Safe-by-design approach to sunscreens: Synthesis and validation of biomimetic hybrid particles for an eco-sustainable UV protection

Excessive exposure to solar radiation is widely known to cause severe skin damage, including the risk of cancer. Consequently, using effective sunscreen to protect against harmful UV rays has become increasingly important. Considering this, we developed a novel eco-friendly solar product through a safe-by-design approach, as effective and safe as commercial formulations. The process takes the moves from a nature-inspired biomineralization technique, in which nanostructured titanium-doped hydroxyapatite (TiHA), is synthesized and grown onto Alginate (Alg) organic matrix. This enables the creation of an innovative UV filter, referred to as AlgTiHA, which is completely biocompatible, biodegradable, and devoid of any photocatalytic effects. Its excellent reflectance and absorption properties have been demonstrated by UV-Vis spectroscopy. Its excellent reflectance and absorption properties were demonstrated by UV-Vis spectroscopy. AlgTiHA is environmentally friendly, releasing harmless degradation compounds such as calcium, phosphate, and titanium ions, without detectable TiO₂. Formulated alone or with organic/inorganic filters, AlgTiHA significantly enhanced SPF: in vivo, SPF increased by 30% for organic-filter formulations (average SPF ≈31) and 34% for inorganic-filter formulations (average SPF ≈16.7), with no irritation observed. These results highlight AlgTiHA as a safe, effective, and eco-sustainable booster, enabling reduced concentrations of conventional filters while maintaining high photoprotection and minimizing potential risks to human health and marine ecosystems.