Imaging Depth Enhancement on Tumor Spheroid by Optical Clearing in Optical Coherence Tomography and Confocal Microscopy

The tumor spheroid is becoming a promising model for cancer preclinical drugs test. However, its opacity limits the application of high-resolution imaging modalities to explore the inner core region of a spheroid. In this study, a fast aqueous optical clearing method, ScaleSQ(5), was applied to tumor spheroids achieving tissue transparency for deeper light penetration. The imaging depth enhancement was examined by confocal fluorescence microscopy and optical coherence tomography respectively. As a result, tissue transparency is achieved and the light penetration is enhanced by 61.81% in confocal fluorescence microscopy, and 57.13% in optical coherence tomography. Also, ScaleSQ(5) is compatible with many fluorescence dyes which makes it promising for inner microstructure exploration of tumor spheroids.