title: Toxic effects of gold nanoparticles on Salmonella typhimurium bacteria.
abstract: Nanometer-sized gold, due to its beautiful and bountiful color and unique optical properties, is a versatile material for many industrial and societal applications. We have studied the effect of gold nanoparticles on Salmonella typhimurium strain TA 102. The gold nanoparticles in solution prepared using the citrate reduction method is found not to be toxic or mutagenic but photomutagenic to the bacteria; however, careful control experiments indicate that the photomutagenicity is due to the co-existing citrate and Au³⁺ ions, not due to the gold nanoparticle itself. Au³⁺ is also found to be photomutagenic to the bacteria at concentrations lower than 1 µM, but toxic at higher concentrations. The toxicity of Au³⁺ is enhanced by light irradiation. The photomutagenicity of both citrate and Au³⁺ is likely due to the formation of free radicals, as a result of light-induced citrate decarboxylation or Au³⁺ oxidation of co-existing molecules. Both processes can generate free radicals that may cause DNA damage and mutation. Studies of the interaction of gold nanoparticles with the bacteria indicate that gold nanoparticles can be absorbed onto the bacteria surface but not able to penetrate the bacteria wall to enter the bacteria.
authors.affiliation: Department of Chemistry and Biochemistry, Jackson State University, Jackson, MS, USA.
authors.forename: Shuguang
authors.initials: S
authors.lastname: Wang
authors.forename: Rasheeda
authors.initials: R
authors.lastname: Lawson
authors.forename: Paresh C
authors.initials: PC
authors.lastname: Ray
authors.forename: Hongtao
authors.initials: H
authors.lastname: Yu
mesh_terms: D002712:Chlorides / Q000737:chemistry / Q000633:toxicity*; D002951:Citrates / Q000737:chemistry; D017484:Dermatitis, Phototoxic / Q000209:etiology; D004785:Environmental Pollutants / Q000737:chemistry / Q000633:toxicity*; D017612:Gold Compounds / Q000737:chemistry / Q000633:toxicity*; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D046529:Microscopy, Electron, Transmission; D009153:Mutagens / Q000737:chemistry / Q000633:toxicity*; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000528:radiation effects / Q000648:ultrastructure; D014466:Ultraviolet Rays
chemical_list: D002712:Chlorides; D002951:Citrates; D004785:Environmental Pollutants; D017612:Gold Compounds; D009153:Mutagens; C514290:trisodium citrate; C024568:gold tetrachloride, acid