Mechanistic insight into loading of doxorubicin hydrochloride onto carbonized FeNPs@ZIF-8 composite

The increasing global efflux of antibiotics into aquatic environments has significant detrimental impacts on natural ecosystems. Consequently, the controlled release of antibiotics and their metabolites is an important issue. In this paper, a new carbonized iron nanoparticles-metal organic framework (C-Fe3O4@ZIF-8) composite was used to load doxorubicin hydrochloride (DOX), where loading efficiencies of 75.2, 62.1, 48.4 and 20.5% were observed when using C-Fe3O4@ZIF-8, C-ZIF-8, [email protected] and Fe3O4, respectively. A DOX loading efficiency of 94.7% was reached under optimized conditions. Analysis of the UV–Visible spectra of DOX showed that no significant degradation products were evident, indicating that loading of DOX on C-Fe3O4@ZIF-8 was via adsorption. FTIR and XPS analysis together with pH dependant changes in adsorption suggested that C-Fe3O4@ZIF-8 adsorbed DOX through a combination of surface complexation and electrostatic interaction. Furthermore, isothermal adsorption studies revealed that the adsorption of DOX on C-Fe3O4@ZIF-8 followed the Langmuir model, and the pseudo-second-order kinetic model, indicating that adsorption was dominated by chemisorption, and thus the loading mechanism was proposed based on specific site adsorption. Finally, the magnetic property of C-Fe3O4@ZIF-8 was relativity easy to separate, and accordingly have desirable recycle/reuse performance.