title: Adhesion of quantum dots-induced membrane damage of Escherichia coli.
abstract: The toxicity of CdTe QDs modified with three different ligands, namely mercaptopropionic acid (MPA), N-acetyl-L-cysteine (NAC), and glutathione (GSH), were investigated via microcalorimetric, spectroscopic, and microscopic methods. The three ligand-modified QDs have nearly identical hydrodynamic size. The results of the calorimetric experiments and optical density measurements indicate that the QDs inhibited the growth of Gram-negative Escherichia coli. The toxicity order of the three QDs is MPA-CdTe QDs>GSH-CdTe QDs>NAC-CdTe QDs. The inhibitory effects of the QDs, cadmium chloride (CdCl(2)), MPA, and the CdCl(2) and MPA mixture on E. coli growth indicate that the toxicity mechanism of QDs may be related to their bacterial adhesion. When dispersed in the cell suspensions, QDs tend to have their high surface energy reduced through adsorption to the bacterial surface, as confirmed by transmission electron microscopy and inductively coupled plasma atomic emission spectroscopy results. Furthermore, the effect of QDs on the membrane fluidity and permeability was investigated. GSH-CdTe QDs have a greater effect on the membrane function of E. coli than those of MPA-CdTe and NAC-CdTe QDs. This result may be attributed to the stronger lipophilicity of GSH compared with those of MPA and NAC.
authors.affiliation: State Key Laboratory of Virology & Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China.
authors.forename: Lu
authors.initials: L
authors.lastname: Lai
authors.forename: Chen
authors.initials: C
authors.lastname: Lin
authors.forename: Chang-Qing
authors.initials: CQ
authors.lastname: Xiao
authors.forename: Zi-Qiang
authors.initials: ZQ
authors.lastname: Xu
authors.forename: Xiao-Le
authors.initials: XL
authors.lastname: Han
authors.forename: Li
authors.initials: L
authors.lastname: Fu
authors.forename: Dong-Wei
authors.initials: DW
authors.lastname: Li
authors.forename: Ping
authors.initials: P
authors.lastname: Mei
authors.forename: Feng-Lei
authors.initials: FL
authors.lastname: Jiang
authors.forename: Qing-Lian
authors.initials: QL
authors.lastname: Guo
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000111:Acetylcysteine / Q000737:chemistry / Q000633:toxicity*; D019187:Cadmium Compounds / Q000737:chemistry / Q000633:toxicity*; D004926:Escherichia coli / Q000187:drug effects*; D005978:Glutathione / Q000737:chemistry / Q000633:toxicity*; D008024:Ligands; D010316:Particle Size; D045663:Quantum Dots; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000633:toxicity*; D013691:Tellurium / Q000737:chemistry / Q000633:toxicity*; D018675:Toxicity Tests
chemical_list: D019187:Cadmium Compounds; D008024:Ligands; D013438:Sulfhydryl Compounds; D005978:Glutathione; D013691:Tellurium; C023884:thiolactic acid; C028337:cadmium telluride; D000111:Acetylcysteine