1 Targeting of PbSe--Fe 2 O 3 Nanoplatforms by External Magnetic Field under Viscous Flow conditions Lioz Etgar 1* , Arie Nakhmani 2 , Allen Tannenbaum 2,5 , Efrat Lifshitz 1,3 and Rina Tannenbaum 1,4,6 1 Russell Berrie Nanotechnology Institute (RBNI), 2 Department of Electrical Engineering, 3 Schulich Faculty of Chemistry and 4 Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa, Israel; 5 School of Electrical and Computer Engineering and 6 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, USA. ABSTRACT We have studied the flow behavior of chemically-conjugated nanostructures consisting of fluorescent PbSe quantum dots coupled with magnetic γ-Fe 2 O 3 nanoparticles, under viscous flow and an external magnetic field. The γ-Fe 2 O 3 moieties were used to control the trajectories of the nanoplatforms under an external magnetic field in polymers fluids mimicking the viscosity of the bloodstream. The flow was followed by the visualization of the nanoplatform trajectories via a specially-developed image processing package, under various fluid flow rates, viscosities and applied magnetic field strengths. Here we show that even at low magnetic fields (~1 Tesla), the trajectories of the nanoplatforms can be controlled, fact which validates the fundamental drug targeting and delivery strategy in which magnetic nanoparticles are used as the active targeting constituents, indicating the possibility of a paradigm shift in the area of targeted drug delivery. INTRODUCTION This study concentrates on the behavior of magneto-optical conjugate nanostructures under flow conditions in viscous fluids and subjected to the influence of an external magnetic field. These conjugate nanostructures consist of water-soluble, superparamagnetic γ-Fe 2 O 3 nanoparticles (NPs) and PbSe nanocrystalline quantum dots (NQD) bonded via selective interactions between complementary functional groups 1, 2 , and are designed to provide a model * Corresponding author: liozetgar@gmail.com