Antibody-Conjugated CdTe Quantum Dots for Escherichia coli Detection

Abstract

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.

Molecularly imprinted polymer anchored on the surface of denatured bovine serum albumin modified CdTe quantum dots as fluorescent artificial receptor for recognition of target protein

“…The dBSA was prepared by treating BSA with NaBH 4 on the basis of a previous literature report (Kuo et al, 2008;Chen et al, 2009a,b). NaBH 4 was added to the BSA solution with stirring, with aim to reduce the disulfide bonds to sulfhydryl groups (-SH).…”

“…By this reaction, the disulfide bonds of BSA were opened, which made it possible for the stabilizing agent MPA on the surface of CdTe QDs to be substituted by the thiol-group of dBSA through ligand exchange. Because of the high degree of surface defects of the CdTe QDs, dBSA was used to modify the surface via ligand exchange to increase the stability of CdTe QDs (Kuo et al, 2008). And utilizing the dBSA to modify the surface of CdTe QDs could not only improve the chemical stability and photoluminescence quantum yield of the QDs effectively, but also serve as assistant recognition peptide chains as an additional element of monomer to create effective recognition sites.…”

“…Herein, the dBSA was used not only to modify the surface of the CdTe QDs, but also as assistant monomer to create effective recognition sites (Kuo et al, 2008;Wang et al, 2006;Guo et al, 2006). Three proteins were chosen as the template molecules and then the receptors were synthesized by sol-gel process (imprinting process, see Fig.…”

Highly sensitive synchronous fluorescence determination of mercury (II) based on the denatured ovalbumin coated CdTe QDs

“…Denatured ovalbumin was prepared by chemically treating ovalbumin with NaBH 4 [19] as following steps: 0.11 g ovalbumin was dissolved in 50 mL of deionized water, then 0.004 g of NaBH 4 was added under stirring. The reaction proceeded at room temperature for 1 h and then at 70 1C for 30 min until no more gas (H 2 ) was generated.…”

“…For example, with the help of 1-ethyl-3-(3-(dimethylamine)propyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), bovine serum albumin (BSA) was conjugated to TGA-capped CdTe QDs via an amide link interacting with carboxyl of the TGAcapped CdTe, which could develop a novel fluorescent nanosensor for Sb 3 þ determination [17]. Wang et al [18] and Kuo et al [19] used NaBH 4 as reducing agents to promote the disulfide bonds in the BSA molecule being converted to sulfhydryl groups. The thiol group of denatured BSA has strong affinity to Cd atom, so the dBSA was modified to the QDs surface [18], which demonstrated a great enhancement of the fluorescence intensity and stability.…”