No abstract

The role of the retention strength of Cu0 and Ag0 nanoparticles on the induced antibacterial properties of montmorillonite and cellulose-supported polyol dendrimer against Escherichia coli DH5α and Bacillus subtilis 168 was comparatively investigated.

Metal-loaded porous matrices based on clay and cellulose materials displayed appreciable antibacterial activity against Escherichia coli DH5α and Bacillus subtilis 168. BoltornTMH20 polyol dendrimer supported by montmorillonite and cellulose turned out to be effective porous matrices for Cu0 and Ag0 nanoparticles dispersion. The resulting organoclay and polyol-coated cellulose were found to stabilize Cu0 and Ag0 nanoparticles through their terminal hydroxyl groups. This was explained in terms of Lewis Acid-Base interaction between the electron pair of the oxygen atom belonging to the terminal hydroxyl and metal species as supported by XPS data. The metal retention strength was found to correlate with the antibacterial activity, surface basicity and hydrophilic character. These findings are of great importance, because they open promising prospects for vegetal fibers and clay-supported drugs to treat dermatological and gastro-intestinal infections.

The capability of generating magnetically soft and hard phases in a material is important in many aspects, ranging from basic science to applications. Here, the emergence of soft and hard magnetic phases is reported in Fe nanowire (NW) arrays with a diameter of 35 nm fabricated by using a pulsed electrochemical deposition method in porous aluminum oxide templates under different current density (Cd) values in the range of 25‒100 mA/cm2. The variation of Cd influences the grain size, crystallinity, electrodeposition efficiency and length of the Fe NWs, as characterized by X-ray diffraction, high-resolution transmission electron microscopy, vibrating sample magnetometry and field-emission scanning electron microscopy. Increasing Cd from 25 to 80 mA/cm2 results in a significant decrease in coercivity and squareness from 1590 to 900 Oe and 0.9 to 0.5, respectively, inducing the soft and hard phases along the length of Fe NWs. Further increasing the Cd leads to the separation of the phases, as evidenced by first-order reversal curve analysis. From a theoretical aspect, the emergence of the soft phase may lead to the occurrence of the fanning reversal mode in the NWs, for which there is no precedent in previous experimental investigations.