The recent reports of the potential medical risks associated with carbon nanotubes, with a study in Nature showing asbestos-like responses in mice, has highlighted the urgent need for toxicity studies with nanomaterials.
But with so many new materials being created, and a huge variety of ways which toxicity can be measured, what is the best way for this field to go forward? The gold standard for examining toxicity of any material is animal testing, which is a laborious and costly process. Animal testing also tends to focus testing few types of material at a time, when there are many factors which may contribute towards nanomaterial toxicity including particle shape, size, composition and surface.
So why not go the way that drug discovery has gone in the last couple of decades, and get robots to do the work for you? Exactly this has been done by a group of researchers headed by Stanley Shaw at the Massachusetts General Hospital in Boston. Their approach, reported in the latest issue of PNAS, uses a cell-based assay. Human and mouse cells from different tissues including liver and blood were placed into small wells. A robot was then used to dispense the different nanoparticles into each well. In this initial study they have tested 50 different types of nanoparticles at a time, testing each nanoparticle at different concentrations. Various cellular markers of viability and metabolic activity were then measured in response to the addition of the nanoparticles, to create a profile for each material tested. This makes this study one of the largest of it’s kind so far, analysing about 24,000 different wells for nanotoxicity!
Nanoparticles that clustered together showing similar profiles in the cell assay were then tested by injection into mice, and showed that they also behaved similarly in vivo.
Whilst tests like this will never replace animal toxicity studies, it provides a much better starting point, allowing researchers to identify new particles whose effects on cells are similar to those of particles that are known to be safe. This makes it easier to pick which ones to test in animals.
This pilot study holds promise for allowing researchers to rapidly evaluate the ever increasing number of nanomaterials produced, something that consumers are demanding of these new products.
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