The limitation of classical pharmaceutical dosage forms is represented by the non-specific distribution and non-targeted delivery of active ingredients in the body, which is the driving force for the development of novel targeted drug delivery systems. Delivery systems that respond to environmental stimuli are particularly relevant. Such delivery systems can be magnetically guidable, thus enabling targeted drug delivery using a magnetic field gradient. Of particular interest in this group are superparamagnetic iron oxide nanoparticles, which are approved by regulatory agencies as safe for humans. The preparation of a colloidally stable suspension of such particles is relatively simple, since they behave as non-magnetic in the absence of an external magnetic field and consequently do not aggregate magnetically. In the scope of the master's thesis, magnetically-responsive nanoclusters were designed and prepared. Magnetic nanoclusters were prepared and coated with a thin non-porous layer of silicon dioxide (silica) using two different procedures. A thin silica coating protects the magnetic nanoparticles and provides adequate colloidal dispersion stability. The first procedure was unfavorable due to problems with colloidal stability during synthesis, which resulted in the aggregation of nanoclusters. The second procedure was successful due to the addition of surfactant, thus the nanoclusters coated by this procedure were used for further research. They were coated by an additional thicker layer of mesoporous silica, which was added to the thin silica coating. Mesoporous silica layer enables the loading of the active ingredients. We focused on the preparation of relatively large and radially oriented pores. The mesoporous layer of silica was prepared by three different procedures. The application of two different bases was investigated, namely triethanolamine and tris (hydroxymethyl) aminomethane. When removing surfactants after the synthesis of mesoporous coating, we discovered that the most robust coating was formed when the tris (hydroxymethyl) aminomethane was used as the base. Such a coating was resistant to harsh conditions during rinsing, such as elevated temperature and the use of ultrasound. In further research, we successfully introduced amino and carboxy groups on the surface of nanoclusters, which was evaluated by measuring zeta potential of the particles. To prepare colloidally stable nanoclusters for future drug loading, we used two pegylation procedures, whereby direct binding of PEG-silane to the surface of nanoclusters with mesoporous silica resulted in a promising system for further development of magnetically guidable nanodelivery system for targeted drug delivery.
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