Composite hybrid colloids with magnetic and plasmonic properties

Abstract

Three different methods have been applied for the synthesis of magnetic nanoparticle-based materials with a high magnetic separability for applications in biomolecule separation and detection. The three methods employed included (i) a thermal decomposition of iron(III) oleate resulting in a surface decoration of iron oxide nanoparticles on mesoporous silica particles , (ii) a layer-by-layer adsorption where iron oxide nanoparticles were enclosed between polyelectrolytes and (iii) a solvothermal decomposition producing agglomerates of small iron oxide nanoparticles, resembling the shape of flowers. The products obtained by the first and the third method were functionalized using silane chemistry to obtain water dispersible particles (for the first method) and to introduce binding moieties allowing for attachment of biomolecules with specific targeting properties (e.g. antibodies). The magnetic separation behavior of hydrophilic, surface functionalized materials were tested and two particle types (obtained by the first and the third method) were selected as potential candidates for bio-functionalization in upcoming experiments. The second part of this work consisted of combining two efficient heat generating nano-building blocks (gold nanorods with tunable plasmonic properties and superparamagnetic iron oxide nanoparticle) into a multifunctional nano-hybrid to produce a promising candidate for hyperthermia cancer treatment. For this task the procedure for the thermal decomposition of iron(III) oleate was slightly modified to produce gold nanorod core iron oxide nanoparticle decorated mesoporous silica shell particles. The obtained product was characterized by TEM as well as by UV-VIS spectroscopy revealing raspberry like particles with an iron oxide nanoparticle shell and a strong longitudinal surface plasmon resonance band which is located near the first biological window. The particles were then transferred to aqueous media employing silane chemistry allowing for a good dispersability as well as possible attachment of targeting moieties resulting in a potential candidate for hyperthermia cancer treatment by combining photothermia with magnetic hyperthermia.