Fast, accurate test requires a single drop of blood, no refrigeration
Mothers and children in low resource communities may appear well fed but often suffer from micronutrient deficiencies. Now NIBIB-funded researchers have developed a system that can be used for tests to rapidly identify blood micronutrient levels such as iron, iodine, folate, and zinc in remote areas that have limited healthcare infrastructure.
Micronutrient deficiencies can result in stunted growth, anemia, neurological disorders, and death. According to the Centers for Disease Control and Prevention, two billion people worldwide suffer from such deficiencies, and approximately 2.6 million children under age five die each year.1
Accurately identifying populations with low levels of these vital micronutrients requires a blood test. Unfortunately, those most affected by this problem live in underserved communities in developing countries with few doctors or medical facilities. Tests in these conditions must be inexpensive, accurate, easy to use by minimally trained individuals, and able to withstand shipping to remote areas without refrigeration. These are known as point-of-care technologies, which give results in an hour or less so that individuals who may have walked miles to be tested receive results quickly and can potentially start treatment immediately if needed.
Developing such tests is the passion of Mark Styczynski, Ph.D., Associate Professor at the School of Chemical and Biomolecular Engineering and his colleagues at Georgia Tech, with additional collaborators at Northwestern University in Illinois.
The test is based on two proteins made by genes found in bacteria. The researchers put the two genes needed on small loops of DNA called plasmids. While there are individual genes taken from bacteria in the test, there are no bacterial cells, so it is a “cell-free” system. This is important because a cell-free system can be freeze-dried for storage and then reconstituted when performing the test in remote areas in the field.
Adds David Rampulla, Ph.D., director of the NIBIB program in Synthetic Biology for Technology Development, “creation of this cell-free system was dependent on the team’s ability to make the bacterial proteins without the need for bacteria. This is an excellent example of a growing field known as synthetic biology, which harnesses the power of biological systems to create new types of medical diagnostics and treatments.”
The bacterial genes make proteins whose activity is affected by the amount of zinc in the drop of blood. More zinc increases the activity of the proteins, which causes a color shift. The color can range from yellow when little or no zinc is present, to brown or red when zinc is at medium levels, to purple with high levels.
A critical aspect of the test developed by Styczynski and colleagues was overcoming a consistent problem with this type of color-change test. Blood has hundreds of different proteins and other molecules in it. This mix of components differs in each person and can significantly change the degree of color change in the reaction.
The team developed a system of calibration that accounted for the specific changes caused by the unique combination of components in each individual patient’s blood. Their complex chemical calibration method resulted in accurate readings despite variations in the blood chemistry of each patient.
Says Styczynski, “although the test provides a simple visual color-change, making it that simple involved a lot of sophisticated analyses that led us to the exact mix of components that makes the test work in the low-resource environments where it is desperately needed.”
The group is working with interested commercial partners to make the test widely available, says Styczynski. A cell phone app is also being developed that would compile test results and could lead to a database for epidemiological surveys aimed at allocating regional resources for treating micronutrient deficiency.
The study is reported in the September issue of Science Advances2 and was funded by grant R01EB022592 from the National Institute of Biomedical Imaging and Bioengineering, the National Institute of General Medical Sciences, the National Science Foundation, the Air Force Research Laboratory, the U.S. Defense Advanced Research Projects Agency, the Army Research Office, the David and Lucile Packard Foundation, and the Camille Dreyfus Teacher-Scholar Program.
1. Centers for Disease control and Prevention. Micronutrient Facts https://www.cdc.gov/nutrition/micronutrient-malnutrition/micronutrients/index.html