Credit: © 2006 Wiley

Protein adsorption, known as fouling, is a significant problem for implantable materials and surfaces prone to contamination, such as ship hulls and bioreactors. Incorporating the types of enzymes that break down proteins (proteases) into different polymer matrices can reduce fouling, but it is often difficult to add them at sufficiently high density or keep them active.

Now, researchers at the Rensselaer Polytechnic Institute in the US have overcome this problem by conjugating proteases onto single-walled carbon nanotubes to make a composite that effectively eliminates surface fouling. Jonathan Dordick, Ravi Kane and colleagues1 created the composite by attaching protease onto the nanotubes and dispersing them in a poly(methyl methacrylate) polymer matrix.

The protease activity was 30 times higher in this composite than in the control, where the enzymes were conjugated to a non-nanoscale graphite support. Composites incubated with proteins showed up to 95% less protein adsorption when compared with films without the enzymes or those on other supports. Moreover, the films were ‘self-cleaning’ — enzymes broke down proteins that adsorbed onto the films. Furthermore, surfaces coated with paint that contained the composite were able to resist protein binding.