Time- and position-controlled release of drug substances coated onto superparamagnetic nanoparticles

Controlled release of drug substances is a major research issue. In most cases, the goal is to modify the substance properties in order to influence the rate of its dissolution in body. In the present project, we want to make a step further - we want to control not only the dissolution rate but also the position of drug release. The basic idea is to "attach" (adsorb, deposit etc.) the substance onto superparamagnetic nanoparticles which can then be directed to the position of drug release via an external magnetic field. Superparamagnetic nanoparticles are appropriate substrate for preparation of such composite materials because, in the absence of magnetic field, they can be dispersed in certain media which is a precondition for a successful particle functionalization. Superparamagnetic nanoparticles will be coated with a drug substance according to a modified sol-gel procedure similar to that used in functionalization of inorganic particles with organic substances, like organic pigments. The rate of drug dissoluton will be controlled in different ways: by modifying its morphology, crystallinity, porosity. Also controlled will be the thickness of the drug layer which will have an important effect on stability, viscosity and other physical-chemical properties of the dispersion. The rate of drug dissolution/release will be additionally controlled with additional coatings using a third material resulting in an "onion" type of particulate material. A special challenge will represent the fact that the selection of materials used will be highly limited - all will have to be biocompatible and biodegradable.