Detecting heart disease in a person is just a sensor and seconds away, thanks to a promising technique developed by Indian and US researchers.

Biomarker-based biosensors is what the Consortia of Institutes has used for the instantaneous detection of heart attack and other cardiac diseases. Their target is to ultimately develop a device for the purpose.

Researchers from the Indian Institute of Technology Hyderabad (IITH) are collaborating with the Delhi Technological University, IIT Kanpur, the Zoological Survey of India and Iowa State University, US, on the study. They have published their work in the Journal of Materials Chemistry B.

The consortia tested the performance of microfluidic biosensors using the blood samples of cardiac patients. They compared the results with the conventional method called Chemiluminescent immunoassay. The result showed that the microfluidic devices could detect the CVD biomarker -- cTns levels as low as 0.000000000005 grams in one millilitre of blood -- which makes this technique a useful tool for the detection of cardiovascular maladies.

The research team is headed by Renu John of IIT Hyderabad, who says: "Biomarkers are biological molecules that represent health and disease states. They are specific chemicals that are released in the body in response to certain physiological conditions”.

Cardiac troponins or cTns, for example, are biomarkers of heart diseases and are conventionally detected in the blood stream using antibodies that bind specifically to them. Biosensors are devices that combine the sensing element (e.g. antibody of nanosphere or the size of a human hair) with a transducer that converts the interaction of antibody into electrical or optical signal that can be measured.

Conventional biosensing includes such techniques as ELISA, chemiluminescent immunoassay and radioimmunoassay. The clinical complications of Cardiovascular Diseases (CVD) are major causes of morbidity and mortality worldwide.

Primary and specialist health providers use a variety of tools for both clinical assessment of existing heart diseases and to identify vulnerable patients at risk of CVD. Biosensors are one such tool.

The consortia used hollow nickel vanadate nanospheres, modified with chitosan and loaded with antibodies of cTns, in a microfluidic set-up. When blood containing the CVD biomarker, cTns, was passed through the biofluidic set-up loaded with the biosensing nanospheres, cTns was bound by the antibody, and induced an electrical signal in the nanosphere, which was then detected.

The work promises not just reliability in the diagnosis and prediction of heart disorders within minutes, but has the potential of being extended to the detection of other diseases, too, say the authors.

Microfluidics sensors

There has been increased interest in the past decade in the development of microfluidics-based sensors for biomedical applications. Microfluidics deals with the manipulation of very small volumes of fluid in the range of a quadrillionth of a litre – in effect being a ‘miniaturised plumbing’ activity that can squeeze an entire lab into a single micro-sized device.

At such minute volume scales, fluids behave in interesting ways, which makes unusual applications possible. Microfluidics-based biosensors can enable portable analytical devices that can provide almost instantaneous results, compared to long-drawn out lab-tests, the researchers explained.

According to B.D. Malhotra of the Delhi Technological University, the technique can be extended to other diseases as well by changing the biomarker/ antibody that is attached to nanospheres. Microfluidics-based biosensing could, thus, offer new opportunities in quick diagnostics, biomedical research and environmental monitoring, too, he added.

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