doi:10.1038/nindia.2013.128 Published online 24 September 2013
Researchers have developed a porous, biomagnetic sensor that can detect minute traces of catechol, a constituent of catecholamines — hormones that are released into the bloodstream during stress and various diseases . This sensor can be used to diagnose diseases such as hypertension and septic shock.
Catecholamines consist of catechol and amines, such as dopamine. They are secreted by the adrenal glands, which are located above the kidneys. Increased levels of catecholamines in the bloodstream can signal the onset of neurodegenerative disorders and even the formation of tumours in the adrenal glands. Existing techniques for measuring catecholamine levels are complex and expensive, as well as being insensitive and non-selective.
To devise a low-cost, highly sensitive technique for detecting catecholamines, the researchers fabricated the sensor by modifying a glassy carbon electrode made from a composite of iron oxide nanoparticles and a conducting polymer, polyaniline. To test the efficacy of this sensor, they prepared a phosphate buffer solution that maintained a physiological pH of 7.4. They then carried out electrochemical studies by adding synthetic catechol to the buffer solution containing the sensor.
The results showed that the addition of catechol to the buffer solution oxidized catechol, increasing the current. The high surface area and narrow pore size of the sensor made it very easy for catechol to bind to it. The iron oxide nanoparticles assisted binding and facilitated catechol to reach the electrode surface, while the polymer enhances electron transfer, thereby accelerating the reaction rate.
The sensor can selectively detect catechol, even in the presence of interfering biological molecules, such as ascorbic acid. "The sensor was able to measure catechol at nanomolar concentrations, making it a useful diagnostic tool in a clinical set-up," says study co-author Dhirendra Bahadur.