Dissolution and morphology evolution of mesoporous silica nanoparticles under biologically relevant conditions.

Mesoporous silica nanoparticles (MSN) are promising drug vectors due to their high drug loading capacities, degradability under biologically relevant conditions. The dissolution of MSN has been the focus of several recent studies, most of which have, however, been carried out in the absence of proteins, and do therefore not reflect the conditions prevailing during in vitro or in vivo administration of the particles. Furthermore, typically the dissolution studies are limited with respect to the range of MSN concentrations applied. Here, we report results related to the dissolution kinetics and structural particle evolution for MCM-48 MSN carried out in the presence of proteins, and where the particle concentration has been used as a parameter to cover typical concentrations used in in vitro and in vivo studies involving MSNs. Proteins adsorbing to the MSN surface form a diffusion limiting layer that leads to the intermediate formation of core-shell structured particles upon dissolution. Here, the protein concentration controls the kinetics of this process, as the amount of protein adsorbing to the MSN increase with increasing protein concentration. The results thus also imply that the MSN dissolution kinetics is faster under normally applied in vitro conditions as compared to what can be expected under full serum conditions.