News: News, Research, Vic

Golden glucose sensor

As diabetes becomes more prevalent in our society there is an increasing demand for more sensitive and accurate glucose detection. Current enzyme-based glucose sensors are limited to restricted operating temperatures and pH. They are also expensive to produce and can be chemically unstable. A non-enzymatic sensor would overcome these problems.

PhD student Victoria Coyle and her supervisors at RMIT are developing a nanostructured electrochemical glucose sensor covered with gold nanospikes, each approximately 750nm long. The large surface area of the nanospikes is covered with hydroxyl groups that oxidise the glucose during sensing. The oxidation process reduces the electrical potential of the sensor. This change occurs at a very specific voltage, which is different to that for other molecules in the sample being tested. The angular, arrow-like shape of the nanospikes was shown to be the most efficient structure so far for distinguishing glucose’s unique voltage signature. Because the structures are so important for selectivity, optimisation is critical for maximum efficiency.

Ms Coyle uses scanning and transmission electron microscopy and elemental analysis in the AMMRF (now Microscopy Australia) Linked Lab at RMIT to confirm the shape, size, composition and distribution of the nanospikes over the surface. Generally speaking, the nanostructured surface is 400% more sensitive to glucose than a flat gold surface.

Ms Coyle also found that adding cobalt oxide to the nanospikes enhanced glucose sensing even further. She has determined the most synergistic combination and is well on her way to making a viable non-enzymatic glucose sensor for real world applications.

Scanning electron micrograph of gold nanospikes coated with cobalt oxide flakes.