Comparative Cytotoxicity Study of PM2.5 and TSP Collected from Urban Areas.

Ambient particulate matter 2.5 (PM2.5) and total suspended particles (TSPs) are common airborne pollutants that cause respiratory and cardiovascular diseases. We investigated the differences of cytotoxicity and mechanism between PM2.5 and TSP activity in human alveolar epithelial A549 cells. Atmospheric samples from the central district of Seoul were collected and their chemical compositions were analyzed by inductively-coupled plasma mass spectrometry and ion chromatography. PM2.5 and TSP contained high concentrations of heavy metals (Cu, Fe, Zn, and Pb). The most abundant ions in PM2.5 were SO42-, NH4+, and NO3-. A549 cells were exposed to PM2.5 and TSP (25-200 µg/mL) for 24 h. TSP was more cytotoxic than PM2.5 per unit mass. PM2.5 induced oxidative stress, as evidenced by increased levels of a glutamate-cysteine ligase modifier, whereas low-concentration TSP increased hemeoxygenase-1 levels. PM2.5 and TSP did not affect c-Jun N-terminal kinase expression. The levels of nuclear factor erythroid 2-related factor 2 (Nrf2) in PM2.5- and TSP-treated cells decreased significantly in the cytosol and increased in the nucleus. Thus, Nrf2 may be a key transcription factor for detoxifying environmental airborne particles in A549 cells. TSP and PM2.5 could activate the protective Kelch-like ECH-associated protein 1/Nrf2 pathway in A549 cells.

Analysis of gold and silver nanoparticles internalized by zebrafish (Danio rerio) using single particle-inductively coupled plasma-mass spectrometry.

With the increase in the application of nano-consumer products containing engineered nanoparticles (NPs), the unintended environmental exposure to NPs has been inevitable. Because of the bioaccumulation of NPs, concern about their potential cytotoxicity to aquatic organisms is also growing. Although measuring tools for analyzing particle size and/or concentration of NPs in intracellular uptake of tissues have been well developed, a simultaneous analysis of the two characteristics is difficult. The objective of this study was to use single particle-inductively coupled plasma-mass spectrometry (sp-ICP-MS) to measure the bioaccumulation and particle size changes of NPs exposed to zebrafish (Danio rerio) for 7 days. The uptake of NPs in the liver, intestine, and gill tissues was confirmed by electron microscopic (EM) analysis. However, the primary particle size of NPs in tissues could not be determined by the EM analysis. Therefore, sp-ICP-MS coupled with alkaline digestion was used for the easy extraction and immediate analysis of NPs from tissues. Zebrafish were exposed to four NPs (30 and 80 nm gold/silver NPs; AuNPs/AgNPs). Uptake amounts of AgNPs in the liver and intestine were significantly higher than those of AuNPs. Although larger NPs were finally accumulated in the liver and intestine tissues, most of the smaller NPs were filtered in the gills. The sp-ICP-MS method coupled with alkaline digestion enabled the accurate analysis of size, size distribution, and mass concentration of NPs in an aquatic organism.

Green Synthesis of Metal Nanoparticles Using Sprout Plants: Pros and Cons.

A critical need in the field of nanotechnology is the development of a sustainable and eco-friendly process for the synthesis of metallic nanoparticles (NPs). To accomplish this, the use of live plants becomes essential for the production of low-cost, energy-efficient, and nontoxic metallic NPs. In this study, we tried in-vivo synthesis (green synthesis) of silver and gold NPs using seeds of bean, radish, and alfalfa, which were grown hydroponically in aqueous solutions containing metal salts, 20-25 nm sized NPs were found on the inner surfaces of the plants' vascular cylinders and cortex. The amounts of NPs taken up by the intracellular systems were clearly dependent on the exposure time and concentration of the metal salts. Although these results regarding the green synthesis of NPs on the growth of plant species are somewhat interesting and effective, metal salts adversely affected the root growth of the plants. Silver ions in the growth media showed a more negative impact on root growth compared to gold ions. Therefore, even though biosynthesis of metal NPs using live plants is considered as green synthesis, we have to consider their phytotoxicity on plant growth.

Colorimetric detection of Co2+ ion using silver nanoparticles with spherical, plate, and rod shapes.

A highly sensitive colorimetric sensing platform for the selective trace analysis for Co(2+) ions is reported, based on glutathione (GSH)-modified silver nanoparticles (AgNP). The shape of metallic nanoparticles used in colorimetric detection, using the unique optical properties of plasmonic nanoparticles, is almost spherical. Therefore, in this work we attempted to investigate the selective detection of heavy metal ion (Co(2+)), with the shape of AgNPs (nanosphere, nanoplate, and nanorod). GSH-AgNP with spherical shape shows a high sensitivity for all of the metal ions (Ni(2+), Co(2+), Cd(2+), Pb(2+), and As(3+)) but poor selective recognition for target metal ions. Whereas, AgNPs solution containing rod-type GSH-AgNP has a special response to Co(2+), and its selective detection might be based on the cooperative effect of CTAB and GSH. Therefore, Co(2+) ion could be selectively recognized using rod-type GSH-AgNPs.