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J. Phys. Chem. C 2008, 112, 4818-4824
Antibody-Conjugated CdTe Quantum Dots for Escherichia coli Detection Yu-Ching Kuo, Qiang Wang, Chada Ruengruglikit, Hailong Yu, and Qingrong Huang* Department of Food Science, Rutgers UniVersity, 65 Dudley Road, New Brunswick, New Jersey 08901 ReceiVed: August 2, 2007; In Final Form: December 20, 2007
Chemically denatured bovine serum albumin (dBSA)-coated water-soluble cadmium telluride (CdTe) quantum dots (QDs), which can effectively improve the chemical stability and photoluminescence quantum yield of CdTe QDs, were successfully conjugated to an anti-Escherichia coli antibody via a cross-linking reaction. The formation of antibody-conjugated CdTe QDs was confirmed using gel filtration chromatography. The anti-E. coli antibody-conjugated CdTe QDs were then used to detect E. coli O157:H7 and Listeria monocytogenes using fluorescence microscopy. It was shown that, after being conjugated to CdTe QDs, the anti-E. coli antibody still maintained its bioactivity and biorecognition specificity. Succinylated dBSA-coated CdTe QDs also were prepared to conjugate with the anti-E. coli antibody. However, no evidence was found that the succinylation provided a better route for antibody conjugation. Our results demonstrate the potential of bioconjugated CdTe QDs for broad biological applications, such as fluorescence-based pathogen detection and in vitro or in vivo cell imaging.
Introduction The biosecurity of the food and water supply is an imminent concern in light of global events related to bioterrorism. Intentional disruption of the water and food supply by bioterrorists is becoming more and more a reality than ever before. One of the recent examples of bioterrorism is the anthrax attacks in the fall of 2001. Each year in the United States alone, the Centers for Disease Control and Prevention (CDC) estimate that 76 million people experience food-borne illnesses. The National Institute of Allergies and Infectious Diseases (NIAID) biodefense research lists priority food and waterborne pathogens (Category B) including diarrheagenic Escherichia coli, Listeria monocytogenes, and Salmonella, etc. Many of these potential deadly biological agents can be readily isolated from food or environmental samples and deliberately introduced into streams of the municipal water supply or into a food processing plants’ internal water system.1 Therefore, the detection of pathogenic bacteria is of importance not only in food safety and food security but also in clinical research and disease diagnosis. E. coli O157:H7 is one of the most dangerous bioorganisms associated with food-borne diseases. Infection by this harmful bacterium will cause hemorrhagic colitis, hemolytic uremic syndrome, and thrombotic thrombocytopenic purpura (TTP).2 Several reported outbreaks of E. coli O157:H7 have led to death, especially when children and the elderly were involved. A low infectious dose of E. coli O157:H7 (
