Mesostructured Silica for Optical Functionality, Nanomachines, and Drug Delivery.

Silica thin films and nanoparticles prepared using sol-gel chemistry are derivatized with active molecules to generate new functional materials. The mild conditions associated with sol-gel processing allow for the incorporation of a range of dopants including organic or inorganic dyes, biomolecules, surfactants, and molecular machines. Silica nanoparticles embedded with inorganic nanocrystals, and films containing living cells have also been synthesized.

pH clock-operated mechanized nanoparticles.

Mechanized nanoparticles (MNPs) consisting of supramolecular machines attached to the surface of mesoporous silica nanoparticles are designed to release encapsulated guest molecules controllably under pH activation. The molecular machines are comprised of cucurbit[6]uril (CB[6]) rings that encircle tethered trisammonium stalks and can be tuned to respond under specific pH conditions through chemical modification of the stalks. Luminescence spectroscopy demonstrates that the MNPs are able to contain guest molecules within nanopores at neutral pH levels and then release them once the pH is lowered or raised.

Dual-controlled nanoparticles exhibiting AND logic.

Dual-controlled nanoparticles (DCNPs) are synthesized by attaching two different types of molecular machines, light-responsive nanoimpellers and pH-responsive nanovalves, to different regions of mesoporous silica nanoparticles. Nanoimpellers are based on azobenzene derivatives that are tethered to the nanopore interiors, while nanovalves are based on [2]pseudorotaxanes that are tethered to the nanoparticle surfaces. The different molecular machines operate through separate mechanisms to control the release of guest molecules that are loaded into the nanopores.