Characterization of the nanocryosurgical freezing process through modifying Mazur’s model

Nanoparticles enhanced freezing, termed as nanocryosurgery, is a newly emerging cryosurgical technique which has potential advantage in targeted tumor treatment. However, there are currently no models available to predict the effects of nanoparticles on cell-level biophysical events during cryosurgery. Here, we present a theoretical model through modifying Mazur’s equation and ice nucleation theory to predict the kinetic course of the target cell such as water transport and ice nucleation during nanocryosurgical process. The transient temperature response of the target cell, which was a major influential variable of the model, was calculated by coupling the Pennes bioheat equation and the thermal conductivity model of nanoparticle-fluid mixture. With the model, the freezing effect of nanocryosurgical process on target cell at varying distances from cryoprobe can be comprehensively characterized from microto macroscale. Parametric studies revealed that the kinds of nanoparticles and their extracellular volume fraction are two important factors to affect cell-level freezing response compared with other factors such as the cell radius and intracellular volume fraction of nanoparticles. The corresponding sensitivity analysis of various parameters is also reported. This study would help to better understand the role of nanoparticles in the freezing process and benefit to optimize the protocol of tumor treatment when nanocryosurgery is administrated. © 2008 American Institute of Physics. DOI: 10.1063/1.2910676