Label-free Volumetric Imaging of Synthetic Cell Chassis using Optical Coherence Tomography

Bottom-up, chemically formed synthetic cells are usually imaged by optical microscopy, and the cell sizes and shapes are mostly estimated from acquired 2D images. The three-dimensional (3D) structures of a compartmentalised synthetic cell can be analysed by axially stacking 2D images, typically by using a high-resolution imaging systems, such as laser confocal scanning microscopy and light sheet microscopy. However, these techniques require the synthetic cell to be labelled with fluorescent tags, and have performance limits such as being restricted to volumes less than (approximately) 200 ìm3. Here, we present the label-free, 3D imaging of soft, free-standing, multicompartment synthetic cell using optical coherence tomography (OCT). The volumes of sub-cellular compartments within individual synthetic cells can be obtained via OCT imaging measurement. The spatial arrangements of the compartments and their contact angle information can be illustrated and measured, respectively. This approach provides a new method to evaluate multiphase soft materials spanning the range of micrometres to millimetres, towards the optimisation of synthetic cell construction for novel biomimetic material development.