P. Candeloro

Water soluble nanoporous nanoparticle for in vivo targeted drug delivery and controlled release in B cells tumor context.

Multitasking nanoparticles are gaining great attention for smart drug delivery systems. The exploration of the nano-scale opens new concrete opportunities for revealing new properties and undiscovered cell-particle interactions. Here we present a biodegradable nanoporous silicon nanoparticle that can be successfully employed for in vivo targeted drug delivery and sustained release. The bare nanoporous nanocarriers can be accurately designed and fabricated with an effective control of porosity, surface chemistry and particle size, up to a few nm. The proposed nanoparticles exhibit several remarkable features including high payload, biodegradability, no toxicity, and multiple loading in water without the need of additional chemical reagents at room temperature. The targeting strategy is based on phage display technology that was successfully used to discover cell surface binding peptide for murine B lymphoma A20 cell line. The peptide used in combination with the nanoporous nanoparticles allows an efficient in vivo targeting, a sustained release and a sensible therapeutic effect.

Magnetic field dependence of quantized and localized spin wave modes in thin rectangular magnetic dots

The magnetic field dependences of the frequencies of standing spin-wave modes in a tangentially magnetized array of thin rectangular permalloy dots (800 × 550 nm) were measured experimentally by a Brillouin light scattering technique and calculated theoretically using an approximate size-dependent quantization of the spin-wavevector components in the dipole-exchange dispersion equation for spin waves propagating in a continuous magnetic film. It was found that the inhomogeneous internal bias magnetic field of the dot has a strong influence on the profiles of the lowest spin-wave standing modes. In addition, the dynamic magnetization distributions found for both longitudinally and transversely magnetized long magnetic stripes gives a good approximation for mode distributions in a rectangular dot magnetized along one of its in-plane sides. An approximate analytic theory of exchange-dominated spin-wave modes, strongly localized along the dot edge that is perpendicular to the bias magnetic field, is developed. A good quantitative agreement with the results of the BLS experiment is found.

Micro-Optics Fabrication on Top of Optical Fibers Using Two-Photon Lithography

We describe the fabrication of different micro-optical structures on top of optical fibers using two-photon polymerization. We show the convenience of this approach to quickly create generic three-dimensional shapes using a single setup by comparison to previous shape-dependent methods. A set of different structures, designed for different optical functions, are fabricated and characterized to demonstrate the versatility of this approach and their high optical quality.

Fabrication of 3D metallic photonic crystals by X-ray lithography

Photonic crystals (3D) represent one of the most important building blocks towards the achievement of a full optics communication technology. So far the largest interest has been attracted by two-dimensional photonic crystals because they are potentially more amenable to fabrication and much closer to application. Straightforward application of the photonic band gap concept is generally thought to require three-dimensional (3D) photonic crystals that, however, represent a challenge from a fabrication point of view. Recent works have shown that 3D metallic PC can be fabricated and that they can be advantageous in the low frequency region where the metals become almost completely reflectors. In this work we show the possibility to fabricate 3D PC structures by X-ray lithography. Gold and nickel 3D photonic crystals with threefold (Yablonovite) and fourfold rotation symmetry have been fabricated with a lattice parameter ranging from 1 µm down to 300 nm. The total thickness of the 3D PC is of the order of 10 µm, a value which should allow to achieve a complete bulk behavior. This is supported by variable angle reflectance measurements, which have shown clear indications for true 3D dimensionality of our samples.

X-ray lithography for micro- and nano-fabrication at ELETTRA for interdisciplinary applications

ELETTRA (http://www.elettra.trieste.it/index.html) is a third generation synchrotron radiation source facility operating at Trieste, Italy, and hosts a wide range of research activities in advanced materials analysis and processing, biology and nano-science at several various beam lines. The energy spectrum of ELETTRA allows x-ray nano-lithography using soft (1.5 keV) and hard x-ray (10 keV) wavelengths. The Laboratory for Interdisciplinary Lithography (LIILIT) was established in 1998 as part of an Italian national initiative on micro- and nano-technology project of INFM and is funded and supported by the Italian National Research Council (CNR), INFM and ELETTRA. LILIT had developed two dedicated lithographic beam lines for soft (1.5 keV) and hard x-ray (10 keV) for micro- and nano-fabrication activities for their applications in engineering, science and bio-medical applications. In this paper, we present a summary of our research activities in micro- and nano-fabrication involving x-ray nanolithography at LILITs soft and hard x-ray beam lines.

Enhancing plasma peptide MALDI-TOF-MS profiling by mesoporous silica assisted crystallization

Promising profiling techniques based on new material/solid phase extraction for capturing molecular signatures from body fluids are being coupled to MALDI-TOF-MS. Sample preparation significantly influences spectrum quality in this ionization method. Mesoporous silica beads (MSB), by the means of nano-sized porous channels with high surface area, enable harvesting of peptides from plasma and serum excluding large size proteins. We have investigated the morphology of a sample slurry, developed as a new tool for plasma peptides enrichment based on mesoporous materials. Our study highlights a correlation between crystals morphology and enhanced performances in MALDI-TOF-MS analysis. This is the first report which correlates the increase in signal intensity with crystal formation in samples preparations which make use of various kinds of slurries for the analysis of samples clinically relevant like human plasma.

H ferritin silencing induces protein misfolding in K562 cells: A Raman analysis

The redox state of the cell is involved in the regulation of many physiological functions as well as in the pathogenesis of several diseases, and is strictly dependent on the amount of iron in its catalytically active state. Alterations of iron homeostasis determine increased steady-state concentrations of Reactive Oxygen Species (ROS) that cause lipid peroxidation, DNA damage and altered protein folding. Ferritin keeps the intracellular iron in a non-toxic and readily available form and consequently plays a central role in iron and redox homeostasis. The protein is composed by 24 subunits of the H- and L-type, coded by two different genes, with structural and functional differences. The aim of this study was to shed light on the role of the single H ferritin subunit (FHC) in keeping the native correct protein three-dimensional structure. To this, we performed Raman spectroscopy on protein extracts from K562 cells subjected to FHC silencing. The results show a significant increase in the percentage of disordered structures content at a level comparable to that induced by H2O2 treatment in control cells. ROS inhibitor and iron chelator were able to revert protein misfolding. This integrated approach, involving Raman spectroscopy and targeted-gene silencing, indicates that an imbalance of the heavy-to-light chain ratio in the ferritin composition is able to induce severe but still reversible modifications in protein folding and uncovers new potential pathogenetic mechanisms associated to intracellular iron perturbation.

High-resolution complex structures for two-dimensional photonic crystals realized by x-ray diffraction lithography

Two-dimensional photonic band gap structures were fabricated by x-ray lithography combined with ion etching on metalorganic chemical vapor deposition grown GaAs/AlGaAs waveguides. Such structures, more amenable to fabrication than fully three-dimensional photonic crystals, allow the confinement of light in the third direction using index guiding. The feasibility of complex high-resolution (down to 50 nm) unit cell fabrication has been demonstrated by exploiting x-ray diffraction and nonlinear resist response during the development process. Optical characterizations of some samples were performed. These characterizations show the presence of well-defined photonic band gap structures and second harmonic property generation. The results have been discussed and compared with theoretical simulation.

Spin-wave frequency discretization in submicron rectangular prisms

Spin-wave frequency discretization has been observed by Brillouin light scattering in an array of tangentially magnetized 800u2009nm×550u2009nm Ni81Fe19 rectangular prisms with thicknesses of 30 nm and dot separations of 200 nm. For a large wave vector interval, several discrete dispersionless modes were observed. The experimental frequencies were compared to those calculated using a recently developed analytical model for flat uniformly magnetized rectangular prisms. The agreement between the experimental and calculated frequencies is very good. In addition to the above mentioned modes, a low frequency mode was experimentally detected over a wide range of transferred wave vectors. Finally, the decrease in frequency of the first perpendicular standing spin-wave mode, observed in the patterned sample with respect to in the continuous film, was successfully reproduced.

Novel plasmonic nanodevices for few/single molecule detection

This paper reports the fabrication of two reproducible surface enhanced Raman scattering devices using; a) nanoPillar coupled with PC cavity by means of FIB milling and electron beam induced deposition techniques (Device 1), and b) plasmonic gold nanoaggregate structures using electro-plating and e-beam lithography techniques (Device 2). Device 1 consists of photonic crystal cavity as an optical source to couple the incident laser with a metallic tapered nanolens. Exploiting such approach it is possible to overcome the difficulties related to scattering and diffraction phenomena when visible laser (514 nm) illuminates nanostructures. The nanostructure is covered with HMDS and is selectively removed leaving HMDS polymer on nanoPillar only. A clear Raman scattering enhancement has been demonstrated for label-free detection of molecule in sub-wavelength regime. On the other hand, myoglobin protein is deposited on Device 2 using drop coating deposition method and is estimated that the substrate is able to detect the myoglobin concentration down to attomole.