séminaire SIMM

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24 novembre 2014 11:00 » 12:00 — A6 (Boreau)

Building a better nanoparticle

Part one : Doping Colloidal Quantum Dots

Semiconductor quantum dots exhibit fascinating and important physical and chemical properties that can hold the potential to play crucial role in transforming the photovoltaic industry, creating new business opportunities and producing electricity to address the increasing global energy needs. Producing relatively efficient solar cells from quantum dots has been already demonstrated by many research groups. An important goal is to better equip these quantum dots for photovoltaic cells by controlling their electrical properties via chemical doping. The challenge of doping process is to control the chemical synthesis of these quantum dots to increase uniformity of the resulting doped quantum dots. In the discussion, gallium, tin and indium doping of CdSe quantum dots will be used as examples to highlight these challenges as well as demonstrate possible solutions for the challenges. The majority of the currently available materials to produce the needed quantum dots do not hold the potential at industrial scale due to limited supplies, and environmental concerns. Our group’s effort focuses on the recently discovered semiconducting and ‘green’ iron silicide nanoparticles. Although these particles are successfully synthesized, their potential is not fully realized yet.

Part Two : Pulsed magnetic field induced fast drug release from magneto liposomes via ultrasound generation

Fast drug delivery is very important to utilize drug molecules that are short lived under physiological conditions. Techniques that can release model molecules under physiological conditions could play an important role to discover the pharmacokinetics of short lived substances in the body. Here an experimental method is developed for the fast release of the liposomes’ payload without a significant increase in (local) temperatures. This goal is achieved by using short magnetic pulses to disrupt the lipid bilayer of liposomes loaded with magnetic nanoparticles. The drug release has been tested by two independent assays. The first assay relies on the AC impedance measurements of MgSO4 released from the magnetic liposomes. The second standard permeability assay is based on the increase of the fluorescence signal from 5(6)-Carboxyfluorescein dye when it the dye is released from the magneto liposomes. The efficiency of drug release ranges from a few percent to up to 40% in case of the MgSO4. The experiments also indicate that the magnetic nanoparticle generate ultrasound via magnetostriction, which is thought to have a role in the release of the model drugs from the magneto liposomes.

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