Synthesis and properties of hollow Fe3O4@Au hybrid nano-structures for T-1-T-2 MR imaging and a combination of magnetic and photo-induced heating

In the current work, hollow Fe3O4@Au hybrid nanoparticles (h-NPs) with a size of 17 nm were synthesised through seeded growth and galvanic replacement reactions. The influence of the experimental parameters such as the reaction time and precursor concentration on the formation of h-NPs was investigated. The hydrophobic hollow Fe3O4@Au h-NPs were transferred into water by coating with an amphiphilic polymer, poly(maleic anhydride-alt-1-octadecene) (PMAO), to form highly stable colloids. The PMAO coated hollow Fe3O4@Au h-NPs provide an excellent signal enhancement of T-1- and T-2-weighted MRI (r(1) = 8.47 mM(-1) s(-1), r(2) = 74.45 mM(-1) s(-1)). Magnetic and photothermal data of the hollow Fe3O4@Au h-NPs indicated that sample temperature can reach 70 degrees C under a magnetic field of 16 kA m(-1) and a frequency of 450 kHz for 2 min and 808 nm NIR laser at a power density of 0.65 W cm(-2) for 2 min. This effective combination between the magnetic thermia of the magnetic cores and the photothermal effect of the gold shell indicates hollow Fe3O4@Au h-NPs as a potential material for efficient cancer theranostics.