Core-Shell Structured Composite Microparticles With Ability to Store a Chemical Payload and Release a Defined Quantity „On Demand“

Core-shell structured composite microparticles with ability to store a chemical payload and release a defined quantity „on demand“

P. Kovacik, M. Singh, F.Stepanek

ICT Prague, Laboratory of chemical robotics, Technicka 5, 166 28 Prague,  
Tel.: 2 2044 3046, e-mail: kovacikp@vscht.cz

The aim of this work was the preparation of biocompatible microparticles with a hollow interrior. The microparticles must be able to encapsulate and store a chemical payload for a certain time, followed by the release on demand of this payload. In our previous work [1] we have prepared silica microparticles with a hollow core and found that the diffusion across the mesoporous silica shell was strongly dependent on temperature. In this work, we used this dependence and attached iron oxide nanoparticles on the surface of the silica shell to create composite iron oxide/silica microparticles. The iron oxide nanoparticles were able to heat up in the presence of an alternating magnetic field. This property allowed us to use magnetic field as a tool for remote control of diffusion across the microparticle shell. To avoid spontaneous leakage of encapsulated payload in time, we have modified the surface of the composite microparticles with a layer of palm oil. Palm oil is a phase change material which is solid under 37 °C. We showed that the resultant composite microparticles are able to store a payload for several months and release a defined quantity on demand by the application of a magnetic field. The particles were characterised in shape, size, heating ability and their mass transport properties.

[1] Kovacik P., Kremlackova Z., Stepanek F., “Investigation of radiofrequency induced release kinetics from magnetic hollow silica microspheres”, Micropor. Mesopor. Mater. 159, 119-125 (2012)