Functionalized Fe₃O₄ Nanocomposites as Platforms for Bioactive Molecule Immobilization and Targeted Drug Delivery

This review summarises various modern approaches to the synthesis and functionalisation of magnetite (Fe₃O₄) magnetic nanoparticles and analyses their application as platforms for the immobilisation of biologically active molecules and pharmaceutical compounds. The main methods for producing Fe₃O₄ nanoparticles are discussed, in particular coprecipitation, hy drothermal, solvothermal and solgel synthesis, with an emphasis on their influence on the morphology, size and magnetic properties of the materials. Particular attention is paid to the surface functionalisation of nanoparticles via silanisation using APTES, MPTES and TEOS, which promotes the formation of active functional groups (–NH2, –SH, Si–OH) and determines the mechanisms of interaction with drug molecules. The main types of interactions are analysed, in particular electrostatic, hydrogen, covalent and coordination bonds, which determine the efficiency of immobilisation and the kinetics of drug release. Examples are given of the immobilisation of proteins, enzymes, immunoglobulins and anticancer drugs (doxorubicin, cisplatin) on the surface of magnetic nanocomposites. It is shown that the chemical nature of the surface determines not only the adsorption properties but also the biocompatibility, stability and therapeutic efficacy of the systems. The application of Fe3O4 nanoparticles in targeted drug delivery, magnetically controlled systems, hyperthermia and biosensors is considered separately. It is concluded that there is great potential for the creation of multifunctional nanocomposites with controllable surface properties for modern applications in nanomedicine.