Alessandro Pistone

Hybrid composites made of multiwalled carbon nanotubes functionalized with Fe3O4 nanoparticles for tissue engineering applications

A straightforward technique for functionalization of multiwalled carbon nanotubes (MWCNTs) with magnetite (Fe(3)O(4)) nanoparticles was developed. Iron oxide nanoparticles were deposited on MWCNT surfaces by a deposition-precipitation method using Fe(3+)/Fe(2+) salts precursors in basic solution. The characterizations by HRTEM, XRD, SEM/EDX, AAS and TPR analyses confirmed the successful formation of magnetic iron oxide nanoparticles on the MWCNT surface. Fe(3)O(4)/MWCNT hybrid composites were analysed in vitro by incubation with mesenchymal stem cells for 1, 3 and 7 days, either in the presence or absence of a static magnetic field. Analysis of cell proliferation was performed by the MTT assay, quantification of cellular stress was performed by the Lactate Dehydrogenase assay and analysis of cell morphology was performed by actin immunofluorescence and scanning electron microscopy. Results demonstrate that the introduction of magnetite into the MWCNT structure increases biocompatibility of oxidized MWCNTs. In addition, the presence of a static magnetic field further increases Fe(3)O(4)/MWCNT influence on cell behaviour. These results demonstrate this novel Fe(3)O(4)/MWCNT hybrid composite has good potential for tissue engineering applications.

Gold catalysts for the liquid phase oxidation of o-hydroxybenzyl alcohol

Abstract Gold on iron oxide catalysts have been investigated in the liquid phase oxidation of o -hydroxybenzylalcohol (salicylic alcohol) under mild conditions. The presence of gold strongly enhances the catalytic activity of iron oxide, which is practically inactive under the same reaction conditions. The liquid phase oxidation of salicylic alcohol follows a first order reaction rate law with respect to the organic substrate. The order of reaction with respect to the oxygen partial pressure is close to zero. The catalytic activity increases with the gold loading. The oxidation of salicylic alcohol on the catalysts with low gold loading leads to the formation of salicylic aldehyde as the main reaction product. A small amount of salicylic acid was also obtained. On the catalysts with higher gold loading a progressive decrease of the yield to salycilic aldehyde with the conversion level occurs. When the reaction is carried out using benzene as solvent, the salycilic aldehyde is the end products on all the catalysts investigated regardless of the gold content.

Activity of gold catalysts in the liquid-phase oxidation of o-hydroxybenzyl alcohol

Gold catalysts prepared by impregnation of HAuCl4 on Fe2O3, ZnO, CaO, and Al2O3 and aged in a solution of Na2CO3 (IWI/Na2CO3 method) are able to catalyze the oxidation of o-hydroxybenzyl alcohol (salicylic alcohol) under mild conditions. The reaction rate is even higher than that using analogous catalysts prepared by co-precipitation. Salicylic aldehyde is the main reaction product with a selectivity >90% at 90% conversion. The influence of the reaction conditions on the catalytic activity is also discussed.

Recent Advances in Carbon Nanotubes as Delivery Systems for Anticancer Drugs

Problems associated with the administration of anticancer drugs, such as limited solubility, poor biodistribution,lack of selectivity, and healthy tissue damage, can be overcome by the implementation of drug delivery systems. A wide range of materials, including liposomes, microspheres, polymers and recently, carbon nanotubes (CNTs), have been investigated for delivering anticancer drugs on the purpose of reducing the number of necessary administrations, providing more localized and better use of the active agents, and increasing patient compliance. Carbon nanotubes (CNTs) have attracted particular attention as carriers of biologically relevant molecules due to their unique physical, chemical and physiological properties. The exact relationship between the physical-chemical properties of carbon nanotubes, their cell to-cell interactions, reactivity, and biological/systemic consequences are relevant issues and it is important to know suchinter-relationships beforehand to employ the benefits of these nanomaterials without the hazardous consequences. The purpose of this review is to present highlight of recent developments in the application of carbon nanotubes as cargoes for anti cancer drugs and in the diagnosis of cancer diseases.

Isomerisation of (+)citronellal over Zn(II) supported catalysts

Abstract A series of acid catalysts prepared by impregnation of commercial silicas with a solution of ZnBr2 have been characterised with several techniques (BET, adsorption–desorption porosimetry, scanning electron microscopy (SEM), energy dispersive analysis (EDAX), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS)). The results have shown that ZnBr2 is evenly distributed over the surface of the supports regardless of their surface properties. The catalytic surface contains two different sites: physically adsorbed ZnBr2 and Zn(II) sites, obtained from the partial decomposition of the precursor. No correlation between the surface area of the support and the amount of Zn(II) sites has been observed. The ZnBr2/SiO2 based catalysts have been also tested in the isomerisation of (+)citronellal. The catalytic activity results have shown that the structural properties of the support have a scarce influence on the catalytic performance. On all the investigated samples, the selectivity to isopulegols is 100%, whereas the stereoselectivity to (−)isopulegol ranges between 70 and 86%. Zn(II) are the most active sites for the catalytic isomerisation while ZnBr2 has a negligible catalytic activity. However, the presence of ZnBr2 is of fundamental importance to achieve higher selectivity toward the formation of (−)isopulegol.

Toxicological assessment of multi-walled carbon nanotubes on A549 human lung epithelial cells

An in vitro model resembling the respiratory epithelium was used to investigate the biological response to laboratory-made pristine and functionalised multi-walled carbon nanotubes (pMWCNT and MWCNT-COOH). Cell uptake was analysed by MWCNT-COOH, FITC labelled and the effect of internalisation was evaluated on the endocytic apparatus, mitochondrial compartment and DNA integrity. In the dose range 12.5-100μgml(-1), cytotoxicity and ROS generation were assayed, evaluating the role of iron (the catalyst used in MWCNTs synthesis). We observed a correlation between MWCNTs uptake and lysosomal dysfunction and an inverse relationship between these two parameters and cell viability (P<0.01). In particular, pristine-MWCNT caused a time- and dose-dependent ROS increase and higher levels of lipid hydroperoxides compared to the controls. Mitochondrial impairment was observed. Conversely to the functionalised MWCNT, higher micronuclei (MNi) frequency was detected in mono- and binucleate pMWCNT-treated cells, underlining an aneugenic effect due to mechanical damage. Based on the physical and chemical features of MWCNTs, several toxicological pathways could be activated in respiratory epithelium upon their inhalation. The biological impacts of nano-needles were imputable to their efficient and very fast uptake and to the resulting mechanical damages in cell compartments. Lysosomal dysfunction was able to trigger further toxic effects.

graphene quantum dots for cancer targeted drug delivery

A biocompatible and cell traceable drug delivery system Graphene Quantum Dots (GQD) based, for the targeted delivery of the DNA intercalating drug doxorubicin (DOX) to cancer cells, is here reported. Highly dispersible and water soluble GQD, synthesized by acidic oxidation and exfoliation of multi-walled carbon nanotubes (MWCNT), were covalently linked to the tumor targeting module biotin (BTN), able to efficiently recognize biotin receptors over-expressed on cancer cells and loaded with DOX. Biological test performed on A549 cells reported a very low toxicity of the synthesized carrier (GQD and GQD-BTN). In GQD-BTN-DOX treated cancer cells, the cytotoxicity was strongly dependent from cell uptake which was greater and delayed after treatment with GQD-BTN-DOX system with respect to what observed for cells treated with the same system lacking of the targeting module BTN (GQD-DOX) or with the free drug alone. A delayed nuclear internalization of the drug is reported, due to the drug detachment from the nanosystem, triggered by the acidic environment of cancer cells.

Gold promoted Li-Fe2O3 thin films for humidity sensors

Abstract A study of iron oxide thin films doped with Li and Au for humidity sensing applications is reported. The characteristics of sensitivity, linearity and stability of humidity sensors based on these films were investigated and correlated to the structural and textural properties of the sensing layer. Such properties are influenced by the nature of the dopant and the thermal treatment. Li creates preferential adsorption sites for the H2O molecules thus increasing the sensitivity at low RH. Gold instead reduces the drift of the resistance baseline stabilizing the presence of amorphous iron oxide phases. By optimizing the thermal treatment of Au-doped Li–Fe2O3 thin films, humidity sensors with high sensitivity, linearity and good stability have been developed.

Photovoltaic properties of multi-walled carbon nanotubes deposited on n-doped silicon

Multi-wall carbon nanotubes (MWCNTs), grown by catalytic chemical vapor deposition (CCVD) over Fe supported on alumina catalyst, using isobutane as feedstock, are dispersed in aqueous solutions of sodium dodecyl sulfate. Stable and highly photosensitive heterojunctions are developed by liquid-phase deposition of MWCNTs/surfactant mixtures on the top of n-doped monocrystalline silicon wafers. Electrical measurements performed in the dark and under broad-band visible light, show that the hybrid solar cells, despite their non-optimized design, have conversion energy efficiency of the order of 3%.

Low-frequency Raman study of hollow multiwalled nanotubes grown by Fe-catalyzed chemical vapor deposition

In this work, it is shown that some Raman-active modes may be detected, below 500cm−1, in the spectrum of nanotubes synthesized by iron catalyzed chemical vapor deposition. By comparatively discussing results of Raman, high-resolution transmission electron microscopy, and thermogravimetric analyses, demonstration is given that these spectral features originate from scattering by nanoparticles of iron catalyst encapsulated within the tubes under nonstationary growth regime. Their intensity progressively weakens with increasing carbon supply rate until bands disappear as stationary conditions are reached.