Non-invasive and minute-frequency 3D tomographic imaging enabling long-term spatiotemporal observation of single cell fate

Abstract Non-invasive and rapid imaging technique at subcellular resolution is significantly important for multiple biological applications such as cell fate study. Label-free refractive-index (RI) based 3D tomographic imaging constitutes an excellent candidate for 3D imaging of cellular structures, but its full potential in long-term spatiotemporal cell fate observation has been locked due to the lack of efficient system integration. Here, we report a long-term 3D RI imaging system incorporating a cutting-edge white light diffraction phase microscopy (wDPM) module with spatiotemporal stability, and an acoustofluidic device to roll and culture single cells in a customized live cell culture chamber. Using this system, we conducted 3D RI imaging experiments for 250 cells, and demonstrated efficient cell identification with high accuracy. Importantly, long-term and frequency-on-demand 3D RI imaging of K562 and MCF-7 cancer cells revealed different characteristics during normal cell growth, drug-induced cell apoptosis, and necrosis of drug-treated cells. In particular, for the first time, a new two-fold transform mode was observed in the apoptosis regions by 1-minute-frequency imaging in the 10-minute execution phase of apoptosis, which has not been seen otherwise by labeling microscopy. Overall, we believe that the proposed 3D tomographic imaging technique opens up a new avenue for visualizing intracellular structures and will find many applications such as disease diagnosis and nanomedicine.