Scientists develop new HIV diagnostic device

All too often, brilliant research ideas and applications are left in lab due to impediments such as the high cost of the reagents, low turnaround times, the requirement of sophisticated technical skills, the need for a controlled environment and the difficulty of obtaining FDA approval for public use of the product.

However, the field of microfluidics is paving a viable road to turn research ideas into commercial products. The technology dates back to the era when engineers designed precise inkjets in printers for optimal resolutions. It has since grown and expanded across fields as a detection mechanism for rapid screening and simultaneous analysis of biological or chemical targets.

Through modeling extremely thin fluid channels, microfluidics allows scientists to get past the laws of classical physics to a point where turbulent liquid flow does not exist and minute droplets of samples can be used to achieve delicate and accurate measurements.

In order to expand the treatment landscape of microfluidics devices, researchers from Florida Atlantic University, Stanford University and Baskent University in Turkey developed a novel method to count CD4-positive T cells in resource-constrained, extreme weather conditions.

Their idea was derived from pregnancy tests, which have long been available in the public market.

“Similar to pregnancy tests that can be stored at room temperature, we investigated methods to store and preserve multi-layer, immuno-functionalized microfluidic devices in refrigeration-free settings for applications in resource-limited settings at the point-of-care,” said Utkan Demirci, senior author of the paper from Stanford University School of Medicine.

CD4-positive T cells were used due to the significance of their count in the clinical setting. For instance, according to the U.S. Department of Health and Human Services, CD4-positive cell count is the most important indicator of how well an HIV patient’s immune system is working and thus a strong predictor of HIV progression.

“Monitoring HIV patients at point-of-care settings in resource-constrained countries like Africa is critical to knowing how their treatment is progressing and whether or not a particular drug is working the way it should be,” Waseem Asghar, co-first author on the study and assistant professor of electrical engineering in the College of Engineering and Computer Science at FAU said in a press release.

The scientists turned to trehalose, a sugar molecule, to prevent degradation of the capture molecules that target CD4-positive T cells on the microfluidic device. While not holistically characterized, trehalose is present in unicellular organisms as a stress-responsive factor, i.e. it helps maintain integrity under heat, desiccation and cold.

Using this to their advantage, the scientists designed a device that contained trehalose, as well as a few drying agents. The device was stored in a vacuum-sealed plastic bag and was tested at variable times. It proved to be equal in efficiency to a freshly made device up to the four-month mark. Moreover, in terms of detecting CD4 positive T cells versus false positives, the stored device showed similar results to a freshly made device for up to six months of storage.

To simulate extreme conditions, the device was stored at 50 degrees Celsius for 24 hours following five weeks of storage. The efficiency and specificity of the device was unchanged when compared to the freshly made device. Moreover, another set of devices was stored for 24 hours in a 30 degrees Celsius oven at 85 percent humidity. The results showed comparable similarity between the stored and freshly made devices.

The researchers also attached an electronic cell sensor to the device in order to create a cell counter that could be easily used at home. By doing so, the researchers created a portable, microscope-free CD4 T cell counting platform.

“This technology also is widely applicable to global health applications when resources are limited to address viral load, sepsis, tuberculosis and malaria, as well as cancer detection,” Asghar said. “It also offers advantages in the developed world in settings such as in a primary care physician’s office or in the home setting.”