Comparison of the Biological Activity Between Ultrafine and Fine Titanium Dioxide Particles in RAW 264.7 Cells Associated with Oxidative Stress

Abstract

Ultrafine or fine titanium dioxide (TiO(2)) particles are widely used in the production of white pigments, for sunscreens, and in cleanup techniques. However, currently knowledge is deficient concerning cellular responses to these particles. The study evaluated and compared the biological activity of ultrafine and fine TiO(2) particles in RAW 264.7 macrophages according to an oxidative stress paradigm. In vitro exposure of macrophages to ultrafine or fine TiO(2) in the range of 0.5-200 microg/ml did not significantly alter cell viability. However, ultrafine TiO(2) enhanced intracellular generation of reactive oxygen species (ROS) to a greater extent than fine TiO(2) at each exposure concentration. Ultrafine TiO(2) induced ERK1/2 activation in a concentration-dependent manner, while the fine TiO(2)-induced changes were minimal. Phosphorylation of ERK1/2 occurred following 10 min exposure to higher concentrations of ultrafine TiO(2) (> or = 25 microg/ml). Similarly, ultrafine TiO(2) exposure significantly enhanced tumor necrosis factor (TNF)-alpha and macrophage inflammatory protein (MIP)-2 secretion in a concentration-dependent manner, and its potency was higher than fine TiO(2). These findings suggest that when exposure concentration is based upon equivalent mass, ultrafine TiO(2) exerts greater biological activity as measured by ROS generation, ERK 1/2 activation, and proinflammatory mediator secretion in RAW 264.7 macrophages than fine TiO(2).

Biological toxicity of cellulose nanocrystals (CNCs) against the luxCDABE-based bioluminescent bioreporter Escherichia coli 652T7

“…Bioluminescent bioreporters have been used to study the toxicity effects of carbon-based nanomaterials (Jia et al 2014a;Kang et al 2008;Lee et al 2014), but few studies centered specifically on the toxicity of CNCs have been reported. In this work, our aim is to apply the bioluminescent bioreporter E. coli 652T7 for profiling the biological toxicity of CNCs to establish a more comprehensive risk assessment knowledge base.…”

Evaluation of the toxicity of graphene derivatives on cells of the lung luminal surface

“…Several studies proposed oxidative stress as a key mechanism involved in the toxicity of various nanomaterials [31,[45][46][47] that results from the imbalance between excessive [12,31,40,48], which is based on the conversion of the non-fluorescent 2 0 ,7 0 -dichlorodihydrofluorescein diacetate to the highly fluorescent 2 0 ,7 0 -dichlorofluorescein; the substrate is oxidized preferentially by peroxides [39,49]. GO enhanced the formation of intracellular ROS in both A549 and RAW 264.7 cells at the highest concentration of 12.5 lg/cm 2 up to 3.5-times compared to control cells, already after 30 min (Fig.…”

“…The original method was described by Wan et al [39], and has been already used in other studies on NM toxicity [12,31,40] and moreover, it is the assay recommended by the NANOMMUNE consortium http://ki.projectcoordinator.net/projectweb/490599f501abc/ Index.html). The non-fluorescent 2 0 ,7 0 -dichlorodihydrofluorescein diacetate (H 2 DCF-DA, Molecular Probes) is a cell permeable dye due to its diacetate group.…”

Role of Chemical Composition in Determining the Cardiovascular Effects of Particles

“…Rats exposed to three forms of ultrafi ne TiO 2 particles and quartz particles confi rmed that the quartz produced greater pulmonary infl ammation, cytotoxicity, and adverse lung tissue effects than rutile and anatase/ rutile UFPs, suggesting that crystal structure, inherent pH of the particles, and surface chemical reactivity are important determinants of UFP toxicity (Warheit et al, 2007 ). Comparison of the oxidative potential between ultrafi ne and fi ne TiO 2 in vitro found that, at equivalent mass, TiO 2 NPs were more potent in inducing intracellular generation of reactive oxygen species, extracellular regulated kinase (ERK) phosphorylation, and release of tumor necrosis factor -alpha (TNF -α ) and MIP -2 than fi ne TiO 2 (Kang et al, 2008 ). In monocytic cells, ultrafi ne TiO 2 induced MAP kinase activation and release of infl ammatory mediators in a concentration -dependent manner.…”