Three Possible Encapsulation Mechanics of TiO2Nanoparticles into Single-Walled Carbon Nanotubes

Titanium dioxide nanoparticle (TiO2-NP) is widely used in manufactured nanomaterials such as sunscreens, cosmetics, drugs, and some food products. It can be encapsulated in a single-walledcarbon nanotube (SWNT) depending on their physical and chemical interactions. On applyingthe Lennard-Jones potential function and the continuous approximation, we determine threeencapsulation mechanisms for spherical shape TiO2-NP entering a tube: (i) head-on at the tubeopen end, (ii) around the edge of the tube open end, and (iii) through a defect opening on the tubewall. The total potential energy of the system is obtained as an exact expression by performingdouble surface integrals. We find that the TiO2-NP is most (least) likely to be encapsulated intoa SWNT by head-on configuration (around the edge of the tube open end). This encapsulationprocedure is a potential application for targeted drug delivery. For convenience, throughout thisanalysis all configurations are assumed to be in vacuum and the TiO2-NP is initially at rest