Dissolution kinetic behavior of drug nanoparticles and their conformity to the diffusion model

Advances in nanomedicine are expected to escalate in the coming years, particularly related to the availability and delivery of optimum dosage. It is crucial that the dissolution behavior of such novel dosage forms be adequately scrutinized to maximize their therapeutic benefits. In this work, the dissolution behavior of irregularly shaped nanoparticles was analyzed using a modified negative-two-thirds-root diffusion model (with shape factor, sigma, incorporated into the equation to describe shape evolution). The model was shown to be effective in describing the transition from peanut-shape nanoparticles (connected by bridges) to discrete spheres during the dissolution process. Due to the eventual aggregation of the discrete spheres in solution, description of the dissolution behavior was limited to the aggregate as a whole. Scanning electron microscopy, diffusion layer thickness calculations, and sonication studies provide information to show that, during dissolution, the bridges dissolve, yielding discrete spheres which then aggregate randomly in solution. Viscosity experiments reveal that the dissolution behavior was predominantly diffusion-controlled. The dissolution behavior of irregularly shaped nanoparticles in solution is described as going from bridged particles to discrete particles, to aggregates, and finally to full dissolution.