Testing anti-cancer drugs with holographic incoherent-light-source quantitative phase imaging

Quantitative Phase Imaging is becoming an important tool in the objective evaluation of cellular responses to experimental treatment. The technique is based on interferometric measurements of the optical thickness of cells in tissue culture reporting on the distribution of dry mass inside the cells. As the measurement of the optical thickness is interferometric, it is not subjected to the Abbe resolution limit, and the use of an incoherent-light source further increases the accuracy practically achieving 0.93nm in optical path difference corresponding to 4.6 femtograms/μm². Holographic mode reduces the exposure in comparison to phase-shifting or phase-stepping interference microscopy and allows observation of faster dynamics. An attractive application is in the development of novel anti-cancer drugs and there is an important potential for pretesting chemotherapeutic drugs with biopsy material for personalized cancer treatment. The procedure involves the preparation of live cells in tissue culture, seeding them into suitable observation chambers, and time-lapse recording with an adjusted microscope. Subsequent image processing and statistical analysis are essential last steps producing the results, which include rapid measurements of cell growth in terms of dry-mass increase in individual cells, speed of cell motility and other dynamic morphometric parameters.