Hollow Fe₃O₄/Graphene Oxide Nanocomposites as Novel Rapamycin Carrier: Formulation Optimization and Characterization.

In the present research an attempt was made to develop and optimize rapamycin (Rapa) loaded hollow magnetic Fe3O4/graphene oxide (Fe3O4/GO) nanocomposites using solvent evaporation technique and response surface methodology (RSM). A Box-Behnken design (BBD) with a three-level, three-factor was used to determine preparation parameters that would achieve the highest encapsulation efficiency (EE) and drug loading capacity (DLC). At optimum conditions such as mass ratio of Rapa to Fe3O4/GO (Rapa: Fe3O4/GO) 0.45, oscillation rate 144.0, and volume ratio of water to solvent (W/S) 4.2, the EE and DLC of experimentally prepared particles reached 84.92 ± 5.50% and 28.68 ± 2.54% respectively. The morphological assessment results showed that hollow Fe3O4 nano-aggregates were evenly and tightly dispersed on the layer of GO membrane. After the addition of GO and encapsulation of Rapa, the Fe3O4/GO nanocomposites and Rapa loaded magnetic Fe3O4/GO (Fe3O4/GO-Rapa) nanocomposites showed saturation magnetization of 57.77 and 40.71 emu/g respectively. The drug releasing experiment indicated a slightly acidic atmosphere, which was suitable for Rapa releasing from the obtained Fe3O4/GO nanocomposites. The cell counting Kit-8 (CCK-8) assays demonstrated the hollow Fe3O4/GO nanocomposites could effectively improve the efficacy of Rapa in killing HepG2 cells, which displayed a concentration-dependent manner. All these results suggested the prepared Fe3O4/GO nanocomposites have a potential application in drug delivery system.