Nanocrystals for Photocatalysis and Imaging Applications

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dc.contributor.advisorChen, Jennifer I-Ling
dc.contributor.authorMalile, Brian
dc.date.accessioned2023-08-04T15:08:28Z
dc.date.available2023-08-04T15:08:28Z
dc.date.issued2023-08-04
dc.date.updated2023-08-04T15:08:28Z
dc.degree.disciplineChemistry
dc.degree.levelDoctoral
dc.degree.namePhD - Doctor of Philosophy
dc.description.abstractNanocrystals, contrary to the bulk counterparts, can exhibit size-dependent optical, electronic, magnetic, and catalytic properties. These materials can be tailored for specific applications including sensing, bioimaging, drug delivery, optoelectronics, and catalysis. This dissertation explores two types of nanocrystals, namely CdS-based quantum dots (QDs) and DNA-conjugated gold nanoparticles (DNA-AuNPs), as photocatalysts for reductive organic transformations and high mass probes for the emerging Imaging Mass Cytometry bioanalytical platform, respectively. QDs are zero-dimensional semiconductor nanocrystals with attractive properties arising from quantum confinement effects. The tunable absorption and emission profiles make QDs desirable candidates in display technologies, lasing, and solar energy applications. On the other hand, non-radiative photophysical processes enhanced by quantum confinement in QDs are underutilised and often perceived as undesirable. One such process – Auger relaxation – can produce hot electrons with high reducing power and can be amplified further by doping the nanocrystal with Manganese (II). Part one of this thesis examines the photoreduction capabilities of Mn2+-doped CdS/ZnS core/shell QDs (Mn:CdS/ZnS QDs). The doped QDs were implemented as photocatalytic coatings on reaction vessels, and several model organic reactions were evaluated including the 6-electron reduction of nitrobenzene to aniline that reached an overall internal quantum efficiency of ~3%. The findings demonstrate several-fold increase in the photoreduction efficiency of Mn:CdS/ZnS over undoped CdS/ZnS QDs, and the film set up allows for facile post-reaction workup and a range of solvent compatibility. Additionally, surface characterizations were performed to probe the changes and address the reusability of the QDs. Lastly, the initial implementation of QD coatings in flow reactors showed success. This work presents new opportunities and diversifies the toolbox of heterogeneous photocatalysts for prospective use in organic reactions. Imaging Mass Cytometry (IMCTM) is a multiparametric imaging technique that utilizes metal-tagged antibodies as probes for investigating subcellular components via mass spectrometry. However, low-abundant cellular components can generate weak or no signals due to the small number of antibodies that bind to them. In the second part of this thesis, DNA-functionalized gold nanoparticles, each comprising >10 000 Au atoms, were examined as high mass probes for targeting low abundant microRNA. The interaction between the DNA strands on the AuNPs and microRNA-210, a biomarker for preeclampsia and hypertensive diseases, leads to the accumulation of DNA-AuNPs in cells as readily imaged with IMC. The results from IMC corroborated with traditional fluorescence-based methods, but with an enhanced sensitivity of a thousand-fold. This work is the first demonstration that DNA-AuNP can serve as high mass probes in IMC for detecting low-abundant nucleic acids.
dc.identifier.urihttps://hdl.handle.net/10315/41314
dc.languageen
dc.rightsAuthor owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.
dc.subjectChemistry
dc.subjectNanoscience
dc.subjectNanotechnology
dc.subject.keywordsPhotoredox catalysis
dc.subject.keywordsPhotocatalysis
dc.subject.keywordsHeterogenous catalysis
dc.subject.keywordsReduction of nitrobenzene
dc.subject.keywordsDoped quantum dots
dc.subject.keywordsQuantum dot films
dc.subject.keywordsMethyl viologen
dc.subject.keywordsCrosslink
dc.subject.keywordsManganese doping
dc.subject.keywordsCadmium sulfide
dc.subject.keywordsManganese assisted auger relaxation
dc.subject.keywordsMn(II): CdS/ZnS
dc.subject.keywordsInternal quantum efficiency
dc.subject.keywordsHot electron
dc.subject.keywordsCore/shell
dc.subject.keywordsFlow reactor
dc.subject.keywordsReactor coating
dc.subject.keywordsThin film
dc.subject.keywordsOrganic photocatalysis
dc.subject.keywordsBioimaging
dc.subject.keywordsImaging Mass Cytometry
dc.subject.keywordsMetal-tagged antibodies
dc.subject.keywordsMultiparametric imaging
dc.subject.keywordsSegmentation analysis
dc.subject.keywordsBoxplots
dc.subject.keywordsMicro RNA
dc.subject.keywordsDNA-gold nanoparticles
dc.subject.keywordsDNA-AuNP
dc.subject.keywordsLSPR
dc.subject.keywordsConfocal microscopy
dc.subject.keywordsmicro-RNA-210
dc.subject.keywordsNanoparticle uptake
dc.subject.keywordsNanoparticle distribution
dc.subject.keywordsHuman trophoblasts
dc.subject.keywordsSequence specific interaction
dc.subject.keywordsNanoparticle accumulation
dc.subject.keywordsNormoxic
dc.subject.keywordsHypoxic
dc.subject.keywordsNanoparticle functionalization
dc.subject.keywordsEndocytosis
dc.titleNanocrystals for Photocatalysis and Imaging Applications
dc.typeElectronic Thesis or Dissertation

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