New Tools

Georgia Tech postdoctoral fellow Jean-Francois Masson holds a microelectrode modified with a biosensing layer capable of measuring adenosine triphosphate (ATP), a chemical involved in energy transport in humans. It’s of interest to medical researchers because elevated levels have been linked with cystic fibrosis, a disease that affects one out of every 2,500 people in the United States.

Researchers are using an innovative, multifunctional sensing tool to investigate adenosine triphosphate (ATP) release and its role in cystic fibrosis. ATP is a chemical involved in energy transport and is of interest to medical researchers, because when at elevated levels it has been linked with cystic fibrosis, a disease that affects one out of every 2,500 people in the United States.

The ATP study marks the first application of a novel sensing system developed by a research team led by Christine Kranz at the Georgia Institute of Technology.

This patented technology adds recessed micro- and nano-electrodes to the tip of an atomic force microscope (AFM), creating a single tool that can simultaneously monitor topography along with electrochemical activity at the cell surface.

Researchers presented information on the research at the American Chemical Society’s 231st meeting in Atlanta in March.

The new multifunctional imaging technique will advance the study of biological samples.

“Conventional AFM can image surfaces, but usually provides limited chemical information,” says Boris Mizaikoff, an associate professor at Georgia Tech’s School of Chemistry and Biochemistry and director of its Applied Sensors Lab. “And though scanning electrochemical microscopy (SECM), another probing technique, provides laterally resolved electrochemical data, it has limited spatial resolution. By combining AFM and SECM functionality into a single scanning probe, our tool provides researchers with a more holistic view of activities at the cell surface.”

Georgia Tech student Justyna Wiedemair, Ph. D., right, and senior research scientist Christine Kranz are part of a research team that has combined atomic force microscopy and scanning electrochemical functionality into a single scanning probe. The tool provides researchers with a more holistic view of activities at the cell surface.

In the ATP study, which is sponsored by the National Institutes of Health and done in collaboration with Douglas Eaton at Emory University’s School of Physiology, the Georgia Tech team used the multiscanning biosensors to study ATP release at the surface of live epithelial cells (cells that cover most glands and organs in the body). Using epithelial cell cultures from Emory, the Georgia Tech researchers have demonstrated that their multifunctional biosensors work at the live-cell surface during in vitro studies.

“Before you can identify what triggers the ATP release, we must be able to quantitatively measure the released species at the cell surface,” Mizaikoff says, noting that many pathological events involve the disruption of chemical communication and molecular signaling between cells, especially in the nervous system, lungs and kidneys.

Improved understanding of cellular communication can lead to new strategies for treating diseases. “Being able to operate sensors in an electrochemical imaging mode at the micro- and nanoscale is an exciting opportunity for complementing optical imaging techniques. There are many clinical research problems that these biosensors can help with,” Mizaikoff adds.

During the same ACS session, the Georgia Tech team also presented findings of a related project.

A collaboration with Estelle Gauda at Johns Hopkins University and also supported by NIH grants, this project monitors ATP release at the carotid body, a chemoreceptor that, among other functions, monitors oxygen content in the blood and helps control respiration.

Chronic oxygen stress—too much or too little oxygen during early postnatal development—can lead to a deficiency in the amount of oxygen reaching body tissues in premature infants and newborn animals. However, little is known about how oxygen stress affects regulatory networks and alters chemoreceptors. To gain insights, the Georgia Tech researchers will study ATP, which is among the signaling molecules released by the carotid body.

Researchers incorporate the same technology used for the multifunctional scanning probe. For this study, however, they have tailored the biosensor to work at a larger scale—microelectrodes are about 25 µ in diameter as opposed to the sub µ dimensions of the combined AFM-SECM approach.

“There are a lot of emerging sensor technologies, but few have been adapted for routine use in medical research, which is one of the development goals at the Applied Sensors Lab,” Mizaikoff says. “As analytical chemists, we want to develop quantitative sensing devices that can answer important questions for clinical researchers.”

This article was originally published in Research Horizons magazine, a publication of the Georgia Institute of Technology.

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