Sniffing out glucose bound to RBC
doi:10.1038/nindia.2011.51 Published online 18 April 2011
Researchers have designed a novel biosensor that can measure levels of glycated haemoglobin — glucose bound to haemoglobin — in diabetic patients. Such a sensor could aid the long-term control of diabetes.
Diabetes is a major health concern for millions around the globe. In addition to the measurement of free glucose level in blood, glucose bound to haemoglobin (HbA1c) is considered to be a very useful diagnostic marker for diabetic patients. HbA1c has been linked to complications of vital organs such as the heart, kidney and eyes in diabetic patients.
Current methods for measuring the HbA1c levels are time-intensive and require significant training. To devise a simpler method, the researchers modified iron oxide magnetic nanoparticles with tetraethyl orthosilicate to provide a coat of silica. Then they used chitosan to transfer amino groups to the nanoparticles, which were electrochemically deposited on gold electrode. Finally, fructosyl amino-acid oxidase was attached to the nanoparticle-modified gold electrode.
The researchers tested the biosensing efficacy of the electrode using blood samples collected from diabetic patients. First, they treated the blood samples with enzyme protease, which broke down HbA1c and released fructosyl valine. The biosensor became active in the presence of fructosyl valine, with the measured current being directly proportional to the fructosyl valine concentration. High levels of fructosyl valine help to measure the concentration of HbA1c.
The biosensor lost 25% of its initial efficacy after 250 uses over a period of three months when stored at 4 ºC. The researchers say that the biosensor is simple to use, fast and highly sensitive, making it potentially useful as a commercial sensor for glycated haemoglobin.