Static and dynamic light scattering of healthy and malaria-parasite invaded red blood cells

Abstract

We present the light scattering of individual Plasmodium falciparum-parasitized human red blood cells (Pf-RBCs), and demonstrate progressive alterations to the scattering signal arising from the development of malaria-inducing parasites. By selectively imaging the electric fields using quantitative phase microscopy and a Fourier transform light scattering technique, we calculate the light scattering maps of individual Pf-RBCs. We show that the onset and progression of pathological states of the Pf-RBCs can be clearly identified by the static scattering maps. Progressive changes to the biophysical properties of the Pf-RBC membrane are captured from dynamic light scattering.

Figure 1

(a) Amplitude and (b) phase map of a healthy RBC. (c) The retrieved light scattering pattern of the same cell. Light-intensity scattering patterns of (d) healthy RBCs, (e) ring, (f) trophozoite, and (g) schizont stage of Pf-RBCs. (h) p-values of scattering patterns (different intraerythrocytic stages of Pf-RBCs are compared to the healthy RBCs).

Figure 2

Dynamic light scattering of Pf-RBCs. (a) Normalized temporal autocorrelations of a healthy RBC as a function of decay time and scattering angle. (b) Normalized temporal autocorrelation of a healthy RBC at two representative scattering angles and fitted curves. (c) Line width Γ extracted from healthy and Pf RBCs as a function of scattering angle. Symbols represent the mean value and the error bars indicate the standard error for 15 RBCs. (d) Scatter plot of ω₀ versus Γ taken for healthy and Pf RBCs. Each symbol represents mean values of 15 RBCs at scattering angles (0 to 21 deg). Lines indicate the boundaries of each group.