Toxicity of Silica Nanomaterials A Summary

Dopants may also leak from the silica matrix, and if this occurs then the toxicity of the silica nanomaterials will be altered. However, under certain circumstances, leakage can be deliberately induced, an example being in the case of drug delivery. Here, anticancer drugs can be doped inside a siUca matrix and then delivered to target cells [15, 21, 26] the subsequent intracellular release of the drug molecules would then result in death of the cancer cells. 

The duration of treatment with nanomaterials in living systems is another important factor that affects silica nanomaterial-induced toxicity. Whilst for in vitro studies a greater toxicity was observed with a prolonged treatment (several days) 

The toxicity of amorphous silica nanomaterials has been investigated both in in vitro and in vivo. Although the severity of the toxic reaction increases as the size of the amorphous silica is reduced to the nanometer scale, compared to metal-containing nanomaterials silica nanomaterials exhibit a relatively lower toxicity, due to their amorphous sihca structure. Among in vitro studies, no significant toxic effect was observed for sihca nanomaterials at concentrations up to lOOngmT  

In summary, whilst the toxicity of silica nanomaterials is generally low-and even more so at lower concentrations-a variety of factors which include the nanomaterials size, shape, surface properties, dopants, treatment dose and time, all affect their toxicity to similar degrees. Although such toxicity is a relatively recently investigated topic, and many studies are still at the experimental stages, the above-described factors are crucial for the safe use of silica nanomaterials in a variety of biological applications. 

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