L. Minati

Multifunctional Branched Gold−Carbon Nanotube Hybrid for Cell Imaging and Drug Delivery

Branched gold nanoparticles were grown on oxidized multiwalled carbon nanotubes by one-step reduction of gold chloride in water. The carbon nanotube/gold hybrids were used for the delivery of the anticancer drug doxorubicin hydrochloride into A549 lung cancer cell line. Doxorubicin (Dox) can be adsorbed in high quantity on both inner and outer surfaces of oxidized carbon nanotubes by π-π stacking interactions between doxorubicin aromatic groups and carbon nanotube (CNT) backbone. Carbon nanotube/gold hybrids display a broad absorption band in the red and near-infrared regions allowing their use for imaging applications. In vitro cellular tests showed that the nanostructures can efficiently transport and deliver doxorubicin inside the cells.

Sustained in vitro release and cell uptake of doxorubicin adsorbed onto gold nanoparticles and covered by a polyelectrolyte complex layer

Gold nanoparticles functionalized with doxorubicin and stabilized with multilayers of degradable polyelectrolyte were allowed to age in aqueous medium in vitro in order to show the possibility of drug release in cellular environment. The chemico-physical characteristics of the nanoparticles are reported. The observed release of doxorubicin (DOX) was pH-dependent, and it increased in acidic environment. Cell uptake of nanoparticles and drug release were monitored by laser scanning confocal microscopy. Data showed that drug-bearing nanoparticles delivered DOX into the nuclei of A549 cells, leading to pronounced cytotoxic effects to this lung tumor cells. Our results suggest that gold nanoparticles conjugated with doxorubicin could be used as a pH-triggered drug releasing carrier for tumor drug delivery.

The C1s core line in irradiated graphite

Recently, plasma deposited amorphous carbon films have been the subject of extensive experimental and theoretical investigations aimed at correlating their electronic, structural, and mechanical properties to growth parameters. To investigate these properties, different spectral parameters reflecting the electronic structure of carbon-based materials are proposed in literature. The effects of various electronic configurations on the carbon photoelectron spectra are analyzed here with particular attention to C1s core line with the aim to better interpret its structure. The latter is commonly fitted under the assumption that it can be described by using just two spectral components related to sp2 and sp3 hybrids. Their relative intensities are then used to estimate the sp2 and sp3 phases. We show that, in the presence of an amorphous network, the C1s line shape is the result of a more complex mixture of electronic states. Ar+ irradiated graphite and successive oxidation was used to identify spectral feature...

Nanocomposite Er-Ag silicate glasses

Particular attention has being given to metal–dielectric nanostructured materials, due to the well known surface plasmon resonance, described as the oscillation of the free electrons with respect to the ionic background of the nanoparticle when they are collectively excited by laser irradiation. It is claimed that metal nanoparticles can be used for increasing the intensity of the luminescence emitted by rare earth ions. This effect is attributed to the strong absorption cross section related to the surface plasmon excitation in noble-metal nanoparticles and/or to the large local field enhancement generated around the excited nanoparticles. In spite of the large amount of work published on this topic, the mechanism of optical amplification remains controversial. Here we present x-ray photoelectron spectra and transmission electron images together with photoluminescence absorption and emission measurements, with the aim of providing a better understanding of the effective role of silver as a sensitizer for erbium.

Synthesis and characterization of PMMA-based superhydrophobic surfaces

Recently, superhydrophobic surfaces are gaining much interest because they may be employed in a series of applications, spanning from the realization of self-cleaning surfaces to microfluidics to special water-impermeable tissues allowing perspiration. It is well-known that superhydrophobicity strictly depends on the combination of superficial micro- and nano-structures. Then, key factors in the process of surface synthesis are the parameters which will define the surface conformation. In this work, we deal with the fabrication of polymer-based superhydrophobic surfaces. We developed a new method to have a good control of the structure of the synthesised surface. A high stability of the superhydrophobic character during time was obtained. Moreover, the synthesis process is green and easily transferable to industry for large production.

Glass-based erbium activated micro-nano photonic structures

In this paper, we present a short review of the activity performed in developing glass-based photonic structures on the nano and micro scale, based on the sol-gel techniques and activated by rare earth ions. Optical and spectroscopic assessment of glass ceramic waveguides is discussed. Luminescence enhancement is demonstrated. Refractive index modulation upon UV exposure is measured in SiO2-SnO2 film. Finally, results concerning Er3+-activated opal-based photonic crystal are presented. In the case of inverted opals a quantum efficiency of 90% was estimated.

Er3+-activated photonic structures fabricated by sol-gel and rf-sputtering techniques

The realization of photonic structures operating at visible and near infrared frequencies is a highly attractive scientific and technological challenge. Since optical fiber innovation, a huge of activity has been performed leading to interesting results, such as optical waveguides and planar lightwave circuits, microphotonic devices, optical microcavities, nanowires, plasmonic structures, and photonic crystals. These systems have opened new possibilities in the field of both basic and applied physics, in a large area covering Information Communication Technologies, Health and Biology, Structural Engineering, and Environment Monitoring Systems. Several materials and techniques are employed to successfully fabricate photonic structures. Concerning materials, Er3+-activated silica-based glasses still play an important role, although recently interesting results have been published about fluoride glass-ceramic waveguides. As far as regards the fabrication methods sol-gel route and rf sputtering have proved to be versatile and reliable techniques. In this article we will present a review of some Er3+-activated photonic structures fabricated by sol gel route and rf sputtering deposition. In the discussion on the sol-gel approach we focus our attention on the silica-hafnia binary system presenting an overview concerning fabrication protocols and structural, optical and spectroscopic assessment of SiO2-HfO2 waveguides activated by Er3+ ions. In order to put in evidence the reliability and versatility of the sol-gel route for photonics applications four different confined structures are briefly presented: amorphous waveguides, coated microspheres, monolithic waveguide laser, and core-shell nanospheres. As examples of rf sputtering technique, we will discuss Er3+-activated silica-hafnia and silica-germania waveguides, the latter system allowing fabrication of integrated optics structures by UV photo-imprinting. Finally, two examples of photonic crystal structures, one prepared by sol-gel process and the other one fabricated by rf sputtering deposition, will be illustrated.

One-step synthesis of magnetic gold nanostars for bioimaging applications

This work presents novel magnetite–gold hybrid nanoparticles formed by multiple magnetic cores inside gold nanostars (SPIO@Au). The nanostructures were produced by one-step hydroxylamine reduction of a gold precursor on the surface of functionalized superparamagnetic iron oxide nanoparticles in an aqueous alkaline medium. The nanoparticles show excellent chemical stability, magnetic properties and an intense surface plasmon resonance in the visible-NIR region. In vitro cellular tests showed that these nanostructures could be efficiently internalized inside A549 cells. The optical properties of the SPIO@Au nanoparticles were exploited for in vitro localization analysis through scattering based imaging. These nanoparticles could have enormous potential for application as contrast agents in combined imaging techniques as well as in bio-analytical applications such as biomolecule and cell separation.

Erbium-activated silica-hafnia: A reliable photonic system

Sol gel-derived silica-hafnia is a reliable and flexible binary system that has proved to be suitable for rare earth doping and fabrication of amorphous and glass ceramic planar waveguides as well as for improving thermal stability of spherical microresonators. Here we present an overview concerning fabrication protocols and structural, optical and spectroscopic assessment of SiO2-HfO2 waveguides activated with Er3+ ions. In order to put in evidence the reliability and versatility of the silica-hafnia system for photonics applications three different confined structures are briefly presented: i) amorphous waveguides; ii) glass-ceramic waveguides; iii) coated microspheres.

Nanocomposite photonic glasses and confined structures optimizing Er3+-luminescent properties

The recent developments of optically confined structures and nanocomposite materials activated by rare earth ions have opened new possibilities in the field of both basic and applied physics, in a large area covering Information Communication Technologies, Health and Biology, Structural Engineering, and Environment Monitoring Systems. As far as optical telecommunications are concerned, Er3+-activated glasses have become one of the key materials because of their relevance for the development of optical amplifiers. The short-term goal is to develop appropriate material systems and devices to exploit at the best the luminescence properties of Erbium. Er3+-activated confined structures at different scales thus offer interesting solutions. The last decade has seen a remarkable increase in the experimental efforts to control and enhance emission properties of emitters by tailoring the dielectric surrounding of the source. The aim of this paper is to give a review concerning the advances in glass-based photonic systems, where light confinement or the presence of nanostructured hosts for the rare-earth induces an enhancement and a control of the optical and/or spectroscopic properties.