Diffusion-Limited Release of Molecules from Nanocarriers with Appreciable Energetic Heterogeneity

Abstract

Carriers with a size of ∼100−200 nm are now used in various applications related, e.g., to drug and vaccine delivery. Such carriers are structurally heterogeneous, and this results in appreciable energetic heterogeneity for the diffusion of cargo molecules. In particular, the diffusion coefficient becomes dependent on the concentration of molecules, and this dependence is related to the distribution of attachment sites over binding energy. Taking this distribution into account and integrating the corresponding diffusion equation, the author shows that in this case, the release kinetics are logarithmic. Such kinetics can be fitted by employing the Weibull expression with the exponent in the range of 0.35 to 0.45. This range is relevant in the context of recent experiments with nanocarriers.