Second skin – wearable drug delivery

26 October 2016



A variety of new polymers and other materials created in the past few years are offering new options for drug delivery, enabling new solutions, such as wearables that medicate the patient by administering the pharmaceutical via skin absorption. Medical Device Developments looks into this area of manufacturing tech to see where the current trends are headed.


The premise may sound like science fiction, but wearable medicine is becoming a perfectly viable idea in medical device developments and one that, in a few years, could become the next big thing that manufacturers will scramble to capture the market for. From sun screen to wound healing, scar diminishing to ‘patches’ and other ways of administering drugs, the possibilities are endless.

When most of us think of wearable medicine, we probably think of nicotine patches that work by slowly releasing nicotine that is then absorbed into your body through your skin. Following the same principle, teams from two of the world’s best science research universities, Harvard University and Massachusetts Institute of Technology (MIT), have come together to develop a new elastic polymer film that can be attached to the skin and – researchers hope – can be used to deliver drugs and a sun-protection serum.

The elastic film, originally cast by the research team that developed it as a wrinkle-filler cosmetic product, has been touted as having the potential to become the most rare of things: a wearable medicine. Professor Robert Langer, from the David H Koch Institute at MIT, and Daniel Anderson, an associate professor in MIT’s department of chemical engineering, led the team working on the product. They explain how it could be manufactured as an easy way to provide a barrier against damaging UV rays and a way to deliver medicine that is absorbed through the skin – a novel, painless and somewhat more sustainable way of delivering drugs into the system, instead of through needles and pills, and one that could be easier for children and other groups.

According to results published in the journal Nature, Langer and Anderson’s team screened more than 100 variant polymers to create the elastic, transparent film. To apply the product, users first smear on a gel-like polymer based on siloxanes (chains of molecules containing silicon and oxygen); they then add another gel that contains a platinum-based catalyst. This two-level process cross-links the polymer chains together to toughen up the material – effectively setting the film – which is only 40–70μm deep. Langer says it is “essentially invisible.”

The team performed trials on humans to test the material’s effectiveness in terms of wearability, prevention of water loss and safety. In wearability, the XPL material outperformed two commercial wound dressings with regard to flexibility, elasticity, thickness and visibility. In moisturisation (hydration) and water loss, “XPL exhibited statistically less water loss and more skin-hydration than expensive commercial moisturisers. Additionally, no skin irritation was observed in these tests.”

The product

About ten years ago, the research team set out to develop a protective coating that could restore the properties of healthy skin for medical and cosmetic applications.

“It’s an invisible layer that can provide a barrier, cosmetic improvement and potentially deliver a drug locally to the area that is being treated. Those three things together could make it ideal for use in humans,” Anderson said in an interview with the MIT news site.

The material can temporarily protect and tighten skin, and smooth wrinkles, and with further development, it is hoped that it could also be used to deliver drugs to help treat skin conditions such as eczema and other types of dermatitis.

The material is a silicone-based polymer that could be applied to the skin as a thin, completely colourless and near-invisible coating that mimics the mechanical and elastic properties of healthy, youthful skin. The invisible coating is made out of cross-linked polymers and it goes on like a liquid before turning into a solid on the body, allowing intricate and detailed firming and shaping properties – which is part of the reason for the cosmetic interest.

The team, however, struggled to find a polymer that would work in the conditions. Researchers went through over 100 possible polymers before they found the right one that could mimic essential properties of human skin.

“It has to have the right optical properties, otherwise it won’t look good, and it has to have the right mechanical properties, otherwise it won’t have the right strength and it won’t perform correctly,” says Langer.

Anderson, Langer and their team announced that in tests with human subjects, the researchers found that the material had several cosmetic elements; it was able to reshape “eye bags” under the lower eyelids and also enhance skin hydration.

But more medically promising was the fact that it could also be used more effectively in the estimated 76,000 new cases of invasive melanoma that will be diagnosed in the US in 2016.

“Developing a second skin that is invisible, comfortable, and effective in holding in water and potentially other materials presents many different challenges, which we are now able to address,” says Langer. The team is now working on engineering different medications into the polymer coating so that it could deliver drugs directly to patients’ skin, without being washed off or ending up in the wrong areas. Eczema medication could be easier to administer to the required area, for example.

Wearing out the risk

There are also similar innovations happening in other academic institutions in the world of wearable medicine that could be ripe for manufacturers to get in on. For example, researchers from Royal Melbourne Institute of Technology University (RMIT) in Melbourne, Australia, have developed transparent, wearable sensor patches that can detect UV radiation poisoning and toxic gases like nitrogen dioxide.

Unlike the polymer, the device is electronic – like most other current wearable medicine solutions on the market. This specific wearable device can be used as skin patches or integrated into clothing and is completely flexible. This means they are easy to carry or wear on the skin and could play a major role in preventing serious medical conditions like skin cancer, as the electronic sensors can be used to find harmful amounts of UV radiation in the atmosphere.

Dr Madhu Bhaskaran, project leader and co-leader of the RMIT Functional Materials and Microsystems Research Group, said the research was based on the idea of turning negatives into a positive.

“Hydrogen leaks can lead to explosions – as happened with the Hindenburg disaster – and nitrogen dioxide is a major contributor to smog,” he said in an interview in 2015. Bhaskaran cited the problems with the gas in the past, but said there were better uses for it in today’s world, and showed its possible uses for our increasingly urbanised and polluted world. “The ability to monitor such gases in production facilities and coal-fired power stations gives vital early warning of explosions, while the ability to sense nitrogen dioxide allows constant monitoring of pollution levels in crowded cities.”

Wearable technology could be the future for solving respiratory issues in places like China’s megacities, or the problem of the astronomically high skin-cancer rate (the world’s highest) in Bhaskaran’s home country of Australia. The potential for far-reaching solutions could be what takes these products from the lab to the factory.

Mass manufacturing

“This ‘skin-conforming’ platform brings with it transport properties that have significant promise to treat underlying conditions,” adds Dr Rox Anderson, a dermatologist at Massachusetts General Hospital and a professor on the Harvard team that co-worked on the project with Langer and Anderson’s teams at MIT. “For eczema or sun protection, as examples, this second-skin platform can serve as a reservoir for controlled-release transdermal drug delivery or SPF ingredients, a possibility we are currently pursuing in our lab.”

The idea of wearable second skins to protect from external dangers is a great one, but how feasible is it? As medical devices continue to achieve great leaps in technological innovation, manufacturers must also consider their production for the mass market.

“Although the focus of this work has been to elucidate the impact of the elasto-mechanical properties of the XPL on skin,” says the project report, “further directions of research and improvement to create better products for barrier protection and cosmetics present unique opportunities to enhance patient compliance and quality of life.”

The researchers clearly see their innovation as something that can be broadly scattered across a host of uses: moisturiser for burn victims, cosmetic skin-tightener, drug delivery for those unable to have normal medicinal applications and a protective layer against UV damage to lower the risk of skin cancer.

These are all fantastic ways of improving quality of life but, at the moment, despite myriad projects around the world investigating their uses, these products are mostly still lab-based, with another several years, or even a decade or more, before they could be brought to a mass market. In the mean time, manufacturers should be looking at this as the next big market to break into and the huge number of ways technology could open profitable new doors.

What is wearable medicine?

While much of it sounds like science fiction, according to HealthIT.com, wearable health devices are things that are simply capable of tracking medically useful health information. Most wearable medicine is in the form of devices, but most healthcare facilities aren’t yet equipped to process and protect this data.                                

Wearable devices can track nearly everything a patient does, from physical activity and exercise to sleep patterns and exposure to sunlight. The wearable medicines’ “versatility and portability appeal to consumers, and make them a consideration for providers that want to cut down on in-person visits,” according to the website.

Devices currently launched or in pre-launch by start-ups include heart-rate monitors for sleep and exercise; back braces that connect to video-game consoles to remind the patient to do regular exercises and stretches to avoid lower-back pain; embedded patches that use Wi-Fi for vital-organ monitoring at a central lab for elderly patients; a smart device that is aimed at helping people to stop smoking (the device is embedded with sensors that detect changes in the body and put into motion algorithms that predict when a person is craving a cigarette and nicotine); and a litany of products associated with smartphones.

The silicone-based polymer coating is invisible and has skin-tightening properties.


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