Lignin-based eco-friendly sunscreen lasts even hours after UV exposure

Researchers have developed a high-performance, eco-friendly sunscreen using natural lignin and titanium dioxide, providing a sustainable alternative for sun protection.

This innovative sunscreen utilizes lignin, a naturally abundant polymer, alongside titanium dioxide (TiO2). The study, led by scientists Yarong Li and Zhiguang Tang, was published in the Journal of Bioresources and Bioproducts.

It highlights the innovative use of a dual-modified lignin sub-microsphere, which not only boosts the SPF of sunscreens but also improves their color, providing a more effective and aesthetically appealing product.

A byproduct of the pulp industry, lignin is praised for its UV-absorbing and antioxidant properties, but its use in sunscreens has been restricted by its low SPF and dark color. To solve these problems, researchers modified its chemical structure and physical form.

The researchers attached methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT) to alkali lignin (AL) to create a new polymer, AL-g-MBBT. They then turned it into tiny spheres, some with and some without TiO2.

Modified lignin sunscreen shows SPF boost and lighter color

Sunscreens made with 10% AL-g-MBBT3 had an SPF of 42.93, a big jump from the 4.74 SPF of unmodified AL. The modified sunscreen was also much lighter in color, with a value of 45.6 ΔE compared to 49.5 ΔE for the unmodified version, making it more suitable for cosmetics.

The researchers enhanced the sunscreen’s effectiveness by creating TiO2-loaded sub-micron spheres. These AL-g-MBBT3/TiO2@C sunscreens reached an SPF of 66.20, surpassing both the unmodified AL and the versions without TiO2. Additionally, the color improved significantly, with a ΔE value of 36.3.

The study also assessed the photostability and biocompatibility of the lignin-based sunscreen. The results indicated that the sunscreen retained its sun protection effectiveness and color even after three hours of UV exposure.

Non-toxic and safe for skin application

Biocompatibility tests revealed that the modified lignin-containing sunscreen was non-toxic to human keratinocytes, indicating its safety for skin application.

This finding suggests that the innovative formulation not only provides effective sun protection but also ensures that it is gentle and safe for use on human skin, making it a promising option for consumers seeking eco-friendly and safe skincare products.

This research represents an important step forward in using lignin as a sustainable and effective alternative to traditional sunscreen ingredients. By demonstrating lignin’s ability to provide UV protection while being eco-friendly, the study opens the door for a new generation of sunscreen products.