Holotomography

Holotomography (HT) is a laser technique to measure the three-dimensional refractive index (RI) tomogram of a microscopic sample such as biological cells and tissues.

In order to measure 3-D RI tomogram of samples, HT employs the principle of holographic imaging and inverse scattering.

The first theoretical proposal was presented by Emil Wolf,[1] and the first experimental demonstration was shown by Fercher et al.[2] From 2000s, HT techniques had been extensively studied and applied to the field of biology and medicine, by several research groups including the MIT spectroscopy laboratory.

Intracellular lipid droplets play important roles in energy storage and metabolism, and are also related to various pathologies, including cancer, obesity, and diabetes mellitus.

[12] Recently, HT was used to evaluate the therapeutic effects of a nanodrug designed to affect the targeted delivery of lobeglitazone by measuring lipid droplets in foam cells.

3D RI tomography directly provides morphological properties including volume, surface area, and sphericity (roundness) of a cell.

Measurements of dynamic cell membrane fluctuation, which can also be obtained with a HT instrument, provides information about cellular deformability.

The invasion of plasmodium falciparum, or malaria inducing parasites, to individual red blood cells were measured using HT.

[21] The cell volume and dry mass of individual bacteria or micro algae can be effectively quantified using HT.