Nanoparticles With Dual Function Based On Magnetic And Biologic: Preparation And Properties

Based on the unique magnetic property and biocompatibility, magnetic nanoparticlesoffer a high potential for several biomedical applications, such as drug targeting,magnetic cell separation, magnetic resonance imaging (MRI), magnetic hyperthermia,enzyme immobilization, DNA and RNA purification. For these applications, theparticles must have multifunctional properties of biocompatibility, fluid stabilization,high magnetic saturation and interactive functions at the surface. In the other hand,homing peptide as excellent alternative targeting agents for human tumor was animportant development of the tumor treatment. In the last decade, severalinvestigators have successfully used phage-display library methods to discover cellsurface binding peptides that may be useful for tumor targeting. Results frompreclinical studies with some peptides are encouraging in their targeting potential.Various biological molecules such as antibodies, protein, targeting ligands, etc., mayalso be bound to the polymer surfaces onto the nanoparticles through physicaladsorption as well as chemical bonding to make the particles target specific. In thiswork, a novel nanoparticle with dual function (magnetic targeting and biologicaltargeting) was constructed with magnetic nanoparticles and homing peptide. The mainresults are as follows:1 Magnetite nanoparticles were prepared by controlled chemical coprecipitation method. Adsorption of GFP-labeled homing peptide (A54-GFP) on nanosized magnetic particles was carried out in phosphate buffer solution (PBS). The binding efficiency was analyzed by performing adsorption equilibrium study. The experimental results showed that Langmuir equation was well fitted for the adsorption behavior, which indicated a monolayer of A54-GFP molecules binding on the magnetic nanoparticles. Fourier-transform infrared spectroscopy confirmed the attachment of A54-GFP molecules on magnetic particles. Adsorption of A54-GFP on magnetic nanoparticles was carried through hydrogen bonding. In contrast, covalent bonding played a leading role in the adsorption process after activated by carbodiimide. Magnetization measurements of A54-GFP-bound magnetic nanoparticles showed that the saturation magnetization value of Fe₃O₄-starch nanoparticle amounted to 61emu/g at room temperature. The biologic experiment of specificity in vitro demonstrated coating with homing peptide endowed magnetic nanoparticles...