Cancer Treatment "Magic Bullet" Nanoparticles Safety Tested

Medical science has long sought a “magic bullet” for cancer that would target only cancer cells, while leaving healthy cells alone. Certain nanoparticles have shown potential for this use, but one great question is whether the nanoparticles themselves might actually prove toxic to healthy cells. 

Nanoparticles of gold and ferromagnetic materials have been singled out for cancer treatments. One promising technique uses high frequency electric currents that cause the particles to heat and kill cancer cells from the inside. One of the most promising types of nanoparticles for diagnosing and treating cancer is so-called upconversion nanoparticles (UCNPs). These particles convert near-infrared radiation, which can penetrate deep into human tissue, into visible light, making it possible to detect cancerous cells in body tissue. UCNPs can also be used to release drugs.

To test whether these particles are actually suitable for use in humans, researchers at the Moscow Institute of Physics and Technology State University have carried out what they claim is the first systematic study of the effects of nanoparticles on cells.

The researchers studied the properties of one of the most common types of UCNPs, which is derived from sodium yttrium fluoride (Na[YF4]) doped with the rare-earth elements. The group tested how these nanoparticles are absorbed by fibroblasts (the cells of human connective tissue)and keratinocytes (epidermal cells), and studied how nanoparticles affect these cells' viability.

The results show that the cytotoxicity of UCNPs depends on the cell type. They are not toxic for dermal fibroblasts and slightly toxic for keratinocytes. However, the toxicity for keratinocytes depends on the concentration of the nanoparticles, meaning that these cells can be used as a biological indicator for evaluating the safety of different types of UCNPs.

In addition to the "naked" nanoparticles, the researchers tested several modifications of polymer-coated nanoparticles. In these cases, the difference between the response of fibroblasts and keratinocytes was even greater. The particles coated with polyethylenimine, for example, interfered with the intracellular metabolism of the keratinocytes, but had no effect on the fibroblasts. The group identified the types of polymer coating that made the nanoparticles as safe as possible.

For more about the researchers work, as well as images that help illustrate their work, see their press release