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Superparamagnetic and thermally blocked iron oxide nanoparticles have found potential applications in different areas of bio-medicine due to their size, high stability and remarkable magnetic properties. In-vitro and in-vivo experiments using this kind of nano-materials showed the particles to be particularly useful in several field within medicine, such as diagnostic, therapeutic and drug delivery applications.
In our research, we focused on the synthesis and surface modification of thermally-blocked nanoparticles with extremely narrow size distribution and excellent magnetic response.
These materials were designed for a newly developed method of simultaneous detection of different biomolecules by detecting the change of the nanoparticles hydrodynamic volume as a result of the attachment of the biomolecules to their surface.
Brownian relaxation mechanism of such nanostructured materials is highly sensitive and magneto-relaxometry measurement can be used to quantify the concentration of the desired biomolecules in real samples, such as plasma or serum.
Different methods, i.e. co-precipitation and hydrolysis of metal chelates, have been used to synthesise nanoparticles with different size and size distribution. The surface of fabricated nanoparticles has been coated by biocompatible layers, e.g. gold or silica in order to allow further functionalization with specific biomolecules.
Particles prepared by co-precipitation show superparamagnetic behaviour. However nanoparticles produced by high temperature hydrolysis of metal chelates are thermally-blocked and thus can be used in suggested magnetorelaxometry approach for diagnostic analysis.
Both static and dynamic magnetic measurements confirm that these nanomaterials have excellent magnetic properties and narrow size distribution, in good agreement with transmission electron microscopy images and photon correlation spectroscopy.
The presence of biocompatible layer for functionalization shows stability of particles, tendency to specific binding of biomolecules without any participation of cross-linking agents as well as magnetic behaviour that is needed for the biosensor application.
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