Light scattering spectroscopy of cells: A study based on Mie and fractal models

The changes in light scattering induced by acetic acid in cervical cancer cell suspensions and the attached monolayer cells were studied using elastic light scattering spectroscopy. The results show that Mie scattering is dominant in small forward scattering angles (<10.0 degrees). However Mie fitting was found not to be able to provide a satisfactory interpretation of the scattering spectral signals in the large scattering angles. This creates challenge to extract accurate information on the refractive index of cellular organelles. The internal structures in the cells do not make appreciable contribution to light scattering in the small scattering angles while these structures show up and dominate the light scattering in larger angles. The fractal mechanism captures these internal structures. After applying acetic acid solution to the cells, it was found that the volume fraction of the small size scatterers increases and the largest scatterer size decreases. Meanwhile, the fluctuation amplitude of intracellular refractive index increases. Overall, the results provide the evidence that small-sized organelles are the major contributors to the acetowhitening effect.