Biochip Offers Leukocyte Counting for HIV Diagnosis

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"In response to this challenge, we had developed a technique to selectively deplete target leukocytes," Hassan added. "And our biochip takes whole blood as input, eliminating the need of off-chip sample preparation and effectively reducing the assay time as well."

In addition to the microfluidic "capture chamber," the new chip incorporates separate ports for lysing reagents and quenching buffers that preserve the leukocytes for counting by the microfabricated electrodes. Specific leukocytes like CD4 T cells get captured as they interact with the antibodies in the capture chamber; a second counter recounts the remaining leukocytes. The difference in the respective cell counts give the concentration of the cells captured.

In clinical trials, the differential immuno-capture biochip achieved more than 90 per cent correlation with a flow cytometer for both CD4 T cells for CD8 T cell counts using HIV infected blood samples. The biochip can also be adapted to enumerate other specific cell types such as somatic cells or cells from tissue or liquid biopsies.

The novel biosensor has the potential to be an automated portable blood cell counter for point-of-care applications in developed and resource-limited regions worldwide. Bashir's group is working on miniaturizing the setup to make the technology handheld, as well as designing a cartridge that can be mass-produced.

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