A schematic representation of glucose oxidase immobilized on the nanocolumns, and the chemical state of the zinc atoms as monitored by XPS (© Adriana Rodrigues, UFRGS, Porto Alegre, Brazil).Diabetes is one of the most serious health problems of our age. Approximately 450 million people worldwide are now living with diabetes – a number predicted to exceed 600 million by 2040.
Care for diabetics already swallows up at least 10 per cent of the health budgets of rich countries like the UK. Now new sensors could help monitor the condition.
Diabetes symptoms arise when the body’s insulin system for controlling glucose stops working, causing a rise in blood sugar levels that can lead to severe organ damage.
Diabetics control their blood sugar by carefully balancing a healthy diet and the right levels of exercise, and by taking insulin if required. They, and their doctors, therefore need methods for measuring blood glucose that are fast, accurate and reliable, as well as cheap and easy to use.
A group of scientists at the Federal University of Rio Grande do Sul (UFRGS) in Porto Alegre, Brazil, have created a nanotechnology-based glucose biosensor that could tick all these boxes. They have published their findings in Applied Surface Science.
“We deposited a film of zinc oxide onto stainless steel plates, and then immobilised the enzyme glucose oxidase onto the zinc oxide particles to act as the sensor,” says the lead author of the paper, Jonder Morais. “Glucose reacts with the immobilised enzyme to produce hydrogen peroxide, which generates an electrical signal proportional to the glucose concentration when it is oxidised.”
These sensors can detect glucose concentrations quickly and accurately within the range that would be most useful to diabetic patients and their carers.
The technique used to create the zinc oxide film, chemical bath deposition (CBD), is inexpensive and simple to use, and all the materials involved – stainless steel, zinc oxide and glucose oxidase – are also quite cheap and readily available. “Stainless steel has only rarely been used to form the base for biosensors, but it is an ideal choice because it is non-toxic, chemically stable and resistant to corrosion,” says Morais.
Morais and his colleagues examined the zinc oxide particles making up the film with X-ray photoelectron spectroscopy and electron microscopy and found they were tiny, vertically orientated columns about a thousandth as wide as a strand of hair. This size gives them a relatively large surface area to which the glucose oxidase can bind.
The researchers hope that their technology will also be used to develop biosensors for monitoring other diseases.
Article details:
Rodrigues, A., et al.: "Development and surface characterization of a glucose biosensor based on a nanocolumnar ZnO film," Applied Surface Science (2017)