Facile synthesis of multifunctional La1−xSrxMnO3@Au core–shell nanoparticles for biomedical applications

Abstract

Multifunctional high-performance La_1−xSr_xMnO₃@Au core–shell nanoparticles were successfully synthesized by a modified nanoemulsion method with the assistance of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO). X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses confirm the structure and morphology of the nanoparticles. The measurements obtained using ultraviolet-visible light absorbance spectrometry (UV-vis), vibrating sample magnetometry (VSM), and a physical property measurement system (PPMS) demonstrate that the nanoparticles exhibit a surface plasmon resonance (SPR) absorption band around 561 nm from nanostructured Au and a unique magnetic nature at room temperature. Particularly, a sharp, tight phase transition from ferromagnetic to superparamagnetic states is observed in a free-standing La_1−xSr_xMnO₃ nanoparticle system for the first time with a Curie temperature around room temperature. The cytotoxicity of the nanoparticles was studied for safe biomedical applications using an MTT assay. The results show that the La_1−xSr_xMnO₃@Au core–shell nanoparticles with lower cytotoxicity, well-defined magnetic and optical properties are promising for optical, magnetic, and biomedical application.