Synthetic melanin-infused cream protects and heals skin from sun and toxins

03 Nov 2023 --- Scientists at Northwestern University, US, have designed a skin cream that heals damage throughout the day when the skin is exposed to sunlight or environmental toxins using synthetic, biomimetic melanin.

When applied in a cream, the synthetic melanin can protect skin from sun exposure and heal skin injured by sun damage or chemical burns, the scientists say. The technology works by scavenging free radicals, which are produced by injured skin, such as sunburn. 

The scientists show that their synthetic melanin, mimicking the natural melanin in human skin, can be applied topically to injured skin and accelerate wound healing. These effects occur in the skin itself and systemically in the body.

Left unchecked, free radical activity damages cells and ultimately may result in skin aging and skin cancer.

“People don’t think of their everyday life as an injury to their skin. If you walk barefaced every day in the sun, you suffer a low-grade, constant bombardment of ultraviolet light,” says co-corresponding author and dermatologist Dr. Kurt Lu, professor of Dermatology at Northwestern University Feinberg School of Medicine.

“This is worsened during peak mid-day hours and the summer season. We know sun-exposed skin ages versus skin protected by clothing, which doesn’t show age nearly as much.”

The paper is titled: “Topical Application of Synthetic Melanin Promotes Tissue Repair” and published in the Nature npj Regenerative Medicine.

Synthetic melanin for healing
Melanin in humans and animals provides pigmentation to the skin, eyes and hair. The substance protects your cells from sun damage with increased pigmentation in response to sunlight — a process commonly referred to as tanning.

Northwestern University researchers discover biomimetic melanin to help damage skin (Image credit: Northwestern University).That same pigment in your skin also naturally scavenges free radicals in response to damaging environmental pollution from industrial sources and automobile exhaust fumes.

The skin also ages due to chronological aging and external environmental factors, including environmental pollution.

“All those insults to the skin lead to free radicals, which cause inflammation and break down the collagen. That’s one of the reasons older skin looks very different from younger skin,” asserts Lu.

When the scientists created the synthetic melanin-engineered nanoparticles, they modified the melanin structure to have a higher free radical scavenging capacity.

“The synthetic melanin is capable of scavenging more radicals per gram compared to human melanin,” says co-corresponding author Nathan Gianneschi, professor of Chemistry, Materials Science & Engineering, Biomedical Engineering and Pharmacology at Northwestern University.

“It’s like super melanin. It’s biocompatible, degradable, nontoxic and clear when rubbed onto the skin. In our studies, it acts as an efficient sponge, removing damaging factors and protecting the skin.”

Once applied to the skin, the melanin sits on the surface and is not absorbed into the layers below.

“The synthetic melanin stabilizes and sets the skin on a healing pathway, which we see in both the top layers and throughout the body,” Gianneschi details.

Reducing sun damage
The scientists, who have been studying melanin for nearly ten years, first tested their synthetic melanin as a sunscreen.

“It protected the skin and skin cells from damage,” explains Gianneschi. “Next, we wondered if the synthetic melanin, which functions primarily to soak up radicals, could be applied topically after a skin injury and have a healing effect on the skin. It turns out to work exactly that way.”

Lu envisions the synthetic melanin cream as a sunscreen booster for added protection and an enhancer in moisturizer to promote skin repair.

“You could put it on before you go out in the sun and after you have been in the sun. In both cases, we showed a reduction in skin damage and inflammation. You are protecting the skin and repairing it simultaneously. It’s continuous repair,” adds Lu.Synthetic melanin is being crafted to protect the skin.

The cream could also potentially be used for blisters and open sores.

Quieting immune system
Gianneschi and Lu discovered that the synthetic melanin cream quieted the immune system by soaking up the free radicals after an injury.

The stratum corneum, the outer layer of mature skin cells, communicates with the epidermis below.

It is the surface layer, receiving signals from the body and the outside world. By calming the destructive inflammation at that surface, the body can begin healing instead of becoming even more inflamed.

“The epidermis and the upper layers are in communication with the entire body. This means that stabilizing those upper layers can lead to a process of active healing,” says Lu.

Experiment procedure
The scientists used a chemical to create a blistering reaction to a human skin tissue sample in a dish. The blistering appeared as a separation of the upper layers of the skin from each other.

The researchers waited a few hours and then applied their topical melanin cream to the injured skin. Within the first few days, the cream facilitated an immune response by initially helping the skin’s radical scavenging enzymes to recover and then by halting the production of inflammatory proteins.

The effect initiated a “cascade of responses” in which the scientists observed significantly increased healing rates. This included the preservation of healthy skin layers underneath. In samples that did not have the melanin cream treatment, the blistering persisted.

By Sabine Waldeck