ORLANDO – “The diameter of a single hair shaft is tens of thousands of nanometers,” said Dr. Adam Friedman. Nanotechnology is the branch of technology related to dimensions and tolerances ranging from 0.1 to 100 nanometers.
“At this size, matter behaves somewhat differently,” Dr. Friedman, of Albert Einstein Medical Center in New York, said. As the size of material decreases, the surface area relative to volume decreases. There is more surface to interact with the environment.
“The three properties of matter – chemical, optical, and physical – can be manipulated and exploited at the nano scale,” Dr. Friedman said. For example, something that is too bulky at the macro level to go into an aqueous vehicle can be distributed more easily in nano form. And “if something is smaller than the wavelength of visible light, guess what? It is going to be invisible,” he said at the Orlando Dermatology Aesthetic and Clinical Conference.
By the year 2012, nanotechnology is predicted to be a $12 million industry in the United States, and the cosmetic and cosmeceutical industries are leading the way, Dr. Friedman noted. He discussed several nanomaterials with diagnostic and therapeutic applications for dermatologists:
• Nanoparticles. The term nanoparticle is somewhat generic, Dr. Friedman said. The term refers to a small object that behaves as a whole unit in terms of its transport and properties. Nanoparticles can be derived from organic and nonorganic materials. For example, gold nanoparticles can be used to introduce an antibody or targeting molecule into the body to target tumors. Once the tumors are bound to the gold, they can be treated using selective photolysis, in which radiation is used to heat the gold enough to kill the tumor cells. In one study of mice, hollow gold nanoparticles were used to successfully treat melanoma, said Dr. Friedman. Silver nanoparticles are already in products ranging from clothing to plastic food storage containers, to take advantage of their antimicrobial properties, he said.
• Nanoemulsions. Nanoemulsions are already widely used in dermatology, in emollients, and as delivery vehicles for antiaging products. Nanoemulsions have an appealing nongreasy texture, are invisible, and penetrate the skin rapidly, Dr. Friedman said. Nanoemulsion products currently on the market include L’Oréal Plenitude Revitalift and Caudalie Vinosun Anti-Aging Suncare.
• Quantum dots. “These highly fluorescent nanoscale crystals absorb a broad range of wavelengths; however, they only re-emit one color,” said Dr. Friedman. In dermatology, quantum dots are being used to identify sentinel lymph nodes in patients with melanoma and Merkel cell carcinoma.
• Nanomagnets. Nanosized magnetic materials “no longer exhibit a net magnetic force,” Dr. Friedman said. These materials could be used to create magnetic field–directed imaging or therapy.
• Nanopigments. Many currently available sunblocks include nanoparticles of titanium or zinc oxide, such as SunVex Dailywear lotions and ZinClear Nano Zinc Oxide.
About safety: “From a purely theoretical standpoint, nanoparticles should be harmful,” said Dr. Friedman. The same properties that make nanoparticles useful could come with side effects. Improved skin penetration can be beneficial for dermatology, but factors that determine the potential toxicity of nanoparticles include size, chemical purity, and the activity of the surface.
The current international stance on nanoparticle safety is that it is unlikely that significant amounts of the zinc or titanium used in sunblock products will result in local or systemic toxicity. However, “the safety of nanoscale zinc and titanium in sunscreen must be fully addressed,” Dr. Friedman said. In 2009, the American Academy of Dermatology established a task force to study nanotechnology and educate the dermatology community, the public, and policy makers.
Dermatologists who are intrigued by the potential of nanotechnology can join the fledgling Nanodermatology Society, which had its first meeting for the 2011 AAD annual meeting in New Orleans. For more information, visit the society’s Web site at www.nanodermsociety.org.
Dr. Friedman serves on the advisory board of Makefield Therapeutics.