Self-propelled janus mesoporous silica nanomotors with sub-100 nm diameters for drug encapsulation and delivery

The synthesis of an innovative self-propelled Janus nanomotor with a diameter of about 75 nm that can be used as a drug carrier is described. The Janus nanomotor is based on mesoporous silica nanoparticles (MSNs) with chromium/platinum metallic caps and propelled by decomposing hydrogen peroxide to generate oxygen as a driving force with speeds up to 20.2 μm s ^-1 (about 267 body lengths per second). The diffusion coefficient (D) of nanomotors with different H₂O₂ concentrations is calculated by tracking the movement of individual particles recorded by means of a self-assembled fluorescence microscope and is significantly larger than free Brownian motion. The traction of a single Janus MSN nanomotor is estimated to be about 13.47×10^-15 N. Finally, intracellular localization and drug release in vitro shows that the amount of Janus MSN nanomotors entering the cells is more than MSNs with same culture time and particle concentrations, meanwhile anticancer drug doxorubicin hydrochloride loaded in Janus MSNs can be slowly released by biodegradation of lipid bilayers in cells. Drugs in motion: Self-propelled Janus mesoporous silica nanomotors with diameters of sub-100 nm are presented. This new active delivery system combines an autonomous nanomotor and a smart cargo into an integrated system and may be helpful in dealing with current nanoparticle drug-delivery system obstacles (see picture).