Paola Rivolo

Silicon-based thin films and nanostructures are of paramount importance in a wide range of applications, including microelectronics, photovoltaics, large area sensors, and biomedicine. The wide accessibility of silicon and its relatively low cost have driven a continuous improvement of technology based on this element. Plasma technology has been widely used for the synthesis of coatings and nanostructures based on silicon. Moreover, it has made a fundamental contribution to continuous improvement of the physicochemical properties of silicon-based materials and allows the synthesis of nanometric structures with well-defined shapes and morphologies. In this work, we have reviewed the most interesting developments in plasma-assisted processes for the synthesis of Si-based materials, both inorganic and organic, in the last five years. Special attention has been paid to new techniques, or modifications of already-existing ones, that open up new possibilities for the synthesis of materials with new properties, as well as nanostructures with novel characteristics.

Silicon-based thin-films and nanostructures are of paramount importance in a wide range of applications, including microelectronics, photovoltaics, large area sensors, as well as biomedicine. The wide accessibility of silicon and its relatively low cost have driven a continuous improvement of the technology based on this element. Plasma technology has been widely used for the synthesis of coatings and nanostructures based on silicon. Moreover, it has given a fundamental contribution for continuously improving the control of the physicochemical properties of silicon-based materials, and for allowing the synthesis of nanometric structures with well-defined shape and morphology. In this work, we have reviewed the most interesting developments of plasma-assisted processed for the synthesis of Si-based materials, both inorganic and organic, in the last five years. A special attention has been given to the new techniques, or modifications of already existing ones, that open new possibilities for the synthesis of materials with new properties, as well as nanostructures with novel characteristics.

Dental implants have dramatically changed the rehabilitation procedures in dental prostheses but are hindered by the possible onset of peri-implantitis. This paper aims to assess whether an anodization process applied to clinically used surfaces could enhance the adhesion of fibroblasts and reduce bacterial adhesion using as a reference the untreated machined surface. To this purpose, four different surfaces were prepared: (i) machined (MAC), (ii) machined and anodized (Y-MAC), (iii) anodized after sand-blasting and acid etching treatment (Y-SL), and (iv) anodized after double acid etching (Y-DM). All specimens were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Moreover, the mean contact angle in both water and diiodomethane as well as surface free energy calculation was assessed. To evaluate changes in terms of biological responses, we investigated the adhesion of Streptococcus sanguinis (S. sanguinis) and Enterococcus faecalis (E. faecalis), fetal bovine serum (FBS) adsorption, and the early response of fibroblasts in terms of cell adhesion and viability. We found that the anodization reduced bacterial adhesion, while roughened surfaces outperformed the machined ones for protein adsorption, fibroblast adhesion, and viability independently of the treatment. It can be concluded that surface modification techniques such as anodization are valuable options to enhance the performance of dental implants.

A sharpened control over the parameters affecting the synthesis of plasmonic nanostructures is often crucial for their application in biosensing, which, if based on surface-enhanced Raman spectroscopy (SERS), requires well-defined optical properties of the substrate. In this work, a method for the microfluidic synthesis of Ag nanoparticles (NPs) on porous silicon (pSi) was developed, focusing on achieving a fine control over the morphological characteristics and spatial distribution of the produced nanostructures to be used as SERS substrates. To this end, a pSi membrane was integrated in a microfluidic chamber in which the silver precursor solution was injected, allowing for the real-time monitoring of the reaction by UV–Vis spectroscopy. The synthesis parameters, such as the concentration of the silver precursor, the temperature, and the flow rate, were varied in order to study their effects on the final silver NPs’ morphology. Variations in the flow rate affected the size distribution of the NPs, whereas both the temperature and the concentration of the silver precursor strongly influenced the rate of the reaction and the particle size. Consistently with the described trends, SERS tests using 4-MBA as a probe showed how the flow rate variation affected the SERS enhancement uniformity, and how the production of larger NPs, as a result of an increase in temperature or of the concentration of the Ag precursor, led to an increased SERS efficiency.

In this work graphene coatings have been deposited on aluminum alloy samples to investigate whether they can improve wear strength and promote friction reduction, which means components reliability and efficiency. Tribological performance has been tested by pin-on-disk wear tests. Three procedures to coat the samples have been explored. One is based on transferred graphene method and the other two are based on percolative graphene. Results show that graphene coatings last little time onto the sample surface, though strongly reducing the coefficient of friction of aluminum samples as far as they endure.