Anomalous diffusion and self-propulsion of radioactive colloidal particles

Abstract

A novel concept of self-propelled, radioactively-driven colloidal particles is introduced. The focus of this work is on assessing the impact of alpha emissions on the colloidal kinematics of radioactive microparticles and radioactive Janus particles. Using Langevin dynamics and a random walk model, a theory has been developed to describe the motion of a radioactively-driven colloid. This theory shows a special case of anomalous diffusion. Numerical simulations have substantiated the theory. It is shown that alpha-particle emission can significantly affect the motion of a radioactive microparticle, although a short-lived radioisotope is required. Using Brownian dynamics, a second theory has been developed to describe the motion of a radioactive Janus particle. Non-Gaussian behavior is shown in addition to the special case of anomalous diffusion. The augmented motion of radioactive Janus particles is great enough to be experimentally observed for radionuclides with moderate half-lives. The results presented herein are important for the design of radioactive colloidal particle based radiotherapeutic cancer treatments.