Utilizing bottom-up controllable molecular assembly, the bio-inspired polyelectrolyte multilayer conical nanoswimmers with gold-nanoshell functionalization on different segments are presented to achieve the optimal upstream propulsion performance. The experimental investigation reveals that the presence of the gold nanoshells on the big openings of the nanoswimmers could not only bestow efficient directional propulsion but could also minimize the impact from the external flow. The gold nanoshells at the big openings of nanoswimmers facilitate the acoustically powered propulsion against a flow velocity of up to 2.00 mm s-1, which is higher than the blood velocity in capillaries and thus provides a proof-of-concept design for upstream nanoswimmers.
Keywords: colloidal motor; layer-by-layer; nanoarchitecture; nanoswimmer; upstream motion.