Updated: Jan 8, 2021
Are you a fan of the Star Trek multiverse? Did science fiction blow your mind with its intricate plot line and its universe of scientific possibilities? In the 24th century Star Trek’s home medicine cabinet or ship’s nursing room has a good old dermal regenerator. The technology was used in the series to instantly close the skin of wound with the help of a light beam, the technology of which was not known during that era. Sounds amazing, right?
Figure 1: AN IMAGE DEPICTING THE USE OF DERMAL REGENERATOR
IMAGE FROM STARTREK.COM
What if I tell you that the penultimate wound healing technique has been brought to life by the advent of nanotechnology? The intricate process of wound healing has been indeed revolutionized with the advent of metallic nanoparticles like silver, gold, and zinc. 
Science fiction has played a huge role in introducing the world to nanotechnology, often in the/a negative light. This popular science fiction culture of demonizing the nanobots or the nano-submarines has been effectively challenged by the scientists time and again.
Nanotechnology is deemed as the technology that relies on particles of 1-100 nm in diameter. These really tiny particles are often used in the field of medicine to carry or deliver an active ingredient (for instance, an anticancer drug). The major advantages of this technology are improved drug delivery for poorly water-soluble drugs, enhanced availability to the site of injury or disease because of the small size, and the site-specific targeting helps in avoiding the toxicity in healthy tissues. For more details on nanotechnology, check out our previous article.
As a matter of fact, the concept of nanotechnology is not new to cosmetics. The roots can be traced back to 4000 BC when early Egyptians, Romans and Greeks used nanoemulsions to formulate HAIR DYES! 
The minute size comes with an advantage of larger surface area, which helps in more bioavailability and high targeting capacity, which is successfully employed in many sunscreens, antiwrinkle creams, moisturizing creams, skin whitening creams, hair serums, shampoos and conditioners. You might therefore stumble upon the word nano in your day to day life. In the present era, nanocosmetics have made their mark also thanks to the amazing property of controlling the release of the functional ingredient, making the cosmetic last longer than usual, such as in the case of the exotic Allure perfume series by Chanel (hence, the skyrocketing price). 
Talking about Chanel, we distinctly remember the time when La Maison Chanel launched its Moisture Mist: the dewy long-lasting tropical orange mist created quite a buzz in the beauty industry. A deeper look in the ingredient list would reveal the oil in water emulsion, dispersed as nanodroplets, which is known to prolong the fragrance.  The exact size of these droplets is not revealed by Chanel owing to the fear that revolves around nanotechnology.
But what exactly are these minute nanoemulsions and why are they so useful? When you take an oil (say avocado and jojoba seed oil) and mix it with water or any other aqueous solvent, you might observe something that is known as a biphasic mixture. To form an emulsion or simple to blend these two liquids together, surfactants like spans, tweens or PEG-30 DIPOLYHYDROXYSTEARATE (used in Chanel’s Mist) are employed. When the resulting liquid undergoes droplet reduction process, we get transparent, light or low viscous droplets of size range 50-200 nm. The droplet reduction could be performed by many techniques- sonication (high energy method), in which sound energy is used to agitate and disperse the nanoparticles evenly break the macromolecules or by using homogenizers which disperse the particles in nano sizes.  Unlike its macro ally, nanoemulsions do not undergo sedimentation or creaming but are quickly and rapidly absorbed by the skin, due to their small size and better penetration properties. These thermodynamically stable emulsions have many advantages: 1. They can be used to deliver a lot of active ingredients (like Indian pennywort, which is used for its soothing calming effect by Chanel’s Precision Solution Destressante, again as a nanoemulsion), 2. They can easily penetrate the pilosebaceous follicles or the hair scalp spacing, 3. They have a better shelf life than normal emulsions, 4. They are visually more appealing, clear or transparent, 5. They are absorbed quickly and more effectively by the skin. [3, 4]
Nanoemulsions are a popular medium now for sunscreens, lotions, serums, shampoos, conditioners, deodorants and nail enamels. Loreal’s Aqua Oleum is another hair serum that employs the nanoemulsion of avocado and jojoba oil. The beneficial activity can be due to the fact that these droplets are over 100 times smaller than the hair spacing on the scalp. 
What is still controversial about these materials is definitely the safety issue. Although it has been established that nanoemulsions are biologically safe and not toxic to human cells, many studies have shown that, when given in high concentrations, certain ingredients can have toxic adverse reactions. A proper toxicity evaluation is therefore required for nanoemulsions. For example, the popular quercetin, which is known for its anti-inflammatory and skin-soothing effects, when formulated as nanoemulsion, was shown to have haemorrhagic activities. Another exotic product, pomegranate seed oil, can also have mild toxicity when given in higher doses than recommended. 
The regulation of nanoemulsions is still in its fetal stage. There are no separate definitions given to nanoemulsions, but many global regulatory agencies have defined nanomaterials in general. The lack of in vivo animal studies makes it even more difficult to understand the long term reactions of nanoemulsions. In the European Union, the people responsible for cosmetic manufacture or import or a third party have to register the cosmetic on CPNP or Cosmetic Productions Notification Portal (Regulation (EC) No 1223/2009, Art. 13 (1). The notification is also required to particularly label the nanomaterials with its identification as well as the exposure conditions.
The current scenario requires a pressing need for new laws and new studies to be made, in order to move away from science fiction and to incorporate the full potential of nanoemulsions in dermatology.
What do you think will happen in the next 100 years with Nanotech? Share your imagination in the responses, let it be documented for when it’s transmuted into reality.
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