Posted on | August 4, 2011 | No Comments
- Hsueh-Chia Chang
Bayer Corporation Professor
Chemical and Biomolecular Engineering
Much smaller now than when they were first introduced, today’s cell phones can call anyone, anywhere in the world. They can also check the weather, plan a menu, identify a bird, create a custom workout program, read the Wall Street Journal, and confirm a flight departure time. Medical laboratories, at least the work that has traditionally been conducted in them, have also shrunk dramatically in size in the last two decades … so that they too can fit in one hand. Most people are familiar with the personal glucose monitors used by diabetics; in a matter of seconds they can measure blood sugar levels. Imagine that same concept applied to miniature diagnostic kits in order to detect a range of diseases, pathogens, or physiological markers. Faculty at the University of Notre Dame have done more than imagine; they are developing microfluidic technology for use in a handheld biosensor that can identify different diseases and toxic substances on-site and in real time.
The focus on portable diagnostic assays over the last 20 years is quite understandable. A biochemical technique for detecting and identifying bacteria, toxins, and diseased cells, a diagnostic assay can rapidly detect cancer cells and E. Coli as well as identify sepsis and bird flu. The key, says Hsueh-Chia Chang, the Bayer Corporation Professor of Chemical and Biomolecular Engineering and Director of the Center for Microfluidics and Medical Diagnostics, is portability. “Being able to quickly and correctly pinpoint pathogens and other harmful substances in any liquid sample could literally change the world one person at a time.” Not only could medical workers in developing countries quickly identify antibody-resistant tuberculosis or malaria bacteria, but they would also be able to test and determine if a toxin was present in a city’s water or food supplies. Instead of sending samples to a lab, the “lab” would be handheld and allow for the specific genetic identification of a range of pathogens and organisms.
In fact, Chang and his collaborators — Alex Revzin (University of California at Davis); Leslie Yeo and James Friend (Australia’s Monash University); Weijia Wen (Hong Kong University of Science and Technology); and from Notre Dame David Go (aerospace and mechanical engineering); Elaine Zhu (chemical and biomolecular engineering); as well as David Lodge, Jeffrey Feder, Jeff Schorey, and Dave Severson (biological sciences) — have developed such a device.
Dielectrophoresis, an electrokinetic nanobead-manipulation technique, serves as the basis for multifluidic, multitarget miniature diagnostic kits, such as the one Hsueh-Chia Chang and his team have developed. Its integrated continuous flow supports the use of different frequencies at different gates so that the materials can be separated into three distinct channels, without using molecular-sieves or microfilters.
Widely used in cellular and colloid manipulations, dielectrophoresis (DEP) is the movement of polarizable particles induced in an electric field. This schematic shows the set-up used in Notre Dame’s DEP experiments focusing on the development of a handheld biosensor that could provide rapid portable genetic detection outside a laboratory environment.
“My scientific contribution is from the transport angle,” says Chang, “how to concentrate and sort molecules, detecting them on small devices. These are engineering challenges involving a lot of transport and flow physics. They are also the primary scientific issues in designing biosensors and diagnostics for in-field applications.” The team, operating under the auspices of the Advanced Diagnostics and Therapeutics initiative at Notre Dame, has been devel-oping a prototype. The portable device they are currently testing targets minute amounts of harmful substances found in a range of fluids, from blood and saliva to the water in lakes and streams.
It not only holds the potential of revolutionizing conventional technologies in the areas of medical diagnostics, environmental safety, and homeland security, but this technology has also been licensed by FCubed, LLC, a start-up company at Innovation Park at Notre Dame. FCubed is developing prototypes in conjunction with an Environmental Protection Agency project to test bacteria in recreational water.
Cheng, I-Fang; Senapati, Satyajyoti; Cheng, Xinguang; Basuray, Sagnik; Chang, Hsien-Chang; and Chang, Hsueh-Chia, “A Rapid Field-use Assay for Mismatch Number and Location of Hybridized DNAs,” Lab-on-a-Chip, 2010, 10, 828-31.
Basuray, Sagnik; Senapati, Satyajyoti; Aijian, Andrew; Mahon, Andrew R.; and Chang, Hsueh-Chia, “Shear and AC Field Enhanced Carbon Nanotube Impedance Assay for Rapid, Sensitive, and Mismatch-discriminating DNA Hybridization,” ACS Nano, 2009, 4, 7, 1823-30.
Senapati, Satyajyoti; Mahon, Andrew R.; Gordon, Jason; Nowak, Carsten; Sengupta, Shramik; Powell, Thomas H. Q.; Feder, Jeffrey; Lodge, David M.; and Chang, Hsueh-Chia, “Rapid On-chip Genetic Detection Microfluidic Platform for Real World Applications,” Biomicrofluidics, 2009, 3, 2, 022407-13.
Gagnon, Zachary; Senapati, Satyajyoti; Gordon, Jason; and Chang, Hsueh-Chia, “Dielectrophoretic Detection and Quantification of Hybridized DNA Molecules on Nano-genetic Particles,” Electrophoresis, 2008, 29, 4808-12.
Chang, Hsueh-Chia, “Nanobead Electrokinetics: The Enabling Microfluidic Platform for Rapid Multi-target Pathogen Detection,” AIChE Journal, 2007, 53, 10, 2486-92.