Spiked Nobel Prize Materials That Stab Bacteria Before They Can Stick

In the fight against stubborn biofilms, the newest antibacterial surface does not poison microbes at all, it skewers them. At Chalmers University of Technology in Sweden, researchers have turned Nobel Prize winning metal-organic frameworks into microscopic spike fields that physically puncture bacteria on contact, as described in a new Advanced Science study. The team shows that their mechano-bactericidal coating can kill up to 83 percent of incoming Escherichia coli simply by tearing open cells before a biofilm ever forms.

It is an almost perversely simple idea. Instead of trying to outsmart bacterial chemistry with antibiotics or toxic metal ions, you let geometry and mechanics do the killing. If a bacterium touches the wrong part of the surface, the surface wins.

From Nobel material to bacterial minefield

The work builds on metal-organic frameworks, or MOFs, porous crystalline materials made of metal ions linked by organic molecules. The class of materials was honored with the 2025 Nobel Prize in Chemistry, largely for their tunable structures and huge internal surface areas. The Chalmers team treats those same structural talents as a weapon.

They engineer a hybrid MOF-on-MOF particle called MoU, with a robust zirconium-based UiO-66 core and an iron-based MIL-88B shell that grows into spike like nanopillars. Each spike is about 300 nanometers long, roughly a thousand times thinner than a human hair, with a base diameter near 200 nanometers and a tip narrower than 5 nanometers. The spikes are spaced about 500 nanometers apart, carefully tuned so bacteria cannot squeeze between them yet still feel substantial local stress where each tip presses into the cell envelope.

“If the distance between the nanotips is too large, bacteria can slip through and attach to the surface. If the distance is too small, however, the mechanical stress exerted by the nanotips on the bacterial cell capsule may be reduced so that the bacteria survive, the same principle that allows you to lie on a bed of nails without getting hurt,” says Cao.

The challenge is not only to grow these barbed particles, but to arrange them into continuous surfaces that bacteria cannot easily dodge. The team uses two scalable assembly strategies. In situ growth builds an ordered MOF layer directly on a silicon chip, then grows MIL-88B spikes vertically from that base, giving a one pin up orientation. Ex situ dropcasting instead sprinkles preformed MoU particles onto glass, where their eight headed geometry tends to settle with four spikes pointing upward, creating a denser and more randomly oriented forest of tips.

Both approaches work, but they are not equally lethal.

Stretching, impaling, and squeezing cells to death

To isolate mechanical killing, the researchers first rule out chemical toxicity. In zone of inhibition tests, none of the MOF surfaces create a clear halo where bacteria refuse to grow, which indicates that for E. coli there is little or no antibacterial action from ions or leached molecules. Individual UiO-66, MIL-88B, and a physical mixture of the two also fail to show strong killing, reinforcing that geometry rather than composition is the critical change.

When E. coli are allowed to colonize the surfaces for 24 hours, the numbers diverge sharply. On a control glass slide, the bacteria assemble a dense biofilm. On the in situ MoU surface, colony counts drop and microscopy shows scattered clusters rather than a uniform layer, corresponding to a modest mechano-bactericidal efficiency of about 32 percent. On the dropcast MoU surface, the effect is far more dramatic: the coating kills roughly 83 percent of attached E. coli, placing it in the upper tier of purely mechanical antibacterial surfaces reported so far.

The difference lies in coverage. Image analysis shows that about 35 percent of the in situ surface area is still uncovered, offering safe landing pads where bacteria can survive. The dropcast coating leaves only about 15 percent of the substrate exposed, creating a much more continuous hazard field. Live dead fluorescence imaging backs this up, with large green patches of live cells on control glass, scattered islands on the in situ MoU, and mostly isolated, dying cells on dropcast MoU.

Under the scanning electron microscope, the killing mechanisms become disturbingly explicit. On in situ MoU surfaces, some E. coli are pinned at several points and visibly stretched, their envelopes thinned and torn. On dropcast MoU, the team sees direct impaling, with spikes piercing the membrane and leaving deflated, leaking cells. Other bacteria show squeezed, distorted shapes where they are crushed against MOF features without full penetration, a non piercing injury that is nonetheless known to trigger lethal stress responses.

Finite element simulations support what the images suggest. By modeling bacterial cells as elastic shells resting on MoU nanopillars, the authors estimate maximum local stresses of 114 mPa for E. coli and 54 mPa for Staphylococcus aureus, values that exceed the critical elastic stress reported for bacterial envelopes. The highest stresses occur exactly where the nanopillar tips contact the cell, consistent with a puncture mechanism.

“Our study shows that these nanostructures can act like tiny spikes that physically injure the bacteria, quite simply puncturing them so that they die. It’s a completely new way of using such metal-organic frameworks,” says the study’s lead author Zhejian Cao, PhD in Materials Engineering and researcher at Chalmers.

Toward scalable, low temperature anti-biofilm coatings

Although MIL-88B can chemically harm Gram positive bacteria through iron driven Fenton reactions, which complicates purely mechanical measurements in Staphylococcus strains, the MOF-on-MOF architecture remains attractive for real world use. Both UiO-66 and MIL-88B are already regarded as scalable and commercially accessible, and the epitaxial growth process combines their production in a way that stays compatible with industry.

The fabrication temperatures are strikingly low compared with many nanostructured mechano-bactericidal surfaces. In situ MOF synthesis runs at about 120 degrees Celsius, while dropcasting is performed at room temperature. That makes it realistic to coat temperature sensitive polymers used in catheters, implants, and other medical devices, as well as plastics used in industrial piping or food packaging.

There is, however, a catch. Over 72 hours, the bactericidal efficiency of the dropcast surface drops from about 83 percent to 51 percent, likely because the very debris of success dead cells and extracellular material accumulates and blankets the spikes. The authors note that any long term application will need a robust cleaning strategy to strip away that organic armor and reset the mechanical threat.

Seen together, the results offer a clear proof of concept. MOFs, recently celebrated for capturing gases and storing energy, can also be arranged into lethal landscapes that prevent microbes from ever gaining a foothold. The surface does not negotiate, it simply waits, with thousands of invisible spears poised a few hundred nanometers above the material beneath.

Journal: Advanced Science
Article title: Mechano-Bactericidal Surfaces Achieved by Epitaxial Growth of Metal–Organic Frameworks
Authors: Zhejian Cao, Santosh Pandit, Francoise M. Amombo Noa, Jian Zhang, Wengeng Gao, Shadi Rahimi, Lars Öhrström, Ivan Mijakovic
DOI: 10.1002/advs.202505976