Interaction between Pharmaceutical Drugs and Polymer-Coated Fe₃O₄ Magnetic Nanoparticles with Langmuir Monolayers as Cellular Membrane Models

Surface modification of magnetic nanoparticles (MNPs) has been reported to play a significant role in determining their interactions with cell membranes. In this research, the interactions between polymer functionalized (chitosan, CHI or diethylamino-ethyl dextran, DEAE-D) Fe₃O₄ MNPs, pharmaceutical drugs and model cell membranes were investigated by Langmuir isotherms and adsorption measurements. In this study, 1,2-distearoyl-sn-glycerol-3-phosphate (DSPA) phospholipid monolayers were used as cell membrane models. Insertion experiments demonstrate that diclofenac (DCFN) is not absorbed at the air–water interface, whereas triflupromazine (TFPZ) has a MIP (maximum insertion pressure) of 35 m Nm⁻¹. The insertion of composites MNPs:TFPZ or DCFN has larger MIP values, indicating that the MNPs are adsorbed on the monolayer with the drugs. An Fe₃O₄@CHI:DCFN composite presented an MIP of 39 m Nm⁻¹ and Fe₃O₄@DEAE-D:DCFN presented an impressive MIP of 67 mNm⁻¹. In the case of TFPZ, the enhancement in the MIP values is also evident, being 42 mNm⁻¹ for Fe₃O₄@CHI:TFPZ and 40 mNm⁻¹ for Fe₃O₄@DEAE-D:DCFN composite. All MNPs:drugs composites have MIP values greater than commonly accepted membrane pressure values, indicating that MNPs:drugs can penetrate a cellular membrane. The fact that the composite MNPs:drugs present greater MIP values than separated compounds indicates that polymer-coated MNPs can act as good drug delivery systems.