Dec 13, 2011
Soft nanohairy surface keeps bacteria at bay
Bacteria that contaminate systems ranging from medical implants to industrial pipelines are tough to eradicate once they attach to such surfaces as slimy "biofilms". The conventional countermeasure of surface chemistry treatments only works for a number of hours, as secreted proteins and small molecules quickly mask the treated surface and re-enable colonization. Taking a radically different approach, researchers at Harvard University, US, have designed biofilm-inhibiting surfaces that rely only on nanoscale geometric and mechanical factors to reduce bacterial attachment.
The work brings together two recent findings: (1) bacteria can be artificially and arbitrarily patterned as they attach to a surface that presents an array of nanoposts; and (2) bacteria decide to attach to materials based in part on mechanical stiffness, preferring stiffer substrates.
To determine the parameters of a nanopost array that drive bacterial patterning, the scientists tested asymmetric and combinatorial nanopost array surfaces with gradients of geometry. They found that the spacing between neighbouring nanoposts was key to bacterial insertion between posts and to maximizing cell contact with the array.
Next, the team asked: if bacteria can sense the stiffness of a flat surface, why not the effective stiffness of a soft "hairy" surface? Could the cells be tricked into perceiving the surface as being "too soft" to colonize?
Decreased bacterial attachment
Indeed, the group found that below a threshold effective stiffness, a super-flexible nanopost array significantly decreased bacterial attachment to a polymer surface compared with flat surfaces made from the same material. This was true even beyond 24 hours of incubation.
Surfaces with nanoarrays that induce bacterial patterning as well as effectively emulate a super-soft surface could be a new, longer-lasting way to control biofilm growth and consequently reduce biofilm-borne infections and damage. What's more, such a "hairy" nanoarray could be cast or imprinted as part of the base material for one-step manufacturing of biofilm-resistant equipment.
More information can be found in the journal Nanotechnology.
About the author
Alexander K Epstein is a fifth-year PhD candidate in the Aizenberg Biomineralization and Biomimetics Group, an interdisciplinary team spanning materials science, nanotechnology and bioengineering at the Harvard University School of Engineering and Applied Sciences. Epstein's research involves the development and application of "smart," functional, nanostructured surfaces for the strategic areas of biofilm and biofouling control, liquid wettability, environmental sensing and actuation.