THESIS
2021
1 online resource (xiii, 106 pages) : illustrations (some color)
Abstract
Significant advantages of microfluidics such as lower sample consumption and shorter reaction time make it
become popular in chemical and biological analysis. Luminescence sensors are attractive to measure these
parameters as they provide high sensitivity, non-invasive detection, and fast response. In this dissertation,
luminescence sensors were integrated with different microfluidic systems to monitor the temperature or pH
value during the analytical process. These systems were designed, proposed, and extensively discussed.
Several integration methods have been explored that combines sensor probes and microfluidics as a detection
scheme, which simplified the fabrication process and reduced the cost. The methods for temperature sensing,
poly(styrene-co-acrylonitrile) and temperature pro...[
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Significant advantages of microfluidics such as lower sample consumption and shorter reaction time make it
become popular in chemical and biological analysis. Luminescence sensors are attractive to measure these
parameters as they provide high sensitivity, non-invasive detection, and fast response. In this dissertation,
luminescence sensors were integrated with different microfluidic systems to monitor the temperature or pH
value during the analytical process. These systems were designed, proposed, and extensively discussed.
Several integration methods have been explored that combines sensor probes and microfluidics as a detection
scheme, which simplified the fabrication process and reduced the cost. The methods for temperature sensing,
poly(styrene-co-acrylonitrile) and temperature probe tris(1,10-phenanthroline)ruthenium(II) was generated
by blade coating on a glass substrate. This sensing layer was directly bound to PDMS with microfluidic
channels which led to a microfluidic system that was feasible for temperature detection in the microchannel
by imaging. In DNA melting curve analysis, the chips could be employed to generate and measure thermal
gradients in the resolution of 0.13 ℃. Analysis of the fluorescence intensity of stained DNA through
multispectral optical imaging illuminated by LED was done, giving the results for screening of the BRCA 2
breast cancer gene that enabled to discriminate two double-strand DNA even in 0.7 ºC difference. For pH
sensing, the fluorescent pH probe fluorescein isothiocyanate was conjugated to fluorinated silica
nanoparticles, which formed the droplets by Pickering emulsion. This conjugation led to stabilization of the
emulsified droplets as well as capability of detecting the pH in the droplets. This pH sensor innovatively used
in the microdroplet system could measure the pH of the extracellular microenvironment (pH
e) of single-cell
and provided support for the growth of cells in the droplets. The pH
e showed 6.84 ± 0.04 and 6.81 ± 0.04 for
cancer cells (MCF-7 and A549, respectively) and 7.36 ± 0.03 for healthy cells (HUVEC), which can be
potentially applied in circulating tumor cells distinguishing. Such coupling leads to better accuracies and
sensitivities in the assays, making the microsystems more convenient to use in temperature or pH detection.
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