Materials Today Volume 00, Number 00 January 2016 NEWS
News
Nanoparticles keep sunscreen on the skin
Encasing the active ingredient of sunsc-
reens inside sticky polymer nanoparticles
stops penetration into the skin, preventing
exposure to potentially harmful chemicals,
researchers at Yale University have found.
Commercial sunscreens contain organic
or inorganic ultraviolet (UV) filters that
block radiation from the sun, which can
cause sunburn, skin aging, and skin cancers.
But over the past few decades, studies have
indicated that organic UV filters in particu-
lar can penetrate the skin or hair follicles
and find their way into the bloodstream and
other bodily fluids, where they could act as
allergens or hormone disruptors. In combi-
nation with sunlight, there are also con-
cerns that some of these active agents can
generate reactive oxygen species (ROS) that
cause damage at the cellular and DNA level.
To get around this problem, W. Mark
Saltzman and his team encapsulated one
such organic UV filter, padimate-O, with
polymeric bioadhesive nanoparticles (or
Transmission electron microscopy images of BNPs. The scale bar represents 200 nm. (Photo credit: Yang
BNPs) [Deng, et al., Nat. Mater. (2015), Deng.)
doi:10.1038/nmat4422]. The nanoparticles,
which are typically just under 100 nm in
diameter, comprise a polylactic acid (PLA) on the surface and do not penetrate The BNP-based sunscreen has an addi-
core and a surface of hyperbranched poly- into the skin, in marked contrast to non- tional practical advantage—while it is water
glycerol (HPG). The UV filter is held in the bioadhesive nanoparticles or padimate-O resistant, it can be readily wiped off with a
core of the nanoparticle and the hydroxyl alone. Moreover, a much lower concen- towel or left to slough off with dead skin
surface is converted to one rich in aldehyde tration of active sunscreen has a compa- cells without any harmful effect.
groups, which stick to biological molecules rable anti-UV effect when applied in Encapsulating padimate-O in nanoparti-
like proteins. combination with BNPs compared with cles appears to have another benefit, as well.
‘‘The bioadhesive nanoparticles adhere commercial formulations. In fact, the In the researchers’ study, the BNP-based
strongly to the skin and retain UV filter researchers found that just 5% of the formulation significantly reduces a type of
molecules within the core,’’ explains Saltz- amount of UV filter used in commercial DNA damage called double-strand breaks.
man. sunscreens is needed to achieve the same ‘‘We have taken UV agents that are
In mouse models, the team found level of protection in their nanoparticle- known to be effective, combined them with
that the UV filter-containing BNPs remain based formulation. materials that are known to be safe, and
1369-7021/http://dx.doi.org/10.1016/j.mattod.2016.01.003
1
Please cite this article in press as: C. Sealy, Mater. Today (2016), http://dx.doi.org/10.1016/j.mattod.2016.01.003
MATTOD-688; No of Pages 2
NEWS Materials Today Volume 00, Number 00 January 2016
produced a better sunblock,’’ says Saltzman. now planning the first tests of the BNP- Peter J. McHugh of the University of
‘‘[Our] sunblock is more effective, longer- based formulation on human volunteers. Oxford.
lasting, and less toxic than any previously ‘‘This is a promising approach that could This paper was originally published in
described.’’ protect against the collateral damage po- Nano Today (2015), doi:10.1016/j.nantod.
Saltzman believes the tactic should tentially inflicted by the penetration of 2015.10.003.
work with other UV filters too, and is active sunscreen agents into cells,’’ says Cordelia Sealy NEWS
2
Please cite this article in press as: C. Sealy, Mater. Today (2016), http://dx.doi.org/10.1016/j.mattod.2016.01.003