# Innovative Safe Sunscreens Technology: Evaluation of Skin Penetration Through In Vitro/In Vivo Assays and Environmental Friendliness

## TL;DR

This study introduces a new sunscreen technology that prevents skin penetration, is safe for sensitive skin, and provides strong UV protection.

## Contribution

A novel microencapsulation method prevents UV filter penetration while maintaining sunscreen efficacy.

## Key findings

- The innovative sunscreen showed zero penetration of UV filters in in vitro tests for 6 hours.
- Raman spectroscopy confirmed no penetration into the stratum corneum for 4 hours and no penetration into the epidermis for 8 hours.
- The formulation was nonirritating, nonallergenic, and well-tolerated by sensitive skin volunteers.

## Abstract

Conventional sunscreens can penetrate the skin, potentially causing irritation and raising safety concerns. This study introduces a novel sunscreen technology designed to prevent skin penetration while maintaining high efficacy.

To evaluate the safety, efficacy, and skin penetration profile of an innovative sunscreen that microencapsulated UV filters (octocrylene and avobenzone) within a silk peptide modified polysilicone‐14, and to compare it to a conventional, nonencapsulated formulation.

The innovative formulation was assessed using a Human Repeated Insult Patch Test (HRIPT) to determine irritation and allergenic potential. Sun protection efficacy was measured in vivo (SPF, PFA). Skin penetration was evaluated using in vitro Franz cell assays with a Strat‐M membrane and in vivo via Raman spectroscopy, which measured penetration into the stratum corneum and epidermis over time. Sensory assessment and tolerability were also conducted on volunteers with sensitive skin.

The HRIPT confirmed the innovative sunscreen was nonirritating and nonallergenic. It demonstrated equivalent sun protection efficacy to the conventional sunscreen, with an SPF of ~30 and PFA of ~10. Crucially, the Franz cell assay showed zero (0.00%) penetration of UV filters for 6 h. Raman spectroscopy confirmed no penetration into the stratum corneum for 4 h and no penetration into the epidermis for 8 h. The formulation was well‐tolerated by sensitive skin volunteers. In contrast, the conventional sunscreen showed significant skin penetration and caused irritation.

The innovative microencapsulation technology successfully creates a safe, non‐skin‐penetrating sunscreen with high UVA/UVB protection. This technology offers a superior safety profile, making it particularly suitable for populations with sensitive skin.