Bacterial cellulose (BC) functionalized with silver nanoparticles (AgNPs) is evaluated as an antimicrobial membrane for wound-healing treatment. A facile green synthesis of silver nanoparticles inside the porous three-dimensional weblike BC network has been obtained by UV light irradiation. AgNPs were photochemically deposited onto the BC gel network as well as they were chemically bonded to the cellulose fiber surfaces. AgNPs with a narrow size distribution along with some aggregates in the BC network were evidenced from the morphological analyses. A highly crystalline nature of the BC membranes was observed in X-ray diffraction measurements, and the presence of metallic silver confirmed the photochemical reduction of Ag+ → Ag0 in Ag/BC composites. Antibacterial activity of the hybrid composites, such as pellicles, performed against the Gram-negative bacteria (Escherichia coli) by disk diffusion and growth dynamics methods showed high bacteria-killing performance. No significant amount of silver release was observed from the Ag/BC pellicles even after a long soaking time. As composite pellicles are preserved in a moist environment that also favors wound recovery, by combining all of these properties the material could be useful in wound-healing treatments.

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Surface treatments of textile fibers and fabrics significantly increase their performances for specific biomedical applications. Nowadays, silver is the most used antibacterial agent with a number of advantages. Among them, it is worth to note the high degree of biocompatibility, an excellent resistance to sterilization conditions, antibacterial properties with respect to different bacteria associated with a long-term of antibacterial efficiency. However, there are only a few antibacterial fibres available, mainly synthetic with high production cost and limited effectiveness. Cotton yarns with antimicrobial properties are most suitable for wound healing applications and other medical treatments thanks to their excellent moisture absorbance while synthetic based fibres are most suitable for industrial applications such as automotive tapestry and air filters. The silver-coated fibers were developed applying an innovative and low cost silver deposition technique for natural and synthetic fibers or yarns. The structure and morphology of the silver nanoclusters on the fibers was observed by scanning electron microscopy (SEM), atomic force microscopy analysis (AFM) and XRD analysis, and quantitatively confirmed by thermogravimetric analysis (TGA) measurements. Good silver coating stability has been confirmed performing several industrial washing. Antimicrobial tests with Escherichia coli were performed.

Rare-earth oxide materials emit thermal radiation in a narrow spectral region, and can be used for a variety of different high-temperature applications, such as the generation of electricity by thermophotovoltaic conversion of thermal radiation. However, because a detailed understanding of the mechanism of selective emission from rare-earth atoms has so far been missing, attempts to engineer selective emitters have relied mainly on empirical approaches. In this work, we present a new quantum thermodynamic model to describe the mechanisms of thermal pumping and radiative de-excitation in rare-earth oxide materials. By evaluating the effects of the local crystal-field symmetry around a rare-earth ion, this model clearly explains how and why only some of the room-temperature absorption peaks give rise to highly efficient emission bands at high temperature (1,000-1,500 degrees C). High-temperature emissivity measurements along with photoluminescence and cathodoluminescence results confirm the predictions of the theory.

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Antibacterial coatings on catheters for acute dialysis were obtained by an innovative and patented silver deposition technique based on the photo-reduction of the silver solution on the surface of catheter, with consequent formation of antibacterial silver nanoparticles. Aim of this work is the structural and morphological characterization of these medical devices in order to analyze the distribution and the size of clusters on the polymeric surface, and to verify the antibacterial capability of the devices treated by this technique against bacterial proliferation. The structure and morphology of the silver nanoparticles were investigated by using scanning and transmission electron microscopy. The antimicrobial capability of the catheters after silver deposition was confirmed by antibacterial tests with Escherichia coli. Both scanning electron microscopy analysis and antibacterial tests were performed also after washing catheters for 30 days in deionized water at 37°C, relating these data to thermogravimetric analysis and to energy dispersive spectroscopy, in order to check the resistance of coating and its antimicrobial capability after the maximum time of life of these devices.

TiO 2 microspheres (TMS) with perfect spherical morphology were synthesized by spray drying of a hydrothermally cured aqueous suspension of TiO 2 nanoparticles. TiO 2 powders (TP) obtained by drying the nanoparticle suspension were studied simultaneously to determine which was the most efficient photocatalyst. SEM images and laser granulometry on TMS show spherical morphology with the diameter ranging from 2 to 10 μm. TMS had high specific surface area after annealing as seen from BET analyses. XRD analyses show that TMS consist of anatase and rutile crystalline phases where the rutile fraction increases with annealing temperature and above 500 °C rutile dominates anatase. Raman spectroscopy shows several Raman bands from anatase and rutile phases and supports the XRD results of phase transformation with increasing annealing temperature. Photodegradation of organic pollutants in aqueous solution under UV light irradiation establishes the higher photocatalytic activity of TMS with respect to TP. The highest efficiency was found on the 400 °C annealed TMS.