Semipermanent Tattoos

July 13, 2007 — -- Getting inked is a big commitment. Whether you carefully choose a meaningful design or get one on a drunken whim, tattoos are meant to be permanent. Successfully removing one involves thousands of dollars in laser surgery, often with multiple procedures. In light of these costs, many people resign themselves to living with a tattoo they've outgrown, or they choose not to get one in the first place.

Now scientists at Harvard Medical School, Brown University, and Duke University have engineered safe, permanent, and easily removable tattoo inks, made from tiny microcapsules of natural pigments. Researchers say these inks are designed to be removed with just one laser treatment, and they may also help reduce allergic reactions and other health problems commonly experienced with traditional inks.

"What led to this was a frustration from seeing people who had tattoos that couldn't be removed, or were hurting their health," says Rox Anderson, a professor of dermatology at Harvard Medical School. "I saw a patient a few years back, this woman who had a red lip-liner tattoo, and she had such an allergic reaction that the swelling in the mouth was such that she couldn't eat, and we had to surgically remove her lips. Seeing someone whose life was basically ruined by that got me going."

The Food and Drug Administration does not regulate the tattoo industry, and inks can comprise heavy metals and other chemicals, depending on the tattoo artist who mixes the colors. Often the same inks that are used for printing and paints are used in tattooing, and some inks may be carcinogenic. While most people suffer no adverse effects from tattoos, others may experience inflammation around the area, an increased sensitivity to light, or other health problems.

To combat these effects, Anderson's first goal was to find safe, biocompatible pigments. To date, he has designed black and brown pigments using carbon and iron oxide, and yellow and orange pigments using beta-carotene. All are nontoxic substances. Anderson is also experimenting with food dyes to fashion other shades. However, he found that simply applying these pigments directly to the skin is far from permanent, as colors tend to fade after several days. Anderson needed a way to keep the pigments from being absorbed by the body.

That's why he teamed up with Edith Mathiowitz, a professor of medical science and engineering at Brown University. Mathiowitz specializes in microencapsulation, or designing tiny beads to transport drugs into the body and release their contents in specific places and at specific times. Anderson partnered with Mathiowitz to engineer a microcapsule containing his biocompatible pigments, which would keep them from fading into the skin. The biggest test, says Mathiowitz, was finding a polymer material that was both nontoxic and clear enough for the pigments to show through.

"The challenge is how to make it artistically appealing for tattoo artists," says Mathiowitz. "They are not going to use something that's just safer, but something they like the look of. There's a lot of art and science involved."

Mathiowitz and Anderson found an ideal candidate in the polymer polymethyl methacrylate, or PMMA--a transparent plastic originally used as an alternative to glass that has been shown to be nontoxic in human tissue. PMMA is now used in contact lenses and heart valves, as well as in cosmetic surgery to smooth wrinkles and scars. Mathiowitz designed tiny, nano-sized PMMA beads to house Anderson's biodegradable pigments. Researchers found that these microencapsulated inks held up for months in animal studies.

The final challenge was to modify the inks so that they're easily removable with one laser treatment. Traditionally, to remove a single tattoo, a dermatologist matches a laser's wavelength to a specific color in a tattoo. Black is the easiest to target, since it can absorb all wavelengths. The laser breaks the pigment into smaller particles, which are then absorbed by the body's immune system. Since artists use a wide range of pigments and sometimes mix their own, it's difficult to exactly match a laser to a given color, which is why multiple treatments are often needed to fully erase a tattoo.

To get around this problem, Anderson inserted a tiny "energy-absorbing target" into each microcapsule--a substance that looks black. The target is small enough that it doesn't affect the ink's appearance but big enough to react to laser light, so that the bead ruptures and releases the pigments.

"They're basically taking the individualization out of it," says Ranella Hirsch, president elect of the American Society of Cosmetic Dermatology and Aesthetic Surgery. "And the simplicity and beauty of this is in standardizing the ink."

Anderson has formed a company, Freedom-2, to commercialize the inks, and he hopes to bring the first generation of microencapsulated inks to market in the next year. He adds that the design opens up possibilities for a whole range of specially timed tattoos. "You could sit around and think of all kind of things, like a time-limited tattoo, one that would last three years and then disappear, or tattoos that only appear at night."