Dendritic Janus Nanomotors with Precisely Modulated Coverages and Their Effects on Propulsion.

Asymmetric dual-function Janus micro-/nanoparticles (NPs) that have different surface modifications, structures, or material properties are extremely promising as building blocks in constructing micro-/nanomotors. However, current synthesis strategies make it usually difficult to precisely control the percentages of coverages of Janus micro-/NPs, which hinders in-depth research studies of their effects on the performance of Janus nanomotors. This study demonstrates a versatile approach for fabrication of Janus dendritic porous silica nanomotors with precisely modulated coverages from 0 to 100% by controlling the embedded depth of aminopropyl-modified dendritic porous silica NPs (DPSNs-NH2) with positive charges and subsequently adsorbing the oppositely charged Pt NPs. The diffusion coefficients of DPSNs-NH2 with different coverages of Pt NPs are systematically investigated. The propulsion can be enhanced by the improvement of catalytic activity of DPSNs, and half-coated DPSNs-NH2 exhibit highest propulsion among DPSNs-NH2 with other coverages. More importantly, compared with solid silica nanospheres, the initial increase of the coverage of DPSNs-NH2 makes more enhancements to the motion performance, which can be used to optimize the relations between the propulsion velocity and loading efficiency of bovine serum albumin. This work paves the way to fabricate tunable multifunctional Janus micro-/nanomotors for future advanced devices.