Publications (22)145.76 Total impact
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Article: Prevention of Self-Quenching in Fluorescent Silica Nanoparticles by Efficient Energy Transfer.
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ABSTRACT: Stars that shine bright: A high local dye concentration in doped silica-based core-shell nanoparticles causes self-quenching and spectral broadening (top images). This phenomenon jeopardizes the potential advantages of heavily doped systems. Förster resonance energy transfer (FRET) to an acceptor co-included in the silica led to ultrabright nanoparticles (bottom images) with a preselected narrow-band emission and a pseudo-Stokes shift of 129 nm.Angewandte Chemie International Edition 04/2013; · 13.45 Impact Factor -
Article: Structural Changes in a Protein Fragment from Abalone Shell during the Precipitation of Calcium Carbonate.
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ABSTRACT: Mineralized tissues grow through biologically controlled processes in which specific macromolecules are involved. Some of these molecules, which are present in very low concentrations and are difficult to localize and characterize, become entrapped inside the mineralized tissue. Herein, a protein fragment, GP, which was obtained by the alkaline digestion of the green sheet of the abalone shell, is used as a probe to study the changes in molecular structure that occur during the precipitation of calcium carbonate. This important goal was achieved by exploiting a fluorescent tag in GP. The experimental results that were obtained by using spectroscopic-, chromatographic-, and microscopic techniques indicate that GP controls the precipitation kinetics and morphology of calcium carbonate crystals, and that it only undergoes structural reorganization when entrapped inside calcium carbonate crystals. To the best of our knowledge, this report represents one of the first studies on the conformational changes of a protein fragment that is involved in biomineralization processes on moving from the solution phase into the mineral phase.Chemistry 09/2012; 18(45):14367-74. · 5.93 Impact Factor -
Article: Temperature-dependent fluorescence of cu(5) metal clusters: a molecular thermometer.
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ABSTRACT: The heat is on: A Cu(5) metal cluster presents distinctive photophysical properties that result in a temperature-dependent fluorescent quantum yield and excited-state lifetime between -45 and +80 °C, both in solution and as a solid. Unprecedented accuracy in temperature determination by fluorescence measurements was achieved with this complex, thus making it suitable for applications in, for example, biology and (nano)materials research.Angewandte Chemie International Edition 08/2012; 51(38):9662-5. · 13.45 Impact Factor -
Article: A versatile strategy for tuning the color of electrochemiluminescence using silica nanoparticles.
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ABSTRACT: Colour emission of core-shell silica-PEG nanoparticles in water is tuned with an electrochemically induced energy transfer approach. The lack of solubility problems, side electrochemical reactions involving donors and acceptors within the nanoparticle, and the possibility of using many classes of dyes in ECL applications confirm the validity of this strategy.Chemical Communications 03/2012; 48(35):4187-9. · 6.17 Impact Factor -
Article: Targeted dual-color silica nanoparticles provide univocal identification of micrometastases in preclinical models of colorectal cancer.
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ABSTRACT: Despite the recent introduction of targeted bio-drugs, the scarcity of successful therapeutic options for advanced colorectal cancer remains a limiting factor in patient management. The efficacy of curative surgical interventions can only be extended through earlier detection of metastatic foci, which is dependent on both the sensitivity and specificity of the diagnostic tools. We propose a high-performance imaging platform based on silica-poly(ethylene glycol) nanoparticles doped with rhodamine B and cyanine 5. Simultaneous detection of these dyes is the basis for background subtraction and signal amplification, thus providing high-sensitivity imaging. The functionalization of poly(ethylene glycol) tails on the external face of the nanoparticles with metastasis-specific peptides guarantees their homing to and accumulation at target tissues, resulting in specific visualization, even of submillimetric metastases. The results reported here demonstrate that our rationally designed modular nanosystems have the ability to produce a breakthrough in the detection of micrometastases for subsequent translation to clinics in the immediate future.International Journal of Nanomedicine 01/2012; 7:4797-807. · 3.13 Impact Factor -
Article: Multicolor core/shell silica nanoparticles for in vivo and ex vivo imaging.
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ABSTRACT: Biocompatible highly bright silica nanoparticles were designed, prepared and tested in small living organisms for both in vivo and ex vivo imaging. The results that we report here demonstrate that they are suitable for optical imaging applications as a possible alternative to commercially available fluorescent materials including quantum dots. Moreover, the tunability of their photophysical properties, which was enhanced by the use of different dyes as doping agents, constitutes a very important added value in the field of medical diagnostics.Nanoscale 12/2011; 4(3):824-30. · 5.91 Impact Factor -
Article: A versatile strategy for signal amplification based on core/shell silica nanoparticles.
Chemistry 11/2011; 17(48):13429-32. · 5.93 Impact Factor -
Article: Fullerenol entrapment in calcite microspheres.
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ABSTRACT: Hybrid microspheres of calcium carbonate/fullerenol were synthesized and characterized. Their morphology depends on the concentration of the fullerenol solutions. XRD and FT-IR measurements proved that the mineral phase is consistently calcite, while fluorescence confocal microscopy indicated that fullerenol is homogenously included in the crystalline matrix.Chemical Communications 09/2011; 47(38):10662-4. · 6.17 Impact Factor -
Article: Green and blue electrochemically generated chemiluminescence from click chemistry--customizable iridium complexes.
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ABSTRACT: Cationic cyclometalated iridium complexes containing two anionic phenylpyridine (ppy) ligands and the neutral bidentate triazole-pyridine ligand, 2-(1-substituted-1H-1,2,3-triazol-4-yl)pyridine (pytl), were investigated. The complexes display a rich and reversible electrochemical behavior, upon investigations by cyclic voltammetry in strictly aprotic conditions, that couples with excellent emission quantum yields and long lifetimes of the excited states. Therefore, in organic media, all complexes have generated intense green electrochemiluminescence (ECL) through the so-called annihilation procedure and, importantly, a modulation of the emission energy (to blue) has been easily obtained by simple fluorination of the ppy ligand. Finally, taking advantage of their remarkable solubility in water, intense ECL was also obtained from aqueous buffer solutions using the co-reactant method, thus making all the investigated complexes highly promising for their effective use as ECL labels in bioanalytical applications.Chemistry 03/2011; 17(16):4640-7. · 5.93 Impact Factor -
Article: Luminescent silica nanoparticles: extending the frontiers of brightness.
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ABSTRACT: Silica nanoparticles are versatile platforms with many intrinsic features, such as low toxicity. Proper design and derivatization yields particularly stable colloids, even in physiological conditions, and provides them with multiple functions. A suitable choice of dyes and synthetic strategy may, in particular, yield a very bright nanosystem. Silica nanoparticles thus offer unique potential in the nanotechnology arena, and further improvement and optimization could substantially increase their application in fields of high social and economic impact, such as medical diagnostics and therapy, environmental and food analysis, and security. This paper describes silica-based, multicomponent nanosystems with intrinsic directional energy- and electron-transfer processes, on which highly valued functions like light harvesting and signal amplification are based.Angewandte Chemie International Edition 03/2011; 50(18):4056-66. · 13.45 Impact Factor -
Article: Multicolor, large-area fluorescence sensing through oligothiophene-self-assembled monolayers.
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ABSTRACT: We present a new strategy to realize self-assembled monolayers (SAMs) on quartz and silicon with a multicolour fluorescence pattern starting from a single, proton sensitive oligothiophene dye exposed at a defined pH. Fine tuning of the SAMs emission color over the entire visible range, including white, is demonstrated. Finally, integration of SAMs in patterned thin layer cells (TLCs) is exploited to demonstrate cation sensing potential in real devices.Chemical Communications 02/2011; 47(6):1689-91. · 6.17 Impact Factor -
Article: Luminescent chemosensors based on silica nanoparticles.
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ABSTRACT: The field of nanoparticles is amazingly many-sided and consequently their applications range between many different areas from industry to bio-analysis and catalysis. In particular, luminescent nanoparticles attract close attention in the areas of biology, medical diagnosis and therapy, where they already find many applications. In this so fascinating and wide framework we have focussed our attention on luminescent silica nanoparticles able to act as sensing materials. We highlight here the importance, especially with the aim of sensing, of gaining precise knowledge and control of their structures; the performance of a chemosensor is, in fact, totally dependent on its design. We then briefly present the state of the art and the progress both in the synthetic protocols and in the application of luminescent silica nanoparticles as chemosensors. We present many recent examples, organized into two main sections, the first dealing with systems presenting the signalling units on the surface (dye coated silica nanoparticles, DCSNs) and the second with systems entrapping the dyes inside the silica matrix (dye doped silica nanoparticles, DDSNs).Topics in current chemistry 01/2011; 300:93-138. · 4.29 Impact Factor -
Article: Energy transfer from silica core-surfactant shell nanoparticles to hosted molecular fluorophores.
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ABSTRACT: Very monodisperse water-soluble silica core-surfactant shell nanoparticles (SCSS NPs) doped with a rhodamine B derivative were prepared using micelles of F127 as nanoreactors for the hydrolysis and condensation of the silica precursor tetraethoxysilane (TEOS). The functionalization of the rhodamines with a triethoxysilane group allowed the covalent binding of the fluorophores to the silica core: no leaking of the dye was observed when the NPs were purified either by ultrafiltration (UF) or dialysis. The diameter of the core (d(c) = 10 ± 1 nm) was determined by TEM and subtracted from the hydrodynamic diameter, measured by DLS, (d(H) = 24 nm, PdI = 0.1) to calculate the shell thickness (∼7 nm). The presence of a single population of NPs with a radius compatible with the one measured by DLS after UF was confirmed by AF4-MALS-RI measurements. The concentration of the NPs was measured by MALS-RI. This allowed us to determine the average number of rhodamine molecules per NP (10). The ability of the NPs to host hydrophobic species as cyanines in the SS was confirmed by fluorescence anisotropy measurements. Steady-state and time-resolved fluorescence measurements allowed us to observe the occurrence of a very efficient Förster resonance energy transfer process from the covalently linked rhodamines to the hosted cyanines. In particular, the analysis of the TCSPC data and steady-state measurements revealed that the adsorption of a single cyanine molecule causes an almost complete quenching of the fluorescence of the NP. Thanks to these observations, it was possible to easily determine the concentration of the NPs by fluorescence titration experiments. Results are in good agreement with the concentration values obtained by MALS-RI. Finally, the hosted cyanine molecule could be extracted with (±)-2-octanol, demonstrating the reversibility of the adsorption process.The Journal of Physical Chemistry B 11/2010; 114(45):14605-13. · 3.70 Impact Factor -
Chapter: Energy Transfer in Silica Nanoparticles: An Essential Tool for the Amplification of the Fluorescence Signal
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ABSTRACT: The careful design of dye doped silica nanoparticles in order to induce controllable energy transfer processes can yield very sophisticated species able to perform precious and complex functions. They can be therefore exploited in many fields of great economical and social importance, such as medical diagnostics, molecular biology, and solar energy conversion. In this chapter, we present the characterization of some functionalized silica nanoparticles with a particular emphasis on the discussion of the the energy transfer processes at the basis of their properties. Since a careful design is fundamental in the realization of more and more sophisticated materials, we also discuss the synthesis of these systems, in order to suggest new routes for the preparation of such valuable and versatile objects.08/2010: pages 119-137; -
Article: Solvent-induced switching between two supramolecular assemblies of a guanosine-terthiophene conjugate.
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ABSTRACT: We report here our findings on a lipophilic guanosine derivative armed with a terthiophene unit that undergoes a pronounced variation of its supramolecular organisation by changing the polarity of the solvent. In chloroform the guanosine derivative, templated by alkali metal ions, assembles via H-bonding in G-quartet based D(4)-symmetric octamers; the polar guanine bases are located into the inner part of the assembly and act as a scaffold for the terthienyl pendants. On the other hand, in the more polar (and H-bond competing) acetonitrile, different aggregates are observed in which the terthiophene chains are pi-pi stacked in a helicoidal (left-handed) arrangement in the central core, and the guanine bases (free from hydrogen bonding) are located at the periphery and exposed to the solvent. The system can be switched back and forth by subsequent addition of chloroform and acetonitrile. The solvent-induced switching can be easily followed by circular dichroism spectroscopy: the CD exciton-couplet in the guanine chromophore absorption region observed in chloroform disappears after addition of acetonitrile, indicating the disassembly of the G-quartet based octameric structure, while an intense quasi-conservative exciton splitting in the 300-450 nm spectral region becomes predominant in the CD spectrum. This latter strong bisignate optical activity can be ascribed to the helical packing of conjugated terthiophene moieties stabilised by pi-pi interactions. NMR spectra and photophysical investigations confirm the structures of the guanine-directed and thiophene-directed assemblies in chloroform and acetonitrile, respectively.Organic & Biomolecular Chemistry 02/2010; 8(4):774-81. · 3.70 Impact Factor -
Article: Facile tuning from blue to white emission in silica nanoparticles doped with oligothiophene fluorophores
Journal of Materials Chemistry 01/2010; 20(44):9903-9909. · 5.97 Impact Factor -
Article: Photothermal sensitisation and therapeutic properties of a novel far-red absorbing cyanine.
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ABSTRACT: A water-soluble disulfonate cyanine was prepared by chemical synthesis and shown to possess photophysical properties which are particularly favourable for the promotion of photothermally sensitised processes, including a very low (<0.1) quantum yield of fluorescence emission and ultra-short (110 to 400 ps) excited state lifetimes, as well as the presence of intense absorption bands at wavelengths longer than 800 nm. This allows the possibility of high-energy irradiation by means of a Ti:sapphire laser operated in a pulse regime. The cyanine was accumulated in comparable amounts by B78H1 amelanotic melanoma cells and HT1080 transformed fibroblasts, however only the B78H1 cells could be extensively damaged by photothermal sensitisation with the cyanine, which was endocellularly distributed as suggested by observations at the optical microscope; the efficiency of the photoprocess could be enhanced by formation of aggregated intracellular cyanine clusters. On the other hand, only a modest photoinactivation of HT1080 cells was induced by photothermal sensitisation, possibly owing to the localization of the cyanine at the periphery of such cells. The cyanine also exhibited a good selectivity of amelanotic melanoma targeting in C57BL/6 mice, bearing the tumour subcutaneously transplanted in the dorsal area: the ratio of cyanine concentration in the melanoma and the surrounding cutaneous districts was as large as 3.8 at 1 h post-injection. The cyanine underwent a fast clearance from the organism, since only traces of the photosensitiser were observed in all the studied tissues at 3 h after i.v. administration. Thus, irradiations were performed at post-injection times shorter than 1 h. Maximum photothermal sensitisation efficiency was obtained at 10 min after injection with a 50% cure rate. Thus, photothermal therapy (PTT) appears to be a very promising and efficient modality of tumour treatment.Photochemical and Photobiological Sciences 10/2009; 8(10):1422-31. · 2.58 Impact Factor -
Article: Iridium doped silica-PEG nanoparticles: enabling electrochemiluminescence of neutral complexes in aqueous media.
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ABSTRACT: We report for the first time the stable electrochemiluminescence of a completely insoluble neutral Ir(III) complex in aqueous media. The strategy adopted is the encapsulation of emitting dye into silica-PEG nanoparticles. This nanoassembly by limiting water and oxygen quenching and allowing solubilization makes the electrogeneration of the excited state feasible under typical bioassay conditions.Journal of the American Chemical Society 09/2009; 131(40):14208-9. · 9.91 Impact Factor -
Article: Amplified fluorescence response of chemosensors grafted onto silica nanoparticles.
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ABSTRACT: In conventional fluorescent chemosensors, the recognition of the target by the receptor unit affects the fluorescence properties of a single covalently coupled fluorescent moiety. Here we show for the first time that when a suitable TSQ derivative is densely grafted onto the surface of preformed silica nanoparticles electronic interactions between the individual chemosensor units enable the free units to recognize the state of the surrounding complexed ones. As a result, the fluorescence transduction is not limited to the local site where binding occurs, but it involves a wider region of the fluorophore network that is able to transfer its excitation energy to the complexed units. Such behavior leads to an amplification of the fluorescence signal. What we report here is the first example of amplification in the case an off-on chemosensor due to its organization onto the surface of silica nanoparticles. We also describe a simple general model to approach amplification in multifluorophoric systems based on the localization of the excited states, which is valid for assemblies such as the supramolecular ones where molecular interactions are weak and do not significantly perturb the individual electronic states. The introduction of an amplification factor f in particular allows for a simple quantitative estimation of the amplification effects.Langmuir 07/2008; 24(15):8387-92. · 4.19 Impact Factor -
Article: Induced fit interanion discrimination by binding-induced excimer formation.
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ABSTRACT: The synthesis, photophysical, and anion-binding properties of a series of di-, tri-, and tetrapodal anion-binding hosts based on aminopyridinium units with pyrenyl reporter groups are described. The ditopic mesitylene-derived calix[4]arene-based host 4 binds strongly to dicarboxylates, particularly malonate, in a 2:1 anion:host ratio but is essentially nonemissive in the presence of all anions except chloride because of intramolecular quenching by the pyridinium units. Addition of chloride results in a conformational change, giving an initial increase in emission assigned to intramolecular excimer formation. Further chloride addition also results in an increase in the intensity of the pyrenyl monomer emission as chloride binding reduces the acceptor ability of the pyridinium groups. This behavior is not exhibited by control compounds 5 and 6, which lack the ditopic geometry and calixarene spacer unit; however, tripodal 6 forms 1:2 anion:host complexes with a range of anions.Journal of the American Chemical Society 04/2008; 130(12):4105-13. · 9.91 Impact Factor
Top co-authors
Top Journals
Institutions
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2012
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Università degli studi di Parma
Parma, Emilia-Romagna, Italy
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2009
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University-Hospital of Padova
Padova, Veneto, Italy
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2007–2009
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University of Bologna
- "Giacomo Ciamician" Department of Chemistry CHIM
Bologna, Emilia-Romagna, Italy
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