Characterization of Fe3O4-PLGA Nanocomposites

Hydrodynamic diameter and zeta potential of the particles were determined by a dynamic light scattering (DLS) particle size analyzer (Malvern Nano-ZS90). Fourier transform infrared (FT-IR) spectra were measured on a FT-IR spectrometer (Vertex 80V, Bruker Germany) in the range of 4000–400 cm⁻¹ to confirm the chemical composition and structure information. Crystal structure of Fe₃O₄–PLGA was analyzed using X-ray diffraction (XRD, D&ADVANCE, Bruker Germany). The morphology microstructure of the nanocomposites was observed by transmission electron microscopy (TEM) (JEM-2100F STEM, JEOL Japan) and atomic force microscope (AFM) (Multimode 8, Bruker Germany). UV-vis spectra were obtained using a PerkinElmer Lambda 35 spectrophotometer (UV-2550, SHIMADZU, Japan) to analyze the catalytic oxidation activity. The hysteresis loops (300 K) of different Fe₃O₄ NPs were tested on a vibrating sample magnetometer (VSM) (model 7404, LakeShore USA) to characterize their saturation magnetization. Fluorescence spectra were obtained using a fluorescence spectrum analyzer (LS55, PerkinElmer USA). Electron paramagnetic resonance (EPR) spectra were measured by JEOL JES-FA200 spectrometer (JEOL, Japan). The cytotoxicity of HeLa cell was observed by a fluorescence microplate reader (Synergy TM MX, Berton Corporation USA), and the ROS was observed on fluorescence microscope (Olympus IX71) and confocal laser scanning microscope (Leica TCS SP5 II).