Porous Silicon Photonic Crystals in Single Cell and Bulk Analysis

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Copyright: Piya, Ranjana
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Abstract
The global aim of this project was to fabricate cell microarrays and single cell arrays using porous silicon (PSi) and to study the response of individual cells to specific stimuli which is the pathway to study cellular heterogeneity. To achieve these goals, PSi Bragg reflectors were fabricated by electrochemical etching of p-type silicon. To use PSi as a label-free biosensor, there should be a detectable optical shift in the reflectivity. Since the aim of this current research is to detect a response of single cells, PSi sensor used should be very sensitive. To add the sensitivity, PSi Bragg reflectors were optimized for the narrow spectral resonances. Narrow band Bragg reflector with full-width half maxima of 7 nm was fabricated and the performance of this sensor was tested with broad band Bragg reflector etched at similar etching conditions. The result showed that narrow band Bragg reflector is more sensitive than the broad one. For the fabrication of cell microarrays and single cell arrays, PSi Bragg reflector was first modified with GRGDS peptide for the selective attachment of cells at predefined locations. Then, poly(ethylene glycol) hydrogel (PEG) patterning was performed using a photolithographic technique to generate the micropatterns with cytophilic and cytophobic regions. The size of the micropatterns was controlled by using the photomask features of different size. Single cell arrays of J774 macrophage cells were successfully fabricated on 20 micron pattern. To show that individual cell response can be detected using PSi biosensors, cells on microarrays were lysed with lysis buffer as well as osmotically using water and the reflectivity was measured from the individual spots of the microarrays. The results demonstrated that PSi biosensors have potential to detect a response from individual cells. Hence this system can be used to study cellular heterogeneity. A fluorescence based measurement was also performed to detect the MMPs released by a small group and single J774 macrophage cells. Since macrophage cells are a component of the immune system, their activities are related to immune responses, inflammation and foreign body responses. Therefore, detecting MMPs released by a single macrophage cell can provide the information of macrophage activity in the immune system.
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Author(s)
Piya, Ranjana
Supervisor(s)
Gooding, Justin
Reece, Peter
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Publication Year
2018
Resource Type
Thesis
Degree Type
PhD Doctorate
UNSW Faculty
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