In biotechnology, different types of nanoparticles have found extensive use in the cosmetics industry and medicine. In biomedicine, they are used as tools such as imaging agents and drug carriers. For example, liposomes are commonly applied nanoparticles used for delivery of therapeutic drugs, vaccines or other molecules. Another fast developing trend in biomedicine, therapeutic use of siRNA, has been combined with nanotechnology for treatment of cancer. Use of a nanoparticle/ siRNA delivery system prevents the RNA molecules from being destroyed by the body before reaching their target. For example, a delivery system in which nanoparticles are used to transport siRNA into cells has been reported for treatment of Ewing’s Sarcoma. The siRNA molecules target growth-promoting genes in sarcoma tumors and use of this delivery system was shown to reduce cell replication in mice grafted with human tumors, by up to 80%.
Because of their ultra-small size, nanoparticles can penetrate cell membranes and integrate themselves into larger molecules. They can resist cellular defense systems but are large enough to interfere with cell processes. Despite widespread use in public consumables such as makeup and creams, and the knowledge that very traits that make them useful might also render them toxic, thorough testing on the safety of nanoparticles, once absorbed through the skin, has not been done. When used for remediation, their release in the environment is also risky due to possible exposure to humans and other animal species.
In a press release on April 17, 2007, the American Association for Cancer Research (AACR) reported research presented at the 2007 annual meeting that suggests nanoparticles could cause cancer and should be thoroughly investigated and used with caution. Researchers at the University of Massachusetts studied two types of nanoparticles (silica and C60 fullerene), in MCF-7 and breast cancer cells, and found an increase in DNA damage (single and double-stranded breakages) with both dose- and time-dependent results.
Although DNA breakages do not necessarily mean a substance is cancer-causing, it is widely accepted that chemicals causing DNA damage are highly likely to promote mutations which can lead to cancer.
There are different types of nanoparticles including the fullerenes (buckyballs) which are known to attract electrons and cause generation of damaging free radicals. Nanotubes are carbon-based tubes that can be used as carriers for drugs. Modifications to the carbon surface of nanotubes, making them more soluble, have been shown to reduce their toxicity. Fullerenes can also be modified to reduce free radical formation and make them less toxic.