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Application of Nanoparticles to the Analysis of Biomarkers

In this work a well established analytical format, the optical ELISA test, was combined with a novel concept of controlled gold nanoparticle (AuNP) bioconjugation procedures aiming to improve the analytical performances without increasing significantly the complexity of the procedure. AuNPs have been adopted as multi-enzyme carriers in the enzyme-based immunoassay for the analysis of CA15-3 biomarker, which generated an amplified optical read-out while keeping low background signals.
In addition to the standard spectrophotometric detection format, normally adopted in ELISA tests, an electrochemical detection has also been developed. This consisted on measuring the current signal generated applying a fixed potential during the reduction of the enzyme substrate, oxidized by the Horseradish Peroxidase (HRP) signaling enzyme in the last step of the ELISA. Screen-printed electrodes with silver pseudo-reference, carbon auxiliary and carbon working electrodes all-built-in, were used for the current measurements in a voltammetric cell. The current signal resulted directly proportional to the antigen concentration (CA 15-3) and hence it can be used as an alternative tool to quantify unknown samples.
The presence of AuNPs confirmed the higher assay sensitivity due to the signal enhancement, already obtained with the optical detection.
This simple concept of using AuNPs as effective signal enhancer could be easily exploited to improve the analytical performances of commercially available ELISA tests, especially those requiring high accuracy to facilitate physicians in deciding the appropriate medical treatment.

Mostra/Nascondi contenuto.
iv ABSTRACT Nanotechnology is any technology which studies and exploits phenomena and materials that only occur at the scale of single atoms and small molecules: the nanometer scale. At this small scale, nanomaterials display unique physical and chemical features that lead to new properties depending on the size. When it decreases, in fact, the surface/volume ratio increases considerably, giving nanostructure unique optical, mechanical, photochemical, electronic and magnetic properties not seen at the bulk scale, which makes them attractive for a wide range of applications, such as environmental monitoring, detection of pathogens, proteomics, genomics, drug delivery, catalysis and bioanalysis. Within nanomaterials, nanoparticles have received great interest due to their attractive electronic, optical, thermal, catalytic properties and potential application in the fields of physics, chemistry, biology, medicine, and material sciences. Nanoparticles are clusters of a few hundred to a few thousand atoms sized between 1 and 100 nanometers, that behave as whole units in terms of transport and properties. They can be composed of a single constituent material (metal, semiconductor or oxide) or be a composite of several materials and can be realized in a variety of shapes, morphologies and phases. “Biomarker” can be defined as a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. As the definition suggests, there are many types of biomarkers, including biochemical markers, physiologic markers, anatomic markers, histological markers and physical markers. They can be used in clinical practice to identify risk for or diagnose a disease, assess disease severity or progression, predict prognosis, or guide treatment. Tumor markers are substances, most often proteins, that can be found in the blood or urine when cancer is present. They can be products of the cancer cells themselves, or made by the body in response to cancer or other conditions.

Laurea liv.II (specialistica)

Facoltà: Scienze Matematiche, Fisiche e Naturali

Autore: Federico Airò Contatta »

Composta da 97 pagine.

 

Questa tesi ha raggiunto 114 click dal 13/12/2010.

Disponibile in PDF, la consultazione è esclusivamente in formato digitale.