Alexander Revzin, a UC Davis biomedical engineer professor, along with UCLA electrical engineer Prof. Aydogan Ozcan, have created a microfluidic device, called "lab on a chip," specifically for HIV testing.

The "lab on a chip" instructs antibodies to detect and "capture" HIV-infected white blood cells called T-cells, and the test then calculates the levels and types of cytokines (inflammatory proteins) that the cells are releasing. It is a holographic, lens-free imaging mechanism that counts the number of cytokine molecules and captured T-cells and is able to deliver results in seconds, which is six to 12 times faster than other related blood sample tests.

The test is made of polymer film with an array of miniature spots that contain antibodies that are specific to the CD4 and CD8 T-cells as well as three different types of cytokines which are "printed in the same array." The T-cells stop and stick on these miniature spots when blood flows across them. Then, T-cell types are captured on antibody spots "specific for the cytokines they might produce," and antibodies activate the cells helping spots adjacent to the cells catch cytokines they secreted. With T-cell subsets now connected to their secreted cytokines, the antibody spots' visible color intensity allows researchers to see differences in cytokine production, which makes T-cell count possible without mechanical scanning or lenses. 

Diagnosing and monitoring HIV today requires many highly trained specialists and expensive machines in order to count two types of T-cells, calculate the ratio between them and count cytokines as well. The process is called flow cytometry, and AIDS activists and healthcare workers have been asking for easier and less expensive ways to test for HIV.

In response to these requests, this particular "lab on a chip" test is currently being altered so it can be used for multi-parametric blood analysis in both the developing world and "resource-poor" areas. It is also affordable, and Revzin is hoping it will be available for clinical use at some point.

"While the point of care field focuses on detection of single parameter (e.g. CD4 counts), we believe that the simplicity of the test need not compromise information content," said Revzin. "So, we set out to develop a test that could be simple and inexpensive but would provide several parameters based on a single injection of a small blood volume."

Revzin and his team along with Ozcan published their study on the HIV testing device in Analytical Chemistry's May 2010 issue.

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