Polymer-decorated anisotropic silica nanotubes with combined shape and surface properties for guest delivery

We report on amphiphilic diblock copolymer-decorated anisotropic silica nanotubes with well-defined dual functions of shape and surface properties in one nanocontainer. Amphiphilic poly(lactic acid)-block-poly(ethylene glycol) (PLA-b-PEG) diblock copolymers are covalently grafted to the surface of mesoporous silica nanotubes via silane chemistry and esterification. The released percentage of probe molecules from the resultant silica-g-(PLA-b-PEG) hybrid nanocontainer is around 40% over a release time of 48 h, in contrast to 90% from bare silica nanotubes prior to surface modification. The diblock copolymer-decorated anisotropic nanocontainers with large aspect ratio lead to enhanced viability of NIH 3T3 fibroblast cells. A theoretical model based on the free energy cost for cell membranes to encapsulate nanocontainers is utilized to understand the cytotoxicity. This work demonstrates that the release dynamics of the active molecules and the interaction of hybrid nanocontainers with cell membranes can be regulated by the synergistic effect of nanocontainer shape and surface properties.