New biosensor promises faster kidney function test

The biosensor can accurately measure both the pH and urea concentration with a single drop of urine

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By Bhavya Khullar

New Delhi: Indian Institutes of Technology at Mumbai and Indore have jointly developed a biosensor that makes it possible to detect kidney disorders in less than eight minutes.

The biosensor can accurately measure both the pH and urea concentration with a single drop of urine. Researchers who developed the biosensor believe that it will help make a point-of-care test to ascertain if kidneys are functioning normally.

For a kidney function test, doctors need an estimate of pH and urea as most kidney disorders result in reduced pH and a higher concentration of urea. The available methods urea are accurate patients have to undergo two tests. In addition, there is a problem of contaminating components in urine such as calcium, chloride, ascorbic acid, sodium, and potassium.

The new biosensor, developed by Rashmi Chaudhari, Abhijeet Joshi, and Rohit Srivastava, can detect both pH and urea. It is made by encapsulating an enzyme urease and a molecule FITC-dextran in alginate microspheres. The combo emits fluorescence in response to chemical reaction with urea and changes in pH when urine is added. The fluorescence reduces when the pH is acidic and increases when it is alkaline. The changes in fluorescence intensity are measured, which helps to calculate the values of pH and urea.

“It is made using alginate which is safe and nontoxic to handle. It can work in the ideal pH range of 4-8, and is able to detect even low concentrations of urea up to 50 millimolar”, says Rashmi Chaudhari.

Abhijeet Joshi, a co-author and faculty at the IIT Indore told that “we tested the biosensor on samples of patients suffering from chronic kidney disease procured from KEM Hospital and Apex Kidney Care in Mumbai and it showed an accuracy of more than 97%”.

Rohit shrivatava Biosensor Rashmi Chaudhari biosensor Abhijeet Joshi Biosensor

Picture: Rohit Srivastava, Abhijeet Joshi, and Rashmi Chaudhari, who developed the biosensor to detect kidney disorders.  

Rohit Srivastava, professor at the Department of Biosciences and Bioengineering of the IIT-Bombay, who led the study adds that, “the biosensor is stable for up to a month in a refrigerator and gives results that are unaffected by other components in urine samples”. It will help make a rapid and accurate point-of-care diagnostic test for kidney disorders, he says.

Bansi D Malhotra, professor at the Department of Biotechnology of the Delhi Technological University, who is not connected to the study, however, commented that while the biosensor uses fluorescence-based technique to detect urea in urine sample, “it is not user-friendly and cost-effective, compared to other (electrochemical) techniques, which is routinely used for this purpose.”

Results of the study, funded by the Department of Biotechnology (DBT) and the Department of Science and Technology (DST), have been published in journal Scientific Reports. (India Science Wire)