Size Effect of Mesoporous and Hollow Silica Nanoparticles on Solid Tumor Targeting and Penetration

In cancer therapy, the leaky vasculature of solid tumors endows critical advantages for nano-enabled drug delivery systems, which is denoted as the enhanced permeability and retention (EPR) effect. However, the passive targeting has limited efficiency because of the sequestration of nanoparticles by reticuloendothelial system (RES) and limited tumor penetration. Previously, it was found that the particle size would influence their location and penetration in tumor. Mesoporous silica nanoparticles (MSNs) have recently attracted much attention in the biomedical field due to their unique characteristics, including high surface area, large pore volume and uniform porosity, making them excellent candidates for drug delivery. To our knowledge, there has been little attention paid on the size effect of MSNs with sub-micrometer size on their tumor targeting ability. In this study, we synthesized a kind of mesoporous and hollow silica nanoparticles (MHSNs), silica nanorattles, with size of 60, 120, 325 and 580 nm and systematically studied the size effect of MHSNs on tumor passive targeting and penetration. The results demonstrated that particle size plays vital important roles in determining the distribution and tumor targeting and penetration of mesoporous and hollow silica nanoparticles.