Molecular engineering of melanin for enhanced biological γ-ray protection.

The escalating utilization of ionizing radiation across medicine and industry underscored the paramount urgency of effective radioprotective materials. Conventional materials such as lead and concrete are widely used, and lead-free materials have also emerged to solve the problems of cumbersome and toxic lead, such as metal-containing micro/nano materials and polymers. Nevertheless, there is still a significant challenge in meeting the urgent need for lightweight and biocompatible alternatives. To tackle this challenge, this work utilizes molecular engineering of melanin to develop a panel of metal-free melanin materials with enhanced conjugation, heightened physical shielding against radiation and effective antioxidant properties. Furthermore, engineered melanin materials demonstrated in vivo γ-ray protection, increasing mice survival from ~12% to 100% after 6 Gy total body irradiation.