Naturally trapped enzymes

Enzymes trapped in biomimetically synthesised silica retain their activity.

By using biomimetic conditions to prepare silica in the presence of enzymes, researchers at two Air Force Research Laboratories in the US have found that enzymes can be trapped in the silica without losing any activity.

Rajesh Naik and his colleagues used synthetic peptides based on a natural peptide from single-celled algae (diatoms) to catalyse the formation of the silica. Diatoms form cell walls made from a porous network of silica nanoparticles and it was this process that Naik intended to mimic. Existing methods for trapping enzymes generally require harsh conditions and consequently they reduce enzyme activity. By using a biomimetic process to prepare the silica Naik and co-workers are able to trap the enzymes at neutral pH and room temperature. Their preliminary studies indicate that the entrapped enzymes retain comparable activity to the free soluble enzyme. ’This is a huge step forward for enzyme entrapment,’ says Naik, adding that ’integration of the entrapped enzymes into biosensors or devices would be the next step’.

The same method is also effective for trapping inorganic nanoparticles in the silica and Naik postulates that trapping magnetic nanoparticles with the enzymes would help to separate the trapped enzymes from a reaction mixture.

Carole Perry, head of the chemistry division within the school of science at Nottingham Trent University, UK, comments that ’this paper shows the potential for generating enzymatically functioning materials via benign or "green" chemistry where activity, normally only exhibited in solution, is present in dried materials. The extent and range of enzymes for which this holds true and the longevity of this activity remain to be seen but this route could be one way to store and/or transport sensitive materials such as enzymes’.

Caroline Evans