Polyphenolic condensation assembly enabled biocompatible, antioxidative, and light-colored tea sunscreen formulations with broadband UV protection

Abstract

The concerns about the health and environmental effects of the active ingredients in current sunscreens have spurred the enthusiasm for seeking out biosafe and efficient alternatives, especially from nature. However, the present improvement is generally associated with multistep, expensive nanotechnologies and complex formulations of multiple active ingredients for achieving efficient ultraviolet (UV) protection, and the absence of antioxidative activity and the dark color further hinder the practical application of these naturally sourced absorbers. Herein, a facile and efficient strategy is introduced to prepare a biocompatible, antioxidative and light-colored sunscreen solely from naturally reproducible tea polyphenols with only UVB absorption. We demonstrate that the Mannich condensation assembly of polyphenol nanoparticles gave rise to broadband UV shielding and enhanced extinction efficacy. These nanoparticles have strong antioxidative activities and offer a wide range of selections for particle-stabilized emulsion formulations with a cosmetically acceptable appearance and, most importantly, with good anti-UV performance and photostability under UV exposure. Favorable UV protection against inflammation, epidermal hyperplasia, and hyperkeratosis was achieved in an acute photodamage model. The particle-stabilized emulsions are also adhesive, water-resistant and comfortable to apply. This study lays the foundation for formulating polyphenol-based sunscreens, and the acquisition of broadband UV protection by molecular assembly of a UVB absorber is validated as an effective strategy to be beneficial for future UV absorber development.