Validation of a lipopeptide approach to a safe-and-sustainable-by-design strategy on TiO₂ nanoparticles UV filters

Titanium dioxide nanoparticles (TiO₂ NPs) are well suited for cosmetics and polymer films because they efficiently absorb UV light while remaining transparent to visible light. Their widespread use requires strategies for managing potential human and environmental risks. Implementing the Safe and Sustainable by Design (SSbD) methodology to advanced chemicals and materials is a major global challenge and a concept that is included in several EU research projects. This study employed a SSbD strategy by functionalizing the surface of TiO₂ nanoparticles with a lipopeptide-based biosurfactant (Sodium Surfactin, SS). A colloidal heterocoagulation approach was used to produce SS-modified TiO₂ nanoparticles. Different design options (TiO₂ source, order of addition, TiO₂/SS weight ratio) were investigated, and the properties were compared by measuring the UV filtering capability, photoreactivity, dustiness index, biological and ecotoxicological endpoints. This allowed us to estimate the safety and sustainability profile in agreement with the steps suggested by the JRC SSbD framework. The lipopeptide-based coating was essential for managing UV light-induced photoactivity and significantly lowering both in vitro cytotoxicity and ecotoxicity while simultaneously enhancing photostability when applied in cosmetic formulations. These results demonstrate that a colloidal process, which can be easily scaled up for industrial purposes, is a promising and exploitable SSbD strategy for the design and implementation of TiO₂ NPs based UV filters.