Chemical template-assisted synthesis of monodisperse rattle-type FeO@C hollow microspheres as drug carrier.

Unlabelled: A chemical template strategy was put forward to synthesize monodisperse rattle-type magnetic carbon (FeO@C) hollow microspheres. During the synthesis procedure, monodisperse FeO microspheres were used as chemical template, which released Fe ions in acidic solution and initiated the in-situ polymerization of pyrrole into polypyrrole (PPy) shell. With the continual acidic etching of FeO microspheres, rattle-type FeO@PPy microspheres were generated with the cavity appearing between the PPy shell and left FeO core, which were then transformed into FeO@C hollow microspheres through calcination in nitrogen atmosphere. Compared with traditional physical template, the shell and cavity of rattle-type hollow microspheres were generated in one step using the chemical template method, which obviously saved the complex procedures including the coating and removal of middle shells. The experimental results exhibited that the rattle-type FeO@C hollow microspheres with different parameters could be regulated through controlled synthesis of the intermediate FeO@PPy product. Moreover, when the rattle-type FeO@C hollow microspheres were investigated as drug carrier, they manifested sustained-release behaviour of doxorubicin, justifying their promising applications as carriers in drug delivery.

Statement Of Significance: The aim of the present study was first to synthesize rattle-type FeO@C hollow microspheres through a simple synthesis method as a drug carrier. Here a chemical template synthesis of rattle-type hollow microspheres was developed, which saved the complex procedures including the coating and removal of middle shells in traditional physical template. Second, all the influence factors in the reaction processes were systematically investigated to obtain rattle-type FeO@C hollow microspheres with controlled parameters. Third, the rattle-type FeO@C hollow microspheres were studied as drug carriers and the influences of their structural parameters on drug loading and releasing performance were investigated.