UBC Theses and Dissertations

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UBC Theses and Dissertations

Design of quantum dot and smartphone-based luminescent bioassay platforms for prospective point-of-care diagnostics Petryayeva, Eleonora


Smartphones are essential components of daily life. These devices feature built-in cameras and light sources, data storage, and wireless data transmission, making them emerging devices for optical imaging and diagnostic bioassays. To date, the majority of smartphone-based diagnostics have been developed for colourimetric assays, which often suffer from limited multiplexing capability and poor sensitivity. In general, fluorescence-based assays offer greater sensitivity and multiplexing capacity, and in combination with smartphone platform may help to overcome these limitations. This thesis describes research toward the development of smartphone platforms for fluorescence-based bioassays using quantum dots (QDs) and Förster resonance energy transfer (FRET), and addresses two critical challenges: multiplexing and analysis of biological sample matrices. Multiplexing was achieved by matching the built-in RGB (red-green-blue) channels of smartphone cameras with the narrow, bright, and tunable emission of QDs. The QDs provided superior brightness in comparison to traditional fluorescent dyes and proteins, and served as excellent FRET donors in assays that used proteases as model analytes. Up to threeplex assays were demonstrated for the detection of trypsin, chymotrypsin, and enterokinase. The analytical performance of the smartphone-based platform matched that of a bench-top spectrofluorimeter, where the smartphone was a fraction of the cost and size. A smartphone based platform was also developed for detection of analytes in serum and whole blood. Most clinical samples will take this form and necessitate careful assay design to overcome challenges associated with physical, optical and chemical properties of whole blood. Blood is strongly absorbing, scattering, autofluorescent, and contains high concentrations of proteins and small molecules. A well-thought-out combination of QDs, FRET, and a paper-in-PDMS chip enabled direct, single-step and quantitative fluorescence-based detection of thrombin activity in whole blood. The research in this thesis is a foundation for the development of novel point-of-care diagnostics assays with consumer electronics that could help enable personalized health care.

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