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Halloysite nanotubes (HNTs) and salicylic acid (SA) are natural substances widely used in different fields. HNTs are very promising as nanocarriers because of their biocompatibility, atoxicity, anti-inflammatory properties and capacity to maintain the biological activity of immobilized enzymes. Because of its bactericidal and antiseptic properties, salicylic acid (SA) is used in pharmaceutical formulations, and as an additive for preserving foods and cosmetics. In this study, we set up a procedure for the loading of HNTs with SA for their possible application in active food packaging. Pristine HNTs were studied together with acidic etched HNTs with enlarged internal lumen, and various pH values for the loading solutions were tested in order to obtain the maximum loading. The HNTs—empty and loaded with SA—were characterized by TG-FTIR, FTIR SEM, STEM, and nitrogen adsorption/desorption isotherms measurements. We obtained a maximum loading of 10.5% (w/w), using HNTs pretreated with H2SO4 2 M at 25 °C for 48...

We propose ion-induced dewetting of Au thin films as a mechanism to modify and control the morphology of Si nanowires formed through metal-assisted chemical etching. We show that the patterns formed upon irradiation resemble those typical of dewetting phenomena, with a characteristic length in the nanometer range. Irradiated Au films are then used as a template for the fabrication of Si nanowires, and we show that a long-range order exists also in etched substrates, although at much longer length scales in the micrometer range. Investigation of the optical properties reveals that the Si nanowires emit broadband photoluminescence peaked at 700 nm. The proposed synthesis method allows tuning the morphological features of the nanowire bundles at the nanoscale without affecting the optical properties. This approach can be exploited for the engineering of nanowires-based devices where the morphological features become important.

A green and fast methodology was developed to synthesize silver nanoparticles using rosemary essential oil (EO) as a renewable reducing agent. The synthesis process was microwave (MW) assisted, using a coaxial dipole antenna immersed into the reaction medium. This configuration was used to promote both: i) rosemary EO extraction by hydrodistillation, and ii) silver nanoparticle synthesis in an aqueous solution at atmospheric pressure. The effect of two different silver salt substrates and the time reaction on the morphology of the silver nanoparticles was explored. The coaxial microwave-assisted hydrodistillation of rosemary yields 0.4% (w/w) in 30 min and contains ethers (17%), ketones (50%) and alcohols (15%). Silver nanoparticles with a tuneable particle size (from 7 to 18 nm) and morphology (from spherical to round-like shapes) were obtained in reaction times ranging from 2 to 30 min. The nanoparticle formation was followed by UV-vis spectroscopy and SEM imaging.