Synthesis and Characterisation of Hollow Composite Magnetite/Silica Microparticles for Drug Delivery Systems

Synthesis and characterisation of hollow composite magnetite/silica microparticles for drug delivery systems

Kovacik Pavel, Stepanek Frantisek

ICT Prague, Department of Chemical Engineering, Laboratory of Chemical Robotics

kovacikp@vscht.cz

The aim of this work is to prepare hollow composite magnetite/silica microparticles in the size range of tens of micrometers via soft templating route. The microparticles have a porous silica (SiO₂) shell in which nanoparticles of magnetite (Fe₃O₄) are dispersed (Figure 1). As a silica source is used tetraethyl orthosilicate (TEOS) and as a liquid template octylamine (OA). Magnetite nanoparticles used for this work were prepared by the co-precipitation method and stabilized with oleic acid. This modification evokes their hydrophobicity and ensures that they are dispersible in the organic template phase (OA). After removal of the template the magnetite nanoparticles are either in the silica shell or inside the hollow core. Such prepared microparticles can be useful in systems for target delivery.

Figure  SEQ Figure \* ARABIC 1: Scheme of preparation of hollow composite magnetite/silica microparticles with a porous shell via soft templating route.

We will show that particle size can be systematically varied in the range of 1-50 µm and that the composite microparticles are able to heat up in presence of an external alternating magnetic field. The particle size distribution was measured by the laser scattering method, external alternating magnetic field was created by PowerCube 32/400 at 400 kHz and the temperature rise was recorded with time. The microstructure of the porous microparticles was visualized by SEM and confocal microscopy. The permeability of the silica shell was characterised indirectly by measuring the uptake/release kinetics of octylamine (marked by nile red dye) using UV/VIS spectrophotometry.