Diffusive and directional intracellular dynamics measured by field-based dynamic light scattering

Abstract

Quantitative measurement of diffusive and directional processes of intracellular structures is not only critical in understanding cell mechanics and functions, but also has many applications, such as investigation of cellular responses to therapeutic agents. We introduce a label-free optical technique that allows non-perturbative characterization of localized intracellular dynamics. The method combines a field-based dynamic light scattering analysis with a confocal interferometric microscope to provide a statistical measure of the diffusive and directional motion of scattering structures inside a microscopic probe volume. To demonstrate the potential of this technique, we examined the localized intracellular dynamics in human epithelial ovarian cancer cells. We observed the distinctive temporal regimes of intracellular dynamics, which transitions from random to directional processes on a timescale of ~0.01 sec. In addition, we observed disrupted directional processes on the timescale of 1~5 sec by the application of a microtubule polymerization inhibitor, Colchicine, and ATP depletion.

Inverse-power-law behavior of cellular motility reveals stromal–epithelial cell interactions in 3D co-culture by OCT fluctuation spectroscopy

“…A richness of functional information can be garnered from the time-dependent properties of tissues revealed by speckle fluctuations in coherence imaging techniques, including intracellular motility [1,2], hemodynamics [3], apoptosis [4], and ciliary activity [5]. While speckle fluctuation models have been well-developed for particle flow and diffusion in OCT [6,7], we are only beginning to understand the fluctuation spectra arising from intracellular motions in living tissues.…”

Quantitative Imaging of Cerebral Blood Flow Velocity and Intracellular Motility using Dynamic Light Scattering–Optical Coherence Tomography

“…This intracellular motility (IM) has been shown to exhibit diffusion-like dynamics by using either fluorescence label-based methods [1][2] or label-free methods based on dynamic light scattering (DLS) analysis. [3][4][5][6][7] However, IM has not been imaged in the cerebral cortex of a living animal, probably because the dynamics are obscured by the larger contribution from cerebral blood flow (CBF). In this paper, we describe a novel method for label-free in vivo imaging of both IM and CBF.…”

Fast three-dimensional imaging of gold nanoparticles in living cells with photothermal optical lock-in Optical Coherence Microscopy

“…Furthermore, it gives access to both amplitude and phase of the scattered light and has been successfully applied to functional cell imaging [15,16]. Recently, we reported on a dark-field configuration for OCM (dfOCM) that offers enhanced sensitivity to very weak scattering signals and enables transparent cell samples to be imaged with high contrast [17].…”