Schematic diagram of proposed photocatalysis and band-gap narrowing mechanism, photo-excited and accepted electrons, adsorption of MB, and e ⁻ and h ⁺ transfer of La/TiO ₂ @La/ZnO–B–RGO TNCs under sunlight irradiation.

In this paper, zinc ferrite@meso-porous (abbreviated as m) zinc oxide–nitrogen doped reduced graphene oxide (ZnFe₂O₄@mZnO–N/RGO) and zinc ferrite@mZnO–reduced graphene oxide (ZnFe₂O₄@mZnO–RGO) as dual ultrasound (US) and pH-sensitive nano-devices have been prepared by sol–gel method. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer spectroscopy (VSM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), thermogravimetric analyzer (TGA), dynamic light scattering (DLS), zeta potential, Brunauer–Emmett–Teller (BET) surface area and MTT assay were applied as techniques for characterizing prepared nano-devices. The amount of drug loading efficiency of ZnFe₂O₄@mZnO–RGO and ZnFe₂O₄@mZnO–N/RGO nano-devices was as high as 65.49 and 73.32 mg mg⁻¹, respectively. Moreover, developed nano-devices have released curcumin (Cur) molecules by dual US and pH approaches. These dually responsive nano-devices showed no cytotoxicity, and can load the Cur reagent with a prolonged sustained release pattern. The release is controllable by ultrasound radiation and pH (7.4 and 5.5) in a binary buffer at 37 °C. Herein, we report two precisely designed sonodynamic drug carriers that have a US-drug release property via reactive oxygen species (ROS) generation (O₂ ⁻˙, OH˙, HO₂˙) from ZnFe₂O₄@mZnO species. Toxicity test results on the fibroblast and A549 cells showed that nano-devices are biocompatible for healthy cells, but toxic for cancer cells.