Effect of Silica Nanomaterial Shape

Although, until now, investigations into the effect of nanomaterial shape on toxicity have been limited in number, currently available information suggests that the shape of a nanomaterial can affect its toxicity in two ways. First, the shape of a nanomaterial has an effect on the rate of its cellular uptake and second, the shape of a nanomaterial can affect the extent of its aggregation, and hence alter its cytotoxic properties. 

An initial study of the toxicity of carbon nanotubes and fuUerene implied that fiber-shaped nanomaterials were more toxic than spherical nanomaterials [25]. In the case of the carbon nanotube, its shape appeared to hamper the processes of endo-cytosis and phagocytosis, such that chronic pulmonary toxicity occurred. However, a recent in vitro toxicity study using different sizes of sihca nanomaterials showed spherical nanomaterials be more toxic than rods [68]. The suggested reason for this was that the sihca nanorod aggregated much more easily than the spherical sihca nanomaterials consequently, the large aggregates not only reduced the surface area-to-volume ratio of the nanomaterials but also slowed their rate of cehular uptake. It was also shown to be more difficult for ehiphcal nanomaterials to penetrate the skin layer than spherical ones [98]. Overall, however, the results of these studies indicated that the shape of nanomaterials could indeed affect their toxicity. 

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