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Nuovi catalizzatori per reazioni di ossidazione in fase liquidaFrattini, Alessandra <1980> 20 May 2008 (has links)
No description available.
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Mass spectrometry-based protein profiling strategies for biomarker discovery in liver and inflammatory bowel diseasesNanni, Paolo <1979> 18 March 2008 (has links)
The study of protein expression profiles for biomarker discovery in serum and in
mammalian cell populations needs the continuous improvement and combination of
proteins/peptides separation techniques, mass spectrometry, statistical and bioinformatic
approaches.
In this thesis work two different mass spectrometry-based protein profiling strategies have
been developed and applied to liver and inflammatory bowel diseases (IBDs) for the
discovery of new biomarkers.
The first of them, based on bulk solid-phase extraction combined with matrix-assisted laser
desorption/ionization - Time of Flight mass spectrometry (MALDI-TOF MS) and
chemometric analysis of serum samples, was applied to the study of serum protein
expression profiles both in IBDs (Crohn’s disease and ulcerative colitis) and in liver
diseases (cirrhosis, hepatocellular carcinoma, viral hepatitis).
The approach allowed the enrichment of serum proteins/peptides due to the high
interaction surface between analytes and solid phase and the high recovery due to the
elution step performed directly on the MALDI-target plate. Furthermore the use of
chemometric algorithm for the selection of the variables with higher discriminant power
permitted to evaluate patterns of 20-30 proteins involved in the differentiation and
classification of serum samples from healthy donors and diseased patients. These proteins
profiles permit to discriminate among the pathologies with an optimum classification and
prediction abilities. In particular in the study of inflammatory bowel diseases, after the
analysis using C18 of 129 serum samples from healthy donors and Crohn’s disease,
ulcerative colitis and inflammatory controls patients, a 90.7% of classification ability and a
72.9% prediction ability were obtained. In the study of liver diseases (hepatocellular
carcinoma, viral hepatitis and cirrhosis) a 80.6% of prediction ability was achieved using
IDA-Cu(II) as extraction procedure. The identification of the selected proteins by MALDITOF/
TOF MS analysis or by their selective enrichment followed by enzymatic digestion
and MS/MS analysis may give useful information in order to identify new biomarkers
involved in the diseases.
The second mass spectrometry-based protein profiling strategy developed was based on a
label-free liquid chromatography electrospray ionization quadrupole - time of flight
differential analysis approach (LC ESI-QTOF MS), combined with targeted MS/MS
analysis of only identified differences. The strategy was used for biomarker discovery in
IBDs, and in particular of Crohn’s disease. The enriched serum peptidome and the
subcellular fractions of intestinal epithelial cells (IECs) from healthy donors and Crohn’s
disease patients were analysed.
The combining of the low molecular weight serum proteins enrichment step and the LCMS
approach allowed to evaluate a pattern of peptides derived from specific exoprotease
activity in the coagulation and complement activation pathways. Among these peptides,
particularly interesting was the discovery of clusters of peptides from fibrinopeptide A,
Apolipoprotein E and A4, and complement C3 and C4. Further studies need to be
performed to evaluate the specificity of these clusters and validate the results, in order to
develop a rapid serum diagnostic test.
The analysis by label-free LC ESI-QTOF MS differential analysis of the subcellular
fractions of IECs from Crohn’s disease patients and healthy donors permitted to find many
proteins that could be involved in the inflammation process. Among them heat shock
protein 70, tryptase alpha-1 precursor and proteins whose upregulation can be explained
by the increased activity of IECs in Crohn’s disease were identified. Follow-up studies for
the validation of the results and the in-depth investigation of the inflammation pathways
involved in the disease will be performed.
Both the developed mass spectrometry-based protein profiling strategies have been
proved to be useful tools for the discovery of disease biomarkers that need to be validated
in further studies.
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Electrochemistry of extended aromatic systems and nanostructuresBruno, Carlo <1974> 15 April 2008 (has links)
No description available.
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94 |
Computational investigation of structure and reactivity in organic and bio-organic chemistryCalvaresi, Matteo <1979> 15 April 2008 (has links)
No description available.
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Fotofisica e fotochimica di sistemi organici coniugati di interesse biologico e tecnologicoConti, Irene <1976> 15 April 2008 (has links)
No description available.
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Enantioselective aminocatalysis: new reactions and new directionsCarlone, Armando <1979> 16 April 2008 (has links)
No description available.
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Sviluppo di biosensori: modifiche di superfici elettrodiche e sistemi di immobilizzazione enzimaticaMignani, Adriana <1977> 16 April 2008 (has links)
An amperometric glucose biosensor was developed using an anionic clay matrix (LDH) as
enzyme support. The enzyme glucose oxidase (GOx) was immobilized on a layered double
hydroxide Ni/Al-NO3 LDH during the electrosynthesis, which was followed by crosslinking
with glutaraldehyde (GA) vapours or with GA and bovine serum albumin (GABSA)
to avoid the enzyme release.
The electrochemical reaction was carried out potentiostatically, at -0.9V vs. SCE, using a
rotating disc Pt electrode to assure homogeneity of the electrodeposition suspension,
containing GOx, Ni(NO3)2 and Al(NO3)3 in 0.3 M KNO3. The mechanism responsible of the
LDH electrodeposition involves the precipitation of the LDH due to the increase of pH at
the surface of the electrode, following the cathodic reduction of nitrates.
The Pt surface modified with the Ni/Al-NO3 LDH shows a much reduced noise, giving rise
to a better signal to noise ratio for the currents relative to H2O2 oxidation, and a linear range
for H2O2 determination wider than the one observed for bare Pt electrodes.
We pointed out the performances of the biosensor in terms of sensitivity to glucose,
calculated from the slope of the linear part of the calibration curve for enzimatically
produced H2O2; the sensitivity was dependent on parameters related to the electrodeposition
in addition to working conditions. In order to optimise the glucose biosensor performances,
with a reduced number of experimental runs, we applied an experimental design.
A first screening was performed considering the following variables: deposition time (30 -
120 s), enzyme concentration (0.5 - 3.0 mg/mL), Ni/Al molar ratio (3:1 or 2:1) of the
electrodeposition solution at a total metals concentration of 0.03 M and pH of the working
buffer solution (5.5-7.0).
On the basis of the results from this screening, a full factorial design was carried out, taking
into account only enzyme concentration and Ni/Al molar ratio of the electrosynthesis
solution.
A full factorial design was performed to study linear interactions between factors and their
quadratic effects and the optimal setup was evaluated by the isoresponse curves. The
significant factors were: enzyme concentration (linear and quadratic terms) and the
interaction between enzyme concentration and Ni/Al molar ratio.
Since the major obstacle for application of amperometric glucose biosensors is the
interference signal resulting from other electro-oxidizable species present in the real
matrices, such as ascorbate (AA), the use of different permselective membranes on Pt-LDHGOx
modified electrode was discussed with the aim of improving biosensor selectivity and
stability.
Conventional membranes obtained using Nafion, glutaraldehyde (GA) vapours, GA-BSA
were tested together with more innovative materials like palladium hexacyanoferrate
(PdHCF) and titania hydrogels.
Particular attention has been devoted to hydrogels, because they possess some attractive
features, which are generally considered to favour biosensor materials biocompatibility and,
consequently, the functional enzyme stability. The Pt-LDH-GOx-PdHCF hydrogel
biosensor presented an anti-interferant ability so that to be applied for an accurate glucose
analysis in blood. To further improve the biosensor selectivity, protective membranes
containing horseradish peroxidase (HRP) were also investigated with the aim of oxidising
the interferants before they reach the electrode surface. In such a case glucose determination
was also accomplished in real matrices with high AA content.
Furthermore, the application of a LDH containing nickel in the oxidised state was
performed not only as a support for the enzyme, but also as anti-interferant sistem.
The result is very promising and it could be the starting point for further applications in the
field of amperometric biosensors; the study could be extended to other oxidase enzymes.
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Synthesis, multiscale-multiphase characterization and applications of thiophene-based biohybridsAlesi, Silvia <1980> 15 April 2008 (has links)
Biohybrid derivatives of π-conjugated materials are emerging as powerful tools to study biological events through the (opto)electronic variations of the π-conjugated moieties, as well as to direct and govern the self-assembly properties of the organic materials through the organization principles of the bio component. So far, very few examples of thiophene-based biohybrids have been reported.
The aim of this Ph. D thesis has been the development of oligothiophene-oligonucleotide hybrid derivatives as tools, on one side, to detect DNA hybridisation events and, on the other, as model compounds to investigate thiophene-nucleobase interactions in the solid state.
To obtain oligothiophene bioconjugates with the required high level of purity, we first developed new synthetic ecofriendly protocols for the synthesis of thiophene oligomers. Our innovative heterogeneous Suzuki coupling methodology, carried out in EtOH/water or isopropanol under microwave irradiation, allowed us to obtain alkyl substituted oligothiophenes and thiophene based co-oligomers in high yields and very short reaction times, free from residual metals and with improved film forming properties. These methodologies were subsequently applied in the synthesis of oligothiophene-oligonucleotide conjugates.
Oligothiophene-5-labeled deoxyuridines were synthesized and incorporated into 19-meric oligonucletide sequences. We showed that the oligothiophene-labeled oligonucletide sequences obtained can be used as probes to detect a single nucleotide polymorphism (SNP) in complementary DNA target sequences. In fact, all the probes showed marked variations in emission intensity upon hybridization with a complementary target sequence. The observed variations in emitted light were comparable or even superior to those reported in similar studies, showing that the biohybrids can potentially be useful to develop biosensors for the detection of DNA mismatches.
Finally, water-soluble, photoluminescent and electroactive dinucleotide-hybrid derivatives of quaterthiophene and quinquethiophene were synthesized. By means of a combination of spectroscopy and microscopy techniques, electrical characterizations, microfluidic measurements and theoretical calculations, we were able to demonstrate that the self-assembly modalities of the biohybrids in thin films are driven by the interplay of intra and intermolecular interactions in which the π-stacking between the oligothiophene and nucleotide bases plays a major role.
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Organocatalytic asymmetric mannich-type reactions: an easy approach to optically active amine derivativesFini, Francesco <1979> 15 April 2008 (has links)
The topics I came across during the period I spent as a Ph.D. student are mainly two. The first concerns
new organocatalytic protocols for Mannich-type reactions mediated by Cinchona alkaloids derivatives
(Scheme I, left); the second topic, instead, regards the study of a new approach towards the enantioselective
total synthesis of Aspirochlorine, a potent gliotoxin that recent studies indicate as a highly selective and
active agent against fungi (Scheme I, right).
At the beginning of 2005 I had the chance to join the group of Prof. Alfredo Ricci at the Department of
Organic Chemistry of the University of Bologna, starting my PhD studies. During the first period I started to
study a new homogeneous organocatalytic aza-Henry reaction by means of Cinchona alkaloid derivatives as
chiral base catalysts with good results. Soon after we introduced a new protocol which allowed the in situ
synthesis of N-carbamoyl imines, scarcely stable, moisture sensitive compounds. For this purpose we used
α-amido sulfones, bench stable white crystalline solids, as imine precursors (Scheme II).
In particular we were able to obtain the aza-Henry adducts, by using chiral phase transfer catalysis, with a
broad range of substituents as R-group and excellent results, unprecedented for Mannich-type
transformations (Scheme II).
With the optimised protocol in hand we have extended the methodology to the other Mannich-type
reactions. We applied the new method to the Mannich, Strecker and Pudovik (hydrophosphonylation of
imines) reactions with very good results in terms of enantioselections and yields, broadening the usefulness
of this novel protocol.
The Mannich reaction was certainly the most extensively studied work in this thesis (Scheme III).
Initially we developed the reaction with α-amido sulfones as imine precursors and non-commercially
available malonates with excellent results in terms of yields and enantioselections.3 In this particular case we
recorded 1 mol% of catalyst loading, very low for organocatalytic processes. Then we thought to develop a
new Mannich reaction by using simpler malonates, such as dimethyl malonate.4 With new optimised
condition the reaction provided slightly lower enantioselections than the previous protocol, but the Mannich
adducts were very versatile for the obtainment of β3-amino acids. Furthermore we performed the first
addition of cyclic β-ketoester to α-amido sulfones obtaining the corresponding products in good yield with
high level of diastereomeric and enantiomeric excess (Scheme III).
Further studies were done about the Strecker reaction mediated by Cinchona alkaloid phase-transfer
quaternary ammonium salt derivatives, using acetone cyanohydrin, a relatively harmless cyanide source
(Scheme IV). The reaction proceeded very well providing the corresponding α-amino nitriles in good yields
and enantiomeric excesses.
Finally, we developed two new complementary methodologies for the hydrophosphonylation of imines
(Scheme V). As a result of the low stability of the products derived from aromatic imines, we performed the
reactions in mild homogeneous basic condition by using quinine as a chiral base catalyst giving the α-aryl-α-amido phosphonic acid esters as products (Scheme V, top).6 On the other hand, we performed the addition of
dialkyl phosphite to aliphatic imines by using chiral Cinchona alkaloid phase transfer quaternary ammonium
salt derivatives using our methodology based on α-amido sulfones (Scheme V, bottom). The results were
good for both procedures covering a broad range of α-amino phosphonic acid ester.
During the second year Ph.D. studies, I spent six months in the group of Prof. Steven V. Ley, at the
Department of Chemistry of the University of Cambridge, in United Kingdom. During this fruitful period I
have been involved in a project concerning the enantioselective synthesis of Aspirochlorine. We provided a
new route for the synthesis of a key intermediate, reducing the number of steps and increasing the overall
yield. Then we introduced a new enantioselective spirocyclisation for the synthesis of a chiral building block
for the completion of the synthesis (Scheme VI).
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Sintesi di peptidi e peptidomimetici attivi verso recettori di membranaSquassabia, Federico <1980> 16 April 2008 (has links)
No description available.
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