Place: Buchner-Hörsaal, Butenandtstr. 5-13
Date: 07.02.2014, Time: 16:30h
Mechanized Multifunctional Nanoparticles for Theranostic Applications
Jeffrey I. Zink
University of Los Angeles, California
Mesoporous silica nanoparticles (particle diameter ~ 50 nm, pore diameter ~ 2 nm) are derivatized with molecules designed to induce multiple functionality. The most important functionality is the ability to trap molecules in the pores and release them in response to specific stimuli and/or on external command by using molecular machines. Other functions highlighted in this talk include incorporation of smaller metal nanocrystals (for magnetic heating, resonance imaging and/or manipulation), targeting molecules (towards specific cells), and fluorescence (for imaging). Two types of molecular machines that are based on molecules that undergo large amplitude motion when attached to mesoporous silica are described: impellers and valves. Derivatized azobenzene molecules, attached to the interior pore walls function as impellers that can move other molecules through the pores. Nanoparticles containing toxic molecules in the mesopores are taken up by cancer cells, and optical stimulation of the impellers drives out the toxic molecules and kills the cells. Nanovalves consisting of rotaxanes and pseudorotaxanes, placed at pore entrances, can trap and release molecules from the pores in response to stimuli. Two methods of activation that have been demonstrated for in vitro studies will be discussed: pH changes and oscillating magnetic fields. Lysosomal acidification causes self-opening of the valves, and externally applied magnetic fields affords external control. Activation by both of these methods in living cancer cells will be discussed.
1. Z. Li, J.C. Barnes, A. Bosoy, J.F. Stoddart and J.I. Zink. “Mesoporous silica nanoparticles in biomedical applications,” Chem. Soc. Rev., 41, 2590-2605 (2012)