MESOSCOPIC LIGHT SCATTERING APPROACH FOR STRUCTURAL DISORDER ANALYSIS OF BIOLOGICAL CELLS: APPLICATION IN CANCER DIAGNOSTICS

Optical techniques are often used to study of biological cells and tissues to gain valuable information about them. Recently, the mesoscopic physics based light scattering techniques have provided unprecedented insight into the physical properties of biological systems. In particular, the mesoscopic light transport and light localization approaches allow to measure and quantify nano to micron scale structural alterations in the biological system. The applications of these techniques have been foreseen in efficient diseases diagnostics and therapeutic studies. Genesis and progression of diseases such as cancer is known to accompany with structural alterations in the building blocks of cells, such as DNA, proteins, lipids, etc. In that context, this dissertation presents a detailed study on quantification of structural changes in the cancer cells, by employing the mesoscopic physics based light transport and light localization analysis. Two different techniques, namely the partial wave spectroscopy (PWS) (light transport) and inverse participation ratio (IPR) (light localization), are implemented to image and quantify structural disorder developed as a result of alteration in the cellular structure caused by cancer diseases. The PWS and IPR techniques were used to quantify structural disorder, represented as disorder strength, and thus differentiate normal from cancer cells in several human breast, brain and prostate cell lines. Additionally, the effect of drug resistance developed by the prostate cancer cells, on prolonged chemotherapy treatment, on the structural disorders of the cells was also analyzed. Results show that the cancer cells have higher structural disorder compared to the normal cells and that the degree of structural disorder is correlated with the aggressiveness/metastatic potential of the cancer cells. The results with drug study suggest that the cancer cells which develop resistance to the chemotherapy become more aggressive. Further, the results of this study strongly indicate that the parameter disorder strength can acts as an efficient biomarker/numerical index to asses hierarchy of cancer as well as evaluate efficiency of drug treatment processe