Enhanced killing of HepG2 during cryosurgery with Fe3O4-nanoparticle improved intracellular ice formation and cell dehydration

// Fuquan Yuan 1 , Gang Zhao 1, 2 and Fazil Panhwar 1 1 Center for Biomedical Engineering, Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230027, Anhui, China 2 Anhui Provincial Engineering Research Center for Biopreservation and Artificial Organs, Hefei 230027, Anhui, China Correspondence to: Gang Zhao, email: zhaog@ustc.edu.cn Keywords: cryosurgery, Fe 3 O 4 nanoparticles, intracellular ice formation, cell dehydration, killing efficiency Received: June 20, 2017     Accepted: September 08, 2017     Published: October 05, 2017 ABSTRACT Cryosurgery is a minimally invasive treatment that utilize extreme low temperatures to destroy abnormal tissues. The clinical monitoring methods for cryosurgery are almost based on the visualization of the iceball. However, for a normal cryosurgery process, the effective killing region is always smaller than the iceball. As a result, the end of the cryosurgery process can only be judged by the surgeons according to their experience. The subjective judgement is one of the main reasons for poor estimation of tumor ablation, and it sparks high probability of recurrence and metastasis associate with cryosurgery. Being different from the previous optimization studies, we develop a novel approach with the aid of nanoparticles to enlarge the effective killing region of entire iceball, and thus it greatly decrease the difficulty of precise judgement of the cryosurgery only by applying the common clinical imaging methods. To verify this approach, both the experiments on a tissue-scale phantom with embedded living HepG2 cells in agarose and on a cell-scale cryo-microscopic freeze-thaw stage are performed. The results indicate that the introduction of the self-synthesized Fe 3 O 4 nanoparticles significantly improved cell killing in the cryosurgery and the range of killing is extended to the entire iceball. The potential mechanism is further revealed by the cryo-microscopic experiments, which verifies the presence of Fe 3 O 4 nanoparticles can significantly enhance the probability of intracellular ice formation and the cell dehydration during freezing hence it promote precise killing of the cells. These findings may further promote the widespread clinical application of modern cryosurgery.