Noninvasive sizing of subcellular organelles with light scattering spectroscopy

A long-standing impediment for applications of optical techniques in cellular biology is the inability to characterize subcellular structures whose dimensions are much less than about 1 (mu)m. In this paper, we describe a method based on light scattering spectroscopy that can find the size distribution of subcellular organelles as small as 100 nm with an accuracy of 20 nm. We report experiments using aqueous suspensions of subcellular organelles enriched in mitochondria, zymogen granules, and microsomes. From the observed light scattering spectra, we extract size distributions that are in excellent agreement with the results of electron microscopy. Further studies are underway to extract the shapes of organelles in addition to their sizes.