Polyphosphazene Microparticles with High Free Radical Scavenging Activity for Skin Photoprotection.

Area of Science:

• Materials Science
• Dermatology
• Photochemistry

Background:

• Conventional UV filters in sunscreens face challenges including poor photostability, skin penetration, and generation of reactive oxygen species (ROS).
• These issues raise concerns about the safety and efficacy of existing sunscreen formulations.

Purpose of the Study:

• To develop a novel organic UV filter in the form of self-framed microparticles (HCCP-QC MPs) for enhanced sun protection.
• To evaluate the photostability, UV shielding range, ROS scavenging ability, and skin penetration of the developed microparticles.

Main Methods:

• Facile precipitation polymerization was used to construct quercetin (QC) and hexachlorocyclotriphosphazene (HCCP) into microparticles (HCCP-QC MPs) without carriers.
• In vitro and in vivo experiments were conducted to assess UV protection, ROS scavenging, and biocompatibility.

Main Results:

• HCCP-QC MPs demonstrated an extended UV shielding range across the entire UV spectrum.
• The microparticles significantly reduced UV-induced ROS and prevented skin penetration of QC.
• High QC loading capacity (697 mg g⁻¹) and no small molecule leakage were observed due to the cross-linked structure.

Conclusions:

• HCCP-QC MPs offer superior UV protection and effective ROS scavenging with excellent biocompatibility.
• The non-penetrating nature and stability of these microparticles present a promising advancement for skin protection applications.