Optical tracking of drug release from porous silicon delivery vectors

The controlled and sustained delivery of drugs to a specific location within the body is vitally important for effective treatment of chronic diseases such as cancer. One route in achieving this is to develop drug carrying systems from which release of the drug molecules can be controlled. In this study, the authors present characterisation measurements on such a system - porous silicon microparticles. The kinetic of release of the anti-cancer agent, doxorubicin is tracked in live, endothelial cells over a period of 24 h. The results are consistent with a release process of molecular diffusion from a fixed supply reservoir, with a characteristic release lifetime of 2 h. Detailed stochastic modelling of the diffusion process, mimicking the random walk of drug molecules within a heterogeneous size distribution of pores, provides an excellent fit to the data and indicates a doxorubicin diffusion constant of 2 × 10-11 m2s-1.