| Abstract Scope |
Rising global temperatures have intensified UV-induced skin damage risks, prompting WHO’s sunscreen advocacy. While inorganic sunscreens (ZnO, TiO₂) are considered safer than organic alternatives, they still generate carcinogenic ROS. Herein, we propose a unique, helical coil continuous flow platform (HCFP) that leverages secondary flows to simultaneously engineer surface oxygen vacancies (VO●) and size focusing of oxide bioceramics (OBs) - ZnO and CeO2(x)/ZnO(1-x), enhancing molar absorptivity through photogenerated electron-hole separation. Hydrodynamics and heat transport in HCFP were simulated using ANSYS FLUENT 2021 and correlated with nucleation-growth kinetics to maximise VO●. HR-TEM, XPS, EPR, UV-Vis and PL spectroscopy unveiled monodispersed ZnO (4.5 nm) and CeO2(x)/ZnO(1-x) (8 nm) OBs, their defect-driven band restructuring, achieving long-lasting photostability (>10 h) and broad-spectrum UV attenuation (250–600 nm). Intriguingly, abundant surface VO● (72 %) augmented biocompatibility (>90% at 200 μg/mL) via VO●-driven redox reactions. This study demonstrates a new-fangled strategy for formulating cost-effective multifunctional bioceramic sunscreens. |