title: Photochemical Transformation of Aminoglycoside Antibiotics in Simulated Natural Waters.
abstract: Aminoglycoside antibiotics are widely used in human therapy and veterinary medicine. We report herein a detailed study on the natural-organic-matter- (NOM-) photosensitized degradation of aminoglycosides in aqueous media under simulated solar irradiation. It appears that the direct reaction of the excited states of NOM ((3)NOM*) with aminoglycosides is minor. The contributions of reactive oxygen species (ROSs) in the bulk solutions are also unimportant, as determined by an assessment based on steady-state concentrations and bimolecular reaction rate constants in a homogeneous reaction model. The inhibition of the photodegradation by isopropamide is rationalized through competitive sorption with aminoglycosides on the NOM surface, whereas the addition of isopropanol negligibly affects degradation because it quenches HO(•) in the bulk solution but not HO(•) localized on the NOM surface where aminoglycosides reside. Therefore, a sorption-enhanced phototransformation mechanism is proposed. The sorption of aminoglycosides on NOM follows a dual-mode model involving Langmuir and linear isotherms. The steady-state concentration of HO(•) on the surface of NOM was calculated as 10(-14) M, 2 orders of magnitude higher than that in the bulk solution. This fundamental information is important in the assessment of the fate and transport of aminoglycosides in aqueous environments.
authors.affiliation: Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Li
authors.affiliation: Department of Chemistry & Biochemistry, Florida International University , Miami, Florida 33199, United States.
authors.forename: Cen
authors.initials: C
authors.lastname: Zhao
authors.affiliation: Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yao
authors.affiliation: Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
authors.forename: Shuwen
authors.initials: S
authors.lastname: Yan
authors.affiliation: Department of Chemistry & Biochemistry, Florida International University , Miami, Florida 33199, United States.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: O'Shea
authors.affiliation: Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
authors.forename: Weihua
authors.initials: W
authors.lastname: Song
mesh_terms: D000617:Aminoglycosides / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D010782:Photolysis; D012996:Solutions; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D012996:Solutions; D014874:Water Pollutants, Chemical; D014867:Water