Zhang's Research Enables Earlier Disease Detection
Tuesday, 27 April 2010 00:00

Two research articles published recently in Nanotechnology [20, 23,5201, (2009)], and Applied Physics Letters [96, 131109, (2010)], featured Professor John X.J. Zhang and his associates in the Biomedical Engineering Department at the University of Texas at Austin. Zhang and his associates have demonstrated a key technology enabling a future handheld cancer cell analyzer, through site-controlled patterning of quantum dots as multicolor excitation sources on silicon microchip.

This method, which was invented in Zhang’s laboratory, is based on patterning inorganic colloidal quantum dots as novel nanoscale light sources sandwiched between multi-layers of inorganic materials towards well-confined localized electroluminescence. The light emitting area can be defined through either micro-contact printing or post processing the electrode of the microdevice. The emission wavelength can be tailored by a choice of quantum dots with desired emission wavelengths. Multicolor light emission on silicon was demonstrated by patterned quantum dots of different sizes through so-called quantum-size effect.

This technology opens up exciting opportunities for on-chip fluorescence based cell identification. Specifically, profiling tumor cells circulating in blood enables new diagnostic tools for early cancer detection. The lead authors of the papers, Ashwini Gopal and Kazunori Hoshino in Zhang’s lab, have designed a prototype microchip with integrated multicolor light emitting quantum dots (QDLED) to excite spiked cancer cells for on-chip fluorescence imaging with excitation wavelength of 600 nanometers (refer to the orange-colored image) to demonstrate the multispectral imaging capabilities for detailed immunophenotyping. This may offer a potential breakthrough in designing a new generation of “biochips” for the rapid and sensitive detection of diseases. Through combining the miniaturized multicolor excitation capabilities on-chip, these devices offer the possibility of smaller and less expensive disposable kits that can detect disease even in people with no symptoms by looking for disease markers.

Professor Zhang was recently invited to present at a press conference organized in 2010 American Physical Society Annual Meeting, with a subsequent special session highlighting the “Physics of Biochips for Disease Detection.” Early disease detection is critical in modern medicine since many diseases, including cancer (the number two killer in the United States), are often treated more successfully when discovered in their beginning stages. Worldwide, there is a profound need to find better ways of detecting diseases in order to help curtail the spread of infections like tuberculosis, AIDS, and diarrheal diseases. This is not always a simple task because the majority of the people suffering from these diseases reside in developing countries, where resources are scarce and per capita health care spending may be no more than a few dollars a year. The core technology developed by University of Texas at Austin researchers builds on the strengths of the well-developed semiconductor industry and can potentially bring more intelligence to and lower cost to future healthcare.

“I am very delighted to read these latest papers and results from Professor Zhang’s laboratory in our department,” says Professor Nicholas A. Peppas, Chair of the Biomedical Engineering Department. “These most promising studies open new avenues of merging advanced microdevice concepts and engineering into the emerging fundamental paradigm shift of disease diagnosis and treatment. This underlines once more the leading position of our department in this field.”


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