# Floppy connectors let MIT team build nanoparticle crystals never seen before

> Researchers at MIT have overturned a two-decade assumption by linking gold nanoparticles with flexible rather than rigid molecules, producing ordered crystal structures that have not been observed before.

- Published: 2026-11-07 by Tickety-Boo News
- Section: Science
- Location: United States
- Web page: https://ticketyboonews.co.uk/stories/floppy-connectors-let-mit-team-build-nanoparticle-crystals-never-seen/
- Original report: [MIT Scientists Break a 20-Year Rule And Unlock Never-Before-Seen Crystal Structures](https://www.sciencealert.com/mit-scientists-break-a-20-year-rule-and-unlock-never-before-seen-crystal-structures) (ScienceAlert)

## In brief

- MIT-led researchers linked gold nanoparticles with flexible polymer connectors, not the rigid ones favoured for about 20 years.
- The method produced ordered crystal structures that have not been seen before, with control over bonds per particle.
- The materials' functions still need testing; next steps involve other particle materials and ligand combinations.

A team led by researchers at MIT has built ordered crystal structures from gold nanoparticles that nobody had seen before, and they did it by loosening things up. Instead of joining the particles with stiff connectors, they used floppy ones. The work is published in Nature Materials.

For roughly 20 years, the usual practice has been to design the molecular links between nanoparticles, known as ligands, to be rigid and fixed. The prevailing view was that straying from stiffness would cause the assembly to fall apart. The MIT team decided to test the reverse.

Their ligands were made from PEG, a common flexible polymer, with positive or negative charges at the tips to help the particles attach. Computer simulations were run alongside the experiments to follow what was going on.

With nothing to hold them rigid, the ligands bunch together where particles meet. That caps the number of connections, since there are only so many chains to go around. And because the particles themselves settle the nature of the links as they come together, nobody has to plan in advance where each one will connect.

Control has not vanished altogether. Changing the size of the nanoparticles and the length of the ligand chains still steers the outcome, and smaller particles, for example, produced fewer links.

Materials scientist Rob Macfarlane, of MIT, explains that the polymer's degree of flexibility determines how many bonds each particle forms. That let the team reduce the bond count and assemble lattices never encountered before, which is no mean feat. He calls the technique an exciting new tool precisely because it runs against instinct.

It is early days for the new structures. Their functions have yet to be examined and tested, though the results so far look promising. The team's next steps are to try other particle materials and ligand combinations, and to put the resulting materials to work in realistic settings.

## Why it matters

Materials made from nanoparticles are already widely used, but they can be hard to scale up because the particles pack tightly by default and each material has to be carefully engineered for its job. A looser arrangement should make customising them at scale easier. The researchers say the approach could eventually feed into high-performance materials for photonics, chemical catalysis, medicine and agriculture. Since a material's properties follow from its building blocks and how they are arranged, finer control over structure is a route to materials with new abilities.