REVIEW “Nano Present” and “Nano Future”: The Growing Role of Shrinking Technology in Dermatology, Part 1 Adnan Nasir, MD This is the first of a 2-part series. In this part, Dr. Nasir introduces nanotechnology and its role in skin care products. The use of nanotechnology in medicine and dermatology is too broad to be covered in its entirety. This review is by no means comprehensive and covers only a small subset of applications of nanotechnol- ogy in cosmetic dermatology. It is hoped that readers will get a sense of the promises and challenges of nanotechnology, as well as future applications and safety concerns. The bulk of this review is devoted to cosmetic products forCOS the face. A smaller portion DERM touches on some of the uses of nanotechnology for specific body parts orDo for treatment ofNot specific conditions. Copy anotechnology is a rapidly growing field undesirable qualities. Products incorporating nanotechnol- with enormous implications for consum- ogy are being discovered and manufactured at a growing ers, patients, and society.1-3 Matter made at rate. A substantial proportion of the patents issued for the nanoscale possesses unique properties nanotechnology-based discoveries are in the realm of allowing for the creation of substances with cosmetics and consumer skin care products. The interest Nadvantages over macroscopic precursors. These advan- in nanotechnology and skin care is expected to burgeon. tages include specificity, adaptability, and targeted active- The cosmetic industry leads in the number of patents ingredient delivery. Furthermore, skin care products for nanoparticles, which can be found in sunscreens, hair employing nanotechnology can be engineered to eliminate conditioners, shampoos, lipsticks, eye shadows, after- shave products, moisturizers, deodorants, and perfumes.4 Dr. Nasir is Clinical Assistant Professor of Dermatology, Antiaging products are a major source of excitement for University of North Carolina, Chapel Hill. nanomaterials. Properly engineered, nanomaterials may The author reports no conflict of interest in relation to be able to topically deliver retinoids, antioxidants, and this article. drugs such as botulinum toxin or growth factors for col- Disclaimer: In this article, trade names are used, and much of lagen and elastin into the skin. A recent survey found that the information mentioned on each product comes directly from among the 270 or so nanotechnology products available, manufacturers’ publicly available sources (eg, package inserts and the majority are cosmetics.5 Furthermore, because of corporate advertising in print and electronic media). Redacted com- recent safety concerns, additional products that contain ments are in quotation marks and block quotes, and manufacturers nanomaterials may not advertise their use. declined to provide the author with proprietary, corroborative, or contradictory information. Some products have been discontinued DEFINITION OF NANOTECHNOLOGY but may still be available. Nanotechnology capitalizes on the special properties Correspondence: Adnan Nasir, MD ([email protected]). of matter in the size range of 1 to 100 nm.6 The size of VOL. 22 NO. 3 • march 2009 • Cosmetic Dermatology® 139 Copyright Cosmetic Dermatology 2010. No part of this publication may be reproduced, stored, or transmitted without the prior written permission of the Publisher. NANOPARTICLES nanoparticles is difficult to grasp. cells, cellular organ- regulation, is expected to grow annually at a 16% rate elles, and bacteria are enormous on the nanoscale. The and reach more than $150 million by 2012.11 Sun- adenovirus, which is dwarfed by any eukaryotic cell, screens are expected to account for the bulk of the is a whopping 150 nm. If the adenovirus were cubic growth, but other cosmetics, if they prove superior to and not icosahedral, it could carry more than 3 million current competitors, are likely to follow. The growth 1-nm particles. It is also important to remember that most of antiaging products may continue during a recession, atoms are 0.1 to 0.5 nm in diameter.7 Given the extraordi- especially as their cost is competitive when compared narily tiny dimensions of nanoparticles as compared with to procedures. 1000 nm hair shafts, it is easy to envision nanopar- ticles penetrating skin. It is even easier to envision REPORTING OF NANOTECHNOLOGY nanoparticles penetrating skin with compromised bar- Most of the advances of nanotechnology are patented and rier integrity. proprietary. Manufacturers must balance the advantages At this size range, matter behaves differently.8,9 For and drawbacks to divulging nanomaterial content of example, the chemical reactivity of substances can their products. It is disadvantageous for manufacturers increase.10 As a particle shrinks in size, its surface area to divulge trade secrets to competitors. Some consum- relative to volume grows exponentially. This makes ers may find a new technology or a label with the term available a large number of surface moities for interac- nanotechnology appealing, whereas others, including con- tion with the environment or with other nanoparticles. sumer protection groups and regulatory agencies, may The surface moieties can be hydrophobic, hydrophilic, scrutinize the products more because of safety concerns. or electrically charged. The interactions can allow, for In fact, regulatory hurdles and consumer backlash have example, for the assembly of a nanoliposome, which caused some manufacturers to remove any voluntary ref- could be manufactured to contain an active ingredient, erence to nanomaterials on advertising materials or lists such as a retinoid, for delivery into the epidermis, or an of ingredients. antioxidant, such as ascorbic acid, could be stabilized in a topical nanoliposome formulationCOS for similar delivery. DERM TYPES OF NANOMATE RIALS The optical qualities of matter can also be manipulated IN SKIN CARE at the nanoscale. For example, zinc oxide, a compo- Nanoparticles nent of sunscreens, is opaque at the microscales and Nanoparticles act individually or in combination to carry macroscales. The wavelength of visible light is 400 to out a specific task. Some are made to disperse, some to 700 nm. NanoparticlesDo of zinc can be madeNot so small aggregate, Copy and some to polymerize under the right condi- that it all but vanishes when applied to the skin. Physi- tions. They can be solid or hollow and act as transport cal properties of matter also change at the nanoscale. agents or composite. Microsized and macrosized zinc can be dissolved only in an oily vehicle. Nanoparticles of zinc are more readily Picoparticles dispersed in aqueous vehicles and can be incorporated Picoparticles are approximately 2 to 3 orders of magni- in cosmetically elegant preparations. The 3 properties of tude smaller than that of nanoparticles and appear to matter, chemical, optical, and physical, can be manipu- be on an atomic or small-molecule scale. An example lated and exploited in precise ways by using nanotech- of a picoparticle would be water or an atom of zinc or nology. The ability to achieve this on an industrial scale titanium. One manufacturer, BIONOVA, Inc, for Barneys at a relatively low cost has manufacturers and consum- New York has5 ers interested. developed several proprietary nanotechnologies, which DEFINITION OF NANOCOSMETICS can be used as a technological platform for creation of Nanocosmetics are products that maintain or enhance multiple products oriented toward enhancement of self- the appearance of the skin, hair, and nails and capital- healing processes. This technological platform is based ize on nanotechnology as their principal advantage. A on development of nanotechnology of bioactive complex broader definition would include products that help the modeling, which has the ability to manipulate not only appearance of the teeth and eyes, as well as products that with nano, but also with pico size particles. contain any nanomaterials on their ingredient list, rather than the active or key ingredient. Nanoemulsions In the $200-billion global cosmetic industry, the Nanoemulsions are nanosized packages of oil and current global market for nanotechnology is estimated water emulsions that allow for the stabilization, deeper to be $62 million and, barring curtailment through penetration, and targeted delivery of a variety of 140 Cosmetic Dermatology® • march 2009 • VOL. 22 NO. 3 Copyright Cosmetic Dermatology 2010. No part of this publication may be reproduced, stored, or transmitted without the prior written permission of the Publisher. NANOPARTICLES substances into the skin (eg, antioxidants, vitamins, The company goes on to say, “Many people tell us that hyaluronic acid). Examples of some personal care they are comfortable with their current facial care prod- products and manufacturers that use nanoemulsions ucts, but they would like to extend their cleansing and or nanospheres include L’Oréal revitalift, Freeze 24-7, moisturizing with the deeper and longer-lasting benefits la prairie Skin caviar Intensive ampoule Treatment, of Arouge’s NanoMoisture.”12 Olay, PureOlogy, colorescience, and caudalíe Teint Lancôme makes hydra Zen creams, which contain Divin Suncare regimen. a subcategory of this is the proprietary ingredients Acticalm 2, Biolactone, and nanoscale coatings and thin films. nanoencapsulated triceramides. These are designed for long-lasting hydration, which, according to the manufac- Fullerenes turer, protects the skin and keeps it fully hydrated and Fullerenes are nanosized polyhedral