Browsing by Author "Bossi, Alessandra"

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    Discovery and quantification of proteins of biological relevance through differential proteomics and biosensing
    (Cranfield University, 2012-04) Lonardoni, Francesco; Bossi, Alessandra; Chianella, Iva
    Medical diagnosis is the process of attempting to determine and/or identify a possible disease or disorder. This process is revealed by biomarkers, defined by The Food and Drug Administration (FDA) as “characteristics that are objectively measured and evaluated as indicators of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention”. The process of biomarker discovery has been boosted in the last years by proteomics, a research discipline that takes a snapshot of the entire wealth of proteins in an organism/ tissue/ cell/ body fluid. An implementation of the analysis methods can help in isolate proteins present in the low range of concentrations, such as biomarkers very often are. An established biomarker can further be measured with the help of biosensors, devices that can be employed in the point-of care diagnostics. This PhD thesis shows and discusses the results of three projects in the field of protein biomarkers discovery and quantification. The first project exploited proteomics techniques to find relevant protein markers for Intrauterine Growth Restriction (IUGR) in cordonal blood serum (UCS) and amniotic fluid (AF). A 14 proteins in UCS and 11 in AF were successfully identified and found to be differentially expressed. Molecularly Imprinted Polymers (MIPs) directed towards proteins and peptides containing phosphotyrosine were then produced, with the final goal of selectively extracting phosphopeptides from a peptide mixture. An alteration of the phosphorylation pattern is in fact often associated to important diseases such as cancer. The polymers were produced as nanoparticles, that were characterised with Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM). A recipe was also tested for binding capacity towards phosphotyrosine. A Surface Plasmon Resonance (SPR) biosensor to quantify hepcidin hormone was finally produced. This is the major subject in iron homeostasis in vertebrates and marker of iron unbalance diseases. A calibration curve was made and affinity/kinetic parameters for the ligand employed were measured.
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    Molecularly imprinted polymers for protome analysis
    (Cranfield University, 2008-01) Bonini, Francesca; Piletsky, Sergey A.; Bossi, Alessandra
    Fast and efficient methods for the detection of insurgence and progression of diseases are at the basis of modern diagnostics and medicine. In this concern, biomarkers represent a powerful diagnostic tool, as their expression profiles well correlate with the pathology progression. Thus, the pathological state could be diagnosed by measuring the altered presence of a biomarker. In this direction, conspicuous help has been given by proteomics, intended as the study of the protein pattern of a sample and most frequently performed by two-dimensional electrophoresis. Although the proteome approach is a powerful analytical method, its application to biological samples for the detection and quantification of putative biomarkers is hampered by technical problems, in fact, the wide diversity in concentrations exhibited by the proteins present in the biological samples, with a concentration range spanning over nine orders of magnitude, and the relative abundance of each protein, are responsible of masking the less abundant species and of their loss in traceability. The aim of my PhD project is to apply Molecularly Imprinted Technology to the specific removal of a high abundance protein (Human Serum Albumin, HSA) frequently affecting proteomic analysis, in order to increase the detection of potential biomarkers. This technology allows the creation of artificial recognition sites in synthetic polymers for a specific protein. These sites are tailor-made in situ by co-polymerisation of functional monomers and cross-linkers around the template molecules. Two different approaches have been assayed in order to remove HSA: • Immobilisation of protein template on a rigid silica support (bead) and creation of polymer around beads. • Polymerisation in bulk of a polymer with protein template and application of this polymer to multicompartment electrolyser. In both of the cases, the chemical and structural features of the polymers have been analysed, after that they have been applied to complex proteome pre-treatment, obtaining encouraging results.
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    Patterned gallium surfaces as molecular mirrors
    (Elsevier Science B.V., Amsterdam., 2007-09-30T00:00:00Z) Bossi, Alessandra; Rivetti, Claudio; Mangiarotti, Laura; Whitcombe, Michael J.; Turner, Anthony P. F.; Piletsky, Sergey A.
    An entirely new means of printing molecular information on a planar film, involving casting nanoscale impressions of the template protein molecules in molten gallium, is presented here for the first time. The metallic imprints not only replicate the shape and size of the proteins used as template. They also show specific binding for the template species. Such a simple approach to the creation of antibody-like properties in metallic mirrors can lead to applications in separations, microfluidic devices, and the development of new optical and electronic sensors, and will be of interest to chemists, materials scientists, analytical specialists, and electronic engineers.
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    Substitution of antibodies and receptors with molecularly imprinted polymers in enzyme-linked and fluorescent assays
    (Elsevier Science B.V., Amsterdam., 2001-12-31T00:00:00Z) Piletsky, Sergey A.; Piletska, Elena V.; Bossi, Alessandra; Karim, K.; Lowe, P.; Turner, Anthony P. F.
    A new technique for coating microtitre plates with molecularly imprinted polymers (MIP), specific for low-molecular weight analytes (epinephrine, atrazine) and proteins is presented. Oxidative polymerization was performed in the presence of template; monomers: 3-aminophenylboronic acid, 3- thiopheneboronic acid and aniline were polymerized in water and the polymers were grafted onto the polystyrene surface of the microplates. It was found that this process results in the creation of synthetic materials with antibody-like binding properties. It was shown that the MIP-coated microplates are particularly useful for assay development. The high stability of the polymers and good reproducibility of the measurements make MIP coating an attractive alternative to conventional antibodies or receptors used in ELISA.
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    Surface imprinted beads for the recognition of human serum albumin
    (Elsevier Science B.V., Amsterdam., 2007-04-15T00:00:00Z) Bonini, Francesca; Piletsky, Sergey A.; Turner, Anthony P. F.; Speghini, Adolfo; Bossi, Alessandra
    The synthesis of poly-aminophenylboronic acid (ABPA) imprinted beads for the recognition of the protein human serum albumin (HSA) is reported. In order to create homogeneous recognition sites, covalent immobilisation of the template HSA was exploited. The resulting imprinted beads were selective for HSA. The indirect imprinting factor (IF) calculated from supernatant was 1.6 and the direct IF, evaluated from the protein recovered from the beads, was 1.9. The binding capacity was 1.4 mg/g, which is comparable to commercially available affinity materials. The specificity of the HSA recognition was evaluated with competitive experiments, indicating a molar ratio 4.5/1 of competitor was necessary to displace half of the bound HSA. The recognition and binding of the imprinted beads was also tested with a complex sample, human serum and targeted removal of HSA without a loss of the other protein components was demonstrated. The easy preparation protocol of derivatised beads and a good protein recognition properties make the approach an attractive solution to analytical and bio-analytical problems in the field of biotechnology.
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    Synthesis of controlled polymeric cross-linked coatings via iniferter polymerisation in the presence of tetraethyl thiuram disulphide chain terminator
    (Elsevier Science B.V., Amsterdam., 2010-05-15T00:00:00Z) Bossi, Alessandra; Whitcombe, Michael J.; Uludag, Yildiz; Fowler, S.; Chianella, Iva; Subrahmanyam, S.; Sanchez, I.; Piletsky, Sergey A.
    A “grafting from” approach has been used for controlled deposition of cross- linked polymers by living radical polymerisation. Borosilicate glass was modified with N,N-diethylaminodithiocarbamoylpropyl(trimethoxy)silane, in order to confine the iniferter reactive groups solely at its surface, then placed in solution with monomers and cross-linker. The polymerisation was initiated by UV irradiation. Formation of the cross-linked polymers was studied in terms of time course of the reaction, type of monomers incorporated and influence of oxygen. Grafted surfaces were characterised by AFM, FT-IR, ellipsometry and contact angle measurements. The ability to control the grafted layer improved dramatically when the chain terminator agent, N,N-N′,N′-tetraethyl thiuram disulphide (TED) was added. Upon irradiation TED increases the concentration of passive capping radicals and decreases the possibility of recombination of active macro-radicals, thus prolonging their lifetime. In the absence of TED the thickness of produced coatings was below 10 nm. TED added at different concentrations assisted in the formation of grafted layers of 10–130 nm thickness. Iniferter chemistry in the presence of TED can be used for growing nanometre-scale polymer layers on solid supports. It constitutes a robust general platform for controlled grafting and offer a general solution to address the needs of surface derivatisation in sensors t