Field-induced assembly of colloidal ellipsoids into well-defined microtubules

Abstract

Current theoretical attempts to understand the reversible formation of stable microtubules and virus shells are generally based on shape-specific building blocks or monomers, where the local curvature of the resulting structure is explicitly built-in via the monomer geometry. Here we demonstrate that even simple ellipsoidal colloids can reversibly self-assemble into regular tubular structures when subjected to an alternating electric field. Supported by model calculations, we discuss the combined effects of anisotropic shape and field-induced dipolar interactions on the reversible formation of self-assembled structures. Our observations show that the formation of tubular structures through self-assembly requires much less geometrical and interaction specificity than previously thought, and advance our current understanding of the minimal requirements for self-assembly into regular virus-like structures.

Anisotropic magnetic particles in a magnetic field

“…13 However, care has to be taken when choosing the experimental system, as an external field can not only constrain rotational motion, but may also lead to strong dipolar interactions that then also result in enhanced field-driven self assembly. 15,21–24 Therefore, attempts to use external fields in order to restrict rotational degrees of freedom only will require particles that are able to respond to an externally applied field, but have a magnetic susceptibility or optical polarisability that is small enough to not result in significant dipolar interactions.…”

Polymeric nanoparticles: the future of nanomedicine

“…Mechanical stretching of polymeric NPs is a technique utilized to create unique‐shaped, nonspherical NPs. Ellipsoids were one of the initial shapes created by mechanical stretching, which has now been extended to more intriguing shapes. Champion et al describe a simple, high‐throughput method to make polymeric microparticles and nanoparticles of reproducible, distinct shapes in sizes ranging from 60 nm to 30 µm.…”

Freeze the Moment: High Speed Capturing of Weakly Bonded Dynamic Nanoparticle Assemblies in Solution by Ag Ion Soldering

“…Under certain conditions such as the existence of suitable interparticle forces (electrostatic, magnetostatic, van der Waals, hydrogen bonding, and others) or external fields (electric, magnetic, fluidic, reaction‐diffusional, etc. ), the nanosized colloidal particles undergo a quick and spontaneous assembly into various aggregation phases. The understanding and utilization of the self‐aggregation process are important for the development of colloidal nanotechnologies.…”