Microfabrication of 3D Spheroid Tumor Models and Imaging using Spectral Domain Optical Coherence Tomography

A low-cost, robust, and flexible device for generating an array of miniaturized 3D spheroid tumor models was designed and developed. The device consisting of two layers: a layer with through-hole array and a plain lamination sheet, in which both are bonded so the through-holes acting as confining barriers. The hydrophobic bottom lamination sheet led to drop formation in each through-hole, confirmed by experimental characterization using food color dye of different volumes. Further, 3D tumor spheroid models were grown within through-holes on the lamination sheet by the hanging drop approach. With preliminary experiments, spheroids were gown in a flat substrate using simple micro-pipetting and the classical hanging drop method. The formed 3D spheroid tumor models were consequently characterized by live/dead assay. To verify formation of the 3D tumor spheroid models on days 1, 4, 7, 14, and 21, label-free spectral domain based optical coherence tomography (SD-OCT) technique was employed. Results showed an increase in the height of the spheroids up to 600 μm. By utilizing SD-OCT, we were able to achieve enhanced penetration within the 3D spheroids, allowing us to visualize the structural information at various depths. With spheroids growth, the SD-OCT was performed to quantitatively analyze their sizes and necrotic cores. The length, width and diameter of the spheroids were measured for volumetric analysis, based on the cross-sectional and en face SD-OCT images. Next experiments will consider using the developed device with the SD-OCT technique for personalized medication in clinical field and drug-screening/drug-discovery in pharmaceutical industry.