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Silvia Giordani
Trinity College Dublin, Chemistry, Faculty Member
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Abstract. The importance of molecular conformation to the nature and strength of noncovalent interactions existing between a series of increasingly nonplanar tetraphenylporphyrin (TPP) derivatives and carbon nanotubes was systematically... more
Abstract. The importance of molecular conformation to the nature and strength of noncovalent interactions existing between a series of increasingly nonplanar tetraphenylporphyrin (TPP) derivatives and carbon nanotubes was systematically investigated experimentally in solution using a range of linear and nonlinear optical techniques. Additional complementary molecular dynamics studies were found to support the experimental observations.
Abstract One conventional and two related gemini surfactants have been used for the preparation of stable single-walled carbon nanotube (SWNT) aqueous dispersions. The surfactants investigated are able to disperse SWNTs at... more
Abstract One conventional and two related gemini surfactants have been used for the preparation of stable single-walled carbon nanotube (SWNT) aqueous dispersions. The surfactants investigated are able to disperse SWNTs at surfactant/carbon nanotube weight ratios far lower than widely used conventional surfactants.
Single-walled carbon nanotubes (SWNTs) are promising candidates for a wide range of biomedical applications due to their fascinating properties. However, safety concerns are raised on their potential human toxicity and on the techniques... more
Single-walled carbon nanotubes (SWNTs) are promising candidates for a wide range of biomedical applications due to their fascinating properties. However, safety concerns are raised on their potential human toxicity and on the techniques that need to be used to assess such toxicity. Here, we integrate for the first time 3D tissue-mimetic models in the cytotoxicity assessment of purified (p-) and oxidized (o-) SWNTs.
A chemical treatment for preparing high purity selectively oxidised SWNTs while preserving optical/electronic properties of the material has been developed. Efficient removal of both metal and carbonaceous impurities has been demonstrated... more
A chemical treatment for preparing high purity selectively oxidised SWNTs while preserving optical/electronic properties of the material has been developed. Efficient removal of both metal and carbonaceous impurities has been demonstrated by AFM, TEM, Raman and absorption spectroscopy, while XPS confirmed quantitative conversion of oxidised defects to functionalisable carboxylic acid groups.
Surface enhanced resonance Raman scattering (SERRS) has been applied to investigate defects in purified and carboxylated single-walled carbon nanotubes (SWCNTs). For both samples SERRS spectra with temporal fluctuating peak intensities... more
Surface enhanced resonance Raman scattering (SERRS) has been applied to investigate defects in purified and carboxylated single-walled carbon nanotubes (SWCNTs). For both samples SERRS spectra with temporal fluctuating peak intensities and positions in the range of 1000–1350cm− 1 have been observed. A series of peaks in this window coincide with peak positions that have been assigned to arise from Stone–Thrower–Wales and heptagonal–pentagonal intramolecular junction defects on the nanotubes surface.
Abstract A gradual transition from electrical to optical networks is accompanying the rapid progress of telecommunication technology. The urge for enhanced transmission capacity and speed is dictating this trend. In fact, large volumes of... more
Abstract A gradual transition from electrical to optical networks is accompanying the rapid progress of telecommunication technology. The urge for enhanced transmission capacity and speed is dictating this trend. In fact, large volumes of data encoded on optical signals can be transported rapidly over long distances. Their propagation along specific routes across a communication network is ensured by a combination of optical fibers and optoelectronic switches.
by Cellot, G., Cilia, E., Cipollone, S., Rancic, V., Sucapane, A., Giordani, S., Gambazzi, L., Markram, H., Grandolfo, M., Scaini, D., Gelain, F., Casalis, L., Prato, M., Giugliano, M., and Ballerini, L.(2009). Nat. Nanotechnol. 4,... more
by Cellot, G., Cilia, E., Cipollone, S., Rancic, V., Sucapane, A., Giordani, S., Gambazzi, L., Markram, H., Grandolfo, M., Scaini, D., Gelain, F., Casalis, L., Prato, M., Giugliano, M., and Ballerini, L.(2009). Nat. Nanotechnol. 4, 126–133. Carbon nanotubes (CNTs) are emerging as nanomaterials with a wide range of biomedical applications, including their potential use for neuroprosthesis (Bekyarova et al., 2005).
Abstract Covalent surface modification of multiwall carbon nanotubes leads to enhanced nanotube dispersion in the polymer. Despite this, the mechanical properties of electrospun fibers made of polymethylmethacrylate containing surface... more
Abstract Covalent surface modification of multiwall carbon nanotubes leads to enhanced nanotube dispersion in the polymer. Despite this, the mechanical properties of electrospun fibers made of polymethylmethacrylate containing surface modified nanotubes generally fall below those of fibers with pristine nanotubes, sometimes below those of pure polymer fibers. We show that covalent functionalization produces defects in the graphene structure, leading to mechanical weakening of the nanotube and, therefore, of the nanocomposite.
Abstract Optical studies of single-walled carbon nanotubes (SWNTs) dispersed in aqueous surfactant suspensions have made significant progress since the discovery of their bright band-gap fluorescence in the near-infrared region [MJ... more
Abstract Optical studies of single-walled carbon nanotubes (SWNTs) dispersed in aqueous surfactant suspensions have made significant progress since the discovery of their bright band-gap fluorescence in the near-infrared region [MJ O'Connell et al., Science 297, 593–596 (2002)]. In this article we report the systematic investigation of the effect of chemical purification and oxidation on the spectroscopic properties of SWNTs.
Page 1. © TCD Silvia Giordani Photo by SG Dr. Silvia Giordani Trinity College Dublin, Ireland From smart molecules to functional materials Intel Ireland Research Conference 2012 Dublin, 3 October 2012 Page 2. Computers Chemical... more
Page 1. © TCD Silvia Giordani Photo by SG Dr. Silvia Giordani Trinity College Dublin, Ireland From smart molecules to functional materials Intel Ireland Research Conference 2012 Dublin, 3 October 2012 Page 2. Computers Chemical laboratories Data storage Page 3.
We present three new crystal structures of members from the photochromic spiropyran family, including a rare example of an open (merocyanine) form. The molecular structures are systematically compared with existing crystallographically... more
We present three new crystal structures of members from the photochromic spiropyran family, including a rare example of an open (merocyanine) form. The molecular structures are systematically compared with existing crystallographically relevant data, and a new avenue for stabilizing open spiropyran forms in the solid-state is postulated.
The 1-hexadecyl-3-vinylimidazolium bromide (hvimBr), a water-soluble long-chain imidazolium ionic liquid (IL) with surfactant properties, showed the ability to produce stable homogeneous aqueous dispersions of pristine Single-Walled... more
The 1-hexadecyl-3-vinylimidazolium bromide (hvimBr), a water-soluble long-chain imidazolium ionic liquid (IL) with surfactant properties, showed the ability to produce stable homogeneous aqueous dispersions of pristine Single-Walled Carbon Nanotubes (SWNTs). The purpose of this study is the improvement of SWNT dispersing ability by assessing the effect of different groups in position 3 of the imidazole ring.
Since carbon nanotubes (CNTs) display unique structures and remarkable physical properties, a variety of applications have emerged in both materials and life sciences. In terms of applications, the functionalisation of nanotubes is... more
Since carbon nanotubes (CNTs) display unique structures and remarkable physical properties, a variety of applications have emerged in both materials and life sciences. In terms of applications, the functionalisation of nanotubes is extremely important, as it increases their solubility and processability, and combines the unique properties of single-walled carbon nanotubes (SWCNTs) with those of other classes of materials.
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UK PubMed Central (UKPMC) is an archive of life sciences journal literature.
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Certain molecular switches respond to input stimulations producing detectable outputs. The interplay of these signals can be exploited to reproduce basic logic operations at the molecular level. The transition from simple logic gates to... more
Certain molecular switches respond to input stimulations producing detectable outputs. The interplay of these signals can be exploited to reproduce basic logic operations at the molecular level. The transition from simple logic gates to complex digital circuits requires the design of chemical systems able to process multiple inputs and outputs. We have identified a three-state molecular switch that responds to one chemical and two optical inputs producing two optical outputs. We have encoded binary digits in its inputs and outputs applying positive logic conventions and demonstrated that this chemical system converts three-digit input strings into two-digit output strings. The logic function executed by the three-state molecular switch is equivalent to that of a combinational logic circuit integrating two AND, two NOT, and one OR gate. The three states of the molecular switch are a colorless spiropyran, a purple trans-merocyanine, and its yellow-green protonated form. We have elucidated their structures by X-ray crystallography, (1)H NMR spectroscopy, COSY and NOE experiments, as well as density functional calculations. The three input stimulations controlling the interconversion of the three states of the molecular switch are ultraviolet light, visible light, and H(+). The two outputs are the absorption bands in the visible region of the two colored states of the molecular switch. We have monitored the switching processes and quantified the associated thermodynamic and kinetic parameters with the aid of (1)H NMR and visible absorption spectroscopies.
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We have identified a strategy to communicate a chemical signal between two independent molecular components. One of them is a photoactive merocyanine that switches to a spiropyran, releasing a proton, when stimulated with visible light.... more
We have identified a strategy to communicate a chemical signal between two independent molecular components. One of them is a photoactive merocyanine that switches to a spiropyran, releasing a proton, when stimulated with visible light. The other is a 4,4'-pyridylpyridinium monocation that captures the released proton, producing an electroactive 4,4'-bipyridinium dication. Under the irradiation conditions employed, the photoinduced transformation requires ca. 15 min to reach a photostationary state. In the dark, the ensemble of communicating molecules reequilibrates to the original state in ca. 5 days. These processes can be monitored following the photoinduced enhancement and thermal decay, respectively, of the current for the monolectronic reduction of the 4,4'-bipyridinium dication. The pronounced difference in time scale for the current enhancement and decay steps can be exploited to implement a memory element with a bit retention time of 11 h. A bit of information can be written optically in the chemical system and it can be read electrically and nondestructively. The memory can be reset, extending its permanence in the dark beyond the bit retention time. A binary logic analysis of the signal transduction operated by the communicating molecules reveals the characteristic behavior of sequential logic operators, which are the basic components of digital memories.
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Research Interests: Thermodynamics, Electron Microscopy, Tissue Engineering, Electronics, Nonlinear dynamics, and 24 morePhotonics, Cell Adhesion, Scanning Electron Microscopy, Carbon Nanotube, Fluid Dynamics, Nanotechnology, Neural Network, Multidisciplinary, Nature, Condensed Matter, Patch-clamp and imaging techniques, Cosmology, Bionanotechnology, Neuronal Network, Animals, Neurons, Single Cell, Physical Interaction, Rats, Action Potentials, Biocompatible Materials, Electric Capacitance, Nanotubes Carbon, and Cell Membrane
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[structure: see text] Chemical and optical stimulations control the interconversion of a three-state molecular switch trapped inside a silica monolith. The resulting absorbance changes in the visible region can be exploited to reproduce a... more
[structure: see text] Chemical and optical stimulations control the interconversion of a three-state molecular switch trapped inside a silica monolith. The resulting absorbance changes in the visible region can be exploited to reproduce a sequential logic operator with one optical input and one optical output. This strategy to transfer operating principles for digital processing from bulk solutions to rigid materials can lead to the development of chemical logic gates based on functional solid components.
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Gold quantum dots (AuQDs) were synthesized and electrostatically conjugated to goat-derived anti-human IgG for the purpose of detecting human IgG in solution over a broad range of concentrations. The system is able to detect human IgG by... more
Gold quantum dots (AuQDs) were synthesized and electrostatically conjugated to goat-derived anti-human IgG for the purpose of detecting human IgG in solution over a broad range of concentrations. The system is able to detect human IgG by linear fluorescence quenching over a micromolar to nanomolar concentration range. We have demonstrated the specificity and a wide dynamic range of the proposed immunoassay. The quenching is a result of competitive surface quenching of the AuQDs. Characterization, details of the immunoassay, and the quenching mechanism, are discussed.
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An immunoassay based upon photoluminescent gold quantum dots aimed at detecting human IgG in aqueous solution from micromolar to nanomolar concentrations is described.
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Research Interests: Engineering, Materials Engineering, Condensed Matter Physics, Quantum Physics, Analytical Chemistry, and 32 moreOrganic Chemistry, Technology, Carbon, FTIR spectroscopy, Resonance Raman Spectroscopy, Applied Physics, Carbon Nanotubes, Carbon Nanotube, Transmission Electron Microscopy, Nanotechnology, Atomic Force Microscopy, Electroanalysis, Mathematical Sciences, Conducting Polymer, Functionalization, Absorption spectroscopy, Physical sciences, Plasma Treatment, Macromolecules, CHEMICAL SCIENCES, Thermal Stability, Functional Group, Molecular weight, Raman Scattering, Smart Material, Raman Spectra, Hydrolysis, Size Exclusion Chromatography, Chemical Modification, Molecular Weight Distribution, Thermal gravimetric analysis, and Fourier transform infrared
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Research Interests: Vaccines, Clinical Trial, Carbon Nanotubes, Drug delivery, Carbon Nanotube, and 13 moreChemical, Nanotechnology, Humans, Gene transfer techniques, Drug Delivery Systems, CHEMICAL SCIENCES, Biomedical Application, Antigens, Nanotubes Carbon, Gene Transfer, Molecular Structure, Nucleic Acid, and Cell Membrane
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The implementation of single‐walled carbon nanotubes (SWNTs) into a wide array of applications is hindered by the formation of bundles. Many methods have been suggested to de‐bundle the SWNTs, including both covalent and non‐covalent... more
The implementation of single‐walled carbon nanotubes (SWNTs) into a wide array of applications is hindered by the formation of bundles. Many methods have been suggested to de‐bundle the SWNTs, including both covalent and non‐covalent funtionalisation with surfactants, polymers and macromolecules. These methods have their advantages but the ideal situation must be to dissolve and de‐bundle the SWNTs in an appropriate solvent at concentrations that are useful for their implementation in applications. In this work we ...
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The surface of highly ordered pyrolytic graphite (HOPG) has been modified using a new photochemically induced grafting reaction. Thiols have been revealed to behave as privileged substrates for this efficient grafting process. The... more
The surface of highly ordered pyrolytic graphite (HOPG) has been modified using a new photochemically induced grafting reaction. Thiols have been revealed to behave as privileged substrates for this efficient grafting process. The reaction occurs under extremely mild conditions with visible light and at room temperature. The formation of molecular layers on the graphitic surface has been probed by X-ray photoelectron spectroscopy, cyclic voltammetry, and infrared reflectance absorption spectroscopy. The reaction was ...