Indiana University-Purdue University Indianapolis researchers have developed a new procedure for the synthesis of nano-sized, biomedical research markers known as “quantum dots.”
Their accomplishment, say the researchers, will make quantum dot technology more accessible, allowing laboratories with fairly standard equipment to produce the “dots” that are being increasingly used as imaging probes in the burgeoning field of nanomedicine.
Quantum dots are highly fluorescent solid particles that are a few nanometers in size. (A nanometer is one-billionth of a meter.)
Due to their sheer brightness and high photostability, quantum dots have the ability to act as molecular “beacons.”
“They are like fluorescent labels,” said researcher Christoph Naumann, a professor in the Department of Chemistry & Chemical Biology at IUPUI and one of the co-authors of a project article published March 31, 2006, on the Chemistry of Materials Web site: http://pubs.acs.org/cgi-bin/abstract.cgi/cmatex/asap/abs/cm0505547.htm.
When attached to compounds or proteins under study, quantum dots allow researchers to track movements within lab cultures or whole organisms, significantly impacting the way medical professionals study, diagnose and treat diseases.
Until now the complex procedure for creating quantum dots required temperatures of 250-350 degrees Celsius.
According to Naumann and co-author Eric C. Long, also an IUPUI chemistry professor, quantum dot materials are costly and inconvenient for biomedical laboratories because of the required high-temperature techniques.
As described in “Facile Sonochemical Synthesis of Highly Luminescent ZnS-Shelled CdSe Quantum Dots,” the new synthesis developed at IUPUI makes use of room-temperature sonochemistry – basically the use of ultrasound to produce chemical changes - to generate quantum dots that span the full range of colors in the visible spectrum. The new procedure requires temperatures of only 100-200 degrees Celsius.
The colors of quantum dots are phenomena directly related to their size. Dots range in color from blue, yellow, green to red, with blue dots being the shortest.
“This new, low temperature procedure may also facilitate the large-scale synthesis of quantum dots and allow inclusion of temperature sensitive materials in the synthesis procedure itself,” the IUPUI researchers said.
Any laboratory with the typical equipment used for cell disruption research would have the capacity to create quantum dots using the ultrasound-driven process, Naumann said.
“This is very exciting research—the kind of research that will lead to improvements in medical diagnosis and to further breakthroughs in fundamental science,” said Carl Cowen, dean of the IUPUI School of Science. “This announcement is one of many we have seen and will continue to see from biomaterials researchers of the IUPUI Department of Chemistry & Chemical Biology.”
“The quantum dot research is possible because of IUPUI's investment in the Nanoscale Imaging Center http://www.chem.iupui.edu/Facilities/Nano/index.php, an interdisciplinary facility that puts advanced technology into the hands of our outstanding faculty and students.”
Graduate students who worked on the project include Michael J. Murcia and David L. Shaw. Other researchers were Bruce A. Young, a key designer of the strategy, now at Roche Diagnostics; and Heather Woodruff, an undergraduate student participating in the project.
