Recent advancements in colloidal science have allowed researchers to create self-assembling and self-replicating colloidal microstructures, according to David Pine, physics professor at New York University and featured Jones Seminar speaker at the Thayer School of Engineering on April 24.

Pine and other researchers have focused on developing colloidal particles that interact with each other using various recognition mechanisms. The goal is to create microstructures that can self-assemble and self-replicate using information encoded within their structures, Pine said.

One research project explores shape-directed self-assembly of helical colloidal microstructures using magnetic interactions. A paramagnetic oil mixture is used to create colloidal clusters of polystyrene particles that can be magnetized when a magnetic field is applied. “Dumbbell” colloidal clusters, which contain two dissimilarly sized polystyrene particles each, are designed to arrange into a helical structure that minimizes energy in the presence of a magnetic field. The research could have applications for creating “microswimmers” that can propel through water using a mechanism similar to that of bacteria.

Researchers are also developing particles that can self-replicate. Pine described the current method as “biokleptic,” as it relies upon using complementary DNA strands to bring together individual particles. DNA strands are attached to particles so that, under certain temperatures, a single stranded DNA end from each particle will hybridize with a complementary end on another particle. The goal of the research is the mass-production of complex nanostructures at a reduced cost, which has implications for optics and memory storage.

Another project has modified the DNA-directed self-replicating particles by implementing directional bonding between the colloid particles. DNA is localized to “sticky pads” on the particles instead of covering the entire unit so that only certain structural conformations are possible.

Pine also discussed research involving “Pac-man” particles that use a lock-and-key mechanism similar to that of proteins. Particles are synthesized so that they have a cavity in which a smaller particle will fit. These colloidal structures assemble based on size selectivity.