Modified green synthesis of Fe3O4@SiO2 nanoparticles for pH responsive drug release.

A magnetic field activated drug delivery and pH-sensitive controlled drug release system based on carboxyl-modified green synthesized Fe3O4@SiO2 (Fe3O4@SiO2-Glu) nanoparticles was established. Doxorubicin hydrochloride (DOX), as a drug model, was adsorbed onto the Fe3O4@SiO2-Glu nanoparticles' surface, where the observed drug loading capacity of 34.6 mg/g was attributed to electrostatic interaction between -COO- on the surface of Fe3O4@SiO2-Glu and -NH3+ of DOX. The structure, morphology and physiochemical properties of Fe3O4@SiO2-Glu were characterized via TEM, FTIR, XRD, N2 adsorption/desorption isotherms, and Zeta potential measurements. The green synthesized Fe3O4@SiO2-Glu nanoparticles exhibited multilayer architecture with a BET surface area of 79.9 m2/g and a magnetization saturation of 25.9 emu/g. Drug release experiments indicated that DOX was pH trigger released with 60.8% released within 72 h at pH 3.5. This system has important potential implications for the design of more effective and stable magnetic Fe3O4@SiO2-Glu materials as drug carriers for targeted and controlled drug release.