Protocells: Modular mesoporous silica nanoparticle-supported lipid bilayers for drug delivery

摘要

Mesoporous silica nanoparticle supported-lipid bilayers, termed ‘protocells,’ represent a potentially transformative class of therapeutic and theranostic delivery vehicles. The field of targeted drug delivery poses considerable challenges that cannot be addressed with a single ‘magic bullet’. Consequently the protocell has been designed as a modular platform composed of interchangeable biocompatible components. The mesoporous silica core can have variable size and shape to direct biodistribution and controlled pore size and surface chemistry to accommodate diverse cargos. The encapsulating supported lipid bilayer can be modified with targeting and trafficking ligands as well as PEG to effect selective binding, endosomal escape of cargo, drug efflux prevention, and potent therapeutic delivery, while maintaining in vivo colloidal stability. This mini-review describes the individual components of the platform, including the mesoporous silica nanoparticle core and supported lipid bilayer, their assembly (by multiple techniques) into a protocell, and the combined, often synergistic, performance of the protocell based on in vitro and in vivo studies including assessment of biocompatibility and toxicity. We close by commenting on the many emerging variations of the protocell theme and the future directions for protocell research.