The local heat delivered by metallic nanoparticles selectively attached to their target can be used as a molecular surgery to safely remove toxic and clogging aggregates. We apply this principle to protein aggregates, in particular to the amyloid beta protein (Abeta) involved in Alzheimer's disease (AD), a neurodegenerative disease where unnaturally folded Abeta proteins self-assemble and deposit forming amyloid fibrils and plaques. We show the possibility to remotely redissolve these deposits and to interfere with their growth, using the local heat dissipated by gold nanoparticles (AuNP) selectively attached to the aggregates and irradiated with low gigahertz electromagnetic fields. Simultaneous tagging and manipulation by AuNP of Abeta at different stages of aggregation allow both, noninvasive exploration and dissolution of molecular aggregates.

Articles you may be interested inChemical bonding and magnetic exchange in two-dimensional [M(TCNE)(NCMe)2]X (M = Fe, Mn; X = FeCl4, SbF6) magnets: A pressure study J. Chem. Phys. 138, 014701 (2013); 10.1063/1.4770057Temperature-and magnetic-field-controlled magnetic pole reversal in a molecular magnetic compound Electromagnetic radiation produced by avalanches in the magnetization reversal of Mn 12 -acetate has been measured. Short bursts of radiation have been detected, with intensity significantly exceeding the intensity of the blackbody radiation from the sample. A model based upon superradiance from inversely populated spin levels has been suggested.

Abstract. We investigate the experimental detection of the electromagnetic radiation generated in the fast magnetization reversal in Mn 12 -acetate at low temperatures. In our experiments we used large single crystals and assemblies of several small single crystals of Mn 12 -acetate placed inside a cylindrical stainless steel waveguide in which an InSb hot electron device was also placed to detect the radiation. All this was set inside a SQUID magnetometer that allowed to change the magnetic field and measure the magnetic moment and the temperature of the sample as the InSb detected simultaneously the radiation emitted from the molecular magnets. Our data show a sequential process in which the fast inversion of the magnetic moment first occurs, then the radiation is detected by the InSb device, and finally the temperature of the sample increases during 15 ms to subsequently recover its original value in several hundreds of milliseconds.Molecular clusters are nanomagnets showing important phenomena associated to their magnetic anisotropy and the possibility to tune their quantum mechanical properties by applying a magnetic field. The discovery of the resonant spin tunneling between the degenerate spin levels at both sides of the anisotropy energy barrier [1,2] was the first sign that quantum mechanics can reveal itself in these magnetic units made of several hundreds of atoms. Since then, near thousand papers on molecular magnets have been published [3]. Very recently a new field combining molecular magnets, magnetization studies, cavities and electromagnetic radiation has attracted the attention of different groups. The most recent works on this particular topic deal with the absorption and emission of microwaves [4,5,6,7, 8,9,10,11,12,13,14,15]. In this letter we report low temperature experimental studies of the detection of microwave emission of Mn 12 single crystals inside a cylindrical waveguide. This work follows that published very recently [13], focusing now on the time sequence of the reversal of the magnetic moment, the emission of radiation and the heat release in the sample on the millisecond scale.In Figure 1 we show the details of our experimental setup. Two kinds of samples were investigated. In some experiments, the sample was made by assembling together several tens of oriented single crystals of Mn 12 -acetate with a total volume around 20 mm 3 . In some others, we used only one large single crystal having a magnetic moment M close to one third of that of the assemblies of crystals (M ∼ 1 emu). An InSb hot electron device, with a spectral bandwidth of 60 GHz -3 THz, was used to detect the electromagnetic radiation possibly emitted by the sample. Both the sample and the detector were placed inside a stainless steel cylindrical 1

An electrochemical method for the preparation of magnetic nanoparticles of new Sr−Fe oxides is presented in this work. It consists of the electrolysis of nitrate or chloride solutions with Sr2+ and Fe3+ salts using commercial Fe electrodes. Magnetic materials are collected as precipitates from nitrate media in the pH range 1−3 and from chloride media within the pH range 1−12. The presence of 100−300 ppm aniline in acidic nitrate media yields a decrease in energy cost and particle size. Inductively coupled plasma analysis of materials and energy-dispersive X-ray spectrometry of single particles confirm that they are composed of mixed oxides of Sr and Fe. All synthesized materials crystallize as inverse cubic spinels, usually with intermediate structures between magnetite and maghemite. They are formed by nanoparticles with average sizes from 2 nm to ∼50 nm, as observed by scanning electron microscopy. The electrogenerated mixed oxides have higher saturation magnetization, but lower remanent magnetization and coercive field, than commercial strontium hexaferrite with micrometric particle size.