In Vivo Study of Spiky Fe3O4@Au Nanoparticles with Different Branch Lengths: Biodistribution, Clearance, and Biocompatibility in Mice

Magnetoplasmonic nanoparticles (Fe3O4@Au NPs) have been proven to be effective theranostic agents in gene and drug delivery, as well as in photothermal therapy. Herein, two spiky magnetoplasmonic NPs with different branch lengths and numbers (short- and long-branched spiky Fe3O4@Au NPs) were specifically designed to determine theirs in vivo behaviors. The biocompatibility, biodistribution, and clearance of spiky Fe3O4@Au NPs were examined in mice. Organ distributions showed that intravenously administered spiky Fe3O4@Au NPs accumulated mainly in liver and spleen, and the particle shape significantly affected their in vivo behaviors. The higher tendency in bioaccumulation of short-branched rather than long-branched spiky Fe3O4@Au NPs was observed in the spleen because of long-branched spiky Fe3O4@Au NPs with a high aspect ratio were internalized more slowly than short-branched spiky Fe3O4@Au NPs. Serum biochemistry and transmission electron microscopy of ultra-histological structures indicated that spiky Fe3O4@Au NPs did not exhibit distinct toxicity in vivo and posed no potential risk of causing liver and kidney dysfunction. These findings lay the foundation for the design of future theragnostic agents.