Antibody-Conjugated Gold Nanoparticles for Use as Sensors to Detect Pathogens in Water

Primary Partner: Syracuse University
Project Type: CARTI II
Web Address: http://www-che.syr.edu/faculty/asefa.html

Technical Description:

This material is based upon work supported by the United States Environmental Protection Agency under Award Number EPA 05 X-83232501-0.

Inorganic nanomaterials with controllable sizes and shapes exhibit a wide range of unique physical, chemical, electrical and optical properties. We have recently developed methods for the synthesis of new classes of shaped gold/silica and gold/silica/CdS core-shell nano-particles that have strong shape- and size-dependent optical absorptions in the visible and near-IR region of the spectrum.

This project will exploit the unique optical properties of these materials by developing a new type of sensor which can specifically detect the common pathogens, E. coli and Salmonella. The sensor, which will utilize both antibody-antigen recognition and the optical properties of the nanoparticles will consist of two parts, a microstrip and a probe containing antibodies conjugated to a shaped core-shell nanoparticle. The microstrip will contain a microarray of antibodies that are specific for E. coli and Salmonella. The probe will consist of a nanoparticle of discrete size that has covalently bound antibodies specific for a particular pathogen. Since the size of the shaped nanoparticle determines its optical properties, the probe for each pathogen will have unique optical properties. The basis for pathogen-detection by the sensor will rely on the fact that pathogens bound to a specific position on the microarray of the microstrip will also bind probes through an antibody-antigen interaction.

Expected Outcomes:

Since the location of this interaction can be easily detected by optical methods, the resulting sensor should be useful for rapidly and reliably detecting E. coli and Salmonella under a variety of environmental conditions.

Accomplishments:

We have successfully synthesized anti-E. coli O157:H7 antibody-conjugated gold nanoparticles, and we have attempted to use these as probes for the detection of E. coli in water samples. Due to the high extinction coefficient of the gold nanoparticles, the sensor was expected to be capable of detecting small concentration of E. coli in water samples. Although synthesis of the nanoconjugates and patterning of antibodies on the nitrocellulose were successfully achieved, full investigation of their use for detection of E. coli containing samples was not performed for lack of time and the preliminary experiments with detection were not conclusive.

Papers and Presentations:

DiPasqua, A. J.; Shi, Y.-L.; Mishler, R. E.; Dabrowiak, J. D. *; Asefa, T.* "Antibody-Conjugated Gold Nanoparticles and Sensors for Detection of Waterborne Pathogens" Mater. Lett., 2009, 63, 1876-1879.

Researcher Information:



http://chemistry.syr.edu/faculty/asefa.html