Researchers at the United States and other institutions have developed a new type of biosensor, which is able to conduct diabetes tests in a non-invasive way and detect extremely low glucose concentrations in human saliva and tears. This technology does not require too complicated production steps, thus reducing the cost of sensor manufacturing, and may help eliminate or reduce the probability of using acupuncture for diabetes testing. Relevant research papers were published in the Journal Advanced Functional Materials.
Most sensors can measure blood glucose, but they can't detect the concentration of glucose in tears and saliva. The new method can be applied to saliva, tears, blood and urine, which has not been confirmed before.
The new biosensor consists of three main parts: graphene nanosheet, platinum nanoparticles and glucose oxidase. The nano-flakes are like tiny rose petals, each of which contains a number of stacked graphene layers. The edges of petals are also suspended with incomplete chemical bonds, enabling platinum nanoparticles to attach to them. The combination of nanosheets and platinum nanoparticles can form electrodes, and then glucose oxidase can be attached to platinum nanoparticles. Enzymes convert glucose into peroxides and produce a signal at the electrodes.
Usually, before obtaining nanostructured biosensors, complex processing steps are needed, including lithography, chemical treatment, etching and so on. The advantage of these petals is that they can grow on any surface without going through these steps, so they are ideal for commercialization.
In addition to diabetes testing, this technique can also be used to detect a variety of compounds to match other medical conditions. For example, glucose oxidase can be replaced by glutamate oxidase to measure glutamate in neurotransmitters to test for Alzheimer's disease and Alzheimer's disease, or to monitor alcohol in vivo with ethanol oxidase. It not only has a wide range of applications, but also has the advantages of fast and portable.
Researchers say this is the first time such a low sensing limit has been found in such a wide range of measurements. The detector detects glucose at a concentration of 0.3 micromoles, which is more sensitive than other electrochemical biosensors based on graphene, carbon nanotubes or metal nanoparticles.
In addition, the sensor can distinguish signals from glucose and other compounds, such as uric acid, ascorbic acid and paracetamol, which are commonly found in the blood, and often cause interference to the sensor. In addition, these compounds have electrochemical activity, which means that they can generate electronic signals by themselves, instead of reacting with enzymes to produce single signals like glucose.