Research Highlight

Biosensor to measure flab

Biplab Das

doi:10.1038/nindia.2008.199 Published online 12 May 2008

An Indian research team from Hyderabad has devised a biosensor that measures the levels of triglycerides – the form in which most fat is stored in the body. The device uses magnetic nanoparticles and an enzyme to make rapid estimation of triglycerides.

Enzyme-based field effect transistor (ENFETs) is no stranger to the field of studying small molecules like glucose, urea, creatinine, and organophosphates. Of late, magnetic nanoparticles have been used in biological applications like purification of cells, proteins and gene delivery. Though few metal nanoparticles have been used in FET device, magnetic nanoparticles have not been used so far.

The enzyme-based field effect transistor

The researchers prepared nickel-ferrite nanoparticles and introduced the enzyme lipase onto them. This was placed in the pit of the gate surface of the transistor. A lab magnet attached to the back held the nanoparticles. When triglyceride solution was added in the pit with some external voltage, the device became active.

Lipase breaks down the triglycerides (tributyrin, trioctanoate and triolein) producing fatty acids, glycerol and hydrogen ions. This chemical reaction leads to a change in the solution's pH, which helps measure the levels of triglycerides.

"Our device is electrical and thus less error prone than optical devices," says lead researcher N. Madhusudhana Rao. Magnetic nanoparticles are cheap and the enzyme required is very small, Rao says. Manufacturing of semiconductor device being cost-effective, this hand-held device could be mass-produced in future, he adds.


  1. Vijayalakshmi, A. et al. Enzyme field effect transistor (ENFET) for estimation of triglycerides using magnetic nanoparticles. Biosens. Bioelectron. 23, 1708-1714 (2008)