Award Abstract #0102662
Application of Quantum Dots to Environmental and Cell Biology

NSF Org:	DBI Division of Biological Infrastructure
Initial Amendment Date:	August 17, 2001
Latest Amendment Date:	August 17, 2001
Award Number:	0102662
Award Instrument:	Standard Grant
Program Manager:	Gerald Selzer DBI Division of Biological Infrastructure BIO Directorate for Biological Sciences
Start Date:	September 1, 2001
Expires:	August 31, 2006 (Estimated)
Awarded Amount to Date:	$1001117
Investigator(s):	Ian Kennedy imkennedy@ucdavis.edu (Principal Investigator) Bruce Hammock (Co-Principal Investigator) Subhash Risbud (Co-Principal Investigator) Kit Lam (Co-Principal Investigator) Valerie Leppert (Co-Principal Investigator)
Sponsor:	University of California-Davis OR/Sponsored Programs Davis, CA 95618 530/754-7000
NSF Program(s):	NANOSCALE: INTRDISCPL RESRCH T, ENGINEERING RESEARCH CENTERS, PARTICULATE &MULTIPHASE PROCES, ENVIRONMENTAL IMPLICATIONS
Field Application(s):
Program Reference Code(s):	EGCH, BIOT, AMPP, 9197, 9184, 9162, 1674
Program Element Code(s):	1674, 1480, 1415, 1179

ABSTRACT

This award in the Nanoscale Science and Engineering Initiative (Nanoscale: Interdisciplinary Research Teams) will support the application of materials science and engineering to biosystems and environmental biology at the nanoscale. This new approach can open up new and exciting possibilities for researchers in many fields of biology. A multidisciplinary team has been assembled to explore the potential for the application of semiconductor quantum dots to two areas in particular, environmental immunoassays and cell biology. The unique optical properties that are available via the quantum confinement effect inherent to nanoscale clusters of semiconductor material offer unique possibilities in biosystems research. The emission of light from quantum dots is dependent on the size of the cluster. Hence, it is possible to design clusters of various sizes to emit at a desired wavelength. The visible part of the optical spectrum can be covered by a range of quantum dots whose emissions are spectrally distinct, permitting their use in simultaneous bioassays for environmental pollutants and hazards, as well as replacements of conventional fluorophores in studies of peptide chemistry and binding to cell receptors. In addition, the magnetic properties of quantum dots can be used for the manipulation of biological molecules in magnetic fields.

Quantum dots will be synthesized initially by an established method that can produce CdSe clusters capped by ZnS that permits bioconjugation to molecules of interest via a carboxyl group. Reverse micelles will also be studied as an optional scheme; this method may offer a better control on particle size. A major thrust of the effort will be directed to the identification of quantum dot materials that absorb in the visible spectrum and that can avoid the excitation of strong background fluorescence that is typical of complex environmental samples. Metal oxides will be given particular attention by using our established laser ablation method to screen new materials that have a small bulk bandgap, such as VO. Iron oxide will be studied because of its particularly interesting magnetic properties, and the additional benefit that ferromagnetism may confer in terms of manipulation in bioassays and cell migration studies. A new scheme for the improvement of the laser ablation synthesis of quantum dot materials will be investigated by selecting clusters on-the-fly, based on their functional performance i.e., their optical or magnetic properties. The usefulness of the quantum dots in environmental bioassays will be explored by applying them to immunoassays that are designed to detect a class of molecules that are important in agriculture, atrazines. Simultaneous assays will be designed using spectrally distinct quantum dots as labels in assays using a class specific antibody for atrazine, and using compound specific assays for members of the atrazine family. Monodispersed quantum dots will also be evaluated in cell based systems.The quantum dot surface will be coupled to peptide ligands via functional groups, and used to probe intact lymphoma cells. Analysis will include flow cytometry, tissue or cell staining, and peptide trafficking studies. The quantum dot performance will be compared with that of a conventional fluorochrome such as BODIPY. Initial experiments will involve quantum dots with only one defined wavelength. Once the cellular techniques are perfected, and when monodispersed quantum dots with a series of different sizes are available, multiplexed analysis will be performed using a series of peptides that have different binding affinities to the cell.

Research in biology depends increasingly on the development of rapid and sensitive measurement technologies. The use of nanoscale materials in biology for labeling molecules, with the unique properties that arise as a result of the very small scale of these materials, will play a significant role in contributing to progress in this development. The results of this work will lead to the development of improved, miniaturized detection methods for pollutants in the environment and in human populations, as well as providing a valuable new tool for studying fundamental processes at the cellular level.

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