Ultrafine Particles: Geiser et al. Respond

The use of heterogeneous chemistry for the characterization of functional groups at the gas/particle interface of soot and TiO2 nanoparticles

“…Trimethylamine is a strong base in the gas phase as measured by its proton affinity (PA = 942 kJ Mol -1 compared to 854 kJ Mol -1 for NH 3 ) 28 and is designed to probe strong as well as weak Lewis acidic interfacial sites according to reaction (5) in which the acidic site is…”

“…Particulate matter PM 10 , PM 2.5 and PM 1 which comprise particles whose effective aerodynamic diameter is smaller than 10.0, 2.5 and 1.0 µm, respectively, is sampled in the field on a routine basis. A small fraction of PM 1 , predominantly the ultrafine fraction of less than 100 nm in diameter, is thought to spontaneously cross cellular membranes, both in vitro and in vivo, a process called translocation 4,5 . However, to date the molecular mechanism by which the fine (< 1 µm diameter) and ultrafine (< 0.1 µm) fraction cross cellular borders is not known with certainty.…”

In vitro assessments of nanomaterial toxicity

“…For circulating particles, the liver consistently plays a prominent role in normal host particle clearance, performed by liver-resident Kupffer cells and not hepatocytes [108]. Cell lines selected as models of liver toxicity include Hep2G [109], and BRL3A, an immortalized rat liver cell line chosen simply for its convenience in modeling liver cell toxicity [110]. Therefore, common cell toxicity endpoints -- cellular morphology, mitochondrial function (MTT assay), membrane leakage of lactate dehydrogenase (LDH assay), reduced glutathione (GSH) levels, reactive oxygen species (ROS), and mitochondrial membrane potential (MMP) are assayed.…”

Exposure of sticklebacks (Gasterosteus aculeatus) to cadmium sulfide nanoparticles: Biological effects and the importance of experimental design

“…Engineered nanoparticles (ENPs) are being developed due to their unique physico-chemical properties, including elevated surface: volume ratio, size-dependent optical properties, highly reactive nature and ability to penetrate cellular barriers (Li et al, 2003;Geiser et al, 2005). However, these same properties have precipitated concerns over their fate in, and effect on, the environment (Owen and Depledge, 2005).…”

“…The number of males engaged in nest-building behaviour following exposure to 500 lg l À1 nCdS was reduced and livers of 4/6 fish in the same treatment displayed hepatocellular nuclear pleomorphism. The results are discussed emphasising the fundamental importance of experimental design and the need to understand the behaviour of nanoparticles in the aqueous phase.Engineered nanoparticles (ENPs) are being developed due to their unique physico-chemical properties, including elevated surface: volume ratio, size-dependent optical properties, highly reactive nature and ability to penetrate cellular barriers (Li et al, 2003;Geiser et al, 2005). However, these same properties have precipitated concerns over their fate in, and effect on, the environment (Owen and Depledge, 2005).…”