1,720,984 research outputs found
From single to multiple TiO2 nanotubes layers: Analysis of the parameters which influence the growth
No full textHighly-ordered vertically oriented TiO2 nanotube arrays (TiO2 NTs) are widely exploited in many different fields such as catalysis, electronics and biomedicine. TiO2 NTs can be synthetized by a number of methods; however, the synthesis via anodization in a fluoride-based electrolyte, proposed for the first time in 2001, has been proved to be the procedure which offers the best control over the nanotube dimensions. In literature, four generations of TiO2 NTs obtained with different types of anodization baths have been reported, each bath giving rise to TiO2 NTs with specific morphological features. In this work, we performed the growth of third generation TiO2 NTs by varying different parameters (i.e. voltage, temperature, anodization time, bath composition) and systematically analyzed their influence on NTs morphology. A deep knowledge of the effect of each parameter allowed their suitable combination in order to obtain double and triple NTs layers with different length and aspect ratio. The proposed method can be applied to synthetize multiple layers with predictable and well-defined features
Nanoscale in situ morphological study of proteins immobilized on gold thin films
No full textThe nanoscale organization of acetylcholinesterase (AChE) and of its polyclonal antibody immobilized on gold thin films was studied by means of Energy Dispersive X-ray Reflectometry (EDXR) and Atomic Force Microscopy (AFM). The macromolecules were alternatively deposited over a self-assembled monolayer (SAM) of N-hydroxysuccinimide esters of thioctic acid. The measurements, collected in situ at subsequent deposition stages of the device, gave information on the distribution of the macromolecules on the surface showing that both the proteins can bind covalently to the SAM. In addition to this, we demonstrated that the antigen-antibody reaction takes place when one of the two reactants is anchored to the surface. © 2009 American Chemical Society
Second-Generation Tris(2-pyridylmethyl)amine–Zinc Complexes as Probes for Enantiomeric Excess Determination of Amino Acids
No full textSelf-assembly through imine condensation chemistry in combination with metal coordination is becoming one of the leading strategies for the preparation of stereodynamic probes for the determination of enantiomeric excess. Recently, we reported a novel molecular architecture based on a modified tris(2-pyridylmethyl)amine–zinc(II) complex [TPMA = tris(2-pyridylmethyl)amine] that is able to function as an optical probe for the determination of the enantiomeric excess of amino acids. Herein, we report on how a slight modification of the TPMA ligand enhances both the dichroic response and the stability of the system. The novel probe provides a much higher dichroic signal compared with the previously reported system
Internalisation of core-shell superparamagnetic nanoparticles into human granulocytes
Full text linkIn this paper, multitasking core-shell Fe3O4@Cu@Au
superparamagnetic nanoparticles (MNPs) functionalised either with folic
acid (FA) or methotrexate (MTX) have been used for engulfment of human
granulocytes. MNPs internalisation into phagocytes allows to use the cells as
carriers thus avoiding the rapid clearance and decreasing of concentration
commonly experienced in case of in vivo nanoparticles administration.
MNPs have been coated with poly-L-lysine (PLL), which contributes to
improve their dispersion into polar solvents. Moreover, this coating improves
the cellular uptake and allows the further functionalisation with MTX and FA.
Experimental evidences of granulocytes engulfment have been obtained by
both SEM and fluorescence microscopy, upon prior labelling of the lysines
residues with suitable fluorescent probes. The superparamagnetic nature of the
MNPs makes the system easily drivable into a specific tissue upon exposure to
a defined magnetic field. The success of the internalisation experiments
indicates that the system is a promising tool as theranostic agent for treatment
of a variety of diseases, including tumours
Elettrodi ibridi carbonio/materiale attivo per accumulatori agli ioni di litio Carbon/active material electrodes for lithium ion batteries
No full textLa presente invenzione è relativa alla procedura di realizzazione di un elettrodo negativo per batterie agli ioni litio in cui l’elettrodo è composto da una pluralità di strati di materiale carbonioso e di materiale attivo supportati su un substrato che funge da collettore di corrente. L’invenzione è relativa anche alla produzione di elettrodi nanostrutturati per altri dispositivi atti alla produzione e accumulo di energia elettrica, come per esempio i supercapacitori
Stimuli-responsive monolayers
No full textThe use of self-assembled monolayers (SAMs) for the functionalization of surfaces is extremely widespread among the scientific community, because they are easy to prepare and thermodynamically stable. Inferior binding uniformity, packing density, and molecular alignment have recently been observed also for SAMs made of thioether-based tripodal ligands with respect to the corresponding SAMs made of thiol-based tripodal ligands. This chapter presents an overview of the literature on smart mono-layers which respond to different stimuli both for their characterization and for their interaction with other molecules. It talks about mono-layers such as light-responsive, temperature-responsive, ph-responsive, electrochemically responsive and multi-responsive monolayers in detail. The examples described in the chapter show the high importance of smart SAMs for surface characterization, postimmobilization monitoring, and switching processes
Photoinduced hydrogen evolution with new tetradentate cobalt(ii) complexes based on the TPMA ligand
Full text linkHydrogen production from water splitting is nowadays recognized as a target, fundamental reaction for the production of clean fuels. Indeed, tremendous efforts have been devoted towards the research of suitable catalysts capable of performing this reaction. With respect to heterogeneous systems, molecular catalysts such as metal complexes are amenable to chemical functionalization in order to fine tune the catalytic properties. In this paper a new class of tris(2-pyridylmethyl)-amine (TPMA) cobalt(ii) complexes (CoL0-4) has been synthesized and employed as hydrogen evolving catalysts under photochemical conditions taking advantage of Ru(bpy)32+(where bpy is 2,2′-bipyridine) as a light-harvesting sensitizer and ascorbic acid as a sacrificial electron donor. Tuning of the photocatalytic activity has been attempted through the introduction of different substituents at the catalyst periphery rather than through a direct chemical modification of the chelating TPMA ligand. The results show that CoL0-4 behave as competent hydrogen evolving catalysts (HECs), although the effects played by the different substituents on the catalysis are relatively modest. Possible reasons supporting the observed behavior as well as possible improvements of the aforementioned tuning approach are discussed
Understanding the nature of graphene oxide functional groups by modulation of the electrochemical reduction: a combined experimental and theoretical approach
No full textOxygen functional groups (OFGs) in graphene oxide (GO) are responsible for its different properties and peculiar reactivity in water and different solvents. A detailed assignment, both theoretical and experimental, of OFGs is still missing, and a full reconstruction of GO electrochemical behavior remains unreached. The spatial localization of OFGs is expected to play an important role in the reduction process, but so far, this important aspect remains undisclosed in the literature. Here, the nature and interactions of adjacent OFGs have been investigated, shedding light on the energetics of their electrochemical reduction. GO chemical modifications upon modulated and controlled electrochemical reduction conditions have been studied, in order to excite and reveal the contribution from single reactive OFGs. The characterization has been conducted via X-ray photoelectron spectroscopic analysis supported by theoretical modelling, to compose a detailed picture of the various local environments participating to the rich chemistry of GO. As a result, the interplay between XPS, cyclic voltammetry and DFT computation allowed for a consistent parallel assessment of both the C 1s ionization energy and the electrochemical reduction potential of the various carbonaceous species of GO
Determination of Amino Acid Enantiopurity and Absolute Configuration: Synergism between Configurationally Labile Metal-Based Receptors and Dynamic Covalent Interactions
No full textReliable determination of the enantiomeric excess of free amino acids can be obtained by measuring the induced circular dichroism of a multicomponent assembly formed by a modified tris(2-pyridylmethyl)amine ligand, a zinc salt, and the amino acid of interest. The systems furnish reliable information for all natural amino acids. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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