Enzyme-coated plastic could mean self-cleaning fabrics
A way to attach a coating of 'live' enzymes onto plastic and other materials could lead to clothes that digest stains as soon as they occur, or kitchen surfaces able to kill bacteria.
US researchers have shown they can make plastic films containing active enzymes like those in biological clothes detergents. The process used is based on one typically used to produce thin, flat plastic products such as CDs, DVDs and flat-screen displays.
Known as "spin coating", it involves placing a large dollop of a liquid onto a flat surface which is then rotated at great speed. This generates powerful centrifugal forces that push the solution towards the surface edges and cause some liquid to evaporate, leaving behind a thin, solid film over the entire surface.
The thickness of the film depends on the properties of the original solution, such as its viscosity, and the spinning speed.
In a spin
Using 10-cm plastic discs as their flat surface, the team led by Ping Wang at the University of Minnesota, St. Paul, US, used spin coating to layer four films on top of each other.
First came a thin film of polystyrene modified to chemically bind to enzymes. Then Wang and his team covered this with a solution containing a protein-digesting enzyme known as subtilisin Carlsberg, commonly used in biological washing powders to remove stains.
The enzymes in the solution naturally bound to the chemical groups displayed on the polystyrene film.