A cardiac biomarker widely used for the early detection of acute myocardial infarction – cardiac troponin I – can now be detected in about three minutes and in very low concentrations. And the detection can be done at the bedside. This was made possible by the development of a microfluidic device by a research team of the Indian Institute of Technology (IIT) in Hyderabad.
The heart cells damaged during a heart attack cause the expression of cardiac muscle proteins, such as the cardiac troponin I biomarker, which is released into the blood. The detection of the biomass in the blood serum helps in the early detection of a heart attack.
Commercially available assays have limitations in both sensitivity and time required for detection. These assays can not detect when the biomarker is present in concentrations below 0.02 nanograms per ml, and it takes a long time for it to be detected. In contrast, the microfluidic device developed by Renu John of the Institute of Biomedical Engineering of the IIT Hyderabad can detect the biomarker even if the concentration is only 0.005 nanograms per ml.
"Our device can detect the biomarker over a wide range ̵
Commercially available assays as well as the microfluidic device use the same antibody to bind to the biomarker. The way the device was constructed, however, makes the difference in terms of better sensitivity and fast detection.
Researchers successfully integrated the microfluidic device into chitosan-coated nickel vanadate nanospheres for rapid detection and sensitivity.
The outer surface of the nanospheres is first coated (functionalized) with the antibody binding to the biomarker. As the nanospheres have a larger surface area, more antibodies are present on the surface, increasing the chances and the ability to bind to the biomarker. The functionalized nanospheres are then applied to the working electrode of the microfluidic device.
"The integration of the nanospheres that recognize the biomarker with the compact microfluidic device accelerates the detection process," says Nawab Singh of the IIT Hyderabad and first author of the thesis.
"When the patient serum is introduced into the microfluidic device, the biomarker present in the serum binds to the antibodies present on the nanospheres. This leads to a change in the current flow on microamphärene level, "explains Prof. John. "The electrochemical response of the sensor changes in response to a change in the concentration of the troponin I biomarker that causes a change in current flow." Biomaker can be produced directly at the bedside.
"This is a proof-of-concept work. We have to do large studies with many patient samples before they can be used commercially, "says Prof. John.