Estimation of the Diffusion Coefficient of Doxorubicin Molecules in a Water Solution in the Volume of a Porous Carrier Medium.

An experimental investigation of the phenomenon of diffusion of the solution components in nanosized pores is extremely difficult and in certain cases impossible. An effective approach to obtaining qualitative and quantitative estimates of the diffusion process characteristics is computer simulation. Relying on the method of dissipative particle dynamics, a nanoscale numerical model is proposed for estimating the value of diffusion coefficient of the dissolved substance molecules in the pores of different sizes. An aqueous solution of doxorubicin, an antitumor antibiotic, in the pores of hydroxyapatite (a promising carrier medium for solving the problems of targeted administration of highly toxic drugs) is considered as a model system. Using the proposed model, the diffusion coefficient of doxorubicin in the pores of different linear sizes is evaluated at different volume concentrations of the antibiotic. In particular, it is found out that with an increase in the pore size the diffusion coefficient of doxorubicin increases by an order of magnitude and, starting from the pore size of 300 nm, it attains saturation. An increase in the antibiotic concentration from 0.1 to 5% gives rise to a decrease in the diffusion coefficient by more than a factor of 1.5. The developed model can be applied for solving the problems of predicting the release rate of the solution components (including drug molecules) from the pore volume of different solid-phase carrier media. [ABSTRACT FROM AUTHOR]