Health and Medicine

Sensitivity of Immunoassay Tests Boosted by More Than 1000 Times

Immunoassay

Biomarkers are molecules that indicate a disease or the general health of an individual, and proteins are one of the most important biomarkers. This makes protein detection a critical component of a range of tests, ranging from the diagnosing of malaria, to the detection of heart attacks, and cancer monitoring and screening.  These biomarkers are most commonly detected by using a biochemical test known as an immunoassay. An immunoassay is also the basis of any pregnancy test.

When the accuracy of any test is improved, it leads to results that are more precise. A significant improvement has now been made to immunoassay tests and the study features on the cover of the peer-reviewed journal Analytical Chemistry.

A team of scientists from IBM Research in Zurich and Technion, the Israel Institute of Technology have collaborated to develop a technique which could improve the sensitivity of protein detection in immunoassays by more than 1,000 times when compared to a standard test. The team has designed a microfluidic chip that contains flow channels the width of a human hair to improve the tests.

This new technique is principally important in that it works unbelievably well with protein biomarkers that are present in very small quantities, as is the case during the early stages of a disease.

Moran Bercovici, an assistant professor at the faculty of Mechanical Engineering at Technion noted that the method uses an old focusing technique called isotachophoresis (ITP) in a new way. This is achieved by using a combination of specialized chemistry and electric fields. Proteins can be collected into a tiny volume and then delivered precisely to react with detection antibodies patterned on the surface of the microchannel.

Federico Paratore, a joint PhD student between the groups, and the lead author on the work added that they essentially fool the detector by presenting a protein concentration that is 10,000-fold higher than in the original sample to a standard detector, and the detector then responds accordingly.

 

Paratore explained that the test is very simple with a few drops of the sample being introduced into the microfluidic chip, and then turning on an electric field. The proteins are thereby compressed to a volume of approximately 50 pico-liters. This is approximately 1 million times smaller than the volume of a human tear drop. The result of the test becomes visible in a few minutes.

Dr. Govind Kaigala, a scientist at IBM Research added that the elegance of this approach lies in the huge enhancement to assay sensitivity that can be applied to a range of immunoassays, and its simplicity. The team believes that this technology will help to fill the gaps in existing immunoassay tests. The new test can be applied to biological samples such as saliva, blood, or urine directly.

This new approach could lead to simple devices that will be capable of analyzing small samples, such as a single drop of blood. This would replace the sophisticated, large laboratory equipment needed today.