La richiesta di strumenti in grado di identificare efficientemente la presenza di biomarcatori nel corpo umano, funzionali al rilevamento una grande varietà di patologie, è in progressivo aumento. Questa necessità è generata nella comunità scientifica dalla pressante richiesta dello sviluppo di protocolli di screening affidabili, in grado di migliorare la capacità di identificazione di patologie ancora non in stadio terminale o comunque dannoso per l’organismo. Gli obiettivi principali di questo approccio risiedono in un miglioramento generale della prevenzione medicale, ed in una conseguente riduzione delle spese per la cura di patologie per i sistemi sanitari nazionali. Sensori nanostrutturati chemoresistivi a semiconduttori, in grado di variare la propria conduttanza a seconda delle reazioni chimiche tra la loro superficie e gli analiti gassosi, hanno dimostrato in passato di essere una scelta papabile per la ricerca oncologica (esiste grande riscontro in letteratura scientifica trattante i composti organici volatili per il rivelamento tumorale), e in questo lavoro sono proposti come unità sensibili per dispositivi per lo screening. In questa tesi, un prototipo ospitante un array di sensori ad ossidi, metallici e non, è stato testato per individuare la presenza di marker tumorali esalati da tre differenti tipologie di campioni: sangue umano, tessuti umani da operazioni chirurgiche, e colture cellulari di diversa natura. In tutti gli esperimenti, questi agenti chimici sono stati convogliati ai sensori tramite un circuito per il flusso d’aria, dotato di filtri antibatterici per mantenere la sterilità del sistema. Le risposte sono state poi acquisite, processate e rappresentate graficamente grazie a dei software realizzati in Labview®. Lo studio statistico di questi segnali è stato effettuato mediante approccio a singolo sensore e l’Analisi delle Componenti Principali. Test sono stati effettuati su colture cellulari osservando che, avendo un solo tipo di cellule coinvolte nell’esalazione dei marcatori, fosse possibile differenziare quelle provenienti da coltura primaria e quelle da linee immortalizzate o tumorali, nonché la possibilità di discriminare anche tra diverse tipologie di cellule, una volta piastrate nello stesso momento ma mantenenti diverso metabolismo. Per ciò che riguarda i test sui campioni sanguigni, sia soggetti maschili che femminili aventi età tra 21 e 91 anni si sono prestati allo studio. I donatori sono stati pazienti affetti da cancro a colon-retto e stomaco, a differenti stadi evolutivi, e/o aventi metastasi localizzate differentemente, posti a confronto con un gruppo di controllo avente medesimi generi ed età. Il prototipo è stato in grado di distinguere tra campioni provenienti da individui affetti da tumori o sani. I risultati ottenuti hanno inoltre mostrato una correlazione tra l’ampiezza delle risposte ed il livello di crescita e vascolarizzazione del tumore, così come una decrescita nel post-screening operatorio a pazienti dopo intervento o chemioterapia. Infine, per i tessuti umani, test sono stati effettuati su campioni provenienti dall’area affetta dal tumore e su quella sana circostante ad esso (durante la rimozione chirurgia, parti del tessuto sano sono inevitabilmente rimosse assieme al cancro stesso; inoltre per alcuni tipi di tumori, come quello al colon-retto, la rimozione di tessuto sano a valle e a monte del tumore è volontaria da parte del chirurgo, così da evitare il field effect, che può diffondere la patologia anche dopo la rimozione della neoplasia originale). I donatori sono stati pazienti già registrati per operazioni chirurgiche, per via di patologie da cui già erano affetti. L’età dei donatori, di sesso maschile e femminile, va da 41 a 91 anni. I risultati sui tessuti umani mostrano che i sensori distinguono tra soggetti sani e affetti da tumori, con i campioni testati dopo due ore e mezza dall’estrazione chirurgica.

The demand for devices capable of efficiently identifying the presence of biomarkers in human body, useful to detect a wide variety of pathologies, is progressively increasing. This urge is generated in the scientific community due to the pressing request of reliable screening protocols, able to enhance in the next future the detection capability on pathologies while not in terminal or harmful state of development. The main goals of this approach lay in the enhancement of the medical prevention, and consequentially the reduction of the national health systems expenses to cure harmful pathologies once degenerated. Nanostructured chemoresistive semiconductor sensors, which can change their conductance depending on the chemical reactions between their surface and the gaseous analytes, showed in the past to be a suitable choice for medical research, especially for oncological purposes (there is plenty of literature discussing volatile organic compounds and tumor detection), and in this work they are proposed as sensing units for a final screening devices implementation. In this thesis, a prototype hosting an array of metal-oxide and non-metal-oxide sensors was tested, in order to detect the presence of airborne tumor markers exhaled from three different kind of samples: human blood from medical sampling, human tissues from surgeries, and cell cultures of different nature. In all the experiments, these chemicals were conveyed to sensors with an air-flow circuit, equipped with antibacterial filters to maintain the sterility of the system. Resulting signals were acquired, processed and plotted thanks custom-made software, realized in Labview®. Statistics on these signals were performed with single sensors approach and Principal Component Analysis. Tests were carried on cell cultures, in order to verify if, having only one type of cell involved in the exhalation of markers, it was possible to observe differences between primary cell lines while compared to the immortalized and tumor strains, and the possibility to discriminate also between different kind of the second macro-group of cells, having them been plated at the same time and still having different metabolisms. For what concerns blood samples, both male and female subjects, ranging between 21 to 91 years of age, have accepted to participate in this study, donating their blood samples. Donors were patients affected by colorectal and stomach cancers, at different stages of evolution, and/or having differently localized metastasis, confronted to a healthy control group sharing same gender and age spectrum. At the end of this part of the study, the prototype proved capable to distinguish between tumor-affected individuals and healthy samples. Obtained results have shown also correlation between the amplitude of the responses and the level of tumor growth and vascularization, as well as a decrease of the response to the healthy threshold for the post-screening of the patients after surgery or chemotherapy. Finally, for human tissues, tests on samples from the tumor-affected area and the healthy surroundings have been effected (during surgical removal, parts from the healthy tissue of the subject are inevitably removed together with the cancer itself; also, for some kind of tumors – like colorectal – the removal of healthy tissue upstream and downstream of the cancer is also voluntary from the surgeons, in order to avoid field effect from the original tumor, which may spread the disease on healthy tissue even after the removal of the original neoplasia). The donors were patients already undergoing surgery, due to the pathologies they were affected from. The donors age, from both sexes, spanned between 41 and 91 years old. The results on human samples have shown that the sensor responses, once processed, well discriminate healthy and tumor-affected subjects, with the specimens tested after two hours and a half from the extraction.

BLOOD, CELLS AND TISSUES: SENSOR STUDY ON HUMAN SAMPLES, FOR ONCOLOGICAL SCREENING PURPOSES

LANDINI, Nicolo'
2019

Abstract

The demand for devices capable of efficiently identifying the presence of biomarkers in human body, useful to detect a wide variety of pathologies, is progressively increasing. This urge is generated in the scientific community due to the pressing request of reliable screening protocols, able to enhance in the next future the detection capability on pathologies while not in terminal or harmful state of development. The main goals of this approach lay in the enhancement of the medical prevention, and consequentially the reduction of the national health systems expenses to cure harmful pathologies once degenerated. Nanostructured chemoresistive semiconductor sensors, which can change their conductance depending on the chemical reactions between their surface and the gaseous analytes, showed in the past to be a suitable choice for medical research, especially for oncological purposes (there is plenty of literature discussing volatile organic compounds and tumor detection), and in this work they are proposed as sensing units for a final screening devices implementation. In this thesis, a prototype hosting an array of metal-oxide and non-metal-oxide sensors was tested, in order to detect the presence of airborne tumor markers exhaled from three different kind of samples: human blood from medical sampling, human tissues from surgeries, and cell cultures of different nature. In all the experiments, these chemicals were conveyed to sensors with an air-flow circuit, equipped with antibacterial filters to maintain the sterility of the system. Resulting signals were acquired, processed and plotted thanks custom-made software, realized in Labview®. Statistics on these signals were performed with single sensors approach and Principal Component Analysis. Tests were carried on cell cultures, in order to verify if, having only one type of cell involved in the exhalation of markers, it was possible to observe differences between primary cell lines while compared to the immortalized and tumor strains, and the possibility to discriminate also between different kind of the second macro-group of cells, having them been plated at the same time and still having different metabolisms. For what concerns blood samples, both male and female subjects, ranging between 21 to 91 years of age, have accepted to participate in this study, donating their blood samples. Donors were patients affected by colorectal and stomach cancers, at different stages of evolution, and/or having differently localized metastasis, confronted to a healthy control group sharing same gender and age spectrum. At the end of this part of the study, the prototype proved capable to distinguish between tumor-affected individuals and healthy samples. Obtained results have shown also correlation between the amplitude of the responses and the level of tumor growth and vascularization, as well as a decrease of the response to the healthy threshold for the post-screening of the patients after surgery or chemotherapy. Finally, for human tissues, tests on samples from the tumor-affected area and the healthy surroundings have been effected (during surgical removal, parts from the healthy tissue of the subject are inevitably removed together with the cancer itself; also, for some kind of tumors – like colorectal – the removal of healthy tissue upstream and downstream of the cancer is also voluntary from the surgeons, in order to avoid field effect from the original tumor, which may spread the disease on healthy tissue even after the removal of the original neoplasia). The donors were patients already undergoing surgery, due to the pathologies they were affected from. The donors age, from both sexes, spanned between 41 and 91 years old. The results on human samples have shown that the sensor responses, once processed, well discriminate healthy and tumor-affected subjects, with the specimens tested after two hours and a half from the extraction.
MALAGU', Cesare
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2487921
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