# On-demand biofilm removal by shape-memory triggered local changes in surface topography

## TL;DR

Researchers developed a method to remove bacterial biofilms from medical devices using shape-memory materials that change surface texture without altering the device's shape.

## Contribution

A novel strategy for biofilm removal using localized surface topography changes in shape-memory polymers, without altering the bulk material shape.

## Key findings

- Microscale surface topography changes triggered by shape-memory polymers removed up to 71.5% of Pseudomonas aeruginosa biofilms.
- The method increased antibiotic susceptibility of remaining biofilm cells.
- Surface topography changes occurred without altering the bulk material's shape.

## Abstract

Bacterial pathogens can form biofilms on implanted biomedical devices, causing persistent infections that are highly tolerant to antibiotics. Previously, we reported a strategy of biofilm control based on dynamic topography, which effectively removes biofilms via horizontal contraction of the substrate surface of a shape-memory polymer (SMP) upon triggered shape recovery. This method is effective and species nonspecific; however, alterations in the bulk material profile limit its applications. In this study, we tested the hypothesis that biofilm can be removed by changes in local topography without altering the shape of the bulk material. Acrylate-based SMPs were prepared to obtain transition temperature of 40℃ to trigger shape recovery in aqueous environment within 10 min. Micron-scale square patterns that are about 6-µm tall with varying width and spacing were prepared by hot compression against PDMS with complementary patterns, while maintaining the bulk shape of the material unchanged. The results demonstrated effective on-demand biofilm removal (e.g., 48 h biofilms of Pseudomonas aeruginosa and 24 h biofilms of Escherichia coli were removed by 71.5% and 70.6%, respectively). In addition, shape recovery triggered topographic changes increased antibiotic susceptibility of attached bacterial cells. Overall, the results from this study demonstrated the feasibility to remove biofilms without changing the shape of the bulk material. These findings are helpful for engineering better antifouling materials.

Bacterial biofilms are the root cause of persistent infections associated with implanted biomaterials. Conventional treatments with antibiotics are often ineffective and promote the development of bacterial drug resistance. Thus, we are motivated to engineer new biomaterials that are self-defensive against bacterial colonization. Previously, we reported that shape-memory polymers (SMPs) can be programed to change the bulk shape (via horizontal stretch) on-demand and effectively remove bacterial biofilms. In this study, we further developed this strategy to control shape change of surface topography alone. The SMP surfaces programmed with microscale square-shaped features were fabricated, which were able to revert to flat surfaces upon triggering with moderate temperature change and disrupt bacterial biofilms (~70%). The shape recovery was limited to surface topography with the bulk shape unchanged. In addition to biofilm removal, shape recovery also enhanced the antibiotic susceptibility of remaining biofilm cells. Further research could explore various forms of surface topographies and different stimuli to enable more effective and reversible changes. In summary, this study reports a new strategy for biofilm control. With further development, it could help reduce medical device-associated infections and biofouling in industrial settings.

On-demand biofilm removal through microscale shape recovery

On-demand biofilm removal through microscale shape recovery

The online version contains supplementary material available at 10.1557/s43577-025-01024-4.