Cross-Linked Polymer Layer Technology for Protecting and Treating Skin

Researchers from the MIT, the Massachusetts General Hospital, Living Proof and the Olivo Labs have created an innovative material with the ability to temporarily protect and tighten skin, and also smooth out wrinkles. With further development, the material could be used to deliver drugs to assist in the treatment of skin diseases such as eczema and other kinds of dermatitis.

“It’s an invisible layer that can provide a barrier, provide cosmetic improvement, and potentially deliver a drug locally to the area that’s being treated. Those three things together could really make it ideal for use in humans,” Daniel Anderson says. CREDIT: Melanie Gonick/MIT.

The material is a silicone-based polymer that can be spread on the skin as a thin, undetectable coating. When applied on skin, its elastic and mechanical properties resemble that of a youthful and healthy skin. Upon investigations involving human subjects, the scientists discovered that the material had the potential to reshape “eye bags” below the lower eyelids and can improve skin hydration as well. According to the scientists, such a “second skin” can be adapted to offer long-lasting protection from harmful ultraviolet rays.

It’s an invisible layer that can provide a barrier, provide cosmetic improvement, and potentially deliver a drug locally to the area that’s being treated. Those three things together could really make it ideal for use in humans.

Daniel Anderson, MIT Department of Chemical Engineering

The polymer was described in a paper published online in the journal Nature Materials on 9 May. Anderson is one of the authors of the paper, and Robert Langer, the David H. Koch Institute Professor at MIT and a member of the Koch Institute, is the senior author of the paper. Betty Yu SM ’98, ScD ’02, former vice president at Living Proof is the lead author of the paper. Langer and Anderson are respectively co-founders of Living Proof and Olivo Labs. Yu earned her master’s and doctorate from MIT.

Mimicking skin

Due to aging, skin turns less elastic and less firm, which can be aggravated by exposure to solar rays. This hinders the ability of the skin to protect against toxins, radiation, extreme temperatures, microorganisms and injury. Nearly a decade ago, the researchers aimed to create a protective coating with the ability to rehabilitate the characteristics of a healthy skin, for cosmetic as well as medical applications.

We started thinking about how we might be able to control the properties of skin by coating it with polymers that would impart beneficial effects. We also wanted it to be invisible and comfortable.

Daniel Anderson, MIT Department of Chemical Engineering

The research team produced a library of over 100 prospective polymers which has a chemical structure termed as siloxane. Siloxane contains a chain of interspersed atoms of oxygen and silicon. The polymers can be arranged in the form of a network called a cross-linked polymer layer (XPL). Then, the research team investigated the polymers in search of one that would best mimic the appearance, elasticity and strength of 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,” explained Langer.

The elastic properties of the best-functioning polymer will be very close to that of a healthy skin. During investigations in the lab, the polymer was stretched to over 250% and was observed to easily attain its original form. It should be noted that natural skin can be stretched to nearly 180%. The new XPL’s elasticity was found to be superior to two other kinds of wound dressings, namely, polyurethane films and silicone gel sheets, used at present on skin.

Creating a material that behaves like skin is very difficult. Many people have tried to do this, and the materials that have been available up until this have not had the properties of being flexible, comfortable, nonirritating, and able to conform to the movement of the skin and return to its original shape.

Barbara Gilchrest, Dermatologist, Massachusetts General Hospital

At present, the delivery of the XPL is carried out in a two-step process. Initially, polysiloxane components are spread on the skin, and then, a platinum catalyst is applied, which has the ability to influence the polymer to form a strong cross-linked film that is retained on the skin for nearly 24 hours. The catalyst has to be delivered only after the polymer as the material turns stiff to apply after this step. Both the components are applied as ointments or creams, and when applied to the skin, the XPL turns necessarily invisible.

High performance

The researchers carried out numerous investigations on humans to verify the effectiveness and safety of the new material. One such investigation involved applying the XPL to the under-eye area in which “eye bags” are normally formed as a result of aging. The eye bags are the result of protrusion of the fat pad present underneath the lower lid skin. On application of the material, it exerted a steady compressive force leading to tightening of the skin. This effect lasted for nearly 24 hours.

In another investigation for testing the elasticity of the XPL, it was spread on forearm skin. When the XPL-applied skin was dilated by means of a suction cup, it attained its original shape quicker than normal skin.

In addition, the research team also investigated the potential of the material to prevent the loss of water from dry skin. Around 2 hours after applying the novel XPL, the treated skin suffered comparatively less water loss than skin treated using an expensive commercial moisturizer. Application of petrolatum on skin was nearly as effective as applying XPL after 2 hours of treatment. However, after 24 hours, skin treated with XPL was observed to retain more water. The study participants did not report any irritation due to the application of XPL.

I think it has great potential for both cosmetic and noncosmetic applications, especially if you could incorporate antimicrobial agents or medications,” stated Thahn Nga Tran, who is a dermatologist and instructor at Harvard Medical School, not involved in the research.

Living Proof has offered the XPL technology to Olivo Laboratories, LLC, a new startup initiated to carry out further advancement of the XPL technology. At first, researchers at Olivo will concentrate on medical applications of the XPL for treating skin diseases such as dermatitis.

Fernanda Sakamoto and Rox Anderson from MGH; Soo-Young Kang from Living Proof; Morgan Pilkenton and Alpesh Patel, formerly from Living Proof; and Ariya Akthakul, Nithin Ramadurai, and Amir Nashat ScD ’03, from Olivo Laboratories are other authors of the paper.

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