The team, led by Xiaohui Fan from Zhejiang University in China, took a systems biology approach to assess the dose- or size-response toxicity of silica particles in mice.

Investigating the relationship between particle size and toxicity of SPs will help to reveal the underlying mechanism of SP-induced toxicity and promote the safe application of SPs in biomedicine.

Using common pathways analysis, the researchers found that the pathways activated in SP300 (300=particle diameter in nanometres) and SP70 treatments were all included in the SP30 treatment and the cellular response pathways activated were size-dependent in this experiment, indicating that SP30 may be the most toxic size among these three particle sizes of SPs and the toxicity induced by nano- or submicron-sized SP was size-dependent when the injected dose was the same.

Interestingly, when the doses were increased in SP70 and SP300 treatments, there were 130 pathways affected in common, and few pathways were affected individually in SP30, SP70 and SP300 treatments at toxic doses.

It is important to note that this study was designed with specific relevance to intravenously administered SPs in medical applications, in which case SPs have direct access to circulating blood within a few seconds. As the dose and dose-rate determine the mechanism of toxicity, and dose-dependent transitions in the mechanism of toxicity do occur, further investigations on the dose- and size-related toxicity of uptake SPs via skin, inhalation or ingestion, where SPs reach the blood circulation over an extended period of time and in very low amounts, are needed.

Full details can be found in the journal Nanotechnology.