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1.
Valentina Aina Gianluca Malavasi Claudio Magistris Giuseppina Cerrato Gianmario Martra Guido Viscardi Ledi Menabue Gigliola Lusvardi 《Journal of materials science. Materials in medicine》2014,25(10):2243-2253
Bioceramics, such as silica-based glasses, are widely used in bone and teeth restoration. Nowadays, the association between nanotechnology and pharmacology is one of the most promising research fields in cancer therapy. The advanced processing methods and new chemical strategies allow the incorporation of drugs within them or on their functionalized surfaces. Bioceramics can act as local drug delivery systems to treat bone and teeth diseases. The present paper reports data related to the development of a pH-stimuli responsive bioactive glass. The glass conjugation with 5-aminofluorescein (5-AF), through a pH-sensitive organic spacer, allows to produce a pH-responsive bioactive biomaterial: when it is exposed to specific pH changes, it can favour the release of 5-AF directly at the target site. 5-AF has been chosen as a simple, low cost, non toxic model to simulate doxorubicin, an anticancer drug. As doxorubicin, 5-AF contains an amino group in its structure in order to form an amide bond with the carboxylic functionalities of the glass. Raman spectroscopy and thermal analysis confirm the glass conjugation of 5-AF by means of an amide bond; the amount of 5-AF loaded was very high (≈65 and 44 wt%). The release tests at two different pH (4.2 and 7.4) show that the amount of released 5-AF is higher at acid pH with respect to physiological one. This preliminary datum evidenced that a pH-sensitive drug delivery system has been developed. The low amount of 5-AF released (<1 wt% of the total 5-AF) is due to the very low solubility of 5-AF in aqueous medium. This disadvantage, may be overcome in a dynamic environment (physiological conditions), where it is possible to obtain a drug release system ensuring an effective therapeutic dose for long times and, at the same time, avoiding the drug toxicity. 相似文献
2.
Unbundling dynamic capabilities: an exploratory study of continuous product innovation 总被引:12,自引:0,他引:12
In order to understand better the organizational sources ofcontinuous innovation, this paper provides an in-depth analysisof Oticon A/S, a leading company in the hearing-aid industry,which showed an impressive ability to develop new products inthe nineties. Findings highlight that dynamic capabilities aremade up of: knowledge creation and absorption, knowledge integrationand knowledge reconfiguration. Discussion links the findingsto previous literature and shows how these knowledge-based processesare all based on a coherent mix of organizational resources. 相似文献
3.
Highly bright and photostable cyanine dye-doped silica nanoparticles for optical imaging: Photophysical characterization and cell tests 总被引:1,自引:0,他引:1
Ivana Miletto Alessandra Gilardino Pollyanna Zamburlin Simona Dalmazzo Davide Lovisolo Giuseppe Caputo Guido Viscardi Gianmario Martra 《Dyes and Pigments》2010,84(1):121-127
Spherical silica nanoparticles containing fluorescent trimethine indocyanine dyes (λabs = 547 nm, λem = 570 nm) were prepared using a water-in-oil microemulsion method. The nanoparticles were of 50 nm diameter and were almost monodispersed in aqueous solution at pH 5.5. Entrapment of dye molecules in the silica matrix stabilised photoemission over several hours of continuous irradiation. The photoemission intensity of the indocyanine was increased 13-fold over that recorded in solution. As each nanoparticle contained 110 dye molecules, the photoemission brightness of each particle was enhanced by three orders of magnitude. The fluorescent nanoparticles have been tested as imaging tools in in vitro tests. As an example of non-macrophagic cells, a highly differentiated neuronal cell line (GT1-7) was used and the results showed that the prepared nanoparticles can be incorporated into these cells with no apparent toxicity for up to three days. 相似文献
4.
F Premoselli E Sesca V Binasco C Franchino L Tessitore 《Canadian Metallurgical Quarterly》1997,73(3-4):71-76
We have recently shown that fasting before initiation markedly stimulated the growth of aberrant crypt foci (ACF) induced by azoxymethane (AOM) in the rat medial colon. Here we investigated the mechanisms by which fasting enhanced the growth of ACF. Rats were exposed to 4 day-starvation, then they were given AOM (20 mg/kg) on the first day of refeeding. 4 day-fasting depressed cell proliferation as shown by the decreased mitotic index and enhanced cell death by apoptosis. On the first day of refeeding, apoptotic index remained higher than control values, while mitotic index markedly increased in the colonic epithelium of fasted/ refed rats. The administration of AOM induced an apoptotic wave, that was higher in controls, and a transient drop in the mitotic index that recovered quickly in the fasted/refed group. These data suggest that starvation-induced apoptosis represents the mitogenic stimulus to increase the rates of cell proliferation responsible for the enhanced growth of ACF in fasted/refed rats. 相似文献
5.
Masaya Matsuoka Kiyoshi Iino Haijun Chen Yukiko Yamasaki Gianmario Marta Salvatore Coluccia Masakazu Anpo 《Catalysis Letters》2005,102(3-4):149-152
Al-ZSM-5 was prepared by treating H-ZSM-5 with an aqueous solution of Al(NO3)3
and used as a support for Pt catalysts. The Pt-loaded Al-ZSM-5 acts as an efficient catalyst for CO oxidation with N2O at 273 K. TEM investigations revealed that Pt clusters with an average particle size of around 1–1.5 nm were homogeneously dispersed within Al-ZSM-5. Moreover, FT-IR and XPS analyses indicated that the small Al2O3 clusters formed within Al-ZSM-5 plays a significant role in the formation of highly dispersed Pt clusters within the pore structure of the ZSM-5 zeolite, leading to the high catalytic activity of Pt/Al-ZSM-5 as compared to Pt/ZSM-5. 相似文献
6.
Claudio Evangelisti Giovanni Vitulli Eleonora Schiavi Maria Vitulli Sergio Bertozzi Piero Salvadori Luca Bertinetti Gianmario Martra 《Catalysis Letters》2007,116(1-2):57-62
Cu supported catalysts (support: γ-Al2O3, Fe2O3, TiO2) have been conveniently prepared by deposition of Cu particles from acetone solvated Cu atoms. The catalysts have been characterized
by HRTEM analysis, showing a quite homogeneous Cu particle size distribution. They are active systems for the partial oxidation
of cyclohexane to cyclohexanol and cyclohexanone. After the catalytic experiment the Cu/γ-Al2O3 and Cu/TiO2 systems can be reused without valuable loss of activity, while the Cu/Fe2O3 system is quite inactive. 相似文献
7.
We consider a controlled stochastic linear differential equation with state- and control-dependent noise in a Hilbert space H. We investigate the relation between the null controllability of the equation and the existence of the solution of “singular” Riccati operator equations. Moreover, for a fixed interval of time, the null controllability is characterized in terms of the dual state. Examples of stochastic PDEs are also considered. 相似文献
8.
New gold catalysts for liquid phase oxidation 总被引:2,自引:1,他引:1
A pre-requisite for good catalytic activity with supported gold is that the metal is present as nanoparticles, but no suitable method for depositing gold on carbon as nanoparticles has previously been reported. The deposition precipitation method which has been used successfully for catalyst preparation with other supports, produces large aggregates with carbon. It is now shown, however, that pre-reduced gold sol is a satisfactory method for preparing gold on carbon catalysts as long as an appropriate choice of sol is made. In this paper the activity of gold on carbon catalysts prepared in a number of different ways is compared in a standardized liquid phase organic oxidation reaction. The activity for Au/C catalysts prepared by the sol method can show a two-fold increase compared with a similar catalyst prepared by deposition precipitation. 相似文献
9.
Factors Ruling the Uptake of Silica Nanoparticles by Mesenchymal Stem Cells: Agglomeration Versus Dispersions,Absence Versus Presence of Serum Proteins
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Federico Catalano Lisa Accomasso Gabriele Alberto Clara Gallina Stefania Raimondo Stefano Geuna Claudia Giachino Gianmario Martra 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(24):2919-2928
The results of a systematic investigation of the role of serum proteins on the interaction of silica nanoparticles (NP) doped in their bulk with fluorescent molecules (IRIS Dots, 50 nm in size), with human mesenchymal stem cells (hMSCs) are reported. The suspension of IRIS Dots in bare Dulbecco‐modified Eagle's medium results in the formation of large agglomerates (≈1.5 μm, by dynamic light scattering), which become progressively smaller, down to ≈300 nm in size, by progressively increasing the fetal bovine serum (FBS) content of the solutions along the series 1.0%, 2.5%, 6.0%, and 10.0% v/v. Such difference in NP dispersion is maintained in the external cellular microenvironment, as observed by confocal microscopy and transmission electron microscopy. As a consequence of the limited diffusion of proteins in the inter‐NP spaces, the surface of NP agglomerates is coated by a protein corona independently of the agglomerate size/FBS concentration conditions (ζ‐potential and UV circular dichroism measurements). The protein corona appears not to be particularly relevant for the uptake of IRIS Dots by hMSCs, whereas the main role in determining the internalization rate is played by the absence/presence of serum proteins in the extracellular media. 相似文献
10.
Vincenzo Augugliaro Salvatore Coluccia Elisa García-López Vittorio Loddo Giuseppe Marcì Gianmario Martra Leonardo Palmisano Mario Schiavello 《Topics in Catalysis》2005,35(3-4):237-244
Photocatalytic degradation of acetonitrile was carried out in gas–solid regime by using two commercial TiO2 samples (Merck and Degussa P25) irradiated in two continuous annular photoreactors. The inlet gas flow consisted of oxygen,
nitrogen, acetonitrile and water vapours. The influence on the photodegradation rate of gas flow rate, acetonitrile, oxygen
and water concentrations and photon flux was investigated. The degradation products of acetonitrile were carbon dioxide and
hydrogen cyanide. The photocatalysts performance was not affected by the presence or absence of water vapour in the reacting
mixture. The Langmuir–Hinshelwood model describes adequately the photoreactivity results and provides the values of kinetic
and equilibrium adsorption constants. FT-IR spectroscopy was used to investigate the adsorption patterns and photo-oxidation
intermediates of acetonitrile on fully hydrated surface of TiO2 powders. Acetonitrile was adsorbed on Ti4+ surface ions and hydroxyl groups for both types of TiO2. In the absence of UV light this interaction was completely reversible for Merck catalyst whereas for Degussa P25 part of
adsorbed acetonitrile molecules reacted to form acetamide-like species. 相似文献