Research interests in our group focus on three general areas centered around the theme of miniaturization in Analytical Chemistry. The first area centers on use of microfluidic techniques for chemical characterization of atmospheric aerosols and other environmental samples. The second area focuses on development of biosensors for understanding spatial and temporal changes in chemical gradients that form in biological tissues. The final area centers around development of ultra-cheap clinical and environmental diagnostic tools made from ordinary filter paper in an area called paper-based microfluidics.
The longest running research area in our group focuses on the use of microchip electrophoresis and related microfluidic techniques for characterizing a variety of environmental samples. At present, our main thrust focuses on developing new tools for measuring the chemical composition of atmospheric aerosols using aerosol chip electrophoresis or ACE. ACE provides 1 minute time resolution of the major ions in aerosols and has been used to characterize aerosols from a range of settings. At present, we are extending our ability to analyze more and more aerosol components simultaneously while making further improvements in the instrumentation to make it more portable and robust during field studies. In addition to these composition measurements, we have also developed sensor technology to measure aerosol reactivity to better understand the impacts aerosols have on human health.
In addition to our interest in aerosol composition, we are also developing related chemistry to quantify persistent pollutants in ground, surface, and drinking water. Our primary focus to date has been on perchlorate as a pollutant but we are extending this to other toxic compounds.
Our second project area focuses on developing new chemical tools to measure the formation of chemical gradients in biological systems. Chemical gradients are important in biology, controlling processes from nerve impulse transduction to ovulation. Our group is focusing on two general technologies for measuring these gradients. In the first project area, we are developing high density electrode arrays in collaboration with colleagues in Electrical Engineering and Biomedical Sciences to follow the formation of NO gradients in brain and ovary slices. NO plays a key role in signaling but little is known about the driving gradients. The second project area focuses on developing new microfluidic tools to measure gradients in either tissue slices or in vitro cell culture. In this project area, the microfluidics provides the spatial resolution and the electrochemical biosensors measure changes in concentration.
In addition to this thrust on measuring chemical gradients in biological tissues, we are also developing novel microfluidic biosensors for detection of cancer biomarkers from dried blood spots as part of an effort to provide new tools for epidemiological screening.
Paper-Based Analytical Devices
Our third project area focuses on development of paper-based analytical devices (PADs). PADs are made from a combination of wax and ordinary filter paper and provide a cheap alternative to traditional assays. The development of the chemistry around these devices was inspired by the need for low cost diagnostic tools in developing countries, and was born out of collaborations between our lab and Dr. Orawon Chailapakul in the Department of Chemistry at Chulalongkorn University in Thailand. In early work in this field, we develop innovative assays for metabolic markers such as glucose, including the first electrochemical PAD or ePAD. At present, we have extended this work to other fields relevant to both developed and developing countries including detection of foodborne pathogens and aerosolized metals in factories, etc.
Sameenoi, Panymeesamer, Supalakorn, Koehler, Chailapakul, Henry, Volckens, "Microfluidic Paper-Based Analytical Devices for Aerosol Oxidative Activity," Environ. Sci. Tech., 2013, 47, 932-940.
Santhiago, Wydallis, Kubota, Henry, "Construction and Electrochemical Characterization of Microelectrodes for Improved Sensitivity in Paper-Based Analytical Devices," Anal. Chem., 2013, 85, 5233-5239.
Cate, Dungchai, Cunningham, Volckens, Henry, "Simple, distance-based measurement for paper analytical devices," Lab Chip, 2013, 13, 2397-2404.
Sameenoi, Koehler, Shapiro, Boonsong, Sun, Collett, Volckens, Henry, "Microfluidic Electrochemical Sensor for On-Line Monitoring of Aerosol Oxidative Activity," J. Am. Chem. Soc., 2012, 134, 10562-10568.
Lynn, N. S.; Tobet, S.; Henry, C. S.; Dandy, D. S., “Mapping Spatio-Temporal Molecular Distributions Using a Microfluidic Array,” Analytical Chemistry, 2012, 84, 1360-1366.
Gertsch, J.; Noblitt, S. D.; Cropek, D. M.; Henry, C. S., “Sub-ppb determination of perchlorate using microchip electrophoresis,” Analytical Chemistry, 2010, 82, 3426-3429.
Dungchai, W.; Chailapakul, O.; Henry, C. S., “Electrochemical Detection for Paper-Based Microfluidics,” Analytical Chemistry, 2009, 81, 5821-5826.
Noblitt, S. D.; Lewis, G. S.; Liu, Y.; Hering, S. V.; Collett, Jr, J. L.; Henry, C. S., “Interfacing microchip electrophoresis to a growth tube particle collector for semi-continuous monitoring of aerosol composition,” Analytical Chemistry, 2009, 81, 10029-10037.