Antibody-conjugated CdTe quantum dots for Escherichia coli detection

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.