Preparation of Light-Colored Botanical Sunscreen from Pink Birch Lignin

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Cosmetic Science

Background:

• Lignin, a natural polymer, shows promise for UV-blocking applications in skincare.
• The dark color of native lignin limits its use in cosmetic formulations.
• Developing lighter-colored lignin derivatives is crucial for broader application.

Purpose of the Study:

• To extract and characterize a pink lignin (PL) from birch under mild conditions.
• To develop PL-encapsulated sunscreen actives for broad-spectrum UV protection.
• To evaluate the efficacy, photostability, and biocompatibility of PL-based sunscreens.

Main Methods:

• Mild extraction of pink lignin (PL) from birch, followed by characterization (molecular weight, PDI, whiteness index).
• One-step ultrasonic cavitation to encapsulate chemical sunscreen actives within PL.
• Formulation of sun creams with PL capsules and evaluation of sun protection factor (SPF), whiteness index, and photostability.

Main Results:

• Successfully extracted pink lignin (PL) with retained native structure and a whiteness index of -25.
• Developed PL capsules (180 nm average diameter) exhibiting broad-spectrum UV absorption.
• Sun creams formulated with 10% and 15% PL capsules achieved SPF values of 130+ and 180+, respectively, with minimal whiteness reduction.
• PL-based sunscreens demonstrated excellent photostability, with only an 18% SPF decrease after 7.5 hours of UV exposure.
• PL capsules showed good biocompatibility.

Conclusions:

• Pink lignin (PL) is a viable, photostable alternative to traditional UV filters in sunscreens.
• PL encapsulation technology enhances UV absorption and delivers high SPF values.
• The developed PL capsules offer promising potential for advanced skincare and UV protection products.