Advancement of sunscreen using sodium surfactin

ABSTRACT

Micron-sized physical ultraviolet filters, including titanium dioxide (TiO2) and zinc oxide (ZnO), are widely utilized in sunscreen formulations due to their broad-spectrum protection and favourable safety profile. However, their performance is often compromised by inherent limitations such as particle aggregation, rapid sedimentation, pronounced white cast, and unsatisfactory skin-feel, which collectively impair both efficacy and user acceptance. This study introduces sodium surfactin as an ecofriendly biosurfactant to enhance the UV protection efficiency of micron-sized physical sunscreens. Results indicate that surfactin significantly enhances the stability of ZnO suspensions, with the addition of 1% surfactin completely inhibiting visible sedimentation of 10% ZnO for over 24 hours. Particle size analysis revealed that surfactin reduced the average particle size of TiO2 and ZnO in aqueous suspensions by 90% and 99%, respectively. Surfactin-incorporated sunscreen formulations showed a SPF increases of 12% for TiO2-based and 25% for ZnO-based products. Furthermore,sensory assessments confirmed that surfactincontaining sunscreens provided superior skinfeel characterized by lighter texture, enhanced spreadability, reduced stickiness, and minimal white cast. Overall, this study addresses key formulation challenges associated with micron-sized physical sunscreens and establishes a scientific foundation for the development of high-performance, userfriendly, and stable sunscreen products

Sunscreen agents are broadly classified as chemical absorbers or physical blockers based on their protection mechanisms. Although chemical filters provide desirable texture and spreadability, concerns over photosensitivity, skin penetration, and ecological toxicity have prompted regulatory limitations in several regions.^1,2