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Available from: Olga Mykhaylyk,
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    ABSTRACT: Carefully designed colloidal properties are the prerequisite for successful diagnostic and therapeutic applications of magnetic fluids (MF). A high degree of dispersion (small particle size, absence of agglomeration) and stability is required. Multisample analytical centrifugation with high resolution photometric detection was applied to characterize the quality of a range of differently stabilized MF's. Comparison of the `fingerprints' gives a fast overview over differences in MF quality (quality of particle stabilization against aggregation, separation stability). Sedimentation kinetics and the distribution of sedimentation velocity allow for a more detailed quantitative comparison and ranking between different products and batches. Even without any material properties well dispersed samples with narrow distribution can be discriminated from samples with broader distribution and oversized particles (agglomeration).
    12/2010; DOI:10.1063/1.3530060
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    ABSTRACT: Magnetic nanoparticles (MNPs) and magnets can be used to enhance gene transfer or cell attachment but gene or cell delivery to confined areas has not been addressed. We therefore searched for an optimal method to simulate and perform local gene targeting and cell delivery in vitro. Localized gene transfer or cell positioning was achieved using permanent magnets with newly designed soft iron tips and MNP/lentivirus complexes or MNP-loaded cells, respectively. Their distribution was simulated with a mathematical model calculating magnetic flux density gradients and particle trajectories. Soft iron tips generated strong confined magnetic fields and could be reliably used for local (~500 μm diameter) gene targeting and positioning of bone marrow cells or cardiomyocytes. The calculated distribution of MNP/lentivirus complexes and MNP-loaded cells concurred very well with the experimental results of local gene expression and cell attachment, respectively. MNP-based gene targeting and cell positioning can be reliably performed in vitro using magnetic soft iron tips, and computer simulations are effective methods to predict and optimize experimental results.
    Pharmaceutical Research 12/2011; 29(5):1380-91. DOI:10.1007/s11095-011-0647-7 · 3.42 Impact Factor
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    ABSTRACT: To target adenoviral vectors to cells of the vasculature and shielding vectors from inactivation by the immune system. Complexes of reporter gene expressing adenoviral vectors with positively charged magnetic nanoparticles were formed by electrostatic interaction in presence or absence of additional negatively charged poly(ethylene glycol)-based polymer. Transduction of HUVEC was analyzed in vitro under flow. Protection from inactivation by the immune system was analyzed by pre-incubation of AdV and complexes with neutralizing antibodies and subsequent reporter protein analysis of infected cells. Physical association of AdV with MNP and polymers was demonstrated by radioactive labelling of components and co-sedimentation in a magnetic field. Ad-MNP+/-polymer resulted in efficient transduction of HUVEC, depending on MOI and flow rate in presence of magnetic field, whereas no transduction was observed without complex formation with MNP or in absence of magnetic field. Association with MNP did result in protection from neutralizing antibodies, with slightly increased protection provided by the polymer. Complex formation of AdV with MNP is a viable means for targeting of vectors to areas of magnetic field gradient. Additional coating with polymer might proof useful in protection from inactivation by the immune system.
    Pharmaceutical Research 12/2011; 29(5):1219-31. DOI:10.1007/s11095-011-0631-2 · 3.42 Impact Factor
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