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Multifunctional nanoplatforms employed for active and passive tumor targeting represent important devices to overcome some of the critical issues related to the cancer therapy, such as the inherent limitations of drugs to cross anatomical and patho-physiological barriers, and to improve the specific drug delivery to tumor tissues. Graphene (G) and its multifunctional derivatives may offer passive targeting toward tumor sites, whereas hyaluronic acid (HA), that counts several specific receptors typically over-expressed on the surface membranes of various tumor cells, is the ideal component of multifunctional platforms for active targeting. Herein, we report the conjugation of Silibinin (Sil), the most active component of a complex of flavonoids contained into silymarin employed mainly as hepatoprotective agent but with application that goes beyond liver diseases and expands to cancer, to G-based and HA-based materials (Fig. 1). The biocompatibility of new platforms has been evaluated on Human Mesenchymal Stem cells and their anticancer effects have been studied on Human Osteosarcoma and Human Breast Cancer cell lines.

In analogy to metal nanocomposites, the investigated hybrid organicinorganic aggregates induce an enhancement of the scattered light. To explain the observed broadening of the absorption band and the wavelength dependence of the scattering, the systems can be considered as a nanoparticle composite. The scattering enhancement obeys the scaling law with the same optical spectral dimension d0 = 0.3 as that obtained through numerical simulations on cluster-cluster aggregates of purely metal nanoparticle composites. ©2012 by Società Italiana di Fisica

We study optical trapping of nanotubes and graphene. We extract the distribution of both centre-of-mass and angular fluctuations from three-dimensional tracking of these optically trapped carbon nanostructures. The optical force and torque constants are measured from auto and cross-correlation of the tracking signals. We demonstrate that nanotubes enable nanometer spatial, and femto-Newton force resolution in photonic force microscopy by accurately measuring the radiation pressure in a double frequency optical tweezers. Finally, we integrate optical trapping with Raman and photoluminescence spectroscopy demonstrating the use of a Raman and photoluminescence tweezers by investigating the spectroscopy of nanotubes and graphene flakes in solution. Experimental results are compared with calculations based on electromagnetic scattering theory.

The plasmon resonance of metallic Au/Ag alloys in the colloidal state was tuned from 400 nm to 500 nm using a laser irradiated technique, performed directly in the liquid state. Interesting optical nonlinearities, trapping effects and spectroscopic enhancements were detected as function of gold concentration in the nanoalloys. In particular a reduction of the limiting threshold was observed by increasing the gold amount. The SERS activity of the Au/Ag alloys was tested in liquid and in solid state in presence of linear carbon chains as probe molecules. The dependence of the increased Raman signals on the nanoparticle Au/Ag atomic ratio is presented and discussed. Finally preliminary studies and prospects for optical and Raman tweezers experiments are discussed.

Controlled creation of SERS-active hot spots in liquid is a challenge in which optical forces can play an important role by promoting the aggregation of metal nanoparticles by optical trapping or by exploiting the radiation pressure. Here we show that laser induced aggregation of gold nanorods in a buffered solution of Bovine Serum Albumin (BSA) leads to the formation of SERS-active agglomerates capable to enhance the Raman scattering of BSA by 5 orders of magnitude, thus allowing the detection of BSA at concentrations as low as 10⁻⁶ M. This occurrence involves optical, mechanical and thermal effects.

Multi-wavelength SERS measurements on dyes molecules adsorbed on gold evaporated nanoparticles substrates are presented. The spectra are correlated with the Localized Surface Plasmon Resonance (LSPR) profile of the nanostructured substrate before and after the adsorption process. The enhancement of the typical vibrational modes of the methylene blue is investigated for the different excitation wavelengths and we show that its behavior follows properly the LSPR profile of nanoparticles "dressed" with the dye molecules.

We study the polarized Surface Enhanced Raman Scattering from randomly oriented molecules adsorbed on near-feld coupled gold nanowires. We show that the scattering is polarized always along the wire-to-wire nanocavities. We fnd the exact angular dependence for the polarized, unpolarized, parallel- and cross-polarized SERS intensity. Finally we develop a model that fts the experimental data and allows to measure the feld enhancement and the re-radiation enhancement factors, independently, and retrieve the depolarization ratio of the probe molecules. © 2011 by the Author(s); licensee Accademia Peloritana dei Pericolanti, Messina, Italy.

Fourier-transform infrared and Raman spectroscopies have been used to investigate the role played by water on the structural organization of 1-butyl-3-methyl-imidazolium tetrafluoroborate and H2Omixtures, over a wide composition range at room temperature. Our measurements provide clear experimental evidence of the prompt association between 'free'watermolecules and anions at very smallwater contents. Moreover, in the case of higher water contents, we obtain indications of the local aggregation of water molecules in the network. Such an aggregation is found to occur even before the saturation of all the anions that are available for H-bonding. We propose that the water clusters favour the organization of ionic liquid in the polar network, where they are embedded, and the aggregation of hydrophobic alkyl tails in amicelle-like structure.Whenmixtureswith watermolar fraction exceeding 0.7 are considered, this local organization starts to weaken owing to the gradual break up of the ion-pair interactions.

Cross-linking content and polymerization degree of poly(methylmethacrylate) PMMA thin films have been investigated by means of Fourier transform infrared and micro-Raman spectroscopic techniques. The samples were deposited by means of pulsed laser ablation of a PMMA target at room temperature. The laser fluence was varied from 0.5 J/cm(2) up to 4 J/cm(2). Experimental results show that it is possible to deposit PMMA thin films with a very low monomer content (smaller than 3%) and to modulate the cross-linking occurrence upon tuning the laser fluence. Moreover, the effect of the post-deposition thermal treatment on the polymerization degree has been exploited. Then, we estimated the value of the polymerization enthalpy, which is comparable to the value at which the complete conversion of monomers in polymer is reached.

The dynamics of the expanding plasma produced by excimer laser ablation of different materials such as silicon, silicon carbide, graphite and tin powder were studied by means of time integrated, spatially resolved emission spectroscopy and fast photography imaging of the expanding plasma. Experiments were performed both in vacuum and in different pure background atmosphere (i.e. oxygen or nitrogen) and, finally, in gaseous mixtures (i.e. in O 2 /Ar and N 2 /Ar mixtures). These investigations were performed to gather information on the nature of the chemical species present in the plasma and on the occurrence of chemical reactions during the interaction between the lasma and the background gas. Then, we tried to correlate the plasma expansion dynamics to the structural and physical properties of the deposited materials. Experimental results clearly indicate that there is a strong correlation between the plasma expansion dynamics and the structural properties of the deposited thin films. In this respect, the investigations performed by means of fast photography and of optical emission spectroscopy revealed themselves as powerful tools for an efficient control of the deposition process itself.

The role played by the solvation water molecules on the macroscopically observed sol-gel transition in lecithin/cyclohexane/water reverse micelles is investigated. The self-diffusion properties of both the surfactant and the water molecules entrapped in the micellar cores are investigated by quasi-elastic neutron scattering, while dielectric relaxation and conductivity measurements furnish information on the structural relaxation processes taking place in the system. The obtained results are compared with the experimental indications for AOT/cyclohexane/water systems. The data from lecithin-based systems can be interpreted only by assuming that, contrary to AOT systems, the water molecules are entrapped at the interfaces without coalescing into an inner water pool. Also, the charge transport mechanisms look very different in the two kinds of systems. In particular. in the case of lecithin, it is shown how the conductivity appears mainly due to inter-micellar bond percolation: it is suggested that the solvated water molecules can induce a change of the surface curvature, in such a way promoting the formation of branch points. The idea of the existence of a percolated network of branched cylindrical micelles agrees with the observed temperature dependence of the system conductivity. The study of the electrorheologic behavior of the system under electric field confirms the existence of a percolated transient network in the get phase. (C) 2002 Elsevier Science B.V. All rights reserved.