Delivery of drugs and molecules to eukaryote animal and plant cells can be enhanced when mediated by mesoporous silica nanoparticle (MSN) materials. This chapter describes, in detail, the synthesis of several different MSN materials used for the transport of various hydrophilic and hydrophobic drug molecules, neurotransmitters, and macromolecules across the cell membrane, and in some cases, the cell wall of plant cells. In addition, the utility of MSN for mediating thedelivery of cell-impermeable proteins is described in detail. Though the experimental descriptions are specifically detailed to research that has been completed, the procedures are applicable to additional drug and protein delivery experiments. Also summarized are several considerations that need to be addressed when utilizing MSN materials with biological systems to avoid complicating experiments.