Label free imaging of cell attachment by photonic crystal enhanced microscopy
The objective of this thesis was to explore the capabilities and limitations of a newly developed imaging technique which is based on the special optical properties of a photonic crystal for imaging live cells. The imaging instrument utilizes a monochromatic angle-tunable illumination to achieve resonant conditions within the crystal sensor in order to image cells by their higher reference index than the surrounding media. Due to evanescent decay, detection of cell matrix is restricted within 100 nm of the sensor surface, allowing detection of cell attachments without bias due to diffraction or absorption by cellular organelles. This work demonstrates the new capabilities this technique offers. Human hepatic and pancreatic cancer cells were imaged at different time points after settling in order to visualize the growing attachment. Induction of apoptosis demonstrated the capability of a pixel-by-pixel analysis of adhesion strength within a single cell as response to drug administration. Cardiomyocytes derived from rat embryos were used to illustrate the ability of the technique to study the effects of substrate composition on cell attachment and contractility. Finally porcine adipose derived stem cells were employed to show the capacity to estimate the progress of differentiation by a change in attachment strength. In summary the new technique is capable of visualizing dynamic cell attachment with a pixel resolution of 0.8 µm. The label-free aspect of PCEM enables the study of cell-ECM attachments in the context of cell growth, locomotion, differentiation, and apoptosis and allows direct comparison between bright field and PCEM images, allowing correlation of cellular morphology with changes in attachment density. This combination of capabilities identifies PCEM as an ideal technique for the study of cell attachment in many contexts, including wound healing, cell culture optimization, stem cell differentiation, and cancer metastasis.
microscopy, cell attachment, label free imaging, Photonic crystal
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign