Photochemically Inert Broad-Spectrum Sunscreen by Metal-Phenolic Network Coatings of Titanium Oxide Nanoparticles

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Titanium dioxide (TiO2) nanoparticles are common sunscreen agents but suffer from high photochemical activity and limited UV absorption.
• Existing solutions like polymer coatings and organic filters face environmental and health concerns.

Purpose of the Study:

• To develop novel TiO2-metal-phenolic network hybrid nanoparticles (TiO2-MPN NPs) as improved sunscreen agents.
• To enhance UV protection by widening the absorption spectrum and suppressing photocatalytic activity.

Main Methods:

• Synthesized TiO2-MPN NPs using tannic acid and multivalent metal ions for a robust coating.
• Investigated the photoexcitation pathway and quantified UV and high-energy visible (HEV) light absorption.
• Assessed the suppression of photoinduced reactive oxygen species (ROS) and the alleviation of cytotoxicity.

Main Results:

• TiO2-MPN NPs exhibited a 4-fold increase in sun protection factor (SPF) and ultraviolet-A protection factor (UVA-PF).
• Achieved 99.9% suppression of photoinduced ROS over 6 hours under simulated solar irradiation.
• Demonstrated significant reduction in UV- and HEV-induced fibroblast cytotoxicity.

Conclusions:

• TiO2-MPN NPs offer a promising strategy for eco-friendly and biocompatible sunscreen formulations.
• This approach effectively inhibits semiconductor photocatalytic activity while broadening optical absorption for superior sun protection.