000231953 001__ 231953
000231953 005__ 20190509132619.0
000231953 0247_ $$2doi$$a10.5075/epfl-thesis-8024
000231953 02470 $$2urn$$aurn:nbn:ch:bel-epfl-thesis8024-5
000231953 02471 $$2nebis$$a11065826
000231953 037__ $$aTHESIS
000231953 041__ $$aeng
000231953 088__ $$a8024
000231953 245__ $$aSoft probes for bio-electrochemical imaging
000231953 260__ $$bEPFL$$c2017$$aLausanne
000231953 269__ $$a2017
000231953 300__ $$a165
000231953 336__ $$aTheses
000231953 502__ $$aGeorges Wagnières (président) ; Prof. Hubert Girault, Dr Andreas Stephan Lesch (directeurs) ; Prof. Anders Hagfeldt, Prof. Frederic  Kanoufi, Prof. Stéphane Arbault (rapporteurs)
000231953 520__ $$aThe aim of bioimaging is to visualize properties and processes of living objects or biological samples and extracts image-related information for revealing important physical structures or map the distribution of specific biomolecules in tissues for clinical purposes. However, current bioimaging methods which mainly rely on the optical detection methods can suffer from optical interferences and thus bias the imaging results. Bio-electrochemical imaging with micrometer resolution represents a promising alternative tool since electrochemical signals, e.g. faradaic currents, depend exclusively on the redox reactions occurring at the sample surface and a sensing probe. Scanning electrochemical microscopy (SECM) is a scanning probe technique that is composed of a micro- or nanoelectrode that can be positioned or scanned in close proximity to an interface. Faradaic current signals can be recorded due to the flux of redox active species between the sample and an amperometric SECM probe. SECM can be used to image the topography and reactivity of biological specimens for mapping localized biochemical activity. Although SECM has been applied to different biological systems, SECM studies of tissues are still under exploration. The reason is due to the shape and high roughness of such real samples and requires overcoming major drawbacks in conventional SECM instrumentation when scanning large, i.e. square centimeter sized areas with irregular surface keeping a constant working distance.  This thesis aims to develop various reliable SECM bioimaging techniques for the study of the antioxidant defense system of fruit peels, distribution of biomarkers and nanomaterials in thin and thick animal samples, as well as human melanoma. Particularly the last is of major importance, because melanoma is the most lethal form of skin cancer striking thousands of people around the world. The survival rate depends on the stage of the cancer when it is diagnosed. Therefore, reliable methodologies for early diagnosis and unequivocal identification of cancer stages are of high relevance. One of the well-known melanoma biomarkers is « tyrosinase » which is the key enzyme involved in the biosynthesis of melanin and fruit maturation. Different tyrosinase SECM detection strategies were developed for the analysis of the spatial distribution of tyrosinase in melanoma as well as in banana samples. It demonstrated in this thesis that that SECM could improve the diagnosis and understanding of different melanoma stages based on highly resolved maps of the tyrosinase distribution while being immune against optical interferences, e.g. from the presence of melanin in the skin samples. Spider probe composed of eight independent microelectrodes developed in this thesis allowed the large area scanning over thin and thick animal tissues in contact mode. The redox active proteins inside the entire mouse heart was imaged for the first time by spider probe.  In addition, the distributions of injected conductive graphene nanoribbons (GONRs) for drug delivery were studied by Soft-Probe-SECM. Through the mapping of feedback mode currents over conductive GONRs, the GONRs were found concentrated inside lobules, which are hexagonal microstructures in the liver. Finally, this thesis describes a non-invasive electrochemical strategy for mapping the antioxidant (AO) activity of apple peels using Soft-Probe-SECM. The global AO activity in the apple peel including lenticels and regions with artific
000231953 6531_ $$aSECM
000231953 6531_ $$asoft probe
000231953 6531_ $$amelanoma
000231953 6531_ $$atyrosinase
000231953 6531_ $$acontact mode
000231953 6531_ $$afeedback mode
000231953 6531_ $$ageneration collection mode
000231953 6531_ $$athick tissue
000231953 6531_ $$agraphene oxide nanoribbon
000231953 6531_ $$aspider probe
000231953 700__ $$0247545$$g232930$$aLin, Tzu-En
000231953 720_2 $$aGirault, Hubert$$edir.$$g105258$$0242739
000231953 720_2 $$aLesch, Andreas Stephan$$edir.$$g208650$$0246751
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000231953 909C0 $$xU10100$$0252090$$pLEPA
000231953 909CO $$pthesis-bn2018$$pDOI$$pSB$$ooai:infoscience.tind.io:231953$$qDOI2$$qGLOBAL_SET$$pthesis
000231953 917Z8 $$x108898
000231953 917Z8 $$x108898
000231953 918__ $$dEDCH$$cISIC$$aSB
000231953 919__ $$aLEPA
000231953 920__ $$b2017$$a2017-10-31
000231953 970__ $$a8024/THESES
000231953 973__ $$sPUBLISHED$$aEPFL
000231953 980__ $$aTHESIS