doi:10.1038/nindia.2014.99 Published online 23 July 2014
Researchers have developed a sensitive sensor that can detect minute traces of hydroxyguanine, a biochemical found in urine1. As the levels of this biochemical increase in urine with the onset of diabetes, this sensor is potentially useful for the early diagnosis of the onset of diabetes.
In diabetes sufferers, the excessive generation of reactive oxygen species breaks down biological molecules, such as lipids, proteins and DNA, resulting in the formation of breakdown products, such as hydroxyguanine, which builds up in the bloodstream and is excreted in urine.
To measure hydroxyguanine levels in diabetic patients, the researchers fabricated the sensor by modifying the surface of an edge-plane pyrolytic graphite electrode with gold nanoparticles and single-walled carbon nanotubes. They carried out electrochemical studies to probe the efficacy of this sensor in detecting hydroxyguanine levels of urine samples taken from diabetic patients and healthy individuals.
The researchers found the peak current increased when the sensor oxidized hydroxyguanine in the urine samples. They observed that hydroxyguanine concentrations of diabetic patients were almost three times higher than those of healthy individuals. They also found that hydroxyguanine molecules strongly bound to the sensor surface through adsorption.
The sensor selectively detected hydroxyguanine levels even in the presence of other urinary metabolites, such as uric acid, ascorbic acid and dopamine. Such selective detection was possible because the sensor oxidized these urinary metabolites at significantly different potentials from that of hydroxyguanine. In addition, the sensor could detect hydroxyguanine within 30 seconds and was stable even after two weeks of use.
“This sensor could potentially be used to monitor the levels of hydroxyguanine to diagnose and treat diabetes at an early stage,” says lead researcher Rajendra N. Goyal.
1. Bishnoi, S. et al. A novel nanogold–single wall carbon nanotube modified sensor for the electrochemical determination of 8-hydroxyguanine, a diabetes risk biomarker. Bioelectrochemistry 99, 24–29 (2014)