Monitoring of Carbonated Hydroxyapatite Growth on Modified Polycrystalline CVD-Diamond Coatings on Titanium Substrates

Production of diamond coatings on titanium substrates has demonstrated as a promising strategy for applications ranging from biosensing to hard tissue engineering. The present study focuses on monitoring the nucleation and growth of bone-like carbonated-hydroxyapatite (C-HA) on polycrystalline diamond (PCD) synthetized on titanium substrate by means of a hot filament chemical vapor deposition (HF-CVD) method. The surface terminations of diamond coatings were selectively modified by oxidative treatments. The process of the C-HA deposition, accomplished by precipitation from simulated body fluid (SBF), was monitored from 3 to 20 days by Raman spectroscopy analysis. The coupling of morphological and structural investigations suggests that the modulation of the PCD surface chemistry enhances the bioactivity of the produced materials, allowing for the formation of continuous C-HA coatings with needle-like texture and chemical composition typical of those of the bone mineral. Specifically, after 20 days of immersion in SBF the calculated carbonate weight percent and the Ca/P ratio are 5.5% and 2.1, respectively. Based on these results, this study brings a novelty in tailoring the CVD-diamond properties for advanced biomedical and technological applications

Nanodiamond-mediated crystallization in fibers of PANI nanocomposites produced by template-free polymerization : conductive and thermal properties of the fibrillar networks

The detonation nanodiamond is a novel versatile nanomaterial with tunable properties and surface chemistry. In this work, we report on a template-free method to synthesize polyaniline based nanocomposite fibers during a chemical oxidative precipitation polymerization where the cooperative interactions between nanodiamond and polyaniline nucleates trigger the final morphology of the nanocomposite. FE–SEM and TEM observations evidence the prominent growth of fibril-like structures assembled in 2-D networks of tightly woven, partially oriented fibers. Optical and Raman spectroscopy and X-ray diffraction analyses reveal that the polymer chains are in a protonated emeraldine form and organize themselves in a highly ordered 3-D spatial arrangement. Conductivity measurements performed on isolated fibers by a conductive tip of an AFM apparatus highlight that the diamond filler does not affect the conductive properties of the polyaniline matrix while increases the thermal stability of the polymer as confirmed by TGA studies

CVD-based techniques for the synthesis of nanographites and nanodiamonds

We report about some Chemical Vapor Deposition approaches used to produce a variety of C-sp2 and C-sp3 crystalline nanostructures. The methodologies developed in our laboratories provide custom-made solutions for the fabrication of specific carbon nanomaterials with properties tailored for applications in the field of nanotechnology

Targeting monocyte chemotactic protein-1 synthesis with bindarit induces tumor regression in prostate and breast cancer animal models

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Preparation and characterization of hybrid Csp2-Csp3 materials and nanodiamond-based systems

Il lavoro di ricerca si è focalizzato sulla preparazione e caratterizzazione di sistemi ibridi innovativi basati su Csp2 e Csp3 connessi mediante legami covalenti e materiali a base di diamante nanocristallino. Questi sistemi composti da nanotubi di carbonio (CNT) e diamante, potrebbero avere proprietà meccaniche uniche, nonché caratteristiche elettriche e di conducibilità termica eccellenti insieme con proprietà di emissione di campo comparabili o migliori di quelle mostrate finora da diamante e nanotubi puri. Questi ibridi posso essere impiegati come rivestimenti antiusura, nel thermal management dei circuiti integrati, nei dispositivi ad emissione di campo e nei dispositivi per schermaggio di campi come nei MEMS. Da ciò ne deriva la necessità di studiare ed esplorare nuovi parametri che riguardano la sintesi di questi materiali così come le loro proprietà. Contemporaneamente, la capacità di ottenere campioni a base di diamante con geometrie 3D complesse costituisce una condizione necessaria per qualsiasi tecnologia a base diamante. Più recentemente, è stata scoperta una nuova classe di materiali al carbonio appartenente alla categoria diamante ma dalle dimensioni nanometriche: questo materiale è spesso denominato diamante ‘ultra-nanocristallino’, perché ha in sé le caratteristiche tipiche del diamante ‘bulk’ ma rimanendo in dimensioni nanometriche. Grazie alla possibilità di sintetizzarlo su larga scala mediante metodi a basso costo basati su un processo di detonazione, nonché alle sue ridotte dimensioni (pochi nm) insieme con un’elevata funzionalizzazione della superficie e biocompatibilità, questo materiale ha raccolto un largo successo all’interno del mondo scientifico. In una prima parte di questo lavoro di tesi vengono descritti e discussi i risultati ottenuti nella sintesi di film di diamante policristallino in architetture predefinite adoperando dei colloidi acquosi di diamante nanocristallino e mediante tecnica di Deposizione Chimica da fase Vapore attivata da filamento caldo (HFCVD). Inoltre, al fine di produrre film di diamante dalle migliori proprietà e qualità, si è proceduto con la sperimentazione dei parametri, generalmente usati per la crescita CVD di diamante, nella sintesi di film di diamante policristallino su un substrato innovativo costituito da un materiale superconduttore come il nitruro di niobio (NbN). L’obiettivo era studiare l’effetto catalitico indotto da NbN durante la crescita CVD, avendo come riferimento un substrato solitamente usato per questo tipo di sintesi quale il Si. Tutti i campioni preparati sono stati studiati sia sotto l’aspetto strutturale che morfologico. Infine, una parte importante del lavoro di tesi è stata dedicata allo studio e ottimizzazione dei parametri di sintesi ad hoc per la crescita ‘one-step’ di sistemi CNT/diamante mediante tecnica CVD e loro caratterizzazione strutturale, morfologica e funzionale. In particolare ottimi risultati sono stati ottenuti nella preparazione di depositi costituiti da CNT coperti da grani di diamante nanocristallino.The research work has been focalized on the preparation and characterization of novel hybrid systems based on Csp2 and Csp3 covalently bonded and nanodiamond based materials. The systems composed by carbon nanotubes (CNT) and diamond, can be expected to have unique mechanical properties, excellent electrical and thermal conductivities and field emission characteristics comparable to or better than pure diamond and CNTs. Diamond/CNT hybrids may thus find applications as wear-resistant coatings, thermal management of integrated circuits (ICs), field emission devices and electrical field shielding in MEMS and microelectronics. As consequence, more research in this field is mandatory in what concerns the synthesis itself and also the properties characterization of this new class of materials. At the same time, the ability to produce diamond specimens with complex three-dimensional shapes is a very challenging requirement of any diamond-based technology. More recently a special class of diamond structure at the nanoscale has been discovered: this material is often called 'ultra-nanocrystalline' diamond with characteristic size of the basic diamond constituents encompassing the range of just few nanometers. It has gained a world-wide attention due to its inexpensive large scale synthesis based on the detonation, small primary particle size (few nanometers), surface functionalization, as well as high biocompatibility. In a first part of this thesis work, the results obtained by using aqueous nanodiamond colloids to produce 'shaped' polycrystalline diamond films with modified hot filament Chemical Vapor Deposition (HFCVD) apparatus are described and discussed. Furthermore, in order to produce diamond films with improved quality and properties, we have exploited the experimental parameters normally used for conventional CVD diamond growth in the synthesis of polycrystalline diamond films onto an innovative substrate constituted by a superconducting material like niobium nitride (NbN). The focal point has been the study of the catalytic effect induced by NbN during the CVD growth compared to the most used Si. The structural and morphological properties of the prepared samples have been characterized and discussed.. More recently, an important task is represented by the study of the benefits obtained by the integration of different nanosized carbon forms for the realization of novel hybrid Csp2-Csp3 systems. Starting from this research, an important part of the thesis work was focused on one-step synthesis, by means of the CVD Technique, of CNTs/nanodiamond systems and their structural, morphological and functional characterizations. In particular, the preparation of deposits formed by CNT arrays coated by nanodiamond grains has been optimized and the results obtained are presented and discussed

Engineering detonation nanodiamond-polyaniline nanocomposites by electrochemical routes: structural features and functional characterizations

Novel detonation nanodiamond (DND) - polyaniline (PANI) composite systems have been prepared by electrochemical polymerization techniques. Thanks to the use of two different electrochemical methods, i.e. cyclic voltammetry and chronoamperometry, it has been possible to emphasize the influence of DND particles on the nucleation mechanism of the conducting polymer. In particular, the presence of DND into the reaction environment has proven to modulate the organization of the aniline oligomers into pstacked aggregates and to induce the production of one-dimensional nanostructures. Scanning and transmission electron microscopy was used to investigate the morphology of the final composites. The protonated conducting form of the PANI matrix has been evidenced by Raman spectroscopy and the ionic/electronic transport of the PANI-DND systems was tested by means of electrocatalysis measurements toward the iodine/iodide redox couple. Based on the present experimental data, the use of nanodiamond as filler for conducting polymer based nanocomposite represents not only a fascinating challenge for the production of advanced technological applications but it can also be exploited for the controlled growth of polymeric units and for the fabrication of tailored polymeric architectures

Engineering detonation nanodiamond e Polyaniline composites byelectrochemical routes: Structural features and functional characterizations

Novel detonation nanodiamond (DND) - polyaniline (PANI) composite systems have been prepared by electrochemical polymerization techniques. Thanks to the use of two different electrochemical methods, i.e. cyclic voltammetry and chronoamperometry, it has been possible to emphasize the influence of DND particles on the nucleation mechanism of the conducting polymer. In particular, the presence of DND intothe reaction environment has proven to modulate the organization of the aniline oligomers into pstackedaggregates and to induce the production of one-dimensional nanostructures. Scanning andtransmission electron microscopy was used to investigate the morphology of the final composites. The protonated conducting form of the PANI matrix has been evidenced by Raman spectroscopy and theionic/electronic transport of the PANI-DND systems was tested by means of electrocatalysis measurements toward the iodine/iodide redox couple. Based on the present experimental data, the use ofnanodiamond as filler for conducting polymer based nanocomposite represents not only a fascinating challenge for the production of advanced technological applications but it can also be exploited for the controlled growth of polymeric units and for the fabrication of tailored polymeric architectures.Copyright: 2011 Elsevier Ltd. All rights reserved

Nanodiamond-triggered organization in fibers of PANI nanocomposites produced by chemical and electrochemical routes: Structural features and functional characterizations

We present some recent results of a systematic study regarding polyaniline-based nanocomposites with detonation nanodiamond as guest component. The peculiar properties of such crystalline nanomaterial not only help in improving the mechanical and thermal properties of the host polymeric matrix, but also influence polymerization mechanism, modifying the morphological features of the polymers. Induced by the nanodiamond presence, the final nanocomposites show a prominent arrangement of polymer segments into tubular forms and a subsequent structural organization suitable for many technological applications. © 2012 Materials Research Society

Nanodiamond-mediated crystallization in fibers of PANI nanocomposites produced by template-free polymerization: Conductive and thermal properties of the fibrillar networks

The detonation nanodiamond is a novel versatile nanomaterial with tunable properties and surface chemistry. In this work, we report on a template-free method to synthesize polyaniline based nanocomposite fibers during a chemical oxidative precipitation polymerization where the cooperative interactions between nanodiamond and polyaniline nucleates trigger the final morphology of the nanocomposite. FE-SEM and TEM observations evidence the prominent growth of fibril-like structures assembled in 2-D networks of tightly woven, partially oriented fibers. Optical and Raman spectroscopy and X-ray diffraction analyses reveal that the polymer chains are in a protonated emeraldine form and organize themselves in a highly ordered 3-D spatial arrangement. Conductivity measurements performed on isolated fibers by a conductive tip of an AFM apparatus highlight that the diamond filler does not affect the conductive properties of the polyaniline matrix while increases the thermal stability of the polymer as confirmed by TGA studies. (C) 2012 Elsevier Ltd. All rights reserved

Characterization of carbon structures produced by graphene self-assembly

Low-dimensional carbon-based materials, in particular two-dimensional graphenic carbon structures, have been produced from single-walled carbon nanotube disruption using high-shear mixing and/or treatments in sulfonitric acid mixtures at both room and high temperature. Among other two-dimensional graphenic carbon structures, colloidal dispersions of graphenic nanoflakes have been obtained. Different structural arrangements, resulting from the reorganization of carbon because of the disruption procedures applied, were observed through selected area electron diffraction (SAED) and through reflection high-energy electron diffraction (RHEED) analyses coupled to transmission and scanning electron microscopy observations. Such combined investigations in the real and reciprocal space provided structural information at the nanoscale on the clustering of graphene layers in nanoplatelets or/and on their assembly into highly ordered (single-crystal) nanosheets. Furthermore, a different carbon phase exhibiting an orthorhombic cell with Cmma symmetry has been detected by SAED and RHEED analyses. In addition, a variety of self-assemblies of hexagonal basal planes have been observed to occur as the result of their different rotational and/or translational stacking faults. Overall, the reported results contribute to define the conditions for a controlled self-assembly of graphene-based structures with tailored dimensions, which is an important technological challenge, as their structure at the nanoscale dramatically affects their electrical properties