topic.