Detecting molecules of life
doi:10.1038/nindia.2011.89 Published online 23 June 2011
Researchers have designed a novel sensor that could be used to measure levels of adenine and adenosine monophosphate (AMP), two important biological molecules found in bodily fluids. Abnormal concentrations of adenine and AMP have been linked to human metabolic disorders.
Adenine — one of the five main nucleobases of DNA and RNA — plays a vital role in coding genetic information in biological systems. Adenine combines with ribose to form adenosine, which in turn generates AMP. AMP has roles in a number of vital biological processes, and hence monitoring the levels of both molecules is important. So far, however, no effective technique has been able to detect both adenine and AMP levels simultaneously in samples of bodily fluids.
The researchers compared the efficacy of a single-walled carbon nanotube (SWNT)-modified edge plane pyrolytic graphite electrode (EPPGE) with that of a bare EPPGE for detecting adenine and AMP.
They found that bare EPPGE exhibited small peaks at high potentials, whereas the SWNT-modified EPPGE showed large, well-defined peaks, under identical conditions. When the AMP concentration was kept constant and the adenine concentration was increased, the electrochemical signal due to adenine rose while the AMP signal remained constant. A similar effect took place when the adenine concentration was kept constant and the AMP concentration was altered. The modified electrode also successfully detected minute amounts of adenine and AMP in human blood and urine samples.
The modified electrode was able to detect adenine and AMP even in the presence of interfering agents such as ascorbic acid, uric acid, xanthine and hypoxanthine — common biological metabolites present in living organisms. The modified electrode exhibited reproducibility and stability in repeated experiments lasting six consecutive days.
"The method is a promising alternative to commonly reported chromatographic methods because of its speed, good recovery and low detection limit," says lead researcher Rajendra N. Goyal.
- Goyal, N. R. et al. Application of modified pyrolytic graphite electrode as a sensor in the simultaneous assay of adenine and adenosine monophosphate. Sensor. Actuator. B. Chem. 156, 198-203 (2011) | Article |