Magneto-mechanical treatment of human glioblastoma cells with engineered iron oxide powder microparticles for triggering apoptosis

International audienceIn nanomedicine, treatments based on physical mechanisms are more and more investigated and are promising alternatives for challenging tumor therapy. One of these approaches, called magneto-mechanical treatment, consists in triggering cell death via the vibration of anisotropic magnetic particles, under a low frequency magnetic field. In this work, we introduce a new type of easily accessible magnetic microparticles (MMPs) and study the influence of their surface functionalization on their ability to induce such an effect, and its mechanism. We prepared anisotropic magnetite microparticles by liquid-phase ball milling of a magnetite powder. These particles are completely different from the often-used SPIONs: they are micron-size, ferromagnetic, with a closed-flux magnetic structure reminiscent of that of vortex particles. The magnetic particles were covered with a silica shell, and grafted with PEGylated ligands with various physicochemical properties. We investigated both bare and coated particles' in vitro cytotoxicity, and compared their efficiency to induce U87-MG human glioblastoma cell apoptosis under a low frequency rotating magnetic field (RMF). Our results indicated that (1) the magneto-mechanical treatment with bare MMPs induces a rapid decrease in cell viability whereas the effect is slower with PEGylated particles; (2) the number of apoptotic cells after magneto-mechanical treatment is higher with PEGylated particles; (3) a lower frequency of RMF (down to 2 Hz) favors the apoptosis. These results highlight a difference in the cell death mechanism according to the properties of particles used – the rapid cell death observed with the bare MMPs indicates a death pathway via necrosis, while PEGylated particles seem to favor apoptosis

Fabrication of nanotweezers and their remote actuation by magnetic fields

International audienceA new kind of nanodevice that acts like tweezers through remote actuation by an external magneticfield is designed. Such device is meant to mechanically grab micrometric objects. The nanotweezersare built by using a top-down approach and are made of two parallelepipedic microelements, at leastone of them being magnetic, bound by a flexible nanohinge. The presence of an external magneticfield induces a torque on the magnetic elements that competes with the elastic torque provided by thenanohinge. A model is established in order to evaluate the values of the balanced torques as a functionof the tweezers opening angles. The results of the calculations are confronted to the expected valuesand validate the overall working principle of the magnetic nanotweezers

Fabrication of magnetic micro/nanotweezers functionalized and dispersed in solution for bio

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