UK scientists have made sugar-detecting spherical gels inspired by aquatic creatures. 

John Fossey, at the University of Birmingham, UK, and Jonathan Cox and Tony James and colleagues at the University of Bath, UK, set hydrogels incorporating boronate units into spherical moulds. They then immersed the spherical gels in a dye solution and showed that the boronate units formed conjugates with the dye, turning the gels orange. When they exposed the gels to fructose solutions, the fructose displaced the dye molecules, releasing the dye and turning the solutions red. 

'We are trying to mimic biological structures by casting gels into a variety of shapes,' says Fossey. 'The original mould for our spheres was a tray for making spherical ice balls which my wife was using to freeze baby food. My colleague, Jonathan Cox, an expert in olfaction (smell sensing), designed a gel ball mould on a more test tube friendly scale.' 

The team demonstrated the gels' sensing ability by assessing the relative amount of boron binding species, such as sugars, in fruit juices. They plan to investigate further applications of the sensors, such as heavy metal or fluoride detection in developing countries' water supplies. They also hope to identify collaborators that will help them miniaturise the gels for on-chip systems. 

'Flexible gel fibrils are a goal of ours since this will be more akin to how aquatic creatures sense their environment,' says Fossey. 'Like a sea anemone has flexible fingers that float in water ready to catch onto passing food items, our sensor will exist in flow environments catching analyte as it passes by.' 

Joanne Thomson