Magnetic silica nanoparticles show great promise for drug delivery. The major advantages correspond to their magnetic nature and ease of biofunctionalization, which favors their ability to interact with cells and tissues. We have prepared magnetic silica nanoparticles with DNA fragments attached on their previously polyelectrolyte-primed surface. The remarkable feature of these materials is the compromise between the positive charges of the polyelectrolytes and the negative charges of the DNA. This dual-agent formulation dramatically changes the overall cytotoxicity and chemical degradation of the nanoparticles, revealing the key role that surface functionalization plays in regulating the mechanisms involved.
The manuscript reports on quantitative microcompression tests performed on novel composite nanoparticles (CNPs) consisting of cobalt boride coated with silica. This material exhibits a complex three-regimes response that entails both elastic and plastic deformation, and may result from several concurring deformation processes (i.e., mechanical, chemical, and magnetic). The results are interpreted in consideration of the pre-existent distribution of radial defects found in the cobalt boride core of the CNPs. Such defects represent a signature feature of such nanocomposites, which sets them apart from any defect-free, single-phase nanoparticle reported previously, and are of great relevance to both reverse plasticity and strain hardening (i.e., proper irreversible plasticity) effects observed. Since the mechanical response is actively pursued for MEMS and NEMS applications (central to these efforts is addressing the relationship between confined volumes and applied stress), the reported results become a major step toward the full potential of nanostructures and consequently of the next generation device technologies.
The cobalt-catalyzed hydrolysis of sodium borohydride (NaBH(4)) has become an attractive process in view of the possibilities of using the hydride for hydrogen storage material and also for the production of amorphous and tunable-size magnetic nanoparticles. This process in which the metallic catalyst transforms into a Co- and B-based magnetic by-product when in contact with NaBH(4) has been modified in order to control the mechanism of formation, tune the final size and study the particular magnetic behavior of the Co-B alloy nanoparticles provided.
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