For those of us in the northern hemisphere, sunscreen season is on the horizon. While the “ultimate natural sunscreen” researchers from the University of California at San Diego (UCSD) have developed is a long way from the marketplace, this is encouraging news (from a May 17, 2017 news item on Nanowerk),
Chemists, materials scientists and nanoengineers at UC San Diego have created what may be the ultimate natural sunscreen.
In a paper published in the American Chemical Society journal ACS Central Science, they report the development of nanoparticles that mimic the behavior of natural melanosomes, melanin-producing cell structures that protect our skin, eyes and other tissues from the harmful effects of ultraviolet radiation.
“Basically, we succeeded in making a synthetic version of the nanoparticles that our skin uses to produce and store melanin and demonstrated in experiments in skin cells that they mimic the behavior of natural melanosomes,” said Nathan Gianneschi, a professor of chemistry and biochemistry, materials science and engineering and nanoengineering at UC San Diego, who headed the team of researchers. The achievement has practical applications.
“Defects in melanin production in humans can cause diseases such as vitiligo and albinism that lack effective treatments,” Gianneschi added.
Vitiligo develops when the immune system wrongly attempts to clear normal melanocytes from the skin, effectively stopping the production of melanocytes. Albinism is due to genetic defects that lead to either the absence or a chemical defect in tyrosinase, a copper-containing enzyme involved in the production of melanin. Both of these diseases lack effective treatments and result in a significant risk of skin cancer for patients.
“The widespread prevalence of these melanin-related diseases and an increasing interest in the performance of various polymeric materials related to melanin prompted us to look for novel synthetic routes for preparing melanin-like materials,” Gianneschi said.
The scientists found that the synthetic nanoparticles were taken up in tissue culture by keratinocytes, the predominant cell type found in the epidermis, the outer layer of skin. Photo by Yuran Huang and Ying Jones/UC San Diego
Melanin particles are produced naturally in many different sizes and shapes by animals—for iridescent feathers in birds or the pigmented eyes and skin of some reptiles. But scientists have discovered that extracting melanins from natural sources is a difficult and potentially more complex process than producing them synthetically.
Gianneschi and his team discovered two years ago that synthetic melanin-like nanoparticles could be developed in a precisely controllable manner to mimic the performance of natural melanins used in bird feathers.
“We hypothesized that synthetic melanin-like nanoparticles would mimic naturally occurring melanosomes and be taken up by keratinocytes, the predominant cell type found in the epidermis, the outer layer of skin,” said Gianneschi.
In healthy humans, melanin is delivered to keratinocytes in the skin after being excreted as melanosomes from melanocytes.
The UC San Diego scientists prepared melanin-like nanoparticles through the spontaneous oxidation of dopamine—developing biocompatible, synthetic analogues of naturally occurring melanosomes. Then they studied their update, transport, distribution and ultraviolet radiation-protective capabilities in human keratinocytes in tissue culture.
The researchers found that these synthetic nanoparticles were not only taken up and distributed normally, like natural melanosomes, within the keratinocytes, they protected the skin cells from DNA damage due to ultraviolet radiation.
“Considering limitations in the treatment of melanin-defective related diseases and the biocompatibility of these synthetic melanin-like nanoparticles in terms of uptake and degradation, these systems have potential as artificial melanosomes for the development of novel therapies, possibly supplementing the biological functions of natural melanins,” the researchers said in their paper.
The other co-authors of the study were Yuran Huang and Ziying Hu of UC San Diego’s Materials Science and Engineering Program, Yiwen Li and Maria Proetto of the Department of Chemistry and Biochemistry; Xiujun Yue of the Department of Nanoengineering; and Ying Jones of the Electron Microscopy Core Facility.
The UC San Diego Office of Innovation and Commercialization has filed a patent application on the use of polydopamine-based artificial melanins as an intracellular UV-shield. Companies interested in commercializing this invention should contact Skip Cynar at invent@ucsd.edu
The Lycurgus Cup has long fascinated me. It’s an ancient piece of art that is nanotechnology-enhanced so that depending on how the light hits it, the cup glows either green or red.
The *History of the Ancient World website (as Nov. 21, 2013 the link has been changed to the Université de Strasbourg,, Matière Condensée et Nanophysique website) recently featured a 2007 article about the Lycurgus Cup by Ian Freestone, Nigel Meeks, Margaret Sax and Catherine Higgitt for the Gold Bulletin, Vol. 40:4 (2007),
The Lycurgus Cup represents one of the outstanding achievements of the ancient glass industry. This late Roman cut glass vessel is extraordinary in several respects, firstly in the method of fabrication and the exceptional workmanship involved and secondly in terms of the unusual optical effects displayed by the glass.
The Lycurgus Cup is one of a class of Roman vessels known as cage cups or diatreta, where the decoration is in openwork which stands proud from the body of the vessel, to which it is linked by shanks or bridges Typically these openwork “cages” comprise a lattice of linked circles, but a small number have figurative designs, although none of these is as elaborate or as well preserved as the Lycurgus Cup. Cage cups are generally dated to the fourth century A.D. and have been found across the Roman Empire, but the number recovered is small, and probably only in the region of 50-100 examples are known. They are among the most technically sophisticated glass objects produced before the modern era.
The article itself can be viewed or downloaded from here. The cup as noted can be two different colours,
The glass of the cup is dichroic; in direct light it resembles jade with an opaque greenish-yellow tone, but when light shines through the glass (transmitted light) it turns to a translucent ruby colour
The presence of colloidal metals (gold-silver) give the glass at least some of its unusual optical properties according to the authors. Although reading between the lines, it seems that even today we can’t duplicate what those 4th century Roman glassmakers achieved.
The Lycurgus Cup demonstrates a short-lived technology developed in the fourth century A.D. by Roman glass-workers. They discovered that glass could be coloured red and unusual colour change effects generated by the addition of a precious metal bearing material when the glass was molten. We now understand that these effects are due to the development of nanoparticles in the glass. However, the inability to control the colourant process meant that relatively few glasses of this type were produced, and even fewer survive. The Cup is the outstanding example of this technology in every respect – its outstanding cut work and red-green dichroism render it a unique record.
There you have it, ancient Roman nanotechnology.
*Nov. 21, 2013 I changed the link to the article as the History of the Ancient World website is no longer hosting this article.
ETA July 21, 2014: April Holloway has written a piece about the Lycurgus Cup which has been published in two places,
Epoch Times: http://www.theepochtimes.com/n3/807475-1600-year-old-goblet-shows-that-the-romans-used-nanotechnology/ (this features an image of the green and red ‘cups’ side-by-side with a ‘nano’ background)
Ancient Origins: http://www.ancient-origins.net/news-history-archaeology/1600-year-old-goblet-shows-romans-used-nanotechnology-00793#!bjfuCU (image of the green and red ‘cups’ side-by-side featured)
The scientists found that the synthetic nanoparticles were taken up in tissue culture by keratinocytes, the predominant cell type found in the epidermis, the outer layer of skin. Photo by Yuran Huang and Ying Jones/UC San Diego
