Advanced skin models for nanomaterials safety assessment

The human skin acts as a biological shield against prolonged exposure to nanomaterials (NMs) and nanoparticles (NPs) coming from cosmetics, textiles, and environmental pollutants that are known to lead to adverse effects such as oxidative stress, skin irritation, and skin diseases. This chapter reviews the main pollutants that our skin are exposed to daily as well as the advanced in vitro skin models used for assessing nanotoxicity. It is widely known that the existing 2D and 3D skin models try to mimic the complexity of skin physiology however they still lack specific skin structures such as vascularization and hair follicles. Skin-on-a-chip (SoC) devices, employing microfluidic technologies, bring the advantage of offering dynamic environments for more realistic evaluations of NMs’ safety assessment. In this chapter, we analyze critically how these models could accelerate nanotoxicity testing and support regulatory decisions. Additionally, we also review existing biological assays for skin toxicity as well as the available computational models (e.g., Nano-QSR) that could help in predicting nanotoxicity taking into consideration the physicochemical properties of NMs. Future research should focus on enhancing skin model complexity and employing computational methods to predict NM behavior, ensuring the safe development of nanomaterials for dermal applications.