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Trajectory Control of PbSe- -Fe 2 O 3 Nanoplatforms under Viscous Flow in the presence of magnetic field. Lioz Etgar , Arie Nakhmani, Allen Tannenbaum, Efrat Lifshitz, and Rina Tannenbaum Nanoscience and Nanotechnology Program Technion-Israel Institute of Technology. Drug molecules.
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Trajectory Control of PbSe- -Fe2O3 Nanoplatforms under Viscous Flow in the presence of magnetic field Lioz Etgar, Arie Nakhmani, Allen Tannenbaum, Efrat Lifshitz, and Rina Tannenbaum Nanoscience and Nanotechnology Program Technion-Israel Institute of Technology
Drug molecules PbSe QDs Organic molecules g-Fe2O3 NPs How do we create functionalized conjugate structures?
1.3nm Conjugate structureof -Fe2O3 Nanoparticles and PbSe Quantum Dots TEM/HRTEM micrographs- • Etgar L.; Lifshitz E.; Tannenbaum R. J. Phys. Chem C, 2007, 111(17), 6238-6244.
Motivation • The motion of these conjugate structures: • In a viscous flow • In the presence of an external magnetic field • Is of crucial importance, since this property should provide us with new insights into the behavior of the conjugate structures as a potential in-vivodrug delivery system.
Goals Studying the NQDs-NPs conjugates under different fluid flow rates (capacitances) and at different fluid viscosities (which will mimic the viscosity of blood), while applying an external magnetic field. Methods • All the flow experiments were conducted with nanoplatform suspensions in aqueous poly(ethylene glycol) (PEG) solutions and recorded by a CCD camera. • The resulting video films were analyzed by a unique software package (developed specifically for this propose), which calculates the velocity, direction and trajectories of each NQDs-NPs conjugate nanostructure separately.
Conjugate structures x N y P q d Flow measurement set-up
The forces which act on the nanoplatforms • Magnetic force. • Viscous drag force (fluidic force). • Nanoplatform-blood cell interactions. • Gravitational force. • Buoyancy force. • Inertial force. • Van der Walls inter-nanoplatform forces.
Several orders of magnitude smaller than the other forces. The forces which act on the nanoplatforms (cont.) • The inertial force and the inter-nanoplatform interactions can be neglected if the total volume occupied by the nanoplatforms per unit volume of fluid is very small. • Buoyancy force • Gravitational force Thus, we consider mainly the magnetic and fluidic forces, while the nanoplatform-blood interactions are already taken into consideration by measuring the transport of the nanoplatforms in fluids with different viscosities.
fluid viscosity conjugate radius x conjugate velocity N fluid velocity. y P q d Fluidic force By considering a motion in the x-y plane,the components of the fluidic force are:
NmpTotal number of nanoplatforms The applied magnetic field VmpNanoplatforms volume Nanoplatform susceptibility Magnetic force Nanoplatform permeability Permeability of the air Ms isthe saturation magnetization of the specific magnet, in this case it equals to 1106 A/m.
Ffx Conjugate structures Fy(total)=Ffy+Fmy Fmx x y q d N P Flow measurement set-up
Representative films 1.25cP 0.05ml/hr 1.25cP 0.3ml/hr 3.71cP 0.3ml/hr 4.13cP 0.7ml/hr+Magnet 6.35cP 0.2ml/hr
Software package Graphical user interface (GUI) was developed in MATLAB
Representative images of the original visualization of the nanopaltforms during flow
Results PEG solutions with different viscosities: 1.25 cP 1.73 cP 2.13 cP 3.71 cP 4.13 cP 6.35 cP Flow rates: 0.03 mL/hr 0.05 mL/hr 0.1 mL/hr 0.2 mL/hr 0.3 mL/hr 0.5 ml/hr 0.7 mL/h 0.9 mL/hr Constant magnetic field The influence of an external magnetic field on the nanoplatform trajectories. • Etgar L., Arie Nahmani, Allen Tannenbaum, Efrat Lifshitz, Rina Tannenbaum. Submitted to Physical Review B, 2008.
X Ffx y Fy(Total)=Ffy+Fmy d Fmx Ffx [pN] Fy(total) [pN] Results (cont.) Force balance on the nanoplatforms during their flow
Summary • 1. We studied the motion of these conjugate structures: • In viscous flows • Under the presence of an external magnetic field 2. Developed quantitative relationships between particle size, fluid viscosity, fluid flow rates and magnetic field strengths, and their effect on the particle trajectories and particle cohesion. 3. Even at low magnetic fields (~1 Tesla), the trajectories of the particles can be controlled, fact which validates the fundamental drug targeting and delivery strategy using magnetic nanoparticles as the active targeting nanoplatforms.