Measurement of particle size distribution in mammalian cells in vitro by use of polarized light spectroscopy

Abstract

We demonstrate the feasibility of measuring the particle size distribution (PSD) of internal cell structures in vitro. We use polarized light spectroscopy to probe the internal morphology of mammalian breast cancer (MCF7) and cervical cancer (Siha) cells. We find that graphing the least-squared error versus the scatterer size provides insight into cell scattering. A nonlinear optimization scheme is used to determine the PSD iteratively. The results suggest that 2-microm particles (possibly the mitochondria) contribute most to the scattering. Other subcellular structures, such as the nucleoli and the nucleus, may also contribute significantly. We reconstruct the PSD of the mitochondria, as verified by optical microscopy. We also demonstrate the angle dependence of the PSD.

Use of focussed beam reflectance measurement (FBRM) for monitoring changes in biomass concentration

“…Effect of cell death on the total FBRM counts for a suspension undergoing apoptosis and for a suspension undergoing necrosis also contribute to the increase in total FBRM counts. Analysis of particle size distributions produced using polarized light spectroscopy has suggested that possible scatterers of light within cells include the cell membrane, nucleus, nucleoli and structures, such as the mitochondria [32]. A number of published studies in the polarized light spectroscopy field reported that the nucleus was a major factor in the backscatter of light [33][34][35].…”

Polarized light imaging in biomedicine: emerging Mueller matrix methodologies for bulk tissue assessment

“…[17][18][19][20][21][22] Depolarization abnormalities, arising from changes in tissue scattering and absorption properties (transport albedo), are related to alterations in the stroma (e.g., collagen remodeling) and cellular compartment disorders (e.g., nuclear enlargement). [23][24][25][26][27] Given the fundamental and clinical importance of these and related changes, Mueller matrix polarimetry yielding depolarization and retardance has been used in a variety of (mostly preclinical) studies. A partial list includes differentiating different tissue types, identifying skin cancer lesions, detecting oral precancerous tissue in animal models, visualizing cervical cancer margins in excised samples, locating myocardial infarctions and observing their regeneration following stem-cell therapy, finding the relation between the distension pressure and anisotropy in bladder wall, identifying bladder obstruction disorders, and imaging collagen structure in ex vivo tissue of animal models.…”

“…The total depolarization Δ parameter varies with transport albedo and depends on the tissue type. [23][24][25][26][27] Next, (2) the retardance matrix can be further decomposed to a linear retardance and a circular retardance matrices; 16 the latter is related to the presence/concentration of biologically interesting chiral substances, such as glucose. 16,20 From the linear retardance matrix, the tissue strength of the structural anisotropy and its orientation can be retrieved in terms of the optical phase retardance δ (proportional to birefringence) and the fast axis θ; [27][28][29][30][31][32][33][34][35][36] this is the aspect that is further pursued in this article in greater detail.…”

Theoretical model for assessing multiple scattering and coherence gating on polarized sensitive images

“…[13][14][15] Accordingly, the polarization-based techniques have been given a lot of attention since their potential for diagnostic purposes including biomedical diagnostics and imaging, 16 as well as the characterization of scattering particles. 13,17,18 Multiple scattering of electromagnetic waves within a randomly inhomogeneous highly scattering medium leads to the loss of the initial polarization direction, phase and wavefront. [19][20][21] The multiple scattering is widely studied by a Monte Carlo (MC) technique.…”