Glucose takes the pace

This is one of the possibilities Manchester University materials science professor Brian Derby sees for a technology that uses industrial inkjet printers to print miniature enzyme-based devices.

Derby is leading a Technology Strategy Board-funded project that aims to make fragile enzymes as sturdy as normal print ink. He and his colleagues at partner Applied Enzyme Technology (AET) are developing enzyme solutions that will be dripped, in picolitre-sized drops, onto carbon electrodes every other microsecond, at operating frequencies above 5kHz.

Derby said these high sheer rates would normally damage proteins and denature them.

’Everyone is familiar with denaturing a protein - it’s called scrambled eggs,’ he said. ’We’re trying to make sure we don’t start off with a protein and end up with a denatured protein that doesn’t do the function that it’s supposed to do.’

Derby will work with AET to create chemical solutions that will package the enzymes so they are robust enough to go through the printing process. The team used a mix of sugars and polyalcohols to develop a packaging solution for the enzyme glucose oxidase. Such enzymes could be printed onto tiny sensors that detect the blood glucose levels of diabetic patients.

Other enzymes, Derby said, are more fragile than glucose oxidase and will require more challenging chemical packaging solutions. For example, the group wants to print enzymes for biofuel cells, but the proteins used for those applications are more sensitive to sheer.

“You could see devices taking power off the patient’s body”

The idea of enzyme-based biofuel cells has interested the scientific community for years. While conventional fuel cells use hydrogen or methanol as their raw material, an enzyme-based fuel cell could use sugar.

Derby said such devices could power biomedical devices such as pacemakers. ’At the moment the lifetime of a pacemaker is determined by the battery,’ he explained. ’If the power supply used enzymes to generate power, you could see them literally taking power off the patient’s own body using the glucose within the bloodstream.’

Derby is also working with printhead supplier Xaar, Oxford Biomaterials and biomaterial consultant Ellis Development. The team hopes to have a printed glucose sensor ready for commercialisation this year and other enzyme-based products in four years.