Detection Of Microbe Using Carbohydrate-modified Quantum Dots And Carbohydrate-modified Gold Nanoparticles

Carbohydrates with the specific recognition and binding capability to protein were coupled with quantum dots (QDs) and gold nanoparticles (AuNPs) for protein detections. Mannose, galactose and lactose-coated QDs (Man-QDs, Gal-QDs, Lac-QDs) and AuNPs (Man-AuNPs、Gal-AuNPs、Lac-AuNPs) were prepared using the thiolated sugars to replace the original ligands on the surface of CdSe/ZnS QDs and AuNPs, according to a ligand exchange method. Structural and spectral characterizations of the resulting glyco-QDs and glyco-AuNPs revealed intense luminescent emission and UV-visible absorption, as well as high solubility and stability in water. Further studies on interactions between the glyco-QDs and glyco-AuNPs as donor and acceptor of FRET demonstrated that Man-QDs and Man-AuNPs occur FRET with corresponding lectin (ConA) in a very short time (5min) and the detection limit of ConA is3nmol/L, Gal-QDs and Gal-AuNPs occur FRET in the presence of RCA120and its detection limit is2nmol/L.In this study, the synthesis method of three quantum dots and gold nanoparticles was constructed. It is confirm that the system of FRET can be used to detect proteins. As the lectin-like adhesins are commonly found on the surfaces of many kinds of bacterial, the method also may be used to detect bacterial, and further work is under way. The present work provides a baseline for the future studies on microbial detections with the system of FRET.