A new article published in ACS Nano reported that the first tattooable intradermal nanosensors have only emerged in the past few years, and none have been demonstrated in human skin.

Here, the authors reported of having developed a photochromic tattoo that serves as an intradermal ultraviolet (UV) radiometer – which provides naked-eye feedback about UV exposure in real time. These small tattoos or "solar freckles", comprise dermally implanted colorimetric UV sensors in the form of nanoencapsulated leuco dyes that become bluer in color with increasing UV irradiance.

The tattoos functionality for both, quantitative and naked-eye UV sensing, was demonstrated in human skin in vivo. It was found that solar freckles offer an alternative and complementary approach to self-monitoring UV exposure for the sake of skin cancer prevention.

This article summarized that activated solar freckles provide a visual reminder to protect the skin, and their color disappears rapidly upon removal of UV exposure or application of topical sunscreen. The sensors are implanted in a minimally invasive procedure that lasts only a few seconds, yet remain functional for months to years. These semipermanent tattoos provide an early proof-of-concept for long-term intradermal sensing nanomaterials that provide users with biomedically relevant information in the form of an observable color change.

Source: ACS Nano. 2020 Sep 22. doi: 10.1021/acsnano.0c05723.