Microwave-Driven Cytocompatible Mn-Doped TiO ₂ –Fe ₃ O ₄ Ordered Heterostructures for Microplastic and Antibiotic Degradation

Precisely assembling diverse nanocrystals is crucial for fabricating advanced heterostructures with complex functionalities, collective properties, and enhanced stability, which are essential for addressing widespread pollutants, such as omnipresent microplastics and antibiotics. Achieving photoactive designs for these materials with low cytotoxicity using rapid one-pot methods remains a significant challenge. Herein, we developed a microwave synthesis strategy for Mn-doped TiO₂-Fe₃O₄ ordered heterostructures (TFM) achieved through polyvinylpyrrolidone (PVP) templating. The rapid microwave heating facilitates both swift nucleation and growth, while PVP's varied affinities for Ti⁴⁺, Fe³⁺, and Mn²⁺ ions promote oriented attachment and the formation of ordered heterostructures. The resultant heterostructures, characterized by coherently aligned nanocrystals, exhibit significantly enhanced photocatalytic activity, as evidenced by their effective photofragmentation of polyethylene glycol microplastic and tetracycline antibiotic. Prior to photocatalysis, cytotoxicity assessments conducted with osteoblast cells confirm the biocompatibility of these materials, suggesting preliminary potential for environmentally relevant applications, provided short-term TFM exposure is considered. This work, therefore, introduces a versatile and rapid fabrication approach for mesocrystal-inspired heterostructures, underscoring their dual role in pollutant remediation and the development of biocompatible materials, thereby bridging the gap between sustainable synthesis and functional application within the field.