Active colloidal molecules assembled via selective and directional bonds

Abstract

The assembly of active and self-propelled particles is an emerging strategy to create dynamic materials otherwise impossible. However, control of the complex particle interactions remains challenging. Here, we show that various dynamic interactions of active patchy particles can be orchestrated by tuning the particle size, shape, composition, etc. This capability is manifested in establishing dynamic colloidal bonds that are highly selective and directional, which greatly expands the spectrum of colloidal structures and dynamics by assembly. For example, we demonstrate the formation of colloidal molecules with tunable bond angles and orientations. They exhibit controllable propulsion, steering, reconfiguration as well as other dynamic behaviors that collectively reflect the bond properties. The working principle is further extended to the co-assembly of synthetic particles with biological entities including living cells, giving rise to hybrid colloidal molecules of various types, for example, a colloidal carrousel structure. Our strategy should enable active systems to perform sophisticated tasks in future such as selective cell treatment.

Reconfigurable artificial microswimmers with internal feedback

“…A promising route to achieve this goal is to exploit the coupling between particle shape and motility. Efficient switching between different propulsion states can, for instance, be reached by the spontaneous aggregation of symmetry-breaking active clusters of varying geometry [12][13][14][15] , albeit this process does not have the desired deterministic control. Conversely, designing colloidal clusters with fixed shapes and compositions offers fine control on motility [16][17][18] but lacks adaptation.…”

Autonomously Propelled Colloids for Penetration and Payload Delivery in Complex Extracellular Matrices

“…One potential way to realize this vision is to use self-propelled particles (SPPs) as delivery vehicles. First demonstrated in 2004 in the form of hydrogen-peroxide-powered platinum/gold nanorods [ 35 ], SPPs are active colloidal particles that typically range in size from 30 nm to 30 µm [ 36 , 37 ] and can convert physical (e.g., magnetic [ 38 , 39 ] or electric fields [ 40 , 41 ] ), ultrasound [ 42 , 43 , 44 ], or chemical (e.g., hydrogen peroxide [ 35 ] and enzymatic reactions [ 45 ]) energy into motion. In addition to autonomous movement, it is well-known that SPPs can carry and deliver payloads to specific locations [ 46 ]; hence, they have been widely considered for drug delivery applications since 2010 ((if not earlier [ 47 ]).…”

Inter-particle adhesion regulates the surface roughness of growing dense three-dimensional active particle aggregates

“…[9][10][11] In the context of active colloids, selective and directional ligand mediated bonds can tune its motion and spatial configuration. 12 Therefore, inter-particle adhesive interactions function as a crucial regulator of the collective dynamics and spatial structure of active matter systems.…”