Low-cost, fast biosensor to detect diseases
doi:10.1038/nindia.2018.146 Published online 19 November 2018
Researchers from the Indian Institute of Technology in Guwahati, have developed a sensitive and low-cost biosensor to detect levels of α-amylase in human blood1.
Alpha-amylase is an enzyme that breaks down large polysaccharides, including starch and glycogen, into glucose and maltose. The levels of this enzyme increase in several diseased states, such as acute pancreatitis, mumps, renal disease, abdominal disorders, stressed states and cancer (lung, pancreatic, and breast cancers).
Amylase levels in a sample can be detected by its interaction with UV rays or by using specific antibodies. But these methods are expensive and time-consuming, and require trained personnel to interpret the results.
In this study, the researchers coated polymer poly-aniline emeraldine base (PANI-EB) on a glass coverslip. Then, a specific amount of a mixture of HAuCl4 and starch was added. The gold in the mixture reduces and forms gold nanoparticles on the surface. Starch acts as the stabilising agent, forming starch-coated gold nanoparticles.
When a serum containing α-amylase is added to the sensor, the enzyme breaks down the starch and depletes the levels of starch-coated gold nanoparticles. As this is reflected in the reduction in the electrical resistance of the sensor, changes in resistance of the sensor can be used to map the levels of α-amylase in the sample within 60 seconds. These results were comparable to results from commercially available tools to measure α-amylase levels.
This device thus provides a tool for a quick, easy, low-cost diagnosis of diseases such as pancreatitis, mumps, certain types of cancer and abdominal diseases. However, this device can currently be used only for human blood, and the researchers hope to further the trajectory of this discovery to other kinds of human samples, such as saliva, sebum or serum.
1. Mandal, N. et al. Point-of-Care-Testing of α-Amylase activity in human blood serum. Biosensors and Bioelectronic (2018)