Nanomaterials toxicity

Jones, C.F. and Grainger, D.W. (2009) In vitro assessments of nanomaterial toxicity. Advanced Drug Delivery Reviews, 61 (6), 438-456. 

Challeng es for assessing carbon nanomaterial toxicity to the skin. Carbon, 44 (6), 1070-1078. 

G. Oberdorster et al., for ILSI Research Foundation/Risk Science Institute Nanomaterial Toxicity Screening Working Group. Principles for characterizing the potential human health... 

Kumar, C. S. S. R. (2006), Nanomaterials Toxicity, Health and Environmental Issues, Wiley, Hoboken, NJ. 

Key words Nanomaterial, Toxicity, Dosimetry, Mass transport... 

C. Kitmar (Ed), Nanomaterials Toxicity (Health and Environment Issues), WILEY-VCH, Weinheirrt, 2006. ISBN 9783527313853, 3527313850. 

Although a large number of studies have investigated the cellular uptakes of many nanomaterials, the understanding of this field is still not sufficient. Fundamental mechanisms underlying internalization pathways and intracellular traffic at the molecular level are not well understood. More importantly, the correlation between cellular uptake and nanomaterial toxicity remains unclear. Further exploration of these issues will be necessary for the design and fabrication of nanotechnology-enhanced orthopedic materials. 

Despite the considerable attention that in vitro systems have received and their growing application to nanomaterial toxicity assessment (Braydich-Stolle et al., 2005 Hussain et al., 2005), little attention has been devoted to a critical examination of their suitability, particularly when it comes to particle solution dynamics and dosimetry (Teeguarden et al., 2007). In contrast to soluble chemicals, particles can settle, diffuse, and aggregate differentially according to their size, density, and surface physicochemistry... 

The poor dispersibility of CNTs in biological media can affect both the cytotoxicity [38] and the in vivo toxicity [39] of such nanomaterials. 

Degradability is an important factor in the assessment of the toxicity of nanomaterials [71]. Nondegradable nanomaterials may in fact accumulate in organs and/or intracellularly, where they would exert toxic effects. 

Herzog, E. et al. (2007) A new approach to the toxicity testing of carbon-based nanomaterials - the clonogenic assay. Toxicology Letters, 174 (1-3), 49-60. 

One of the major breakthroughs in nanotechnology is the use of nanomaterials as catalysts for environmental applications [149]. Nanomaterials have been developed to improve the properties of catalysts, enhance reactivity towards pollutants, and improve their mobility in various environmental media [150]. Nanomaterials offer applications to pollution prevention through improved catalytic processes that reduce the use of toxic chemicals and eliminate wastes. Nanomaterials also offer applications in environmental remediation and, in the near future, opportunities to create better sensors for process controls. 

The increase in environmental awareness and the acute effects of some toxic compounds have raised questions over the safety of using many chemicals invented for agricultural and industrial applications. A great deal of current research addresses the management and remediation of old contaminated sites. Recent concerns regard the safety of consumer chemicals, especially nanomaterials the effect of pharmaceuticals on ecosystems and the combined effect that chemical cocktails have on human and ecosystem health. 

Yuan G (2004) Natural and modified nanomaterials as sorbents of environmental contaminants. J Environ Sci Health, Part A Toxic/Hazardous Subst Environ Eng 39 2661-2670... 

The size of the nanomaterial greatly influences its toxicity particularly as the nanomaterial s size decreases, certain of its parameters changed [3, 11, 118, 119]. Many studies have shown that variations in the size of nanomaterials account for the different toxicity levels between nanosized and micrometer-sized materials [97, 99,100,103], It is known that a reduction in size can increase the rate of uptake and translocation of silica nanomaterials in vitro and in vivo, thereby inducing a more severe and transient toxicity [56]. 

Currently available information suggests that the shape of nanomaterials can affect their toxicity in two ways. First, the shape has an effect on the rate of its cellular uptake and second, it can affect the extent of nanomaterial aggregation, altering its cytotoxic properties. A recent in vitro toxicity study showed spherical nanomaterials to be more toxic than rods [120]. It was also shown to be more difficult for elliptical nanomaterials to penetrate the skin layer than spherical nanomaterials [121]. 

Based on well established silica chemistry, the surface of silica nanomaterials can be modified to introduce a variety of functionalizations [3, 11, 118]. The toxicity of surface-modified nanomaterials is largely determined by their surface functional groups. As an example, Kreuter reported that an apolipoprotein coating on silica nanoparticles aided their endocytosis in brain capillaries through the LDL-receptor [122-124]. Overall, silica nanomaterials are low-toxicity materials, although their toxicity can be altered by surface modifications. 

Dose-dependent toxicity has frequently been observed in the study of nanomaterials [110-116], with increasing doses of silica nanomaterials invariably worsening their toxicity. Both, cell proliferation and viability were greatly hampered at higher doses in in vitro studies [111, 113, 116]. 

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